// Copyright (c) 1994-2006 Sun Microsystems Inc.
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// All Rights Reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// - Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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//
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// - Redistribution in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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//
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// - Neither the name of Sun Microsystems or the names of contributors may
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// be used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// The original source code covered by the above license above has been
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// modified significantly by Google Inc.
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// Copyright 2012 the V8 project authors. All rights reserved.
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#ifndef V8_ASSEMBLER_H_
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#define V8_ASSEMBLER_H_
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#include <forward_list>
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#include <iosfwd>
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#include <map>
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#include "src/allocation.h"
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#include "src/code-reference.h"
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#include "src/contexts.h"
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#include "src/deoptimize-reason.h"
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#include "src/double.h"
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#include "src/external-reference.h"
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#include "src/flags.h"
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#include "src/globals.h"
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#include "src/label.h"
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#include "src/objects.h"
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#include "src/register-configuration.h"
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#include "src/reglist.h"
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#include "src/reloc-info.h"
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namespace v8 {
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// Forward declarations.
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class ApiFunction;
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namespace internal {
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// Forward declarations.
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class EmbeddedData;
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class InstructionStream;
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class Isolate;
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class SCTableReference;
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class SourcePosition;
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class StatsCounter;
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// -----------------------------------------------------------------------------
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// Optimization for far-jmp like instructions that can be replaced by shorter.
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class JumpOptimizationInfo {
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public:
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bool is_collecting() const { return stage_ == kCollection; }
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bool is_optimizing() const { return stage_ == kOptimization; }
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void set_optimizing() { stage_ = kOptimization; }
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bool is_optimizable() const { return optimizable_; }
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void set_optimizable() { optimizable_ = true; }
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// Used to verify the instruction sequence is always the same in two stages.
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size_t hash_code() const { return hash_code_; }
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void set_hash_code(size_t hash_code) { hash_code_ = hash_code; }
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std::vector<uint32_t>& farjmp_bitmap() { return farjmp_bitmap_; }
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private:
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enum { kCollection, kOptimization } stage_ = kCollection;
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bool optimizable_ = false;
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std::vector<uint32_t> farjmp_bitmap_;
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size_t hash_code_ = 0u;
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};
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class HeapObjectRequest {
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public:
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explicit HeapObjectRequest(double heap_number, int offset = -1);
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explicit HeapObjectRequest(CodeStub* code_stub, int offset = -1);
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enum Kind { kHeapNumber, kCodeStub };
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Kind kind() const { return kind_; }
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double heap_number() const {
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DCHECK_EQ(kind(), kHeapNumber);
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return value_.heap_number;
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}
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CodeStub* code_stub() const {
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DCHECK_EQ(kind(), kCodeStub);
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return value_.code_stub;
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}
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// The code buffer offset at the time of the request.
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int offset() const {
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DCHECK_GE(offset_, 0);
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return offset_;
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}
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void set_offset(int offset) {
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DCHECK_LT(offset_, 0);
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offset_ = offset;
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DCHECK_GE(offset_, 0);
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}
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private:
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Kind kind_;
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union {
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double heap_number;
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CodeStub* code_stub;
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} value_;
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int offset_;
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};
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// -----------------------------------------------------------------------------
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// Platform independent assembler base class.
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enum class CodeObjectRequired { kNo, kYes };
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struct V8_EXPORT_PRIVATE AssemblerOptions {
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// Recording reloc info for external references and off-heap targets is
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// needed whenever code is serialized, e.g. into the snapshot or as a WASM
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// module. This flag allows this reloc info to be disabled for code that
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// will not survive process destruction.
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bool record_reloc_info_for_serialization = true;
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// Recording reloc info can be disabled wholesale. This is needed when the
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// assembler is used on existing code directly (e.g. JumpTableAssembler)
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// without any buffer to hold reloc information.
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bool disable_reloc_info_for_patching = false;
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// Enables access to exrefs by computing a delta from the root array.
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// Only valid if code will not survive the process.
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bool enable_root_array_delta_access = false;
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// Enables specific assembler sequences only used for the simulator.
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bool enable_simulator_code = false;
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// Enables use of isolate-independent constants, indirected through the
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// root array.
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// (macro assembler feature).
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bool isolate_independent_code = false;
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// Enables the use of isolate-independent builtins through an off-heap
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// trampoline. (macro assembler feature).
