Mercurial > hg > graal-jvmci-8
diff src/share/vm/opto/loopPredicate.cpp @ 3345:bad7ecd0b6ed
5091921: Sign flip issues in loop optimizer
Summary: Fix integer overflow problem in the code generated by loop optimizer.
Reviewed-by: never
author | kvn |
---|---|
date | Wed, 04 May 2011 13:12:42 -0700 |
parents | 2e038ad0c1d0 |
children | 4e761e7e6e12 |
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--- a/src/share/vm/opto/loopPredicate.cpp Wed May 04 03:42:58 2011 -0700 +++ b/src/share/vm/opto/loopPredicate.cpp Wed May 04 13:12:42 2011 -0700 @@ -341,7 +341,7 @@ // Cut predicate from old place. Node* old = predicate_proj; igvn->_worklist.push(old); - for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) { + for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin;) { Node* use = old->last_out(i); // for each use... igvn->hash_delete(use); igvn->_worklist.push(use); @@ -384,24 +384,25 @@ //--------------------------clone_loop_predicates----------------------- // Interface from IGVN -Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry) { - return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, false, NULL, this); +Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { + return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, false, clone_limit_check, NULL, this); } -Node* PhaseIterGVN::move_loop_predicates(Node* old_entry, Node* new_entry) { - return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, true, NULL, this); +Node* PhaseIterGVN::move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { + return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, true, clone_limit_check, NULL, this); } // Interface from PhaseIdealLoop -Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry) { - return clone_loop_predicates(old_entry, new_entry, false, this, &this->_igvn); +Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { + return clone_loop_predicates(old_entry, new_entry, false, clone_limit_check, this, &this->_igvn); } -Node* PhaseIdealLoop::move_loop_predicates(Node* old_entry, Node* new_entry) { - return clone_loop_predicates(old_entry, new_entry, true, this, &this->_igvn); +Node* PhaseIdealLoop::move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { + return clone_loop_predicates(old_entry, new_entry, true, clone_limit_check, this, &this->_igvn); } // Clone loop predicates to cloned loops (peeled, unswitched, split_if). Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool move_predicates, + bool clone_limit_check, PhaseIdealLoop* loop_phase, PhaseIterGVN* igvn) { #ifdef ASSERT @@ -413,10 +414,16 @@ #endif // Search original predicates Node* entry = old_entry; + ProjNode* limit_check_proj = NULL; + if (LoopLimitCheck) { + limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); + if (limit_check_proj != NULL) { + entry = entry->in(0)->in(0); + } + } if (UseLoopPredicate) { ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (predicate_proj != NULL) { // right pattern that can be used by loop predication - assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); if (move_predicates) { new_entry = move_predicate(predicate_proj, new_entry, Deoptimization::Reason_predicate, @@ -435,11 +442,37 @@ } } } + if (limit_check_proj != NULL && clone_limit_check) { + // Clone loop limit check last to insert it before loop. + // Don't clone a limit check which was already finalized + // for this counted loop (only one limit check is needed). + if (move_predicates) { + new_entry = move_predicate(limit_check_proj, new_entry, + Deoptimization::Reason_loop_limit_check, + loop_phase, igvn); + assert(new_entry == limit_check_proj, "old limit check fall through projection"); + } else { + new_entry = clone_predicate(limit_check_proj, new_entry, + Deoptimization::Reason_loop_limit_check, + loop_phase, igvn); + assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check"); + } + if (TraceLoopLimitCheck) { + tty->print_cr("Loop Limit Check %s: ", move_predicates ? "moved" : "cloned"); + debug_only( new_entry->in(0)->dump(); ) + } + } return new_entry; } //--------------------------eliminate_loop_predicates----------------------- void PhaseIdealLoop::eliminate_loop_predicates(Node* entry) { + if (LoopLimitCheck) { + Node* predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); + if (predicate != NULL) { + entry = entry->in(0)->in(0); + } + } if (UseLoopPredicate) { ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (predicate_proj != NULL) { // right pattern that can be used by loop predication @@ -456,10 +489,15 @@ // Skip related predicates. Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) { Node* predicate = NULL; + if (LoopLimitCheck) { + predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); + if (predicate != NULL) { + entry = entry->in(0)->in(0); + } + } if (UseLoopPredicate) { predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (predicate != NULL) { // right pattern that can be used by loop predication - assert(entry->is_Proj() && entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); IfNode* iff = entry->in(0)->as_If(); ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con); Node* rgn = uncommon_proj->unique_ctrl_out(); @@ -491,10 +529,15 @@ // Find a predicate Node* PhaseIdealLoop::find_predicate(Node* entry) { Node* predicate = NULL; + if (LoopLimitCheck) { + predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); + if (predicate != NULL) { // right pattern that can be used by loop predication + return entry; + } + } if (UseLoopPredicate) { predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (predicate != NULL) { // right pattern that can be used by loop predication - assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); return entry; } } @@ -658,7 +701,7 @@ Node* range = cmp->in(2); if (range->Opcode() != Op_LoadRange) { const TypeInt* tint = phase->_igvn.type(range)->isa_int(); - if (!OptimizeFill || tint == NULL || tint->empty() || tint->_lo < 0) { + if (tint == NULL || tint->empty() || tint->_lo < 0) { // Allow predication on positive values that aren't LoadRanges. // This allows optimization of loops where the length of the // array is a known value and doesn't need to be loaded back @@ -696,7 +739,7 @@ // max(scale*i + offset) = scale*(limit-stride) + offset // (2) stride*scale < 0 // max(scale*i + offset) = scale*init + offset -BoolNode* PhaseIdealLoop::rc_predicate(Node* ctrl, +BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl, int scale, Node* offset, Node* init, Node* limit, Node* stride, Node* range, bool upper) { @@ -709,9 +752,19 @@ Node* max_idx_expr = init; int stride_con = stride->get_int(); if ((stride_con > 0) == (scale > 0) == upper) { - max_idx_expr = new (C, 3) SubINode(limit, stride); - register_new_node(max_idx_expr, ctrl); - if (TraceLoopPredicate) predString->print("(limit - stride) "); + if (LoopLimitCheck) { + // With LoopLimitCheck limit is not exact. + // Calculate exact limit here. + // Note, counted loop's test is '<' or '>'. + limit = exact_limit(loop); + max_idx_expr = new (C, 3) SubINode(limit, stride); + register_new_node(max_idx_expr, ctrl); + if (TraceLoopPredicate) predString->print("(limit - stride) "); + } else { + max_idx_expr = new (C, 3) SubINode(limit, stride); + register_new_node(max_idx_expr, ctrl); + if (TraceLoopPredicate) predString->print("(limit - stride) "); + } } else { if (TraceLoopPredicate) predString->print("init "); } @@ -752,29 +805,36 @@ // Could be a simple region when irreducible loops are present. return false; } + LoopNode* head = loop->_head->as_Loop(); - if (loop->_head->unique_ctrl_out()->Opcode() == Op_NeverBranch) { + if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) { // do nothing for infinite loops return false; } CountedLoopNode *cl = NULL; - if (loop->_head->is_CountedLoop()) { - cl = loop->_head->as_CountedLoop(); + if (head->is_CountedLoop()) { + cl = head->as_CountedLoop(); // do nothing for iteration-splitted loops if (!cl->is_normal_loop()) return false; } - LoopNode *lpn = loop->_head->as_Loop(); - Node* entry = lpn->in(LoopNode::EntryControl); + Node* entry = head->in(LoopNode::EntryControl); + ProjNode *predicate_proj = NULL; + // Loop limit check predicate should be near the loop. + if (LoopLimitCheck) { + predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); + if (predicate_proj != NULL) + entry = predicate_proj->in(0)->in(0); + } - ProjNode *predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); + predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); if (!predicate_proj) { #ifndef PRODUCT if (TraceLoopPredicate) { tty->print("missing predicate:"); loop->dump_head(); - lpn->dump(1); + head->dump(1); } #endif return false; @@ -788,7 +848,6 @@ // Create list of if-projs such that a newer proj dominates all older // projs in the list, and they all dominate loop->tail() Node_List if_proj_list(area); - LoopNode *head = loop->_head->as_Loop(); Node *current_proj = loop->tail(); //start from tail while (current_proj != head) { if (loop == get_loop(current_proj) && // still in the loop ? @@ -862,8 +921,8 @@ const Node* cmp = bol->in(1)->as_Cmp(); Node* idx = cmp->in(1); assert(!invar.is_invariant(idx), "index is variant"); - assert(cmp->in(2)->Opcode() == Op_LoadRange || OptimizeFill, "must be"); Node* rng = cmp->in(2); + assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int() >= 0, "must be"); assert(invar.is_invariant(rng), "range must be invariant"); int scale = 1; Node* offset = zero; @@ -892,14 +951,14 @@ } // Test the lower bound - Node* lower_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, false); + Node* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false); IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If(); _igvn.hash_delete(lower_bound_iff); lower_bound_iff->set_req(1, lower_bound_bol); if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx); // Test the upper bound - Node* upper_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, true); + Node* upper_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, true); IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If(); _igvn.hash_delete(upper_bound_iff); upper_bound_iff->set_req(1, upper_bound_bol);