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// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/compiler/x64/unwinding-info-writer-x64.h"
#include "src/compiler/instruction.h"
namespace v8 {
namespace internal {
namespace compiler {
void UnwindingInfoWriter::BeginInstructionBlock(int pc_offset,
const InstructionBlock* block) {
if (!enabled()) return;
block_will_exit_ = false;
DCHECK_LT(block->rpo_number().ToInt(),
static_cast<int>(block_initial_states_.size()));
const BlockInitialState* initial_state =
block_initial_states_[block->rpo_number().ToInt()];
if (initial_state) {
if (initial_state->register_ != eh_frame_writer_.base_register() &&
initial_state->offset_ != eh_frame_writer_.base_offset()) {
eh_frame_writer_.AdvanceLocation(pc_offset);
eh_frame_writer_.SetBaseAddressRegisterAndOffset(initial_state->register_,
initial_state->offset_);
} else if (initial_state->register_ != eh_frame_writer_.base_register()) {
eh_frame_writer_.AdvanceLocation(pc_offset);
eh_frame_writer_.SetBaseAddressRegister(initial_state->register_);
} else if (initial_state->offset_ != eh_frame_writer_.base_offset()) {
eh_frame_writer_.AdvanceLocation(pc_offset);
eh_frame_writer_.SetBaseAddressOffset(initial_state->offset_);
}
tracking_fp_ = initial_state->tracking_fp_;
} else {
// The entry block always lacks an explicit initial state.
// The exit block may lack an explicit state, if it is only reached by
// the block ending in a ret.
// All the other blocks must have an explicit initial state.
DCHECK(block->predecessors().empty() || block->successors().empty());
}
}
void UnwindingInfoWriter::EndInstructionBlock(const InstructionBlock* block) {
if (!enabled() || block_will_exit_) return;
for (const RpoNumber& successor : block->successors()) {
int successor_index = successor.ToInt();
DCHECK_LT(successor_index, static_cast<int>(block_initial_states_.size()));
const BlockInitialState* existing_state =
block_initial_states_[successor_index];
// If we already had an entry for this BB, check that the values are the
// same we are trying to insert.
if (existing_state) {
DCHECK(existing_state->register_ == eh_frame_writer_.base_register());
DCHECK_EQ(existing_state->offset_, eh_frame_writer_.base_offset());
DCHECK_EQ(existing_state->tracking_fp_, tracking_fp_);
} else {
block_initial_states_[successor_index] = new (zone_)
BlockInitialState(eh_frame_writer_.base_register(),
eh_frame_writer_.base_offset(), tracking_fp_);
}
}
}
void UnwindingInfoWriter::MarkFrameConstructed(int pc_base) {
if (!enabled()) return;
// push rbp
eh_frame_writer_.AdvanceLocation(pc_base + 1);
eh_frame_writer_.IncreaseBaseAddressOffset(kInt64Size);
// <base address> points at the bottom of the current frame on x64 and
// <base register> is rsp, which points to the top of the frame by definition.
// Thus, the distance between <base address> and the top is -<base offset>.
int top_of_stack = -eh_frame_writer_.base_offset();
eh_frame_writer_.RecordRegisterSavedToStack(rbp, top_of_stack);
// mov rbp, rsp
eh_frame_writer_.AdvanceLocation(pc_base + 4);
eh_frame_writer_.SetBaseAddressRegister(rbp);
tracking_fp_ = true;
}
void UnwindingInfoWriter::MarkFrameDeconstructed(int pc_base) {
if (!enabled()) return;
// mov rsp, rbp
eh_frame_writer_.AdvanceLocation(pc_base + 3);
eh_frame_writer_.SetBaseAddressRegister(rsp);
// pop rbp
eh_frame_writer_.AdvanceLocation(pc_base + 4);
eh_frame_writer_.IncreaseBaseAddressOffset(-kInt64Size);
tracking_fp_ = false;
}
} // namespace compiler
} // namespace internal
} // namespace v8
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