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bool inline_offheap_trampolines = false;
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// On some platforms, all code is within a given range in the process,
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// and the start of this range is configured here.
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Address code_range_start = 0;
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// Enable pc-relative calls/jumps on platforms that support it. When setting
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// this flag, the code range must be small enough to fit all offsets into
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// the instruction immediates.
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bool use_pc_relative_calls_and_jumps = false;
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static AssemblerOptions Default(
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Isolate* isolate, bool explicitly_support_serialization = false);
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};
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class V8_EXPORT_PRIVATE AssemblerBase : public Malloced {
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public:
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AssemblerBase(const AssemblerOptions& options, void* buffer, int buffer_size);
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virtual ~AssemblerBase();
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const AssemblerOptions& options() const { return options_; }
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bool emit_debug_code() const { return emit_debug_code_; }
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void set_emit_debug_code(bool value) { emit_debug_code_ = value; }
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bool predictable_code_size() const { return predictable_code_size_; }
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void set_predictable_code_size(bool value) { predictable_code_size_ = value; }
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uint64_t enabled_cpu_features() const { return enabled_cpu_features_; }
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void set_enabled_cpu_features(uint64_t features) {
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enabled_cpu_features_ = features;
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}
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// Features are usually enabled by CpuFeatureScope, which also asserts that
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// the features are supported before they are enabled.
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bool IsEnabled(CpuFeature f) {
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return (enabled_cpu_features_ & (static_cast<uint64_t>(1) << f)) != 0;
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}
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void EnableCpuFeature(CpuFeature f) {
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enabled_cpu_features_ |= (static_cast<uint64_t>(1) << f);
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}
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bool is_constant_pool_available() const {
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if (FLAG_enable_embedded_constant_pool) {
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return constant_pool_available_;
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} else {
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// Embedded constant pool not supported on this architecture.
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UNREACHABLE();
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}
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}
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JumpOptimizationInfo* jump_optimization_info() {
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return jump_optimization_info_;
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}
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void set_jump_optimization_info(JumpOptimizationInfo* jump_opt) {
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jump_optimization_info_ = jump_opt;
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}
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// Overwrite a host NaN with a quiet target NaN. Used by mksnapshot for
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// cross-snapshotting.
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static void QuietNaN(HeapObject* nan) { }
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int pc_offset() const { return static_cast<int>(pc_ - buffer_); }
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// This function is called when code generation is aborted, so that
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// the assembler could clean up internal data structures.
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virtual void AbortedCodeGeneration() { }
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// Debugging
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void Print(Isolate* isolate);
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static const int kMinimalBufferSize = 4*KB;
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static void FlushICache(void* start, size_t size);
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static void FlushICache(Address start, size_t size) {
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return FlushICache(reinterpret_cast<void*>(start), size);
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}
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// Used to print the name of some special registers.
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static const char* GetSpecialRegisterName(int code) { return "UNKNOWN"; }
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protected:
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// Add 'target' to the {code_targets_} vector, if necessary, and return the
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// offset at which it is stored.
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int AddCodeTarget(Handle<Code> target);
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Handle<Code> GetCodeTarget(intptr_t code_target_index) const;
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// Update to the code target at {code_target_index} to {target}.
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void UpdateCodeTarget(intptr_t code_target_index, Handle<Code> target);
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// Reserves space in the code target vector.
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void ReserveCodeTargetSpace(size_t num_of_code_targets) {
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code_targets_.reserve(num_of_code_targets);
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}
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// The buffer into which code and relocation info are generated. It could
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// either be owned by the assembler or be provided externally.
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byte* buffer_;
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int buffer_size_;
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bool own_buffer_;
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std::forward_list<HeapObjectRequest> heap_object_requests_;
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// The program counter, which points into the buffer above and moves forward.
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// TODO(jkummerow): This should probably have type {Address}.
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byte* pc_;
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void set_constant_pool_available(bool available) {
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if (FLAG_enable_embedded_constant_pool) {
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constant_pool_available_ = available;
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} else {
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// Embedded constant pool not supported on this architecture.
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UNREACHABLE();
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}
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}
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// {RequestHeapObject} records the need for a future heap number allocation or
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// code stub generation. After code assembly, each platform's
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// {Assembler::AllocateAndInstallRequestedHeapObjects} will allocate these
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// objects and place them where they are expected (determined by the pc offset
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// associated with each request).
