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// Copyright 2013 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.
#if V8_TARGET_ARCH_ARM64
#include "src/debug/debug.h"
#include "src/arm64/frames-arm64.h"
#include "src/codegen.h"
#include "src/debug/liveedit.h"
namespace v8 {
namespace internal {
#define __ ACCESS_MASM(masm)
void EmitDebugBreakSlot(Assembler* masm) {
Label check_size;
__ bind(&check_size);
for (int i = 0; i < Assembler::kDebugBreakSlotInstructions; i++) {
__ nop(Assembler::DEBUG_BREAK_NOP);
}
DCHECK_EQ(Assembler::kDebugBreakSlotInstructions,
static_cast<int>(masm->InstructionsGeneratedSince(&check_size)));
}
void DebugCodegen::GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode) {
// Generate enough nop's to make space for a call instruction. Avoid emitting
// the constant pool in the debug break slot code.
InstructionAccurateScope scope(masm, Assembler::kDebugBreakSlotInstructions);
masm->RecordDebugBreakSlot(mode);
EmitDebugBreakSlot(masm);
}
void DebugCodegen::ClearDebugBreakSlot(Isolate* isolate, Address pc) {
PatchingAssembler patcher(isolate, reinterpret_cast<Instruction*>(pc),
Assembler::kDebugBreakSlotInstructions);
EmitDebugBreakSlot(&patcher);
}
void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
Handle<Code> code) {
DCHECK(code->is_debug_stub());
PatchingAssembler patcher(isolate, reinterpret_cast<Instruction*>(pc),
Assembler::kDebugBreakSlotInstructions);
// Patch the code emitted by DebugCodegen::GenerateSlots, changing the debug
// break slot code from
// mov x0, x0 @ nop DEBUG_BREAK_NOP
// mov x0, x0 @ nop DEBUG_BREAK_NOP
// mov x0, x0 @ nop DEBUG_BREAK_NOP
// mov x0, x0 @ nop DEBUG_BREAK_NOP
// mov x0, x0 @ nop DEBUG_BREAK_NOP
// to a call to the debug slot code.
// ldr ip0, [pc, #(2 * kInstructionSize)]
// blr ip0
// b skip
// <debug break slot code entry point address (64 bits)>
// skip:
Label skip_constant;
// The first instruction of a patched debug break slot must be a load literal
// loading the address of the debug break slot code.
patcher.ldr_pcrel(ip0, (2 * kInstructionSize) >> kLoadLiteralScaleLog2);
patcher.b(&skip_constant);
patcher.dc64(reinterpret_cast<int64_t>(code->entry()));
patcher.bind(&skip_constant);
// TODO(all): check the following is correct.
// The debug break slot code will push a frame and call statically compiled
// code. By using blr, this call site will be registered in the frame.
// The debugger can now iterate on the frames to find this call.
patcher.blr(ip0);
}
bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
Instruction* current_instr = reinterpret_cast<Instruction*>(pc);
return !current_instr->IsNop(Assembler::DEBUG_BREAK_NOP);
}
void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
DebugBreakCallHelperMode mode) {
__ RecordComment("Debug break");
Register scratch = x10;
{
FrameScope scope(masm, StackFrame::INTERNAL);
// Load padding words on stack.
__ Mov(scratch, Smi::FromInt(LiveEdit::kFramePaddingValue));
__ PushMultipleTimes(scratch, LiveEdit::kFramePaddingInitialSize);
__ Mov(scratch, Smi::FromInt(LiveEdit::kFramePaddingInitialSize));
__ Push(scratch);
// Push arguments for DebugBreak call.
if (mode == SAVE_RESULT_REGISTER) {
// Break on return.
__ Push(x0);
} else {
// Non-return breaks.
__ Push(masm->isolate()->factory()->the_hole_value());
}
__ Mov(x0, 1);
__ Mov(x1, ExternalReference(Runtime::FunctionForId(Runtime::kDebugBreak),
masm->isolate()));
CEntryStub stub(masm->isolate(), 1);
__ CallStub(&stub);
if (FLAG_debug_code) {
for (int i = 0; i < kNumJSCallerSaved; i++) {
Register reg = Register::XRegFromCode(JSCallerSavedCode(i));
// Do not clobber x0 if mode is SAVE_RESULT_REGISTER. It will
// contain return value of the function.
if (!(reg.is(x0) && (mode == SAVE_RESULT_REGISTER))) {
__ Mov(reg, Operand(kDebugZapValue));
}
}
}
// Don't bother removing padding bytes pushed on the stack
// as the frame is going to be restored right away.
// Leave the internal frame.
}
// Now that the break point has been handled, resume normal execution by
// jumping to the target address intended by the caller and that was
// overwritten by the address of DebugBreakXXX.
ExternalReference after_break_target =
ExternalReference::debug_after_break_target_address(masm->isolate());
__ Mov(scratch, after_break_target);
__ Ldr(scratch, MemOperand(scratch));
__ Br(scratch);
}
void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
// We do not know our frame height, but set sp based on fp.
__ Add(masm->StackPointer(), fp, FrameDropperFrameConstants::kFunctionOffset);
__ AssertStackConsistency();
__ Pop(x1); // Function
__ Mov(masm->StackPointer(), Operand(fp));
__ Pop(fp, lr); // Frame, Return address.
ParameterCount dummy(0);
__ CheckDebugHook(x1, no_reg, dummy, dummy);
UseScratchRegisterScope temps(masm);
Register scratch = temps.AcquireX();
// Load context from the function.
__ Ldr(cp, FieldMemOperand(x1, JSFunction::kContextOffset));
// Clear new.target as a safety measure.
__ LoadRoot(x3, Heap::kUndefinedValueRootIndex);
// Get function code.
__ Ldr(scratch, FieldMemOperand(x1, JSFunction::kSharedFunctionInfoOffset));
__ Ldr(scratch, FieldMemOperand(scratch, SharedFunctionInfo::kCodeOffset));
__ Add(scratch, scratch, Code::kHeaderSize - kHeapObjectTag);
// Re-run JSFunction, x1 is function, cp is context.
__ Br(scratch);
}
const bool LiveEdit::kFrameDropperSupported = true;
} // namespace internal
} // namespace v8
#endif // V8_TARGET_ARCH_ARM64
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