Mercurial > hg > graal-jvmci-8
diff src/share/vm/opto/memnode.cpp @ 0:a61af66fc99e jdk7-b24
Initial load
author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ff5961f4c095 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/opto/memnode.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,3222 @@ +/* + * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +// Portions of code courtesy of Clifford Click + +// Optimization - Graph Style + +#include "incls/_precompiled.incl" +#include "incls/_memnode.cpp.incl" + +//============================================================================= +uint MemNode::size_of() const { return sizeof(*this); } + +const TypePtr *MemNode::adr_type() const { + Node* adr = in(Address); + const TypePtr* cross_check = NULL; + DEBUG_ONLY(cross_check = _adr_type); + return calculate_adr_type(adr->bottom_type(), cross_check); +} + +#ifndef PRODUCT +void MemNode::dump_spec(outputStream *st) const { + if (in(Address) == NULL) return; // node is dead +#ifndef ASSERT + // fake the missing field + const TypePtr* _adr_type = NULL; + if (in(Address) != NULL) + _adr_type = in(Address)->bottom_type()->isa_ptr(); +#endif + dump_adr_type(this, _adr_type, st); + + Compile* C = Compile::current(); + if( C->alias_type(_adr_type)->is_volatile() ) + st->print(" Volatile!"); +} + +void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { + st->print(" @"); + if (adr_type == NULL) { + st->print("NULL"); + } else { + adr_type->dump_on(st); + Compile* C = Compile::current(); + Compile::AliasType* atp = NULL; + if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); + if (atp == NULL) + st->print(", idx=?\?;"); + else if (atp->index() == Compile::AliasIdxBot) + st->print(", idx=Bot;"); + else if (atp->index() == Compile::AliasIdxTop) + st->print(", idx=Top;"); + else if (atp->index() == Compile::AliasIdxRaw) + st->print(", idx=Raw;"); + else { + ciField* field = atp->field(); + if (field) { + st->print(", name="); + field->print_name_on(st); + } + st->print(", idx=%d;", atp->index()); + } + } +} + +extern void print_alias_types(); + +#endif + +//--------------------------Ideal_common--------------------------------------- +// Look for degenerate control and memory inputs. Bypass MergeMem inputs. +// Unhook non-raw memories from complete (macro-expanded) initializations. +Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { + // If our control input is a dead region, kill all below the region + Node *ctl = in(MemNode::Control); + if (ctl && remove_dead_region(phase, can_reshape)) + return this; + + // Ignore if memory is dead, or self-loop + Node *mem = in(MemNode::Memory); + if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL + assert( mem != this, "dead loop in MemNode::Ideal" ); + + Node *address = in(MemNode::Address); + const Type *t_adr = phase->type( address ); + if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL + + // Avoid independent memory operations + Node* old_mem = mem; + + if (mem->is_Proj() && mem->in(0)->is_Initialize()) { + InitializeNode* init = mem->in(0)->as_Initialize(); + if (init->is_complete()) { // i.e., after macro expansion + const TypePtr* tp = t_adr->is_ptr(); + uint alias_idx = phase->C->get_alias_index(tp); + // Free this slice from the init. It was hooked, temporarily, + // by GraphKit::set_output_for_allocation. + if (alias_idx > Compile::AliasIdxRaw) { + mem = init->memory(alias_idx); + // ...but not with the raw-pointer slice. + } + } + } + + if (mem->is_MergeMem()) { + MergeMemNode* mmem = mem->as_MergeMem(); + const TypePtr *tp = t_adr->is_ptr(); + uint alias_idx = phase->C->get_alias_index(tp); +#ifdef ASSERT + { + // Check that current type is consistent with the alias index used during graph construction + assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); + const TypePtr *adr_t = adr_type(); + bool consistent = adr_t == NULL || adr_t->empty() || phase->C->must_alias(adr_t, alias_idx ); + // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] + if( !consistent && adr_t != NULL && !adr_t->empty() && + tp->isa_aryptr() && tp->offset() == Type::OffsetBot && + adr_t->isa_aryptr() && adr_t->offset() != Type::OffsetBot && + ( adr_t->offset() == arrayOopDesc::length_offset_in_bytes() || + adr_t->offset() == oopDesc::klass_offset_in_bytes() || + adr_t->offset() == oopDesc::mark_offset_in_bytes() ) ) { + // don't assert if it is dead code. + consistent = true; + } + if( !consistent ) { + tty->print("alias_idx==%d, adr_type()==", alias_idx); if( adr_t == NULL ) { tty->print("NULL"); } else { adr_t->dump(); } + tty->cr(); + print_alias_types(); + assert(consistent, "adr_type must match alias idx"); + } + } +#endif + // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally + // means an array I have not precisely typed yet. Do not do any + // alias stuff with it any time soon. + const TypeInstPtr *tinst = tp->isa_instptr(); + if( tp->base() != Type::AnyPtr && + !(tinst && + tinst->klass()->is_java_lang_Object() && + tinst->offset() == Type::OffsetBot) ) { + // compress paths and change unreachable cycles to TOP + // If not, we can update the input infinitely along a MergeMem cycle + // Equivalent code in PhiNode::Ideal + Node* m = phase->transform(mmem); + // If tranformed to a MergeMem, get the desired slice + // Otherwise the returned node represents memory for every slice + mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; + // Update input if it is progress over what we have now + } + } + + if (mem != old_mem) { + set_req(MemNode::Memory, mem); + return this; + } + + // let the subclass continue analyzing... + return NULL; +} + +// Helper function for proving some simple control dominations. +// Attempt to prove that control input 'dom' dominates (or equals) 'sub'. +// Already assumes that 'dom' is available at 'sub', and that 'sub' +// is not a constant (dominated by the method's StartNode). +// Used by MemNode::find_previous_store to prove that the +// control input of a memory operation predates (dominates) +// an allocation it wants to look past. +bool MemNode::detect_dominating_control(Node* dom, Node* sub) { + if (dom == NULL) return false; + if (dom->is_Proj()) dom = dom->in(0); + if (dom->is_Start()) return true; // anything inside the method + if (dom->is_Root()) return true; // dom 'controls' a constant + int cnt = 20; // detect cycle or too much effort + while (sub != NULL) { // walk 'sub' up the chain to 'dom' + if (--cnt < 0) return false; // in a cycle or too complex + if (sub == dom) return true; + if (sub->is_Start()) return false; + if (sub->is_Root()) return false; + Node* up = sub->in(0); + if (sub == up && sub->is_Region()) { + for (uint i = 1; i < sub->req(); i++) { + Node* in = sub->in(i); + if (in != NULL && !in->is_top() && in != sub) { + up = in; break; // take any path on the way up to 'dom' + } + } + } + if (sub == up) return false; // some kind of tight cycle + sub = up; + } + return false; +} + +//---------------------detect_ptr_independence--------------------------------- +// Used by MemNode::find_previous_store to prove that two base +// pointers are never equal. +// The pointers are accompanied by their associated allocations, +// if any, which have been previously discovered by the caller. +bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, + Node* p2, AllocateNode* a2, + PhaseTransform* phase) { + // Attempt to prove that these two pointers cannot be aliased. + // They may both manifestly be allocations, and they should differ. + // Or, if they are not both allocations, they can be distinct constants. + // Otherwise, one is an allocation and the other a pre-existing value. + if (a1 == NULL && a2 == NULL) { // neither an allocation + return (p1 != p2) && p1->is_Con() && p2->is_Con(); + } else if (a1 != NULL && a2 != NULL) { // both allocations + return (a1 != a2); + } else if (a1 != NULL) { // one allocation a1 + // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) + return detect_dominating_control(p2->in(0), a1->in(0)); + } else { //(a2 != NULL) // one allocation a2 + return detect_dominating_control(p1->in(0), a2->in(0)); + } + return false; +} + + +// The logic for reordering loads and stores uses four steps: +// (a) Walk carefully past stores and initializations which we +// can prove are independent of this load. +// (b) Observe that the next memory state makes an exact match +// with self (load or store), and locate the relevant store. +// (c) Ensure that, if we were to wire self directly to the store, +// the optimizer would fold it up somehow. +// (d) Do the rewiring, and return, depending on some other part of +// the optimizer to fold up the load. +// This routine handles steps (a) and (b). Steps (c) and (d) are +// specific to loads and stores, so they are handled by the callers. +// (Currently, only LoadNode::Ideal has steps (c), (d). More later.) +// +Node* MemNode::find_previous_store(PhaseTransform* phase) { + Node* ctrl = in(MemNode::Control); + Node* adr = in(MemNode::Address); + intptr_t offset = 0; + Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); + AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); + + if (offset == Type::OffsetBot) + return NULL; // cannot unalias unless there are precise offsets + + intptr_t size_in_bytes = memory_size(); + + Node* mem = in(MemNode::Memory); // start searching here... + + int cnt = 50; // Cycle limiter + for (;;) { // While we can dance past unrelated stores... + if (--cnt < 0) break; // Caught in cycle or a complicated dance? + + if (mem->is_Store()) { + Node* st_adr = mem->in(MemNode::Address); + intptr_t st_offset = 0; + Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); + if (st_base == NULL) + break; // inscrutable pointer + if (st_offset != offset && st_offset != Type::OffsetBot) { + const int MAX_STORE = BytesPerLong; + if (st_offset >= offset + size_in_bytes || + st_offset <= offset - MAX_STORE || + st_offset <= offset - mem->as_Store()->memory_size()) { + // Success: The offsets are provably independent. + // (You may ask, why not just test st_offset != offset and be done? + // The answer is that stores of different sizes can co-exist + // in the same sequence of RawMem effects. We sometimes initialize + // a whole 'tile' of array elements with a single jint or jlong.) + mem = mem->in(MemNode::Memory); + continue; // (a) advance through independent store memory + } + } + if (st_base != base && + detect_ptr_independence(base, alloc, + st_base, + AllocateNode::Ideal_allocation(st_base, phase), + phase)) { + // Success: The bases are provably independent. + mem = mem->in(MemNode::Memory); + continue; // (a) advance through independent store memory + } + + // (b) At this point, if the bases or offsets do not agree, we lose, + // since we have not managed to prove 'this' and 'mem' independent. + if (st_base == base && st_offset == offset) { + return mem; // let caller handle steps (c), (d) + } + + } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { + InitializeNode* st_init = mem->in(0)->as_Initialize(); + AllocateNode* st_alloc = st_init->allocation(); + if (st_alloc == NULL) + break; // something degenerated + bool known_identical = false; + bool known_independent = false; + if (alloc == st_alloc) + known_identical = true; + else if (alloc != NULL) + known_independent = true; + else if (ctrl != NULL && + detect_dominating_control(ctrl, st_alloc->in(0))) + known_independent = true; + + if (known_independent) { + // The bases are provably independent: Either they are + // manifestly distinct allocations, or else the control + // of this load dominates the store's allocation. + int alias_idx = phase->C->get_alias_index(adr_type()); + if (alias_idx == Compile::AliasIdxRaw) { + mem = st_alloc->in(TypeFunc::Memory); + } else { + mem = st_init->memory(alias_idx); + } + continue; // (a) advance through independent store memory + } + + // (b) at this point, if we are not looking at a store initializing + // the same allocation we are loading from, we lose. + if (known_identical) { + // From caller, can_see_stored_value will consult find_captured_store. + return mem; // let caller handle steps (c), (d) + } + + } + + // Unless there is an explicit 'continue', we must bail out here, + // because 'mem' is an inscrutable memory state (e.g., a call). + break; + } + + return NULL; // bail out +} + +//----------------------calculate_adr_type------------------------------------- +// Helper function. Notices when the given type of address hits top or bottom. +// Also, asserts a cross-check of the type against the expected address type. +const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { + if (t == Type::TOP) return NULL; // does not touch memory any more? + #ifdef PRODUCT + cross_check = NULL; + #else + if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL; + #endif + const TypePtr* tp = t->isa_ptr(); + if (tp == NULL) { + assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); + return TypePtr::BOTTOM; // touches lots of memory + } else { + #ifdef ASSERT + // %%%% [phh] We don't check the alias index if cross_check is + // TypeRawPtr::BOTTOM. Needs to be investigated. + if (cross_check != NULL && + cross_check != TypePtr::BOTTOM && + cross_check != TypeRawPtr::BOTTOM) { + // Recheck the alias index, to see if it has changed (due to a bug). + Compile* C = Compile::current(); + assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), + "must stay in the original alias category"); + // The type of the address must be contained in the adr_type, + // disregarding "null"-ness. + // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) + const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); + assert(cross_check->meet(tp_notnull) == cross_check, + "real address must not escape from expected memory type"); + } + #endif + return tp; + } +} + +//------------------------adr_phi_is_loop_invariant---------------------------- +// A helper function for Ideal_DU_postCCP to check if a Phi in a counted +// loop is loop invariant. Make a quick traversal of Phi and associated +// CastPP nodes, looking to see if they are a closed group within the loop. +bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) { + // The idea is that the phi-nest must boil down to only CastPP nodes + // with the same data. This implies that any path into the loop already + // includes such a CastPP, and so the original cast, whatever its input, + // must be covered by an equivalent cast, with an earlier control input. + ResourceMark rm; + + // The loop entry input of the phi should be the unique dominating + // node for every Phi/CastPP in the loop. + Unique_Node_List closure; + closure.push(adr_phi->in(LoopNode::EntryControl)); + + // Add the phi node and the cast to the worklist. + Unique_Node_List worklist; + worklist.push(adr_phi); + if( cast != NULL ){ + if( !cast->is_ConstraintCast() ) return false; + worklist.push(cast); + } + + // Begin recursive walk of phi nodes. + while( worklist.size() ){ + // Take a node off the worklist + Node *n = worklist.pop(); + if( !closure.member(n) ){ + // Add it to the closure. + closure.push(n); + // Make a sanity check to ensure we don't waste too much time here. + if( closure.size() > 20) return false; + // This node is OK if: + // - it is a cast of an identical value + // - or it is a phi node (then we add its inputs to the worklist) + // Otherwise, the node is not OK, and we presume the cast is not invariant + if( n->is_ConstraintCast() ){ + worklist.push(n->in(1)); + } else if( n->is_Phi() ) { + for( uint i = 1; i < n->req(); i++ ) { + worklist.push(n->in(i)); + } + } else { + return false; + } + } + } + + // Quit when the worklist is empty, and we've found no offending nodes. + return true; +} + +//------------------------------Ideal_DU_postCCP------------------------------- +// Find any cast-away of null-ness and keep its control. Null cast-aways are +// going away in this pass and we need to make this memory op depend on the +// gating null check. + +// I tried to leave the CastPP's in. This makes the graph more accurate in +// some sense; we get to keep around the knowledge that an oop is not-null +// after some test. Alas, the CastPP's interfere with GVN (some values are +// the regular oop, some are the CastPP of the oop, all merge at Phi's which +// cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed +// some of the more trivial cases in the optimizer. Removing more useless +// Phi's started allowing Loads to illegally float above null checks. I gave +// up on this approach. CNC 10/20/2000 +Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) { + Node *ctr = in(MemNode::Control); + Node *mem = in(MemNode::Memory); + Node *adr = in(MemNode::Address); + Node *skipped_cast = NULL; + // Need a null check? Regular static accesses do not because they are + // from constant addresses. Array ops are gated by the range check (which + // always includes a NULL check). Just check field ops. + if( !ctr ) { + // Scan upwards for the highest location we can place this memory op. + while( true ) { + switch( adr->Opcode() ) { + + case Op_AddP: // No change to NULL-ness, so peek thru AddP's + adr = adr->in(AddPNode::Base); + continue; + + case Op_CastPP: + // If the CastPP is useless, just peek on through it. + if( ccp->type(adr) == ccp->type(adr->in(1)) ) { + // Remember the cast that we've peeked though. If we peek + // through more than one, then we end up remembering the highest + // one, that is, if in a loop, the one closest to the top. + skipped_cast = adr; + adr = adr->in(1); + continue; + } + // CastPP is going away in this pass! We need this memory op to be + // control-dependent on the test that is guarding the CastPP. + ccp->hash_delete(this); + set_req(MemNode::Control, adr->in(0)); + ccp->hash_insert(this); + return this; + + case Op_Phi: + // Attempt to float above a Phi to some dominating point. + if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) { + // If we've already peeked through a Cast (which could have set the + // control), we can't float above a Phi, because the skipped Cast + // may not be loop invariant. + if (adr_phi_is_loop_invariant(adr, skipped_cast)) { + adr = adr->in(1); + continue; + } + } + + // Intentional fallthrough! + + // No obvious dominating point. The mem op is pinned below the Phi + // by the Phi itself. If the Phi goes away (no true value is merged) + // then the mem op can float, but not indefinitely. It must be pinned + // behind the controls leading to the Phi. + case Op_CheckCastPP: + // These usually stick around to change address type, however a + // useless one can be elided and we still need to pick up a control edge + if (adr->in(0) == NULL) { + // This CheckCastPP node has NO control and is likely useless. But we + // need check further up the ancestor chain for a control input to keep + // the node in place. 4959717. + skipped_cast = adr; + adr = adr->in(1); + continue; + } + ccp->hash_delete(this); + set_req(MemNode::Control, adr->in(0)); + ccp->hash_insert(this); + return this; + + // List of "safe" opcodes; those that implicitly block the memory + // op below any null check. + case Op_CastX2P: // no null checks on native pointers + case Op_Parm: // 'this' pointer is not null + case Op_LoadP: // Loading from within a klass + case Op_LoadKlass: // Loading from within a klass + case Op_ConP: // Loading from a klass + case Op_CreateEx: // Sucking up the guts of an exception oop + case Op_Con: // Reading from TLS + case Op_CMoveP: // CMoveP is pinned + break; // No progress + + case Op_Proj: // Direct call to an allocation routine + case Op_SCMemProj: // Memory state from store conditional ops +#ifdef ASSERT + { + assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value"); + const Node* call = adr->in(0); + if (call->is_CallStaticJava()) { + const CallStaticJavaNode* call_java = call->as_CallStaticJava(); + assert(call_java && call_java->method() == NULL, "must be runtime call"); + // We further presume that this is one of + // new_instance_Java, new_array_Java, or + // the like, but do not assert for this. + } else if (call->is_Allocate()) { + // similar case to new_instance_Java, etc. + } else if (!call->is_CallLeaf()) { + // Projections from fetch_oop (OSR) are allowed as well. + ShouldNotReachHere(); + } + } +#endif + break; + default: + ShouldNotReachHere(); + } + break; + } + } + + return NULL; // No progress +} + + +//============================================================================= +uint LoadNode::size_of() const { return sizeof(*this); } +uint LoadNode::cmp( const Node &n ) const +{ return !Type::cmp( _type, ((LoadNode&)n)._type ); } +const Type *LoadNode::bottom_type() const { return _type; } +uint LoadNode::ideal_reg() const { + return Matcher::base2reg[_type->base()]; +} + +#ifndef PRODUCT +void LoadNode::dump_spec(outputStream *st) const { + MemNode::dump_spec(st); + if( !Verbose && !WizardMode ) { + // standard dump does this in Verbose and WizardMode + st->print(" #"); _type->dump_on(st); + } +} +#endif + + +//----------------------------LoadNode::make----------------------------------- +// Polymorphic factory method: +LoadNode *LoadNode::make( Compile *C, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) { + // sanity check the alias category against the created node type + assert(!(adr_type->isa_oopptr() && + adr_type->offset() == oopDesc::klass_offset_in_bytes()), + "use LoadKlassNode instead"); + assert(!(adr_type->isa_aryptr() && + adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), + "use LoadRangeNode instead"); + switch (bt) { + case T_BOOLEAN: + case T_BYTE: return new (C, 3) LoadBNode(ctl, mem, adr, adr_type, rt->is_int() ); + case T_INT: return new (C, 3) LoadINode(ctl, mem, adr, adr_type, rt->is_int() ); + case T_CHAR: return new (C, 3) LoadCNode(ctl, mem, adr, adr_type, rt->is_int() ); + case T_SHORT: return new (C, 3) LoadSNode(ctl, mem, adr, adr_type, rt->is_int() ); + case T_LONG: return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long() ); + case T_FLOAT: return new (C, 3) LoadFNode(ctl, mem, adr, adr_type, rt ); + case T_DOUBLE: return new (C, 3) LoadDNode(ctl, mem, adr, adr_type, rt ); + case T_ADDRESS: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr() ); + case T_OBJECT: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr()); + } + ShouldNotReachHere(); + return (LoadNode*)NULL; +} + +LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) { + bool require_atomic = true; + return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic); +} + + + + +//------------------------------hash------------------------------------------- +uint LoadNode::hash() const { + // unroll addition of interesting fields + return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); +} + +//---------------------------can_see_stored_value------------------------------ +// This routine exists to make sure this set of tests is done the same +// everywhere. We need to make a coordinated change: first LoadNode::Ideal +// will change the graph shape in a way which makes memory alive twice at the +// same time (uses the Oracle model of aliasing), then some +// LoadXNode::Identity will fold things back to the equivalence-class model +// of aliasing. +Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { + Node* ld_adr = in(MemNode::Address); + + // Loop around twice in the case Load -> Initialize -> Store. + // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) + for (int trip = 0; trip <= 1; trip++) { + + if (st->is_Store()) { + Node* st_adr = st->in(MemNode::Address); + if (!phase->eqv(st_adr, ld_adr)) { + // Try harder before giving up... Match raw and non-raw pointers. + intptr_t st_off = 0; + AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); + if (alloc == NULL) return NULL; + intptr_t ld_off = 0; + AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); + if (alloc != allo2) return NULL; + if (ld_off != st_off) return NULL; + // At this point we have proven something like this setup: + // A = Allocate(...) + // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) + // S = StoreQ(, AddP(, A.Parm , #Off), V) + // (Actually, we haven't yet proven the Q's are the same.) + // In other words, we are loading from a casted version of + // the same pointer-and-offset that we stored to. + // Thus, we are able to replace L by V. + } + // Now prove that we have a LoadQ matched to a StoreQ, for some Q. + if (store_Opcode() != st->Opcode()) + return NULL; + return st->in(MemNode::ValueIn); + } + + intptr_t offset = 0; // scratch + + // A load from a freshly-created object always returns zero. + // (This can happen after LoadNode::Ideal resets the load's memory input + // to find_captured_store, which returned InitializeNode::zero_memory.) + if (st->is_Proj() && st->in(0)->is_Allocate() && + st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) && + offset >= st->in(0)->as_Allocate()->minimum_header_size()) { + // return a zero value for the load's basic type + // (This is one of the few places where a generic PhaseTransform + // can create new nodes. Think of it as lazily manifesting + // virtually pre-existing constants.) + return phase->zerocon(memory_type()); + } + + // A load from an initialization barrier can match a captured store. + if (st->is_Proj() && st->in(0)->is_Initialize()) { + InitializeNode* init = st->in(0)->as_Initialize(); + AllocateNode* alloc = init->allocation(); + if (alloc != NULL && + alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) { + // examine a captured store value + st = init->find_captured_store(offset, memory_size(), phase); + if (st != NULL) + continue; // take one more trip around + } + } + + break; + } + + return NULL; +} + +//------------------------------Identity--------------------------------------- +// Loads are identity if previous store is to same address +Node *LoadNode::Identity( PhaseTransform *phase ) { + // If the previous store-maker is the right kind of Store, and the store is + // to the same address, then we are equal to the value stored. + Node* mem = in(MemNode::Memory); + Node* value = can_see_stored_value(mem, phase); + if( value ) { + // byte, short & char stores truncate naturally. + // A load has to load the truncated value which requires + // some sort of masking operation and that requires an + // Ideal call instead of an Identity call. + if (memory_size() < BytesPerInt) { + // If the input to the store does not fit with the load's result type, + // it must be truncated via an Ideal call. + if (!phase->type(value)->higher_equal(phase->type(this))) + return this; + } + // (This works even when value is a Con, but LoadNode::Value + // usually runs first, producing the singleton type of the Con.) + return value; + } + return this; +} + +//------------------------------Ideal------------------------------------------ +// If the load is from Field memory and the pointer is non-null, we can +// zero out the control input. +// If the offset is constant and the base is an object allocation, +// try to hook me up to the exact initializing store. +Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { + Node* p = MemNode::Ideal_common(phase, can_reshape); + if (p) return (p == NodeSentinel) ? NULL : p; + + Node* ctrl = in(MemNode::Control); + Node* address = in(MemNode::Address); + + // Skip up past a SafePoint control. Cannot do this for Stores because + // pointer stores & cardmarks must stay on the same side of a SafePoint. + if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && + phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { + ctrl = ctrl->in(0); + set_req(MemNode::Control,ctrl); + } + + // Check for useless control edge in some common special cases + if (in(MemNode::Control) != NULL) { + intptr_t ignore = 0; + Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); + if (base != NULL + && phase->type(base)->higher_equal(TypePtr::NOTNULL) + && detect_dominating_control(base->in(0), phase->C->start())) { + // A method-invariant, non-null address (constant or 'this' argument). + set_req(MemNode::Control, NULL); + } + } + + // Check for prior store with a different base or offset; make Load + // independent. Skip through any number of them. Bail out if the stores + // are in an endless dead cycle and report no progress. This is a key + // transform for Reflection. However, if after skipping through the Stores + // we can't then fold up against a prior store do NOT do the transform as + // this amounts to using the 'Oracle' model of aliasing. It leaves the same + // array memory alive twice: once for the hoisted Load and again after the + // bypassed Store. This situation only works if EVERYBODY who does + // anti-dependence work knows how to bypass. I.e. we need all + // anti-dependence checks to ask the same Oracle. Right now, that Oracle is + // the alias index stuff. So instead, peek through Stores and IFF we can + // fold up, do so. + Node* prev_mem = find_previous_store(phase); + // Steps (a), (b): Walk past independent stores to find an exact match. + if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { + // (c) See if we can fold up on the spot, but don't fold up here. + // Fold-up might require truncation (for LoadB/LoadS/LoadC) or + // just return a prior value, which is done by Identity calls. + if (can_see_stored_value(prev_mem, phase)) { + // Make ready for step (d): + set_req(MemNode::Memory, prev_mem); + return this; + } + } + + return NULL; // No further progress +} + +// Helper to recognize certain Klass fields which are invariant across +// some group of array types (e.g., int[] or all T[] where T < Object). +const Type* +LoadNode::load_array_final_field(const TypeKlassPtr *tkls, + ciKlass* klass) const { + if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { + // The field is Klass::_modifier_flags. Return its (constant) value. + // (Folds up the 2nd indirection in aClassConstant.getModifiers().) + assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); + return TypeInt::make(klass->modifier_flags()); + } + if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { + // The field is Klass::_access_flags. Return its (constant) value. + // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) + assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); + return TypeInt::make(klass->access_flags()); + } + if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) { + // The field is Klass::_layout_helper. Return its constant value if known. + assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); + return TypeInt::make(klass->layout_helper()); + } + + // No match. + return NULL; +} + +//------------------------------Value----------------------------------------- +const Type *LoadNode::Value( PhaseTransform *phase ) const { + // Either input is TOP ==> the result is TOP + Node* mem = in(MemNode::Memory); + const Type *t1 = phase->type(mem); + if (t1 == Type::TOP) return