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void RequestHeapObject(HeapObjectRequest request);
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private:
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// Before we copy code into the code space, we sometimes cannot encode
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// call/jump code targets as we normally would, as the difference between the
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// instruction's location in the temporary buffer and the call target is not
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// guaranteed to fit in the instruction's offset field. We keep track of the
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// code handles we encounter in calls in this vector, and encode the index of
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// the code handle in the vector instead.
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std::vector<Handle<Code>> code_targets_;
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const AssemblerOptions options_;
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uint64_t enabled_cpu_features_;
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bool emit_debug_code_;
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bool predictable_code_size_;
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// Indicates whether the constant pool can be accessed, which is only possible
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// if the pp register points to the current code object's constant pool.
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bool constant_pool_available_;
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JumpOptimizationInfo* jump_optimization_info_;
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// Constant pool.
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friend class FrameAndConstantPoolScope;
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friend class ConstantPoolUnavailableScope;
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};
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// Avoids emitting debug code during the lifetime of this scope object.
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class DontEmitDebugCodeScope BASE_EMBEDDED {
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public:
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explicit DontEmitDebugCodeScope(AssemblerBase* assembler)
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: assembler_(assembler), old_value_(assembler->emit_debug_code()) {
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assembler_->set_emit_debug_code(false);
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}
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~DontEmitDebugCodeScope() {
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assembler_->set_emit_debug_code(old_value_);
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}
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private:
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AssemblerBase* assembler_;
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bool old_value_;
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};
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// Avoids using instructions that vary in size in unpredictable ways between the
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// snapshot and the running VM.
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class PredictableCodeSizeScope {
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public:
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PredictableCodeSizeScope(AssemblerBase* assembler, int expected_size);
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~PredictableCodeSizeScope();
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private:
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AssemblerBase* const assembler_;
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int const expected_size_;
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int const start_offset_;
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bool const old_value_;
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};
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// Enable a specified feature within a scope.
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class CpuFeatureScope BASE_EMBEDDED {
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public:
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enum CheckPolicy {
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kCheckSupported,
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kDontCheckSupported,
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};
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#ifdef DEBUG
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CpuFeatureScope(AssemblerBase* assembler, CpuFeature f,
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CheckPolicy check = kCheckSupported);
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~CpuFeatureScope();
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private:
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AssemblerBase* assembler_;
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uint64_t old_enabled_;
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#else
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CpuFeatureScope(AssemblerBase* assembler, CpuFeature f,
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CheckPolicy check = kCheckSupported) {}
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// Define a destructor to avoid unused variable warnings.
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~CpuFeatureScope() {}
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#endif
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};
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// CpuFeatures keeps track of which features are supported by the target CPU.
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// Supported features must be enabled by a CpuFeatureScope before use.
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// Example:
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// if (assembler->IsSupported(SSE3)) {
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// CpuFeatureScope fscope(assembler, SSE3);
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// // Generate code containing SSE3 instructions.
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// } else {
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// // Generate alternative code.
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// }
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class CpuFeatures : public AllStatic {
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public:
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static void Probe(bool cross_compile) {
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STATIC_ASSERT(NUMBER_OF_CPU_FEATURES <= kBitsPerInt);
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if (initialized_) return;
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initialized_ = true;
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ProbeImpl(cross_compile);
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}
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static unsigned SupportedFeatures() {
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Probe(false);
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return supported_;
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}
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static bool IsSupported(CpuFeature f) {
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return (supported_ & (1u << f)) != 0;
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}
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static inline bool SupportsOptimizer();
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static inline bool SupportsWasmSimd128();
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static inline unsigned icache_line_size() {
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DCHECK_NE(icache_line_size_, 0);
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return icache_line_size_;
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}
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static inline unsigned dcache_line_size() {
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DCHECK_NE(dcache_line_size_, 0);
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return dcache_line_size_;
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}
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static void PrintTarget();
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static void PrintFeatures();
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private:
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friend class ExternalReference;
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friend class AssemblerBase;
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// Flush instruction cache.
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static void FlushICache(void* start, size_t size);
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// Platform-dependent implementation.
