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// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/globals.h"
#if defined(TARGET_ARCH_DBC)
#include "vm/code_patcher.h"
#include "vm/cpu.h"
#include "vm/debugger.h"
#include "vm/instructions.h"
#include "vm/stub_code.h"
namespace dart {
#ifndef PRODUCT
RawCode* CodeBreakpoint::OrigStubAddress() const {
return reinterpret_cast<RawCode*>(static_cast<uintptr_t>(saved_value_));
}
static Instr* CallInstructionFromReturnAddress(uword pc) {
return reinterpret_cast<Instr*>(pc) - 1;
}
static Instr* FastSmiInstructionFromReturnAddress(uword pc) {
return reinterpret_cast<Instr*>(pc) - 2;
}
void CodeBreakpoint::PatchCode() {
ASSERT(!is_enabled_);
const Code& code = Code::Handle(code_);
const Instructions& instrs = Instructions::Handle(code.instructions());
{
WritableInstructionsScope writable(instrs.PayloadStart(), instrs.Size());
saved_value_ = *CallInstructionFromReturnAddress(pc_);
switch (breakpoint_kind_) {
case RawPcDescriptors::kIcCall:
case RawPcDescriptors::kUnoptStaticCall: {
// DebugBreak has an A operand matching the call it replaces.
// This ensures that Return instructions continue to work - as they
// look at calls to figure out how many arguments to drop.
*CallInstructionFromReturnAddress(pc_) = SimulatorBytecode::Encode(
SimulatorBytecode::kDebugBreak,
SimulatorBytecode::DecodeArgc(saved_value_), 0, 0);
break;
}
case RawPcDescriptors::kRuntimeCall: {
*CallInstructionFromReturnAddress(pc_) = SimulatorBytecode::kDebugBreak;
break;
}
default:
UNREACHABLE();
}
// If this call is the fall-through for a fast Smi op, also disable the fast
// Smi op.
if ((SimulatorBytecode::DecodeOpcode(saved_value_) ==
SimulatorBytecode::kInstanceCall2) &&
SimulatorBytecode::IsFastSmiOpcode(
*FastSmiInstructionFromReturnAddress(pc_))) {
saved_value_fastsmi_ = *FastSmiInstructionFromReturnAddress(pc_);
*FastSmiInstructionFromReturnAddress(pc_) =
SimulatorBytecode::Encode(SimulatorBytecode::kNop, 0, 0, 0);
} else {
saved_value_fastsmi_ = SimulatorBytecode::kTrap;
}
}
is_enabled_ = true;
}
void CodeBreakpoint::RestoreCode() {
ASSERT(is_enabled_);
const Code& code = Code::Handle(code_);
const Instructions& instrs = Instructions::Handle(code.instructions());
{
WritableInstructionsScope writable(instrs.PayloadStart(), instrs.Size());
switch (breakpoint_kind_) {
case RawPcDescriptors::kIcCall:
case RawPcDescriptors::kUnoptStaticCall:
case RawPcDescriptors::kRuntimeCall: {
*CallInstructionFromReturnAddress(pc_) = saved_value_;
break;
}
default:
UNREACHABLE();
}
if (saved_value_fastsmi_ != SimulatorBytecode::kTrap) {
Instr current_instr = *FastSmiInstructionFromReturnAddress(pc_);
ASSERT(SimulatorBytecode::DecodeOpcode(current_instr) ==
SimulatorBytecode::kNop);
*FastSmiInstructionFromReturnAddress(pc_) = saved_value_fastsmi_;
}
}
is_enabled_ = false;
}
#endif // !PRODUCT
} // namespace dart
#endif // defined TARGET_ARCH_DBC