Type::TOP; + Node* adr = in(MemNode::Address); + const TypePtr* tp = phase->type(adr)->isa_ptr(); + if (tp == NULL || tp->empty()) return Type::TOP; + int off = tp->offset(); + assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); + + // Try to guess loaded type from pointer type + if (tp->base() == Type::AryPtr) { + const Type *t = tp->is_aryptr()->elem(); + // Don't do this for integer types. There is only potential profit if + // the element type t is lower than _type; that is, for int types, if _type is + // more restrictive than t. This only happens here if one is short and the other + // char (both 16 bits), and in those cases we've made an intentional decision + // to use one kind of load over the other. See AndINode::Ideal and 4965907. + // Also, do not try to narrow the type for a LoadKlass, regardless of offset. + // + // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) + // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier + // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been + // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, + // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. + // In fact, that could have been the original type of p1, and p1 could have + // had an original form like p1:(AddP x x (LShiftL quux 3)), where the + // expression (LShiftL quux 3) independently optimized to the constant 8. + if ((t->isa_int() == NULL) && (t->isa_long() == NULL) + && Opcode() != Op_LoadKlass) { + // t might actually be lower than _type, if _type is a unique + // concrete subclass of abstract class t. + // Make sure the reference is not into the header, by comparing + // the offset against the offset of the start of the array's data. + // Different array types begin at slightly different offsets (12 vs. 16). + // We choose T_BYTE as an example base type that is least restrictive + // as to alignment, which will therefore produce the smallest + // possible base offset. + const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); + if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header? + const Type* jt = t->join(_type); + // In any case, do not allow the join, per se, to empty out the type. + if (jt->empty() && !t->empty()) { + // This can happen if a interface-typed array narrows to a class type. + jt = _type; + } + return jt; + } + } + } else if (tp->base() == Type::InstPtr) { + assert( off != Type::OffsetBot || + // arrays can be cast to Objects + tp->is_oopptr()->klass()->is_java_lang_Object() || + // unsafe field access may not have a constant offset + phase->C->has_unsafe_access(), + "Field accesses must be precise" ); + // For oop loads, we expect the _type to be precise + } else if (tp->base() == Type::KlassPtr) { + assert( off != Type::OffsetBot || + // arrays can be cast to Objects + tp->is_klassptr()->klass()->is_java_lang_Object() || + // also allow array-loading from the primary supertype + // array during subtype checks + Opcode() == Op_LoadKlass, + "Field accesses must be precise" ); + // For klass/static loads, we expect the _type to be precise + } + + const TypeKlassPtr *tkls = tp->isa_klassptr(); + if (tkls != NULL && !StressReflectiveCode) { + ciKlass* klass = tkls->klass(); + if (klass->is_loaded() && tkls->klass_is_exact()) { + // We are loading a field from a Klass metaobject whose identity + // is known at compile time (the type is "exact" or "precise"). + // Check for fields we know are maintained as constants by the VM. + if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) { + // The field is Klass::_super_check_offset. Return its (constant) value. + // (Folds up type checking code.) + assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); + return TypeInt::make(klass->super_check_offset()); + } + // Compute index into primary_supers array + juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); + // Check for overflowing; use unsigned compare to handle the negative case. + if( depth < ciKlass::primary_super_limit() ) { + // The field is an element of Klass::_primary_supers. Return its (constant) value. + // (Folds up type checking code.) + assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); + ciKlass *ss = klass->super_of_depth(depth); + return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; + } + const Type* aift = load_array_final_field(tkls, klass); + if (aift != NULL) return aift; + if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc) + && klass->is_array_klass()) { + // The field is arrayKlass::_component_mirror. Return its (constant) value. + // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.) + assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror"); + return TypeInstPtr::make(klass->as_array_klass()->component_mirror()); + } + if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) { + // The field is Klass::_java_mirror. Return its (constant) value. + // (Folds up the 2nd indirection in anObjConstant.getClass().) + assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); + return TypeInstPtr::make(klass->java_mirror()); + } + } + + // We can still check if we are loading from the primary_supers array at a + // shallow enough depth. Even though the klass is not exact, entries less + // than or equal to its super depth are correct. + if (klass->is_loaded() ) { + ciType *inner = klass->klass(); + while( inner->is_obj_array_klass() ) + inner = inner->as_obj_array_klass()->base_element_type(); + if( inner->is_instance_klass() && + !inner->as_instance_klass()->flags().is_interface() ) { + // Compute index into primary_supers array + juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); + // Check for overflowing; use unsigned compare to handle the negative case. + if( depth < ciKlass::primary_super_limit() && + depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case + // The field is an element of Klass::_primary_supers. Return its (constant) value. + // (Folds up type checking code.) + assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); + ciKlass *ss = klass->super_of_depth(depth); + return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; + } + } + } + + // If the type is enough to determine that the thing is not an array, + // we can give the layout_helper a positive interval type. + // This will help short-circuit some reflective code. + if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc) + && !klass->is_array_klass() // not directly typed as an array + && !klass->is_interface() // specifically not Serializable & Cloneable + && !klass->is_java_lang_Object() // not the supertype of all T[] + ) { + // Note: When interfaces are reliable, we can narrow the interface + // test to (klass != Serializable && klass != Cloneable). + assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); + jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); + // The key property of this type is that it folds up tests + // for array-ness, since it proves that the layout_helper is positive. + // Thus, a generic value like the basic object layout helper works fine. + return TypeInt::make(min_size, max_jint, Type::WidenMin); + } + } + + // If we are loading from a freshly-allocated object, produce a zero, + // if the load is provably beyond the header of the object. + // (Also allow a variable load from a fresh array to produce zero.) + if (ReduceFieldZeroing) { + Node* value = can_see_stored_value(mem,phase); + if (value != NULL && value->is_Con()) + return value->bottom_type(); + } + + return _type; +} + +//------------------------------match_edge------------------------------------- +// Do we Match on this edge index or not? Match only the address. +uint LoadNode::match_edge(uint idx) const { + return idx == MemNode::Address; +} + +//--------------------------LoadBNode::Ideal-------------------------------------- +// +// If the previous store is to the same address as this load, +// and the value stored was larger than a byte, replace this load +// with the value stored truncated to a byte. If no truncation is +// needed, the replacement is done in LoadNode::Identity(). +// +Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { + Node* mem = in(MemNode::Memory); + Node* value = can_see_stored_value(mem,phase); + if( value && !phase->type(value)->higher_equal( _type ) ) { + Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) ); + return new (phase->C, 3) RShiftINode(result, phase->intcon(24)); + } + // Identity call will handle the case where truncation is not needed. + return LoadNode::Ideal(phase, can_reshape); +} + +//--------------------------LoadCNode::Ideal-------------------------------------- +// +// If the previous store is to the same address as this load, +// and the value stored was larger than a char, replace this load +// with the value stored truncated to a char. If no truncation is +// needed, the replacement is done in LoadNode::Identity(). +// +Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) { + Node* mem = in(MemNode::Memory); + Node* value = can_see_stored_value(mem,phase); + if( value && !phase->type(value)->higher_equal( _type ) ) + return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF)); + // Identity call will handle the case where truncation is not needed. + return LoadNode::Ideal(phase, can_reshape); +} + +//--------------------------LoadSNode::Ideal-------------------------------------- +// +// If the previous store is to the same address as this load, +// and the value stored was larger than a short, replace this load +// with the value stored truncated to a short. If no truncation is +// needed, the replacement is done in LoadNode::Identity(). +// +Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { + Node* mem = in(MemNode::Memory); + Node* value = can_see_stored_value(mem,phase); + if( value && !phase->type(value)->higher_equal( _type ) ) { + Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) ); + return new (phase->C, 3) RShiftINode(result, phase->intcon(16)); + } + // Identity call will handle the case where truncation is not needed. + return LoadNode::Ideal(phase, can_reshape); +} + +//============================================================================= +//------------------------------Value------------------------------------------ +const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { + // Either input is TOP ==> the result is TOP + const Type *t1 = phase->type( in(MemNode::Memory) ); + if (t1 == Type::TOP) return Type::TOP; + Node *adr = in(MemNode::Address); + const Type *t2 = phase->type( adr ); + if (t2 == Type::TOP) return Type::TOP; + const TypePtr *tp = t2->is_ptr(); + if (TypePtr::above_centerline(tp->ptr()) || + tp->ptr() == TypePtr::Null) return Type::TOP; + + // Return a more precise klass, if possible + const TypeInstPtr *tinst = tp->isa_instptr(); + if (tinst != NULL) { + ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); + int offset = tinst->offset(); + if (ik == phase->C->env()->Class_klass() + && (offset == java_lang_Class::klass_offset_in_bytes() || + offset == java_lang_Class::array_klass_offset_in_bytes())) { + // We are loading a special hidden field from a Class mirror object, + // the field which points to the VM's Klass metaobject. + ciType* t = tinst->java_mirror_type(); + // java_mirror_type returns non-null for compile-time Class constants. + if (t != NULL) { + // constant oop => constant klass + if (offset == java_lang_Class::array_klass_offset_in_bytes()) { + return TypeKlassPtr::make(ciArrayKlass::make(t)); + } + if (!t->is_klass()) { + // a primitive Class (e.g., int.class) has NULL for a klass field + return TypePtr::NULL_PTR; + } + // (Folds up the 1st indirection in aClassConstant.getModifiers().) + return TypeKlassPtr::make(t->as_klass()); + } + // non-constant mirror, so we can't tell what's going on + } + if( !ik->is_loaded() ) + return _type; // Bail out if not loaded + if (offset == oopDesc::klass_offset_in_bytes()) { + if (tinst->klass_is_exact()) { + return TypeKlassPtr::make(ik); + } + // See if we can become precise: no subklasses and no interface + // (Note: We need to support verified interfaces.) + if (!ik->is_interface() && !ik->has_subklass()) { + //assert(!UseExactTypes, "this code should be useless with exact types"); + // Add a dependence; if any subclass added we need to recompile + if (!ik->is_final()) { + // %%% should use stronger assert_unique_concrete_subtype instead + phase->C->dependencies()->assert_leaf_type(ik); + } + // Return precise klass + return TypeKlassPtr::make(ik); + } + + // Return root of possible klass + return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); + } + } + + // Check for loading klass from an array + const TypeAryPtr *tary = tp->isa_aryptr(); + if( tary != NULL ) { + ciKlass *tary_klass = tary->klass(); + if (tary_klass != NULL // can be NULL when at BOTTOM or TOP + && tary->offset() == oopDesc::klass_offset_in_bytes()) { + if (tary->klass_is_exact()) { + return TypeKlassPtr::make(tary_klass); + } + ciArrayKlass *ak = tary->klass()->as_array_klass(); + // If the klass is an object array, we defer the question to the + // array component klass. + if( ak->is_obj_array_klass() ) { + assert( ak->is_loaded(), "" ); + ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); + if( base_k->is_loaded() && base_k->is_instance_klass() ) { + ciInstanceKlass* ik = base_k->as_instance_klass(); + // See if we can become precise: no subklasses and no interface + if (!ik->is_interface() && !ik->has_subklass()) { + //assert(!UseExactTypes, "this code should be useless with exact types"); + // Add a dependence; if any subclass added we need to recompile + if (!ik->is_final()) { + phase->C->dependencies()->assert_leaf_type(ik); + } + // Return precise array klass + return TypeKlassPtr::make(ak); + } + } + return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); + } else { // Found a type-array? + //assert(!UseExactTypes, "this code should be useless with exact types"); + assert( ak->is_type_array_klass(), "" ); + return TypeKlassPtr::make(ak); // These are always precise + } + } + } + + // Check for loading klass from an array klass + const TypeKlassPtr *tkls = tp->isa_klassptr(); + if (tkls != NULL && !StressReflectiveCode) { + ciKlass* klass = tkls->klass(); + if( !klass->is_loaded() ) + return _type; // Bail out if not loaded + if( klass->is_obj_array_klass() && + (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) { + ciKlass* elem = klass->as_obj_array_klass()->element_klass(); + // // Always returning precise element type is incorrect, + // // e.g., element type could be object and array may contain strings + // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); + + // The array's TypeKlassPtr was declared 'precise' or 'not precise' + // according to the element type's subclassing. + return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); + } + if( klass->is_instance_klass() && tkls->klass_is_exact() && + (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) { + ciKlass* sup = klass->as_instance_klass()->super(); + // The field is Klass::_super. Return its (constant) value. + // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) + return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; + } + } + + // Bailout case + return LoadNode::Value(phase); +} + +//------------------------------Identity--------------------------------------- +// To clean up reflective code, simplify k.java_mirror.as_klass to plain k. +// Also feed through the klass in Allocate(...klass...)