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static void ProbeImpl(bool cross_compile);
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static unsigned supported_;
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static unsigned icache_line_size_;
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static unsigned dcache_line_size_;
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static bool initialized_;
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DISALLOW_COPY_AND_ASSIGN(CpuFeatures);
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};
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// -----------------------------------------------------------------------------
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// Utility functions
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// Computes pow(x, y) with the special cases in the spec for Math.pow.
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double power_helper(Isolate* isolate, double x, double y);
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double power_double_int(double x, int y);
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double power_double_double(double x, double y);
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// -----------------------------------------------------------------------------
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// Constant pool support
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class ConstantPoolEntry {
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public:
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ConstantPoolEntry() {}
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ConstantPoolEntry(int position, intptr_t value, bool sharing_ok,
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RelocInfo::Mode rmode = RelocInfo::NONE)
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: position_(position),
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merged_index_(sharing_ok ? SHARING_ALLOWED : SHARING_PROHIBITED),
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value_(value),
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rmode_(rmode) {}
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ConstantPoolEntry(int position, Double value,
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RelocInfo::Mode rmode = RelocInfo::NONE)
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: position_(position),
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merged_index_(SHARING_ALLOWED),
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value64_(value.AsUint64()),
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rmode_(rmode) {}
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int position() const { return position_; }
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bool sharing_ok() const { return merged_index_ != SHARING_PROHIBITED; }
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bool is_merged() const { return merged_index_ >= 0; }
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int merged_index(void) const {
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DCHECK(is_merged());
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return merged_index_;
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}
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void set_merged_index(int index) {
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DCHECK(sharing_ok());
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merged_index_ = index;
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DCHECK(is_merged());
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}
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int offset(void) const {
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DCHECK_GE(merged_index_, 0);
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return merged_index_;
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}
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void set_offset(int offset) {
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DCHECK_GE(offset, 0);
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merged_index_ = offset;
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}
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intptr_t value() const { return value_; }
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uint64_t value64() const { return value64_; }
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RelocInfo::Mode rmode() const { return rmode_; }
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enum Type { INTPTR, DOUBLE, NUMBER_OF_TYPES };
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static int size(Type type) {
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return (type == INTPTR) ? kPointerSize : kDoubleSize;
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}
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enum Access { REGULAR, OVERFLOWED };
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private:
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int position_;
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int merged_index_;
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union {
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intptr_t value_;
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uint64_t value64_;
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};
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// TODO(leszeks): The way we use this, it could probably be packed into
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// merged_index_ if size is a concern.
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RelocInfo::Mode rmode_;
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enum { SHARING_PROHIBITED = -2, SHARING_ALLOWED = -1 };
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};
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// -----------------------------------------------------------------------------
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// Embedded constant pool support
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class ConstantPoolBuilder BASE_EMBEDDED {
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public:
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ConstantPoolBuilder(int ptr_reach_bits, int double_reach_bits);
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// Add pointer-sized constant to the embedded constant pool
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ConstantPoolEntry::Access AddEntry(int position, intptr_t value,
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bool sharing_ok) {
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ConstantPoolEntry entry(position, value, sharing_ok);
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return AddEntry(entry, ConstantPoolEntry::INTPTR);
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}
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// Add double constant to the embedded constant pool
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ConstantPoolEntry::Access AddEntry(int position, Double value) {
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ConstantPoolEntry entry(position, value);
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return AddEntry(entry, ConstantPoolEntry::DOUBLE);
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}
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// Add double constant to the embedded constant pool
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ConstantPoolEntry::Access AddEntry(int position, double value) {
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return AddEntry(position, Double(value));
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}
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// Previews the access type required for the next new entry to be added.
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ConstantPoolEntry::Access NextAccess(ConstantPoolEntry::Type type) const;
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bool IsEmpty() {
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return info_[ConstantPoolEntry::INTPTR].entries.empty() &&
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info_[ConstantPoolEntry::INTPTR].shared_entries.empty() &&
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info_[ConstantPoolEntry::DOUBLE].entries.empty() &&
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info_[ConstantPoolEntry::DOUBLE].shared_entries.empty();
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}
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// Emit the constant pool. Invoke only after all entries have been
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// added and all instructions have been emitted.
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// Returns position of the emitted pool (zero implies no constant pool).
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int Emit(Assembler* assm);
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// Returns the label associated with the start of the constant pool.
