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// Copyright 2012 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_MIPS
#include "src/debug/debug.h"
#include "src/codegen.h"
#include "src/debug/liveedit.h"
namespace v8 {
namespace internal {
#define __ ACCESS_MASM(masm)
void EmitDebugBreakSlot(MacroAssembler* masm) {
Label check_size;
__ bind(&check_size);
for (int i = 0; i < Assembler::kDebugBreakSlotInstructions; i++) {
__ nop(MacroAssembler::DEBUG_BREAK_NOP);
}
DCHECK_EQ(Assembler::kDebugBreakSlotInstructions,
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 trampoline pool in the debug break slot code.
Assembler::BlockTrampolinePoolScope block_pool(masm);
masm->RecordDebugBreakSlot(mode);
EmitDebugBreakSlot(masm);
}
void DebugCodegen::ClearDebugBreakSlot(Isolate* isolate, Address pc) {
CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotInstructions);
EmitDebugBreakSlot(patcher.masm());
}
void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
Handle<Code> code) {
DCHECK(code->is_debug_stub());
CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotInstructions);
// Patch the code changing the debug break slot code from:
// nop(DEBUG_BREAK_NOP) - nop(1) is sll(zero_reg, zero_reg, 1)
// nop(DEBUG_BREAK_NOP)
// nop(DEBUG_BREAK_NOP)
// nop(DEBUG_BREAK_NOP)
// to a call to the debug break slot code.
// li t9, address (lui t9 / ori t9 instruction pair)
// call t9 (jalr t9 / nop instruction pair)
patcher.masm()->li(v8::internal::t9,
Operand(reinterpret_cast<int32_t>(code->entry())));
patcher.masm()->Call(v8::internal::t9);
}
bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
Instr current_instr = Assembler::instr_at(pc);
return !Assembler::IsNop(current_instr, Assembler::DEBUG_BREAK_NOP);
}
void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
DebugBreakCallHelperMode mode) {
__ RecordComment("Debug break");
{
FrameScope scope(masm, StackFrame::INTERNAL);
// Load padding words on stack.
__ li(at, Operand(Smi::FromInt(LiveEdit::kFramePaddingValue)));
__ Subu(sp, sp,
Operand(kPointerSize * LiveEdit::kFramePaddingInitialSize));
for (int i = LiveEdit::kFramePaddingInitialSize - 1; i >= 0; i--) {
__ sw(at, MemOperand(sp, kPointerSize * i));
}
__ li(at, Operand(Smi::FromInt(LiveEdit::kFramePaddingInitialSize)));
__ push(at);
// Push arguments for DebugBreak call.
if (mode == SAVE_RESULT_REGISTER) {
// Break on return.
__ push(v0);
} else {
// Non-return breaks.
__ Push(masm->isolate()->factory()->the_hole_value());
}
__ PrepareCEntryArgs(1);
__ PrepareCEntryFunction(ExternalReference(
Runtime::FunctionForId(Runtime::kDebugBreak), masm->isolate()));
CEntryStub ceb(masm->isolate(), 1);
__ CallStub(&ceb);
if (FLAG_debug_code) {
for (int i = 0; i < kNumJSCallerSaved; i++) {
Register reg = {JSCallerSavedCode(i)};
// Do not clobber v0 if mode is SAVE_RESULT_REGISTER. It will
// contain return value of the function returned by DebugBreak.
if (!(reg.is(v0) && (mode == SAVE_RESULT_REGISTER))) {
__ li(reg, 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());
__ li(t9, Operand(after_break_target));
__ lw(t9, MemOperand(t9));
__ Jump(t9);
}
void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
// We do not know our frame height, but set sp based on fp.
__ lw(a1, MemOperand(fp, FrameDropperFrameConstants::kFunctionOffset));
// Pop return address and frame.
__ LeaveFrame(StackFrame::INTERNAL);
ParameterCount dummy(0);
__ CheckDebugHook(a1, no_reg, dummy, dummy);
// Load context from the function.
__ lw(cp, FieldMemOperand(a1, JSFunction::kContextOffset));
// Clear new.target as a safety measure.
__ LoadRoot(a3, Heap::kUndefinedValueRootIndex);
// Get function code.
__ lw(at, FieldMemOperand(a1, JSFunction::kSharedFunctionInfoOffset));
__ lw(at, FieldMemOperand(at, SharedFunctionInfo::kCodeOffset));
__ Addu(t9, at, Operand(Code::kHeaderSize - kHeapObjectTag));
// Re-run JSFunction, a1 is function, cp is context.
__ Jump(t9);
}
const bool LiveEdit::kFrameDropperSupported = true;
#undef __
} // namespace internal
} // namespace v8
#endif // V8_TARGET_ARCH_MIPS
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