._klass. +Node* LoadKlassNode::Identity( PhaseTransform *phase ) { + Node* x = LoadNode::Identity(phase); + if (x != this) return x; + + // Take apart the address into an oop and and offset. + // Return 'this' if we cannot. + Node* adr = in(MemNode::Address); + intptr_t offset = 0; + Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); + if (base == NULL) return this; + const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); + if (toop == NULL) return this; + + // We can fetch the klass directly through an AllocateNode. + // This works even if the klass is not constant (clone or newArray). + if (offset == oopDesc::klass_offset_in_bytes()) { + Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); + if (allocated_klass != NULL) { + return allocated_klass; + } + } + + // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop. + // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass. + // See inline_native_Class_query for occurrences of these patterns. + // Java Example: x.getClass().isAssignableFrom(y) + // Java Example: Array.newInstance(x.getClass().getComponentType(), n) + // + // This improves reflective code, often making the Class + // mirror go completely dead. (Current exception: Class + // mirrors may appear in debug info, but we could clean them out by + // introducing a new debug info operator for klassOop.java_mirror). + if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() + && (offset == java_lang_Class::klass_offset_in_bytes() || + offset == java_lang_Class::array_klass_offset_in_bytes())) { + // We are loading a special hidden field from a Class mirror, + // the field which points to its Klass or arrayKlass metaobject. + if (base->is_Load()) { + Node* adr2 = base->in(MemNode::Address); + const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); + if (tkls != NULL && !tkls->empty() + && (tkls->klass()->is_instance_klass() || + tkls->klass()->is_array_klass()) + && adr2->is_AddP() + ) { + int mirror_field = Klass::java_mirror_offset_in_bytes(); + if (offset == java_lang_Class::array_klass_offset_in_bytes()) { + mirror_field = in_bytes(arrayKlass::component_mirror_offset()); + } + if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) { + return adr2->in(AddPNode::Base); + } + } + } + } + + return this; +} + +//------------------------------Value----------------------------------------- +const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { + // Either input is TOP ==> the result is TOP + const Type *t1 = phase->type( in(MemNode::Memory) ); + if( t1 == Type::TOP ) return Type::TOP; + Node *adr = in(MemNode::Address); + const Type *t2 = phase->type( adr ); + if( t2 == Type::TOP ) return Type::TOP; + const TypePtr *tp = t2->is_ptr(); + if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; + const TypeAryPtr *tap = tp->isa_aryptr(); + if( !tap ) return _type; + return tap->size(); +} + +//------------------------------Identity--------------------------------------- +// Feed through the length in AllocateArray(...length...)._length. +Node* LoadRangeNode::Identity( PhaseTransform *phase ) { + Node* x = LoadINode::Identity(phase); + if (x != this) return x; + + // Take apart the address into an oop and and offset. + // Return 'this' if we cannot. + Node* adr = in(MemNode::Address); + intptr_t offset = 0; + Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); + if (base == NULL) return this; + const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); + if (tary == NULL) return this; + + // We can fetch the length directly through an AllocateArrayNode. + // This works even if the length is not constant (clone or newArray). + if (offset == arrayOopDesc::length_offset_in_bytes()) { + Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase); + if (allocated_length != NULL) { + return allocated_length; + } + } + + return this; + +} +//============================================================================= +//---------------------------StoreNode::make----------------------------------- +// Polymorphic factory method: +StoreNode* StoreNode::make( Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) { + switch (bt) { + case T_BOOLEAN: + case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val); + case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val); + case T_CHAR: + case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val); + case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val); + case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val); + case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val); + case T_ADDRESS: + case T_OBJECT: return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val); + } + ShouldNotReachHere(); + return (StoreNode*)NULL; +} + +StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) { + bool require_atomic = true; + return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic); +} + + +//--------------------------bottom_type---------------------------------------- +const Type *StoreNode::bottom_type() const { + return Type::MEMORY; +} + +//------------------------------hash------------------------------------------- +uint StoreNode::hash() const { + // unroll addition of interesting fields + //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); + + // Since they are not commoned, do not hash them: + return NO_HASH; +} + +//------------------------------Ideal------------------------------------------ +// Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). +// When a store immediately follows a relevant allocation/initialization, +// try to capture it into the initialization, or hoist it above. +Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { + Node* p = MemNode::Ideal_common(phase, can_reshape); + if (p) return (p == NodeSentinel) ? NULL : p; + + Node* mem = in(MemNode::Memory); + Node* address = in(MemNode::Address); + + // Back-to-back stores to same address? Fold em up. + // Generally unsafe if I have intervening uses... + if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) { + // Looking at a dead closed cycle of memory? + assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); + + assert(Opcode() == mem->Opcode() || + phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, + "no mismatched stores, except on raw memory"); + + if (mem->outcnt() == 1 && // check for intervening uses + mem->as_Store()->memory_size() <= this->memory_size()) { + // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. + // For example, 'mem' might be the final state at a conditional return. + // Or, 'mem' might be used by some node which is live at the same time + // 'this' is live, which might be unschedulable. So, require exactly + // ONE user, the 'this' store, until such time as we clone 'mem' for + // each of 'mem's uses (thus making the exactly-1-user-rule hold true). + if (can_reshape) { // (%%% is this an anachronism?) + set_req_X(MemNode::Memory, mem->in(MemNode::Memory), + phase->is_IterGVN()); + } else { + // It's OK to do this in the parser, since DU info is always accurate, + // and the parser always refers to nodes via SafePointNode maps. + set_req(MemNode::Memory, mem->in(MemNode::Memory)); + } + return this; + } + } + + // Capture an unaliased, unconditional, simple store into an initializer. + // Or, if it is independent of the allocation, hoist it above the allocation. + if (ReduceFieldZeroing && /*can_reshape &&*/ + mem->is_Proj() && mem->in(0)->is_Initialize()) { + InitializeNode* init = mem->in(0)->as_Initialize(); + intptr_t offset = init->can_capture_store(this, phase); + if (offset > 0) { + Node* moved = init->capture_store(this, offset, phase); + // If the InitializeNode captured me, it made a raw copy of me, + // and I need to disappear. + if (moved != NULL) { + // %%% hack to ensure that Ideal returns a new node: + mem = MergeMemNode::make(phase->C, mem); + return mem; // fold me away + } + } + } + + return NULL; // No further progress +} + +//------------------------------Value----------------------------------------- +const Type *StoreNode::Value( PhaseTransform *phase ) const { + // Either input is TOP ==> the result is TOP + const Type *t1 = phase->type( in(MemNode::Memory) ); + if( t1 == Type::TOP ) return Type::TOP; + const Type *t2 = phase->type( in(MemNode::Address) ); + if( t2 == Type::TOP ) return Type::TOP; + const Type *t3 = phase->type( in(MemNode::ValueIn) ); + if( t3 == Type::TOP ) return Type::TOP; + return Type::MEMORY; +} + +//------------------------------Identity--------------------------------------- +// Remove redundant stores: +// Store(m, p, Load(m, p)) changes to m. +// Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). +Node *StoreNode::Identity( PhaseTransform *phase ) { + Node* mem = in(MemNode::Memory); + Node* adr = in(MemNode::Address); + Node* val = in(MemNode::ValueIn); + + // Load then Store? Then the Store is useless + if (val->is_Load() && + phase->eqv_uncast( val->in(MemNode::Address), adr ) && + phase->eqv_uncast( val->in(MemNode::Memory ), mem ) && + val->as_Load()->store_Opcode() == Opcode()) { + return mem; + } + + // Two stores in a row of the same value? + if (mem->is_Store() && + phase->eqv_uncast( mem->in(MemNode::Address), adr ) && + phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) && + mem->Opcode() == Opcode()) { + return mem; + } + + // Store of zero anywhere into a freshly-allocated object? + // Then the store is useless. + // (It must already have been captured by the InitializeNode.) + if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { + // a newly allocated object is already all-zeroes everywhere + if (mem->is_Proj() && mem->in(0)->is_Allocate()) { + return mem; + } + + // the store may also apply to zero-bits in an earlier object + Node* prev_mem = find_previous_store(phase); + // Steps (a), (b): Walk past independent stores to find an exact match. + if (prev_mem != NULL) { + Node* prev_val = can_see_stored_value(prev_mem, phase); + if (prev_val != NULL && phase->eqv(prev_val, val)) { + // prev_val and val might differ by a cast; it would be good + // to keep the more informative of the two. + return mem; + } + } + } + + return this; +} + +//------------------------------match_edge------------------------------------- +// Do we Match on this edge index or not? Match only memory & value +uint StoreNode::match_edge(uint idx) const { + return idx == MemNode::Address || idx == MemNode::ValueIn; +} + +//------------------------------cmp-------------------------------------------- +// Do not common stores up together. They generally have to be split +// back up anyways, so do not bother. +uint StoreNode::cmp( const Node &n ) const { + return (&n == this); // Always fail except on self +} + +//------------------------------Ideal_masked_input----------------------------- +// Check for a useless mask before a partial-word store +// (StoreB ... (AndI valIn conIa) ) +// If (conIa & mask == mask) this simplifies to +// (StoreB ... (valIn) ) +Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { + Node *val = in(MemNode::ValueIn); + if( val->Opcode() == Op_AndI ) { + const TypeInt *t = phase->type( val->in(2) )->isa_int(); + if( t && t->is_con() && (t->get_con() & mask) == mask ) { + set_req(MemNode::ValueIn, val->in(1)); + return this; + } + } + return NULL; +} + + +//------------------------------Ideal_sign_extended_input---------------------- +// Check for useless sign-extension before a partial-word store +// (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) +// If (conIL == conIR && conIR <= num_bits) this simplifies to +// (StoreB ... (valIn) ) +Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { + Node *val = in(MemNode::ValueIn); + if( val->Opcode() == Op_RShiftI ) { + const TypeInt *t = phase->type( val->in(2) )->isa_int(); + if( t && t->is_con() && (t->get_con() <= num_bits) ) { + Node *shl = val->in(1); + if( shl->Opcode() == Op_LShiftI ) { + const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); + if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { + set_req(MemNode::ValueIn, shl->in(1)); + return this; + } + } + } + } + return NULL; +} + +//------------------------------value_never_loaded----------------------------------- +// Determine whether there are any possible loads of the value stored. +// For simplicity, we actually check if there are any loads from the +// address stored to, not just for loads of the value stored by this node. +// +bool StoreNode::value_never_loaded( PhaseTransform *phase) const { + Node *adr = in(Address); + const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); + if (adr_oop == NULL) + return false; + if (!adr_oop->is_instance()) + return false; // if not a distinct instance, there may be aliases of the address + for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { + Node *use = adr->fast_out(i); + int opc = use->Opcode(); + if (use->is_Load() || use->is_LoadStore()) { + return false; + } + } + return true; +} + +//============================================================================= +//------------------------------Ideal------------------------------------------ +// If the store is from an AND mask that leaves the low bits untouched, then +// we can skip the AND operation. If the store is from a sign-extension +// (a left shift, then right shift) we can skip both. +Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ + Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); + if( progress != NULL ) return progress; + + progress = StoreNode::Ideal_sign_extended_input(phase, 24); + if( progress != NULL ) return progress; + + // Finally check the default case + return StoreNode::Ideal(phase, can_reshape); +} + +//============================================================================= +//------------------------------Ideal------------------------------------------ +// If the store is from an AND mask that leaves the low bits untouched, then +// we can skip the AND operation +Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ + Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); + if( progress != NULL ) return progress; + + progress = StoreNode::Ideal_sign_extended_input(phase, 16); + if( progress != NULL ) return progress; + + // Finally check the default case + return StoreNode::Ideal(phase, can_reshape); +} + +//============================================================================= +//------------------------------Identity--------------------------------------- +Node *StoreCMNode::Identity( PhaseTransform *phase ) { + // No need to card mark when storing a null ptr + Node* my_store = in(MemNode::OopStore); + if (my_store->is_Store()) { + const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); + if( t1 == TypePtr::NULL_PTR ) { + return in(MemNode::Memory); + } + } + return this; +} + +//------------------------------Value----------------------------------------- +const Type *StoreCMNode::Value( PhaseTransform *phase ) const { + // If extra input is TOP ==> the result is TOP + const Type *t1 = phase->type( in(MemNode::OopStore) ); + if( t1 == Type::TOP ) return Type::TOP; + + return StoreNode::Value( phase ); +} + + +//============================================================================= +//----------------------------------SCMemProjNode------------------------------ +const Type * SCMemProjNode::Value( PhaseTransform *phase ) const +{ + return