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// Linking to this label in the function prologue may provide an
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// efficient means of constant pool pointer register initialization
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// on some architectures.
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inline Label* EmittedPosition() { return &emitted_label_; }
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private:
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ConstantPoolEntry::Access AddEntry(ConstantPoolEntry& entry,
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ConstantPoolEntry::Type type);
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void EmitSharedEntries(Assembler* assm, ConstantPoolEntry::Type type);
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void EmitGroup(Assembler* assm, ConstantPoolEntry::Access access,
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ConstantPoolEntry::Type type);
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struct PerTypeEntryInfo {
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PerTypeEntryInfo() : regular_count(0), overflow_start(-1) {}
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bool overflow() const {
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return (overflow_start >= 0 &&
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overflow_start < static_cast<int>(entries.size()));
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}
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int regular_reach_bits;
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int regular_count;
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int overflow_start;
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std::vector<ConstantPoolEntry> entries;
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std::vector<ConstantPoolEntry> shared_entries;
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};
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Label emitted_label_; // Records pc_offset of emitted pool
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PerTypeEntryInfo info_[ConstantPoolEntry::NUMBER_OF_TYPES];
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};
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// Base type for CPU Registers.
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//
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// 1) We would prefer to use an enum for registers, but enum values are
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// assignment-compatible with int, which has caused code-generation bugs.
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//
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// 2) By not using an enum, we are possibly preventing the compiler from
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// doing certain constant folds, which may significantly reduce the
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// code generated for some assembly instructions (because they boil down
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// to a few constants). If this is a problem, we could change the code
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// such that we use an enum in optimized mode, and the class in debug
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// mode. This way we get the compile-time error checking in debug mode
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// and best performance in optimized code.
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template <typename SubType, int kAfterLastRegister>
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class RegisterBase {
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// Internal enum class; used for calling constexpr methods, where we need to
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// pass an integral type as template parameter.
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enum class RegisterCode : int { kFirst = 0, kAfterLast = kAfterLastRegister };
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public:
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static constexpr int kCode_no_reg = -1;
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static constexpr int kNumRegisters = kAfterLastRegister;
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static constexpr SubType no_reg() { return SubType{kCode_no_reg}; }
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template <int code>
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static constexpr SubType from_code() {
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static_assert(code >= 0 && code < kNumRegisters, "must be valid reg code");
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return SubType{code};
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}
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constexpr operator RegisterCode() const {
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return static_cast<RegisterCode>(reg_code_);
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}
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template <RegisterCode reg_code>
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static constexpr int code() {
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static_assert(
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reg_code >= RegisterCode::kFirst && reg_code < RegisterCode::kAfterLast,
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"must be valid reg");
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return static_cast<int>(reg_code);
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}
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template <RegisterCode reg_code>
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static constexpr RegList bit() {
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return RegList{1} << code<reg_code>();
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}
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static SubType from_code(int code) {
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DCHECK_LE(0, code);
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DCHECK_GT(kNumRegisters, code);
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return SubType{code};
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}
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// Constexpr version (pass registers as template parameters).
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template <RegisterCode... reg_codes>
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static constexpr RegList ListOf() {
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return CombineRegLists(RegisterBase::bit<reg_codes>()...);
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}
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// Non-constexpr version (pass registers as method parameters).
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template <typename... Register>
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static RegList ListOf(Register... regs) {
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return CombineRegLists(regs.bit()...);
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}
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bool is_valid() const { return reg_code_ != kCode_no_reg; }
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int code() const {
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DCHECK(is_valid());
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return reg_code_;
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}
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RegList bit() const { return RegList{1} << code(); }
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inline constexpr bool operator==(SubType other) const {
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return reg_code_ == other.reg_code_;
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}
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inline constexpr bool operator!=(SubType other) const {
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return reg_code_ != other.reg_code_;
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}
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protected:
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explicit constexpr RegisterBase(int code) : reg_code_(code) {}
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int reg_code_;
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};
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|
template <typename SubType, int kAfterLastRegister>
|
inline std::ostream& operator<<(std::ostream& os,
|
RegisterBase<SubType, kAfterLastRegister> reg) {
|
return reg.is_valid() ? os << "r" << reg.code() : os << "<invalid reg>";
|
}
|
|
} // namespace internal
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} // namespace v8
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#endif // V8_ASSEMBLER_H_
|
