Mercurial > hg > truffle
diff src/share/vm/asm/assembler.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 98cb887364d3 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/asm/assembler.hpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,309 @@ +/* + * Copyright 1997-2006 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. + * + */ + +// This file contains platform-independant assembler declarations. + +class CodeBuffer; +class MacroAssembler; +class AbstractAssembler; +class Label; + +/** + * Labels represent destinations for control transfer instructions. Such + * instructions can accept a Label as their target argument. A Label is + * bound to the current location in the code stream by calling the + * MacroAssembler's 'bind' method, which in turn calls the Label's 'bind' + * method. A Label may be referenced by an instruction before it's bound + * (i.e., 'forward referenced'). 'bind' stores the current code offset + * in the Label object. + * + * If an instruction references a bound Label, the offset field(s) within + * the instruction are immediately filled in based on the Label's code + * offset. If an instruction references an unbound label, that + * instruction is put on a list of instructions that must be patched + * (i.e., 'resolved') when the Label is bound. + * + * 'bind' will call the platform-specific 'patch_instruction' method to + * fill in the offset field(s) for each unresolved instruction (if there + * are any). 'patch_instruction' lives in one of the + * cpu/<arch>/vm/assembler_<arch>* files. + * + * Instead of using a linked list of unresolved instructions, a Label has + * an array of unresolved instruction code offsets. _patch_index + * contains the total number of forward references. If the Label's array + * overflows (i.e., _patch_index grows larger than the array size), a + * GrowableArray is allocated to hold the remaining offsets. (The cache + * size is 4 for now, which handles over 99.5% of the cases) + * + * Labels may only be used within a single CodeSection. If you need + * to create references between code sections, use explicit relocations. + */ +class Label VALUE_OBJ_CLASS_SPEC { + private: + enum { PatchCacheSize = 4 }; + + // _loc encodes both the binding state (via its sign) + // and the binding locator (via its value) of a label. + // + // _loc >= 0 bound label, loc() encodes the target (jump) position + // _loc == -1 unbound label + int _loc; + + // References to instructions that jump to this unresolved label. + // These instructions need to be patched when the label is bound + // using the platform-specific patchInstruction() method. + // + // To avoid having to allocate from the C-heap each time, we provide + // a local cache and use the overflow only if we exceed the local cache + int _patches[PatchCacheSize]; + int _patch_index; + GrowableArray<int>* _patch_overflow; + + Label(const Label&) { ShouldNotReachHere(); } + + public: + + /** + * After binding, be sure 'patch_instructions' is called later to link + */ + void bind_loc(int loc) { + assert(loc >= 0, "illegal locator"); + assert(_loc == -1, "already bound"); + _loc = loc; + } + void bind_loc(int pos, int sect); // = bind_loc(locator(pos, sect)) + +#ifndef PRODUCT + // Iterates over all unresolved instructions for printing + void print_instructions(MacroAssembler* masm) const; +#endif // PRODUCT + + /** + * Returns the position of the the Label in the code buffer + * The position is a 'locator', which encodes both offset and section. + */ + int loc() const { + assert(_loc >= 0, "unbound label"); + return _loc; + } + int loc_pos() const; // == locator_pos(loc()) + int loc_sect() const; // == locator_sect(loc()) + + bool is_bound() const { return _loc >= 0; } + bool is_unbound() const { return _loc == -1 && _patch_index > 0; } + bool is_unused() const { return _loc == -1 && _patch_index == 0; } + + /** + * Adds a reference to an unresolved displacement instruction to + * this unbound label + * + * @param cb the code buffer being patched + * @param branch_loc the locator of the branch instruction in the code buffer + */ + void add_patch_at(CodeBuffer* cb, int branch_loc); + + /** + * Iterate over the list of patches, resolving the instructions + * Call patch_instruction on each 'branch_loc' value + */ + void patch_instructions(MacroAssembler* masm); + + void init() { + _loc = -1; + _patch_index = 0; + _patch_overflow = NULL; + } + + Label() { + init(); + } +}; + + +// The Abstract Assembler: Pure assembler doing NO optimizations on the +// instruction level; i.e., what you write is what you get. +// The Assembler is generating code into a CodeBuffer. +class AbstractAssembler : public ResourceObj { + friend class Label; + + protected: + CodeSection* _code_section; // section within the code buffer + address _code_begin; // first byte of code buffer + address _code_limit; // first byte after code buffer + address _code_pos; // current code generation position + OopRecorder* _oop_recorder; // support for relocInfo::oop_type + + // Code emission & accessing + address addr_at(int pos) const { return _code_begin + pos; } + + // This routine is called with a label is used for an address. + // Labels and displacements truck in offsets, but target must return a PC. + address target(Label& L); // return _code_section->target(L) + + bool is8bit(int x) const { return -0x80 <= x && x < 0x80; } + bool isByte(int x) const { return 0 <= x && x < 0x100; } + bool isShiftCount(int x) const { return 0 <= x && x < 32; } + + void emit_byte(int x); // emit a single byte + void emit_word(int x); // emit a 16-bit word (not a wordSize word!) + void emit_long(jint x); // emit a 32-bit word (not a longSize word!) + void emit_address(address x); // emit an address (not a longSize word!) + + // Instruction boundaries (required when emitting relocatable values). + class InstructionMark: public StackObj { + private: + AbstractAssembler* _assm; + + public: + InstructionMark(AbstractAssembler* assm) : _assm(assm) { + assert(assm->inst_mark() == NULL, "overlapping instructions"); + _assm->set_inst_mark(); + } + ~InstructionMark() { + _assm->clear_inst_mark(); + } + }; + friend class InstructionMark; + #ifdef ASSERT + // Make it return true on platforms which need to verify + // instruction boundaries for some operations. + inline static bool pd_check_instruction_mark(); + #endif + + // Label functions + void print(Label& L); + + public: + + // Creation + AbstractAssembler(CodeBuffer* code); + + // save end pointer back to code buf. + void sync(); + + // ensure buf contains all code (call this before using/copying the code) + void flush(); + + // Accessors + CodeBuffer* code() const; // _code_section->outer() + CodeSection* code_section() const { return _code_section; } + int sect() const; // return _code_section->index() + address pc() const { return _code_pos; } + int offset() const { return _code_pos - _code_begin; } + int locator() const; // CodeBuffer::locator(offset(), sect()) + OopRecorder* oop_recorder() const { return _oop_recorder; } + void set_oop_recorder(OopRecorder* r) { _oop_recorder = r; } + + address inst_mark() const; + void set_inst_mark(); + void clear_inst_mark(); + + // Constants in code + void a_byte(int x); + void a_long(jint x); + void relocate(RelocationHolder const& rspec, int format = 0); + void relocate( relocInfo::relocType rtype, int format = 0) { + if (rtype != relocInfo::none) + relocate(Relocation::spec_simple(rtype), format); + } + + static int code_fill_byte(); // used to pad out odd-sized code buffers + + // Associate a comment with the current offset. It will be printed + // along with the disassembly when printing nmethods. Currently + // only supported in the instruction section of the code buffer. + void block_comment(const char* comment); + + // Label functions + void bind(Label& L); // binds an unbound label L to the current code position + + // Move to a different section in the same code buffer. + void set_code_section(CodeSection* cs); + + // Inform assembler when generating stub code and relocation info + address start_a_stub(int required_space); + void end_a_stub(); + // Ditto for constants. + address start_a_const(int required_space, int required_align = sizeof(double)); + void end_a_const(); + + // fp constants support + address double_constant(jdouble c) { + address ptr = start_a_const(sizeof(c), sizeof(c)); + if (ptr != NULL) { + *(jdouble*)ptr = c; + _code_pos = ptr + sizeof(c); + end_a_const(); + } + return ptr; + } + address float_constant(jfloat c) { + address ptr = start_a_const(sizeof(c), sizeof(c)); + if (ptr != NULL) { + *(jfloat*)ptr = c; + _code_pos = ptr + sizeof(c); + end_a_const(); + } + return ptr; + } + address address_constant(address c, RelocationHolder const& rspec) { + address ptr = start_a_const(sizeof(c), sizeof(c)); + if (ptr != NULL) { + relocate(rspec); + *(address*)ptr = c; + _code_pos = ptr + sizeof(c); + end_a_const(); + } + return ptr; + } + inline address address_constant(Label& L); + inline address address_table_constant(GrowableArray<Label*> label); + + // Bang stack to trigger StackOverflowError at a safe location + // implementation delegates to machine-specific bang_stack_with_offset + void generate_stack_overflow_check( int frame_size_in_bytes ); + virtual void bang_stack_with_offset(int offset) = 0; + + + /** + * A platform-dependent method to patch a jump instruction that refers + * to this label. + * + * @param branch the location of the instruction to patch + * @param masm the assembler which generated the branch + */ + void pd_patch_instruction(address branch, address target); + +#ifndef PRODUCT + /** + * Platform-dependent method of printing an instruction that needs to be + * patched. + * + * @param branch the instruction to be patched in the buffer. + */ + static void pd_print_patched_instruction(address branch); +#endif // PRODUCT +}; + +#include "incls/_assembler_pd.hpp.incl"