bottom_type(); +} + +//============================================================================= +LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) { + init_req(MemNode::Control, c ); + init_req(MemNode::Memory , mem); + init_req(MemNode::Address, adr); + init_req(MemNode::ValueIn, val); + init_req( ExpectedIn, ex ); + init_class_id(Class_LoadStore); + +} + +//============================================================================= +//-------------------------------adr_type-------------------------------------- +// Do we Match on this edge index or not? Do not match memory +const TypePtr* ClearArrayNode::adr_type() const { + Node *adr = in(3); + return MemNode::calculate_adr_type(adr->bottom_type()); +} + +//------------------------------match_edge------------------------------------- +// Do we Match on this edge index or not? Do not match memory +uint ClearArrayNode::match_edge(uint idx) const { + return idx > 1; +} + +//------------------------------Identity--------------------------------------- +// Clearing a zero length array does nothing +Node *ClearArrayNode::Identity( PhaseTransform *phase ) { + return phase->type(in(2))->higher_equal(TypeInt::ZERO) ? in(1) : this; +} + +//------------------------------Idealize--------------------------------------- +// Clearing a short array is faster with stores +Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ + const int unit = BytesPerLong; + const TypeX* t = phase->type(in(2))->isa_intptr_t(); + if (!t) return NULL; + if (!t->is_con()) return NULL; + intptr_t raw_count = t->get_con(); + intptr_t size = raw_count; + if (!Matcher::init_array_count_is_in_bytes) size *= unit; + // Clearing nothing uses the Identity call. + // Negative clears are possible on dead ClearArrays + // (see jck test stmt114.stmt11402.val). + if (size <= 0 || size % unit != 0) return NULL; + intptr_t count = size / unit; + // Length too long; use fast hardware clear + if (size > Matcher::init_array_short_size) return NULL; + Node *mem = in(1); + if( phase->type(mem)==Type::TOP ) return NULL; + Node *adr = in(3); + const Type* at = phase->type(adr); + if( at==Type::TOP ) return NULL; + const TypePtr* atp = at->isa_ptr(); + // adjust atp to be the correct array element address type + if (atp == NULL) atp = TypePtr::BOTTOM; + else atp = atp->add_offset(Type::OffsetBot); + // Get base for derived pointer purposes + if( adr->Opcode() != Op_AddP ) Unimplemented(); + Node *base = adr->in(1); + + Node *zero = phase->makecon(TypeLong::ZERO); + Node *off = phase->MakeConX(BytesPerLong); + mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); + count--; + while( count-- ) { + mem = phase->transform(mem); + adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off)); + mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); + } + return mem; +} + +//----------------------------clear_memory------------------------------------- +// Generate code to initialize object storage to zero. +Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, + intptr_t start_offset, + Node* end_offset, + PhaseGVN* phase) { + Compile* C = phase->C; + intptr_t offset = start_offset; + + int unit = BytesPerLong; + if ((offset % unit) != 0) { + Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset)); + adr = phase->transform(adr); + const TypePtr* atp = TypeRawPtr::BOTTOM; + mem = StoreNode::make(C, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); + mem = phase->transform(mem); + offset += BytesPerInt; + } + assert((offset % unit) == 0, ""); + + // Initialize the remaining stuff, if any, with a ClearArray. + return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); +} + +Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, + Node* start_offset, + Node* end_offset, + PhaseGVN* phase) { + Compile* C = phase->C; + int unit = BytesPerLong; + Node* zbase = start_offset; + Node* zend = end_offset; + + // Scale to the unit required by the CPU: + if (!Matcher::init_array_count_is_in_bytes) { + Node* shift = phase->intcon(exact_log2(unit)); + zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) ); + zend = phase->transform( new(C,3) URShiftXNode(zend, shift) ); + } + + Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) ); + Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT); + + // Bulk clear double-words + Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) ); + mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr); + return phase->transform(mem); +} + +Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, + intptr_t start_offset, + intptr_t end_offset, + PhaseGVN* phase) { + Compile* C = phase->C; + assert((end_offset % BytesPerInt) == 0, "odd end offset"); + intptr_t done_offset = end_offset; + if ((done_offset % BytesPerLong) != 0) { + done_offset -= BytesPerInt; + } + if (done_offset > start_offset) { + mem = clear_memory(ctl, mem, dest, + start_offset, phase->MakeConX(done_offset), phase); + } + if (done_offset < end_offset) { // emit the final 32-bit store + Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset)); + adr = phase->transform(adr); + const TypePtr* atp = TypeRawPtr::BOTTOM; + mem = StoreNode::make(C, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); + mem = phase->transform(mem); + done_offset += BytesPerInt; + } + assert(done_offset == end_offset, ""); + return mem; +} + +//============================================================================= +// Do we match on this edge? No memory edges +uint StrCompNode::match_edge(uint idx) const { + return idx == 5 || idx == 6; +} + +//------------------------------Ideal------------------------------------------ +// Return a node which is more "ideal" than the current node. Strip out +// control copies +Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){ + return remove_dead_region(phase, can_reshape) ? this : NULL; +} + + +//============================================================================= +MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) + : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), + _adr_type(C->get_adr_type(alias_idx)) +{ + init_class_id(Class_MemBar); + Node* top = C->top(); + init_req(TypeFunc::I_O,top); + init_req(TypeFunc::FramePtr,top); + init_req(TypeFunc::ReturnAdr,top); + if (precedent != NULL) + init_req(TypeFunc::Parms, precedent); +} + +//------------------------------cmp-------------------------------------------- +uint MemBarNode::hash() const { return NO_HASH; } +uint MemBarNode::cmp( const Node &n ) const { + return (&n == this); // Always fail except on self +} + +//------------------------------make------------------------------------------- +MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { + int len = Precedent + (pn == NULL? 0: 1); + switch (opcode) { + case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn); + case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn); + case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn); + case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn); + case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn); + default: ShouldNotReachHere(); return NULL; + } +} + +//------------------------------Ideal------------------------------------------ +// Return a node which is more "ideal" than the current node. Strip out +// control copies +Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { + if (remove_dead_region(phase, can_reshape)) return this; + return NULL; +} + +//------------------------------Value------------------------------------------ +const Type *MemBarNode::Value( PhaseTransform *phase ) const { + if( !in(0) ) return Type::TOP; + if( phase->type(in(0)) == Type::TOP ) + return Type::TOP; + return TypeTuple::MEMBAR; +} + +//------------------------------match------------------------------------------ +// Construct projections for memory. +Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { + switch (proj->_con) { + case TypeFunc::Control: + case TypeFunc::Memory: + return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); + } + ShouldNotReachHere(); + return NULL; +} + +//===========================InitializeNode==================================== +// SUMMARY: +// This node acts as a memory barrier on raw memory, after some raw stores. +// The 'cooked' oop value feeds from the Initialize, not the Allocation. +// The Initialize can 'capture' suitably constrained stores as raw inits. +// It can coalesce related raw stores into larger units (called 'tiles'). +// It can avoid zeroing new storage for memory units which have raw inits. +// At macro-expansion, it is marked 'complete', and does not optimize further. +// +// EXAMPLE: +// The object 'new short[2]' occupies 16 bytes in a 32-bit machine. +// ctl = incoming control; mem* = incoming memory +// (Note: A star * on a memory edge denotes I/O and other standard edges.) +// First allocate uninitialized memory and fill in the header: +// alloc = (Allocate ctl mem* 16 #short[].klass ...) +// ctl := alloc.Control; mem* := alloc.Memory* +// rawmem = alloc.Memory; rawoop = alloc.RawAddress +// Then initialize to zero the non-header parts of the raw memory block: +// init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) +// ctl := init.Control; mem.SLICE(#short[*]) := init.Memory +// After the initialize node executes, the object is ready for service: +// oop := (CheckCastPP init.Control alloc.RawAddress #short[]) +// Suppose its body is immediately initialized as {1,2}: +// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) +// store2 = (StoreC init.Control store1 (+ oop 14) 2) +// mem.SLICE(#short[*]) := store2 +// +// DETAILS: +// An InitializeNode collects and isolates object initialization after +// an AllocateNode and before the next possible safepoint. As a +// memory barrier (MemBarNode), it keeps critical stores from drifting +// down past any safepoint or any publication of the allocation. +// Before this barrier, a newly-allocated object may have uninitialized bits. +// After this barrier, it may be treated as a real oop, and GC is allowed. +// +// The semantics of the InitializeNode include an implicit zeroing of +// the new object from object header to the end of the object. +// (The object header and end are determined by the AllocateNode.) +// +// Certain stores may be added as direct inputs to the InitializeNode. +// These stores must update raw memory, and they must be to addresses +// derived from the raw address produced by AllocateNode, and with +// a constant offset. They must be ordered by increasing offset. +// The first one is at in(RawStores), the last at in(req()-1). +// Unlike most memory operations, they are not linked in a chain, +// but are displayed in parallel as users of the rawmem output of +// the allocation. +// +// (See comments in InitializeNode::capture_store, which continue +// the example given above.) +// +// When the associated Allocate is macro-expanded, the InitializeNode +// may be rewritten to optimize collected stores. A ClearArrayNode +// may also be created at that point to represent any required zeroing. +// The InitializeNode is then marked 'complete', prohibiting further +// capturing of nearby memory operations. +// +// During macro-expansion, all captured initializations which store +// constant values of 32 bits or smaller are coalesced (if advantagous) +// into larger 'tiles' 32 or 64 bits. This allows an object to be +// initialized in fewer memory operations. Memory words which are +// covered by neither tiles nor non-constant stores are pre-zeroed +// by explicit stores of zero. (The code shape happens to do all +// zeroing first, then all other stores, with both sequences occurring +// in order of ascending offsets.) +// +// Alternatively, code may be inserted between an AllocateNode and its +// InitializeNode, to perform arbitrary initialization of the new object. +// E.g., the object copying intrinsics insert complex data transfers here. +// The initialization must then be marked as 'complete' disable the +// built-in zeroing semantics and the collection of initializing stores. +// +// While an InitializeNode is incomplete, reads from the memory state +// produced by it are optimizable if they match the control edge and +// new oop address associated with the allocation/initialization. +// They return a stored value (if the offset matches) or else zero. +// A write to the memory state, if it matches control and address, +// and if it is to a constant offset, may be 'captured' by the +// InitializeNode. It is cloned as a raw memory operation and rewired +// inside the initialization, to the raw oop produced by the allocation. +// Operations on addresses which are provably distinct (e.g., to +// other AllocateNodes) are allowed to bypass the initialization. +// +// The effect of all this is to consolidate object initialization +// (both arrays and non-arrays, both piecewise and bulk) into a +// single location, where it can be optimized as a unit. +// +// Only stores with an offset less than TrackedInitializationLimit words +// will be considered for capture by an InitializeNode. This puts a +// reasonable limit on the complexity of optimized initializations. + +//---------------------------InitializeNode------------------------------------ +InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) + : _is_complete(false), + MemBarNode(C, adr_type, rawoop) +{ + init_class_id(Class_Initialize); + + assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); + assert(in(RawAddress) == rawoop, "proper init"); + // Note: allocation() can be NULL, for secondary initialization barriers +} + +// Since this node is not matched, it will be processed by the +// register allocator. Declare that there are no constraints +// on the allocation of the RawAddress edge. +const RegMask &InitializeNode::in_RegMask(uint idx) const { + // This edge should be set to top, by the set_complete. But be conservative. + if (idx == InitializeNode::RawAddress) + return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); + return RegMask::Empty; +} + +Node* InitializeNode::memory(uint alias_idx) { + Node* mem = in(Memory); + if (mem->is_MergeMem()) { + return mem->as_MergeMem()->memory_at(alias_idx); + } else { + // incoming raw memory is not split + return mem; + } +} + +bool InitializeNode::is_non_zero() { + if (is_complete()) return false; + remove_extra_zeroes(); + return (req() > RawStores); +} + +void InitializeNode::set_complete(PhaseGVN* phase) { + assert(!is_complete(), "caller responsibility"); + _is_complete = true; + + // After this node is complete, it contains a bunch of + // raw-memory initializations. There is no need for + // it to have anything to do with non-raw memory effects. + // Therefore, tell all non-raw users to re-optimize themselves, + // after skipping the memory effects of this initialization. + PhaseIterGVN* igvn = phase->is_IterGVN(); + if (igvn) igvn->add_users_to_worklist(this); +} + +// convenience function +// return false if the init contains any stores already +bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { + InitializeNode* init = initialization(); + if (init == NULL || init->is_complete()) return false; + init->remove_extra_zeroes(); + // for now, if this allocation has already collected any inits, bail: + if (init->is_non_zero()) return false; + init->set_complete(phase); + return true; +} + +void InitializeNode::remove_extra_zeroes() { + if (req() == RawStores) return; + Node* zmem = zero_memory(); + uint fill = RawStores; + for (uint i = fill; i < req(); i++) { + Node* n = in(i); + if (n->is_top() || n == zmem) continue; // skip + if (fill < i) set_req(fill, n); // compact + ++fill; + } + // delete any empty spaces created: + while (fill < req()) { + del_req(fill); + } +} + +// Helper for remembering which stores go with which offsets. +intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { + if (!st->is_Store()) return -1; // can happen to dead code via subsume_node + intptr_t offset = -1; + Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), + phase, offset); + if (base == NULL) return -1; // something is dead, + if (offset < 0) return -1; // dead, dead + return offset; +} + +// Helper for proving that an initialization expression is +// "simple enough" to be folded into an object initialization. +// Attempts to prove that a store's initial value 'n' can be captured +// within the initialization without creating a vicious cycle, such as: +// { Foo p = new Foo(); p.next = p; } +// True for constants and parameters and small combinations thereof. +bool InitializeNode::detect_init_independence(Node* n, + bool st_is_pinned, + int& count) { + if (n == NULL) return true; // (can this really happen?) + if (n->is_Proj()) n = n->in(0); + if (n == this) return false; // found a cycle + if (n->is_Con()) return true; + if (n->is_Start()) return true; // params, etc., are OK + if (n->is_Root()) return true; // even better + + Node* ctl = n->in(0); + if (ctl != NULL && !ctl->is_top()) { + if (ctl->is_Proj()) ctl = ctl->in(0); + if (ctl == this) return false; + + // If we already know that the enclosing memory op is pinned right after + // the init, then any control flow that the store has picked up + // must have preceded the init, or else be equal to the init. + // Even after loop optimizations (which might change control edges) + // a store is never pinned *before* the availability of its inputs. + if (!MemNode::detect_dominating_control(ctl, this->in(0))) + return false; // failed to prove a good control + + } + + // Check data edges for possible dependencies on 'this'. + if ((count += 1) > 20) return false; // complexity limit + for (uint i = 1; i < n->req(); i++) { + Node* m = n->in(i); + if (m == NULL || m == n || m->is_top()) continue; + uint first_i = n->find_edge(m); + if (i != first_i) continue; // process duplicate edge just once + if (!detect_init_independence(m, st_is_pinned, count)) { + return false; + } + } + + return true; +} + +// Here are all the checks a Store must pass before it can be moved into +// an initialization. Returns zero if a check fails. +// On success, returns the (constant) offset to which the store applies, +// within the initialized memory. +intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) { + const int FAIL = 0; + if (st->req() != MemNode::ValueIn + 1) + return FAIL; // an inscrutable StoreNode (card mark?) + Node* ctl = st->in(MemNode::Control); + if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) + return FAIL; // must be unconditional after the initialization + Node* mem = st->in(MemNode::Memory); + if (!(mem->is_Proj() && mem->in(0) == this)) + return FAIL; // must not be preceded by other stores + Node* adr = st->in(MemNode::Address); + intptr_t offset; + AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); + if (alloc == NULL) + return FAIL; // inscrutable address + if (alloc != allocation()) + return FAIL; // wrong allocation! (store needs to float up) + Node* val = st->in(MemNode::ValueIn); + int complexity_count = 0; + if (!detect_init_independence(val, true, complexity_count)) + return FAIL; // stored value must be 'simple enough' + + return offset; // success +} + +// Find the captured store in(i) which corresponds to the range +// [start..start+size) in the initialized object. +// If there is one, return its index i. If there isn't, return the +// negative of the index where it should be inserted. +// Return 0 if the queried range overlaps an initialization boundary +// or if dead code is encountered. +// If size_in_bytes is zero, do not bother with overlap checks. +int InitializeNode::captured_store_insertion_point(intptr_t start, + int size_in_bytes, + PhaseTransform* phase) { + const int FAIL = 0, MAX_STORE = BytesPerLong; + + if (is_complete()) + return FAIL; // arraycopy got here first; punt + + assert(allocation() != NULL, "must be present"); + + // no negatives, no header fields: + if (start < (intptr_t) sizeof(oopDesc)) return FAIL; + if (start < (intptr_t) sizeof(arrayOopDesc) && + start < (intptr_t) allocation()->minimum_header_size()) return FAIL; + + // after a certain size, we bail out on tracking all the stores: + intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); + if (start >= ti_limit) return FAIL; + + for (uint i = InitializeNode::RawStores, limit = req(); ; ) { + if (i >= limit) return -(int)i; // not found; here is where to put it + + Node* st = in(i); + intptr_t st_off = get_store_offset(st, phase); + if (st_off < 0) { + if (st != zero_memory()) { + return FAIL; // bail out if there is dead garbage + } + } else if (st_off > start) { + // ...we are done, since stores are ordered + if (st_off < start + size_in_bytes) { + return FAIL; // the next store overlaps + } + return -(int)i; // not found; here is where to put it + } else if (st_off < start) { + if (size_in_bytes != 0 && + start < st_off + MAX_STORE && + start < st_off + st->as_Store()->memory_size()) { + return FAIL; // the previous store overlaps + } + } else { + if (size_in_bytes != 0 && + st->as_Store()->memory_size() != size_in_bytes) { + return FAIL; // mismatched store size + } + return i; + } + + ++i; + } +} + +// Look for a captured store which initializes at the offset 'start' +// with the given size. If there is no such store, and no other +// initialization interferes, then return zero_memory (the memory +// projection of the AllocateNode). +Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, + PhaseTransform* phase) { + assert(stores_are_sane(phase), ""); + int i = captured_store_insertion_point(start, size_in_bytes, phase); + if (i == 0) { + return NULL; // something is dead + } else if (i < 0) { + return zero_memory(); // just primordial zero bits here + } else { + Node* st = in(i); // here is the store at this position + assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); + return st; + } +} + +// Create, as a raw pointer, an address within my new object at 'offset'. +Node* InitializeNode::make_raw_address(intptr_t offset, + PhaseTransform* phase) { + Node* addr = in(RawAddress); + if (offset != 0) { + Compile* C = phase->C; + addr = phase->transform( new (C, 4) AddPNode(C->top(), addr, + phase->MakeConX(offset)) ); + } + return addr; +} + +// Clone the given store, converting it into a raw store +// initializing a field or element of my new object. +// Caller is responsible for retiring the original store, +// with subsume_node or the like. +// +// From the example above InitializeNode::InitializeNode, +// here are the old stores to be captured: +// store1 = (StoreC init.Control init.Memory (+ oop 12) 1) +// store2 = (StoreC init.Control store1 (+ oop 14) 2) +// +// Here is the changed code; note the extra edges on init: +// alloc = (Allocate ...) +// rawoop = alloc.RawAddress +// rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) +// rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) +// init = (Initialize alloc.Control alloc.Memory rawoop +// rawstore1 rawstore2) +// +Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, + PhaseTransform* phase) { + assert(stores_are_sane(phase), ""); + + if (start < 0) return NULL; + assert(can_capture_store(st, phase) == start, "sanity"); + + Compile* C = phase->C; + int size_in_bytes = st->memory_size(); + int i = captured_store_insertion_point(start, size_in_bytes, phase); + if (i == 0) return NULL; // bail out + Node* prev_mem = NULL; // raw memory for the captured store + if (i > 0) { + prev_mem = in(i); // there is a pre-existing store under this one + set_req(i, C->top()); // temporarily disconnect it + // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. + } else { + i = -i; // no pre-existing store + prev_mem = zero_memory(); // a slice of the newly allocated object + if (i > InitializeNode::RawStores && in(i-1) == prev_mem) + set_req(--i, C->top()); // reuse this edge; it has been folded away + else + ins_req(i, C->top()); // build a new edge + } + Node* new_st = st->clone(); + new_st->set_req(MemNode::Control, in(Control)); + new_st->set_req(MemNode::Memory, prev_mem); + new_st->set_req(MemNode::Address, make_raw_address(start, phase)); + new_st = phase->transform(new_st); + + // At this point, new_st might have swallowed a pre-existing store + // at the same offset, or perhaps new_st might have disappeared, + // if it redundantly stored the same value (or zero to fresh memory). + + // In any case, wire it in: + set_req(i, new_st); + + // The caller may now kill the old guy. + DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); + assert(check_st == new_st || check_st == NULL, "must be findable"); + assert(!is_complete(), ""); + return new_st; +} + +static bool store_constant(jlong* tiles, int num_tiles, + intptr_t st_off, int st_size, + jlong con) { + if ((st_off & (st_size-1)) != 0) + return false; // strange store offset (assume size==2**N) + address addr = (address)tiles + st_off; + assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); + switch (st_size) { + case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; + case sizeof(jchar): *(jchar*) addr = (jchar) con; break; + case sizeof(jint): *(jint*) addr = (jint) con; break; + case sizeof(jlong): *(jlong*) addr = (jlong) con; break; + default: return false; // strange store size (detect size!=2**N here) + } + return true; // return success to caller +} + +// Coalesce subword constants into int constants and possibly +// into long constants. The goal, if the CPU permits, +// is to initialize the object with a small number of 64-bit tiles. +// Also, convert floating-point constants to bit patterns. +// Non-constants are not relevant to this pass. +// +// In terms of the running example on InitializeNode::InitializeNode +// and InitializeNode::capture_store, here is the transformation +// of rawstore1 and rawstore2 into rawstore12: +// alloc = (Allocate ...) +// rawoop = alloc.RawAddress +// tile12 = 0x00010002 +// rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) +// init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) +// +void +InitializeNode::coalesce_subword_stores(intptr_t header_size, + Node* size_in_bytes, + PhaseGVN* phase) { + Compile* C = phase->C; + + assert(stores_are_sane(phase), ""); + // Note: After this pass, they are not completely sane, + // since there may be some overlaps. + + int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; + + intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); + intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); + size_limit = MIN2(size_limit, ti_limit); + size_limit = align_size_up(size_limit, BytesPerLong); + int num_tiles = size_limit / BytesPerLong; + + // allocate space for the tile map: + const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small + jlong tiles_buf[small_len]; + Node* nodes_buf[small_len]; + jlong inits_buf[small_len]; + jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] + : NEW_RESOURCE_ARRAY(jlong, num_tiles)); + Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] + : NEW_RESOURCE_ARRAY(Node*, num_tiles)); + jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] + : NEW_RESOURCE_ARRAY(jlong, num_tiles)); + // tiles: exact bitwise model of all primitive constants + // nodes: last constant-storing node subsumed into the tiles model + // inits: which bytes (in each tile) are touched by any initializations + + //// Pass A: Fill in the tile model with any relevant stores. + + Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); + Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); + Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); + Node* zmem = zero_memory(); // initially zero memory state + for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { + Node* st = in(i); + intptr_t st_off = get_store_offset(st, phase); + + // Figure out the store's offset and constant value: + if (st_off < header_size) continue; //skip (ignore header) + if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) + int st_size = st->as_Store()->memory_size(); + if (st_off + st_size > size_limit) break; + + // Record which bytes are touched, whether by constant or not. + if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) + continue; // skip (strange store size) + + const Type* val = phase->type(st->in(MemNode::ValueIn)); + if (!val->singleton()) continue; //skip (non-con store) + BasicType type = val->basic_type(); + + jlong con = 0; + switch (type) { + case T_INT: con = val->is_int()->get_con(); break; + case T_LONG: con = val->is_long()->get_con(); break; + case T_FLOAT: con = jint_cast(val->getf()); break; + case T_DOUBLE: con = jlong_cast(val->getd()); break; + default: continue; //skip (odd store type) + } + + if (type == T_LONG && Matcher::isSimpleConstant64(con) && + st->Opcode() == Op_StoreL) { + continue; // This StoreL is already optimal. + } + + // Store down the constant. + store_constant(tiles, num_tiles, st_off, st_size, con); + + intptr_t j = st_off >> LogBytesPerLong; + + if (type == T_INT && st_size == BytesPerInt + && (st_off & BytesPerInt) == BytesPerInt) { + jlong lcon = tiles[j]; + if (!Matcher::isSimpleConstant64(lcon) && + st->Opcode() == Op_StoreI) { + // This StoreI is already optimal by itself. + jint* intcon = (jint*) &tiles[j]; + intcon[1] = 0; // undo the store_constant() + + // If the previous store is also optimal by itself, back up and + // undo the action of the previous loop iteration... if we can. + // But if we can't, just let the previous half take care of itself. + st = nodes[j]; + st_off -= BytesPerInt; + con = intcon[0]; + if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { + assert(st_off >= header_size, "still ignoring header"); + assert(get_store_offset(st, phase) == st_off, "must be"); + assert(in(i-1) == zmem, "must be"); + DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); + assert(con == tcon->is_int()->get_con(), "must be"); + // Undo the effects of the previous loop trip, which swallowed st: + intcon[0] = 0; // undo store_constant() + set_req(i-1, st); // undo set_req(i, zmem) + nodes[j] = NULL; // undo nodes[j] = st + --old_subword; // undo ++old_subword + } + continue; // This StoreI is already optimal. + } + } + + // This store is not needed. + set_req(i, zmem); + nodes[j] = st; // record for the moment + if (st_size < BytesPerLong) // something has changed + ++old_subword; // includes int/float, but who's counting... + else ++old_long; + } + + if ((old_subword + old_long) == 0) + return; // nothing more to do + + //// Pass B: Convert any non-zero tiles into optimal constant stores. + // Be sure to insert them before overlapping non-constant stores. + // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) + for (int j = 0; j < num_tiles; j++) { + jlong con = tiles[j]; + jlong init = inits[j]; + if (con == 0) continue; + jint con0, con1; // split the constant, address-wise + jint init0, init1; // split the init map, address-wise + { union { jlong con; jint intcon[2]; } u; + u.con = con; + con0 = u.intcon[0]; + con1 = u.intcon[1]; + u.con = init; + init0 = u.intcon[0]; + init1 = u.intcon[1]; + } + + Node* old = nodes[j]; + assert(old != NULL, "need the prior store"); + intptr_t offset = (j * BytesPerLong); + + bool split = !Matcher::isSimpleConstant64(con); + + if (offset < header_size) { + assert(offset + BytesPerInt >= header_size, "second int counts"); + assert(*(jint*)&tiles[j] == 0, "junk in header"); + split = true; // only the second word counts + // Example: int a[] = { 42 ... } + } else if (con0 == 0 && init0 == -1) { + split = true; // first word is covered by full inits + // Example: int a[] = { ... foo(), 42 ... } + } else if (con1 == 0 && init1 == -1) { + split = true; // second word is covered by full inits + // Example: int a[] = { ... 