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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/arm64/unwinding-info-writer-arm64.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->saved_lr_ != saved_lr_) {
eh_frame_writer_.AdvanceLocation(pc_offset);
if (initial_state->saved_lr_) {
eh_frame_writer_.RecordRegisterSavedToStack(lr, kPointerSize);
eh_frame_writer_.RecordRegisterSavedToStack(fp, 0);
} else {
eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
}
saved_lr_ = initial_state->saved_lr_;
}
} 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_EQ(existing_state->saved_lr_, saved_lr_);
} else {
block_initial_states_[successor_index] =
new (zone_) BlockInitialState(saved_lr_);
}
}
}
void UnwindingInfoWriter::MarkFrameConstructed(int at_pc) {
if (!enabled()) return;
// Regardless of the type of frame constructed, the relevant part of the
// layout is always the one in the diagram:
//
// | .... | higher addresses
// +----------+ ^
// | LR | | |
// +----------+ | |
// | saved FP | | |
// +----------+ <-- FP v
// | .... | stack growth
//
// The LR is pushed on the stack, and we can record this fact at the end of
// the construction, since the LR itself is not modified in the process.
eh_frame_writer_.AdvanceLocation(at_pc);
eh_frame_writer_.RecordRegisterSavedToStack(lr, kPointerSize);
eh_frame_writer_.RecordRegisterSavedToStack(fp, 0);
saved_lr_ = true;
}
void UnwindingInfoWriter::MarkFrameDeconstructed(int at_pc) {
if (!enabled()) return;
// The lr is restored by the last operation in LeaveFrame().
eh_frame_writer_.AdvanceLocation(at_pc);
eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
saved_lr_ = false;
}
void UnwindingInfoWriter::MarkLinkRegisterOnTopOfStack(int pc_offset,
const Register& sp) {
if (!enabled()) return;
eh_frame_writer_.AdvanceLocation(pc_offset);
eh_frame_writer_.SetBaseAddressRegisterAndOffset(sp, 0);
eh_frame_writer_.RecordRegisterSavedToStack(lr, 0);
}
void UnwindingInfoWriter::MarkPopLinkRegisterFromTopOfStack(int pc_offset) {
if (!enabled()) return;
eh_frame_writer_.AdvanceLocation(pc_offset);
eh_frame_writer_.SetBaseAddressRegisterAndOffset(fp, 0);
eh_frame_writer_.RecordRegisterFollowsInitialRule(lr);
}
} // namespace compiler
} // namespace internal
} // namespace v8
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