42, foo() ... } + } + + // Here's a case where init0 is neither 0 nor -1: + // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } + // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. + // In this case the tile is not split; it is (jlong)42. + // The big tile is stored down, and then the foo() value is inserted. + // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) + + Node* ctl = old->in(MemNode::Control); + Node* adr = make_raw_address(offset, phase); + const TypePtr* atp = TypeRawPtr::BOTTOM; + + // One or two coalesced stores to plop down. + Node* st[2]; + intptr_t off[2]; + int nst = 0; + if (!split) { + ++new_long; + off[nst] = offset; + st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp, + phase->longcon(con), T_LONG); + } else { + // Omit either if it is a zero. + if (con0 != 0) { + ++new_int; + off[nst] = offset; + st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp, + phase->intcon(con0), T_INT); + } + if (con1 != 0) { + ++new_int; + offset += BytesPerInt; + adr = make_raw_address(offset, phase); + off[nst] = offset; + st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp, + phase->intcon(con1), T_INT); + } + } + + // Insert second store first, then the first before the second. + // Insert each one just before any overlapping non-constant stores. + while (nst > 0) { + Node* st1 = st[--nst]; + C->copy_node_notes_to(st1, old); + st1 = phase->transform(st1); + offset = off[nst]; + assert(offset >= header_size, "do not smash header"); + int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); + guarantee(ins_idx != 0, "must re-insert constant store"); + if (ins_idx < 0) ins_idx = -ins_idx; // never overlap + if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) + set_req(--ins_idx, st1); + else + ins_req(ins_idx, st1); + } + } + + if (PrintCompilation && WizardMode) + tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", + old_subword, old_long, new_int, new_long); + if (C->log() != NULL) + C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", + old_subword, old_long, new_int, new_long); + + // Clean up any remaining occurrences of zmem: + remove_extra_zeroes(); +} + +// Explore forward from in(start) to find the first fully initialized +// word, and return its offset. Skip groups of subword stores which +// together initialize full words. If in(start) is itself part of a +// fully initialized word, return the offset of in(start). If there +// are no following full-word stores, or if something is fishy, return +// a negative value. +intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { + int int_map = 0; + intptr_t int_map_off = 0; + const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for + + for (uint i = start, limit = req(); i < limit; i++) { + Node* st = in(i); + + intptr_t st_off = get_store_offset(st, phase); + if (st_off < 0) break; // return conservative answer + + int st_size = st->as_Store()->memory_size(); + if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { + return st_off; // we found a complete word init + } + + // update the map: + + intptr_t this_int_off = align_size_down(st_off, BytesPerInt); + if (this_int_off != int_map_off) { + // reset the map: + int_map = 0; + int_map_off = this_int_off; + } + + int subword_off = st_off - this_int_off; + int_map |= right_n_bits(st_size) << subword_off; + if ((int_map & FULL_MAP) == FULL_MAP) { + return this_int_off; // we found a complete word init + } + + // Did this store hit or cross the word boundary? + intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); + if (next_int_off == this_int_off + BytesPerInt) { + // We passed the current int, without fully initializing it. + int_map_off = next_int_off; + int_map >>= BytesPerInt; + } else if (next_int_off > this_int_off + BytesPerInt) { + // We passed the current and next int. + return this_int_off + BytesPerInt; + } + } + + return -1; +} + + +// Called when the associated AllocateNode is expanded into CFG. +// At this point, we may perform additional optimizations. +// Linearize the stores by ascending offset, to make memory +// activity as coherent as possible. +Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, + intptr_t header_size, + Node* size_in_bytes, + PhaseGVN* phase) { + assert(!is_complete(), "not already complete"); + assert(stores_are_sane(phase), ""); + assert(allocation() != NULL, "must be present"); + + remove_extra_zeroes(); + + if (ReduceFieldZeroing || ReduceBulkZeroing) + // reduce instruction count for common initialization patterns + coalesce_subword_stores(header_size, size_in_bytes, phase); + + Node* zmem = zero_memory(); // initially zero memory state + Node* inits = zmem; // accumulating a linearized chain of inits + #ifdef ASSERT + intptr_t last_init_off = sizeof(oopDesc); // previous init offset + intptr_t last_init_end = sizeof(oopDesc); // previous init offset+size + intptr_t last_tile_end = sizeof(oopDesc); // previous tile offset+size + #endif + intptr_t zeroes_done = header_size; + + bool do_zeroing = true; // we might give up if inits are very sparse + int big_init_gaps = 0; // how many large gaps have we seen? + + if (ZeroTLAB) do_zeroing = false; + if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; + + for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { + Node* st = in(i); + intptr_t st_off = get_store_offset(st, phase); + if (st_off < 0) + break; // unknown junk in the inits + if (st->in(MemNode::Memory) != zmem) + break; // complicated store chains somehow in list + + int st_size = st->as_Store()->memory_size(); + intptr_t next_init_off = st_off + st_size; + + if (do_zeroing && zeroes_done < next_init_off) { + // See if this store needs a zero before it or under it. + intptr_t zeroes_needed = st_off; + + if (st_size < BytesPerInt) { + // Look for subword stores which only partially initialize words. + // If we find some, we must lay down some word-level zeroes first, + // underneath the subword stores. + // + // Examples: + // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s + // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y + // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z + // + // Note: coalesce_subword_stores may have already done this, + // if it was prompted by constant non-zero subword initializers. + // But this case can still arise with non-constant stores. + + intptr_t next_full_store = find_next_fullword_store(i, phase); + + // In the examples above: + // in(i) p q r s x y z + // st_off 12 13 14 15 12 13 14 + // st_size 1 1 1 1 1 1 1 + // next_full_s. 12 16 16 16 16 16 16 + // z's_done 12 16 16 16 12 16 12 + // z's_needed 12 16 16 16 16 16 16 + // zsize 0 0 0 0 4 0 4 + if (next_full_store < 0) { + // Conservative tack: Zero to end of current word. + zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); + } else { + // Zero to beginning of next fully initialized word. + // Or, don't zero at all, if we are already in that word. + assert(next_full_store >= zeroes_needed, "must go forward"); + assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); + zeroes_needed = next_full_store; + } + } + + if (zeroes_needed > zeroes_done) { + intptr_t zsize = zeroes_needed - zeroes_done; + // Do some incremental zeroing on rawmem, in parallel with inits. + zeroes_done = align_size_down(zeroes_done, BytesPerInt); + rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, + zeroes_done, zeroes_needed, + phase); + zeroes_done = zeroes_needed; + if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) + do_zeroing = false; // leave the hole, next time + } + } + + // Collect the store and move on: + st->set_req(MemNode::Memory, inits); + inits = st; // put it on the linearized chain + set_req(i, zmem); // unhook from previous position + + if (zeroes_done == st_off) + zeroes_done = next_init_off; + + assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); + + #ifdef ASSERT + // Various order invariants. Weaker than stores_are_sane because + // a large constant tile can be filled in by smaller non-constant stores. + assert(st_off >= last_init_off, "inits do not reverse"); + last_init_off = st_off; + const Type* val = NULL; + if (st_size >= BytesPerInt && + (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && + (int)val->basic_type() < (int)T_OBJECT) { + assert(st_off >= last_tile_end, "tiles do not overlap"); + assert(st_off >= last_init_end, "tiles do not overwrite inits"); + last_tile_end = MAX2(last_tile_end, next_init_off); + } else { + intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); + assert(st_tile_end >= last_tile_end, "inits stay with tiles"); + assert(st_off >= last_init_end, "inits do not overlap"); + last_init_end = next_init_off; // it's a non-tile + } + #endif //ASSERT + } + + remove_extra_zeroes(); // clear out all the zmems left over + add_req(inits); + + if (!ZeroTLAB) { + // If anything remains to be zeroed, zero it all now. + zeroes_done = align_size_down(zeroes_done, BytesPerInt); + // if it is the last unused 4 bytes of an instance, forget about it + intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); + if (zeroes_done + BytesPerLong >= size_limit) { + assert(allocation() != NULL, ""); + Node* klass_node = allocation()->in(AllocateNode::KlassNode); + ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); + if (zeroes_done == k->layout_helper()) + zeroes_done = size_limit; + } + if (zeroes_done < size_limit) { + rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, + zeroes_done, size_in_bytes, phase); + } + } + + set_complete(phase); + return rawmem; +} + + +#ifdef ASSERT +bool InitializeNode::stores_are_sane(PhaseTransform* phase) { + if (is_complete()) + return true; // stores could be anything at this point + intptr_t last_off = sizeof(oopDesc); + for (uint i = InitializeNode::RawStores; i < req(); i++) { + Node* st = in(i); + intptr_t st_off = get_store_offset(st, phase); + if (st_off < 0) continue; // ignore dead garbage + if (last_off > st_off) { + tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off); + this->dump(2); + assert(false, "ascending store offsets"); + return false; + } + last_off = st_off + st->as_Store()->memory_size(); + } + return true; +} +#endif //ASSERT + + + + +//============================MergeMemNode===================================== +// +// SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several +// contributing store or call operations. Each contributor provides the memory +// state for a particular "alias type" (see Compile::alias_type). For example, +// if a MergeMem has an input X for alias category #6, then any memory reference +// to alias category #6 may use X as its memory state input, as an exact equivalent +// to using the MergeMem as a whole. +// Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) +// +// (Here, the <N> notation gives the index of the relevant adr_type.) +// +// In one special case (and more cases in the future), alias categories overlap. +// The special alias category "Bot" (Compile::AliasIdxBot) includes all memory +// states. Therefore, if a MergeMem has only one contributing input W for Bot, +// it is exactly equivalent to that state W: +// MergeMem(<Bot>: W) <==> W +// +// Usually, the merge has more than one input. In that case, where inputs +// overlap (i.e., one is Bot), the narrower alias type determines the memory +// state for that type, and the wider alias type (Bot) fills in everywhere else: +// Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) +// Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) +// +// A merge can take a "wide" memory state as one of its narrow inputs. +// This simply means that the merge observes out only the relevant parts of +// the wide input. That is, wide memory states arriving at narrow merge inputs +// are implicitly "filtered" or "sliced" as necessary. (This is rare.) +// +// These rules imply that MergeMem nodes may cascade (via their <Bot> links), +// and that memory slices "leak through": +// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) +// +// But, in such a cascade, repeated memory slices can "block the leak": +// MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') +// +// In the last example, Y is not part of the combined memory state of the +// outermost MergeMem. The system must, of course, prevent unschedulable +// memory states from arising, so you can be sure that the state Y is somehow +// a precursor to state Y'. +// +// +// REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array +// of each MergeMemNode array are exactly the numerical alias indexes, including +// but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions +// Compile::alias_type (and kin) produce and manage these indexes. +// +// By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. +// (Note that this provides quick access to the top node inside MergeMem methods, +// without the need to reach out via TLS to Compile::current.) +// +// As a consequence of what was just described, a MergeMem that represents a full +// memory state has an edge in(AliasIdxBot) which is a "wide" memory state, +// containing all alias categories. +// +// MergeMem nodes never (?) have control inputs, so in(0) is NULL. +// +// All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either +// a memory state for the alias type <N>, or else the top node, meaning that +// there is no particular input for that alias type. Note that the length of +// a MergeMem is variable, and may be extended at any time to accommodate new +// memory states at larger alias indexes. When merges grow, they are of course +// filled with "top" in the unused in() positions. +// +// This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. +// (Top was chosen because it works smoothly with passes like GCM.) +// +// For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is +// the type of random VM bits like TLS references.) Since it is always the +// first non-Bot memory slice, some low-level loops use it to initialize an +// index variable: for (i = AliasIdxRaw; i < req(); i++). +// +// +// ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns +// the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns +// the memory state for alias type <N>, or (if there is no particular slice at <N>, +// it returns the base memory. To prevent bugs, memory_at does not accept <Top> +// or <Bot> indexes. The iterator MergeMemStream provides robust iteration over +// MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. +// +// %%%% We may get rid of base_memory as a separate accessor at some point; it isn't +// really that different from the other memory inputs. An abbreviation called +// "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. +// +// +// PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent +// partial memory states. When a Phi splits through a MergeMem, the copy of the Phi +// that "emerges though" the base memory will be marked as excluding the alias types +// of the other (narrow-memory) copies which "emerged through" the narrow edges: +// +// Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) +// ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) +// +// This strange "subtraction" effect is necessary to ensure IGVN convergence. +// (It is currently unimplemented.) As you can see, the resulting merge is +// actually a disjoint union of memory states, rather than an overlay. +// + +//------------------------------MergeMemNode----------------------------------- +Node* MergeMemNode::make_empty_memory() { + Node* empty_memory = (Node*) Compile::current()->top(); + assert(empty_memory->is_top(), "correct sentinel identity"); + return empty_memory; +} + +MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { + init_class_id(Class_MergeMem); + // all inputs are nullified in Node::Node(int) + // set_input(0, NULL); // no control input + + // Initialize the edges uniformly to top, for starters. + Node* empty_mem = make_empty_memory(); + for (uint i = Compile::AliasIdxTop; i < req(); i++) { + init_req(i,empty_mem); + } + assert(empty_memory() == empty_mem, ""); + + if( new_base != NULL && new_base->is_MergeMem() ) { + MergeMemNode* mdef = new_base->as_MergeMem(); + assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); + for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { + mms.set_memory(mms.memory2()); + } + assert(base_memory() == mdef->base_memory(), ""); + } else { + set_base_memory(new_base); + } +} + +// Make a new, untransformed MergeMem with the same base as 'mem'. +// If mem is itself a MergeMem, populate the result with the same edges. +MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) { + return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem); +} + +//------------------------------cmp-------------------------------------------- +uint MergeMemNode::hash() const { return NO_HASH; } +uint MergeMemNode::cmp( const Node &n ) const { + return (&n == this); // Always fail except on self +} + +//------------------------------Identity--------------------------------------- +Node* MergeMemNode::Identity(PhaseTransform *phase) { + // Identity if this merge point does not record any interesting memory + // disambiguations. + Node* base_mem = base_memory(); + Node* empty_mem = empty_memory(); + if (base_mem != empty_mem) { // Memory path is not dead? + for (uint i = Compile::AliasIdxRaw; i < req(); i++) { + Node* mem = in(i); + if (mem != empty_mem && mem != base_mem) { + return this; // Many memory splits; no change + } + } + } + return base_mem; // No memory splits; ID on the one true input +} + +//------------------------------Ideal------------------------------------------ +// This method is invoked recursively on chains of MergeMem nodes +Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { + // Remove chain'd MergeMems + // + // This is delicate, because the each "in(i)" (i >= Raw) is interpreted + // relative to the "in(Bot)". Since we are patching both at the same time, + // we have to be careful to read each "in(i)" relative to the old "in(Bot)", + // but rewrite each "in(i)" relative to the new "in(Bot)". + Node *progress = NULL; + + + Node* old_base = base_memory(); + Node* empty_mem = empty_memory(); + if (old_base == empty_mem) + return NULL; // Dead memory path. + + MergeMemNode* old_mbase; + if (old_base != NULL && old_base->is_MergeMem()) + old_mbase = old_base->as_MergeMem(); + else + old_mbase = NULL; + Node* new_base = old_base; + + // simplify stacked MergeMems in base memory + if (old_mbase) new_base = old_mbase->base_memory(); + + // the base memory might contribute new slices beyond my req() + if (old_mbase) grow_to_match(old_mbase); + + // Look carefully at the base node if it is a phi. + PhiNode* phi_base; + if (new_base != NULL && new_base->is_Phi()) + phi_base = new_base->as_Phi(); + else + phi_base = NULL; + + Node* phi_reg = NULL; + uint phi_len = (uint)-1; + if (phi_base != NULL && !phi_base->is_copy()) { + // do not examine phi if degraded to a copy + phi_reg = phi_base->region(); + phi_len = phi_base->req(); + // see if the phi is unfinished + for (uint i = 1; i < phi_len; i++) { + if (phi_base->in(i) == NULL) { + // incomplete phi; do not look at it yet! + phi_reg = NULL; + phi_len = (uint)-1; + break; + } + } + } + + // Note: We do not call verify_sparse on entry, because inputs + // can normalize to the base_memory via subsume_node or similar + // mechanisms. This method repairs that damage. + + assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); + + // Look at each slice. + for (uint i = Compile::AliasIdxRaw; i < req(); i++) { + Node* old_in = in(i); + // calculate the old memory value + Node* old_mem = old_in; + if (old_mem == empty_mem) old_mem = old_base; + assert(old_mem == memory_at(i), ""); + + // maybe update (reslice) the old memory value + + // simplify stacked MergeMems + Node* new_mem = old_mem; + MergeMemNode* old_mmem; + if (old_mem != NULL && old_mem->is_MergeMem()) + old_mmem = old_mem->as_MergeMem(); + else + old_mmem = NULL; + if (old_mmem == this) { + // This can happen if loops break up and safepoints disappear. + // A merge of BotPtr (default) with a RawPtr memory derived from a + // safepoint can be rewritten to a merge of the same BotPtr with + // the BotPtr phi coming into the loop. If that phi disappears + // also, we can end up with a self-loop of the mergemem. + // In general, if loops degenerate and memory effects disappear, + // a mergemem can be left looking at itself. This simply means + // that the mergemem's default should be used, since there is + // no longer any apparent effect on this slice. + // Note: If a memory slice is a MergeMem cycle, it is unreachable + // from start. Update the input to TOP. + new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; + } + else if (old_mmem != NULL) { + new_mem = old_mmem->memory_at(i); + } + // else preceeding memory was not a MergeMem + + // replace equivalent phis (unfortunately, they do not GVN together) + if (new_mem != NULL && new_mem != new_base && + new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { + if (new_mem->is_Phi()) { + PhiNode* phi_mem = new_mem->as_Phi(); + for (uint i = 1; i < phi_len; i++) { + if (phi_base->in(i) != phi_mem->in(i)) { + phi_mem = NULL; + break; + } + } + if (phi_mem != NULL) { + // equivalent phi nodes; revert to the def + new_mem = new_base; + } + } + } + + // maybe store down a new value + Node* new_in = new_mem; + if (new_in == new_base) new_in = empty_mem; + + if (new_in != old_in) { + // Warning: Do not combine this "if" with the previous "if" + // A memory slice might have be be rewritten even if it is semantically + // unchanged, if the base_memory value has changed. + set_req(i, new_in); + progress = this; // Report progress + } + } + + if (new_base != old_base) { + set_req(Compile::AliasIdxBot, new_base); + // Don't use set_base_memory(new_base), because we need to update du. + assert(base_memory() == new_base, ""); + progress = this; + } + + if( base_memory() == this ) { + // a self cycle indicates this memory path is dead + set_req(Compile::AliasIdxBot, empty_mem); + } + + // Resolve external cycles by calling Ideal on a MergeMem base_memory + // Recursion must occur after the self cycle check above + if( base_memory()->is_MergeMem() ) { + MergeMemNode *new_mbase = base_memory()->as_MergeMem(); + Node *m = phase->transform(new_mbase); // Rollup any cycles + if( m != NULL && (m->is_top() || + m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { + // propagate rollup of dead cycle to self + set_req(Compile::AliasIdxBot, empty_mem); + } + } + + if( base_memory() == empty_mem ) { + progress = this; + // Cut inputs during Parse phase only. + // During Optimize phase a dead MergeMem node will be subsumed by Top. + if( !can_reshape ) { + for (uint i = Compile::AliasIdxRaw; i < req(); i++) { + if( in(i) != empty_mem ) { set_req(i, empty_mem); } + } + } + } + + if( !progress && base_memory()->is_Phi() && can_reshape ) { + // Check if PhiNode::Ideal's "Split phis through memory merges" + // transform should be attempted. Look for this->phi->this cycle. + uint merge_width = req(); + if (merge_width > Compile::AliasIdxRaw) { + PhiNode* phi = base_memory()->as_Phi(); + for( uint i = 1; i < phi->req(); ++i ) {// For all paths in + if (phi->in(i) == this) { + phase->is_IterGVN()->_worklist.push(phi); + break; + } + } + } + } + + assert(verify_sparse(), "please, no dups of base"); + return progress; +} + +//-------------------------set_base_memory------------------------------------- +void MergeMemNode::set_base_memory(Node *new_base) { + Node* empty_mem = empty_memory(); + set_req(Compile::AliasIdxBot, new_base); + assert(memory_at(req()) == new_base, "must set default memory"); + // Clear out other occurrences of new_base: + if (new_base != empty_mem) { + for (uint i = Compile::AliasIdxRaw; i < req(); i++) { + if (in(i) == new_base) set_req(i, empty_mem); + } + } +} + +//------------------------------out_RegMask------------------------------------ +const RegMask &MergeMemNode::out_RegMask() const { + return RegMask::Empty; +} + +//------------------------------dump_spec-------------------------------------- +#ifndef PRODUCT +void MergeMemNode::dump_spec(outputStream *st) const { + st->print(" {"); + Node* base_mem = base_memory(); + for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { + Node* mem = memory_at(i); + if (mem == base_mem) { st->print(" -"); continue; } + st->print( " N%d:", mem->_idx ); + Compile::current()->get_adr_type(i)->dump_on(st); + } + st->print(" }"); +} +#endif // !PRODUCT + + +#ifdef ASSERT +static bool might_be_same(Node* a, Node* b) { + if (a == b) return true; + if (!(a->is_Phi() || b->is_Phi())) return false; + // phis shift around during optimization + return true; // pretty stupid... +} + +// verify a narrow slice (either incoming or outgoing) +static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { + if (!VerifyAliases) return; // don't bother to verify unless requested + if (is_error_reported()) return; // muzzle asserts when debugging an error + if (Node::in_dump()) return; // muzzle asserts when printing + assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); + assert(n != NULL, ""); + // Elide intervening MergeMem's + while (n->is_MergeMem()) { + n = n->as_MergeMem()->memory_at(alias_idx); + } + Compile* C = Compile::current(); + const TypePtr* n_adr_type = n->adr_type(); + if (n == m->empty_memory()) { + // Implicit copy of base_memory() + } else if (n_adr_type != TypePtr::BOTTOM) { + assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); + assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); + } else { + // A few places like make_runtime_call "know" that VM calls are narrow, + // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. + bool expected_wide_mem = false; + if (n == m->base_memory()) { + expected_wide_mem = true; + } else if (alias_idx == Compile::AliasIdxRaw || + n == m->memory_at(Compile::AliasIdxRaw)) { + expected_wide_mem = true; + } else if (!C->alias_type(alias_idx)->is_rewritable()) { + // memory can "leak through" calls on channels that + // are write-once. Allow this also. + expected_wide_mem = true; + } + assert(expected_wide_mem, "expected narrow slice replacement"); + } +} +#else // !ASSERT +#define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op +#endif + + +//-----------------------------memory_at--------------------------------------- +Node* MergeMemNode::memory_at(uint alias_idx) const { + assert(alias_idx >= Compile::AliasIdxRaw || + alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, + "must avoid base_memory and AliasIdxTop"); + + // Otherwise, it is a narrow slice. + Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); + Compile *C = Compile::current(); + if (is_empty_memory(n)) { + // the array is sparse; empty slots are the "top" node + n = base_memory(); + assert(Node::in_dump() + || n == NULL || n->bottom_type() == Type::TOP + || n->adr_type() == TypePtr::BOTTOM + || n->adr_type() == TypeRawPtr::BOTTOM + || Compile::current()->AliasLevel() == 0, + "must be a wide memory"); + // AliasLevel == 0 if we are organizing the memory states manually. + // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. + } else { + // make sure the stored slice is sane + #ifdef ASSERT + if (is_error_reported() || Node::in_dump()) { + } else if (might_be_same(n, base_memory())) { + // Give it a pass: It is a mostly harmless repetition of the base. + // This can arise normally from node subsumption during optimization. + } else { + verify_memory_slice(this, alias_idx, n); + } + #endif + } + return n; +} + +//---------------------------set_memory_at------------------------------------- +void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { + verify_memory_slice(this, alias_idx, n); + Node* empty_mem = empty_memory(); + if (n == base_memory()) n = empty_mem; // collapse default + uint need_req = alias_idx+1; + if (req() < need_req) { + if (n == empty_mem) return; // already the default, so do not grow me + // grow the sparse array + do { + add_req(empty_mem); + } while (req() < need_req); + } + set_req( alias_idx, n ); +} + + + +//--------------------------iteration_setup------------------------------------ +void MergeMemNode::iteration_setup(const MergeMemNode* other) { + if (other != NULL) { + grow_to_match(other); + // invariant: the finite support of mm2 is within mm->req() + #ifdef ASSERT + for (uint i = req(); i < other->req(); i++) { + assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); + } + #endif + } + // Replace spurious copies of base_memory by top. + Node* base_mem = base_memory(); + if (base_mem != NULL && !base_mem->is_top()) { + for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { + if (in(i) == base_mem) + set_req(i, empty_memory()); + } + } +} + +//---------------------------grow_to_match------------------------------------- +void MergeMemNode::grow_to_match(const MergeMemNode* other) { + Node* empty_mem = empty_memory(); + assert(other->is_empty_memory(empty_mem), "consistent sentinels"); + // look for the finite support of the other memory + for (uint i = other->req(); --i >= req(); ) { + if (other->in(i) != empty_mem) { + uint new_len = i+1; + while (req() < new_len) add_req(empty_mem); + break; + } + } +} + +//---------------------------verify_sparse------------------------------------- +#ifndef PRODUCT +bool MergeMemNode::verify_sparse() const { + assert(is_empty_memory(make_empty_memory()), "sane sentinel"); + Node* base_mem = base_memory(); + // The following can happen in degenerate cases, since empty==top. + if (is_empty_memory(base_mem)) return true; + for (uint i = Compile::AliasIdxRaw; i < req(); i++) { + assert(in(i) != NULL, "sane slice"); + if (in(i) == base_mem) return false; // should have been the sentinel value! + } + return true; +} + +bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { + Node* n; + n = mm->in(idx); + if (mem == n) return true; // might be empty_memory() + n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); + if (mem == n) return true; + while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { + if (mem == n) return true; + if (n == NULL) break; + } + return false; +} +#endif // !PRODUCT