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      1 // Copyright 2012 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #if V8_TARGET_ARCH_X87
      6 
      7 #include "src/codegen.h"
      8 #include "src/debug/debug.h"
      9 #include "src/x87/frames-x87.h"
     10 
     11 namespace v8 {
     12 namespace internal {
     13 
     14 #define __ ACCESS_MASM(masm)
     15 
     16 
     17 void EmitDebugBreakSlot(MacroAssembler* masm) {
     18   Label check_codesize;
     19   __ bind(&check_codesize);
     20   __ Nop(Assembler::kDebugBreakSlotLength);
     21   DCHECK_EQ(Assembler::kDebugBreakSlotLength,
     22             masm->SizeOfCodeGeneratedSince(&check_codesize));
     23 }
     24 
     25 
     26 void DebugCodegen::GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode) {
     27   // Generate enough nop's to make space for a call instruction.
     28   masm->RecordDebugBreakSlot(mode);
     29   EmitDebugBreakSlot(masm);
     30 }
     31 
     32 
     33 void DebugCodegen::ClearDebugBreakSlot(Isolate* isolate, Address pc) {
     34   CodePatcher patcher(isolate, pc, Assembler::kDebugBreakSlotLength);
     35   EmitDebugBreakSlot(patcher.masm());
     36 }
     37 
     38 
     39 void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
     40                                        Handle<Code> code) {
     41   DCHECK_EQ(Code::BUILTIN, code->kind());
     42   static const int kSize = Assembler::kDebugBreakSlotLength;
     43   CodePatcher patcher(isolate, pc, kSize);
     44 
     45   // Add a label for checking the size of the code used for returning.
     46   Label check_codesize;
     47   patcher.masm()->bind(&check_codesize);
     48   patcher.masm()->call(code->entry(), RelocInfo::NONE32);
     49   // Check that the size of the code generated is as expected.
     50   DCHECK_EQ(kSize, patcher.masm()->SizeOfCodeGeneratedSince(&check_codesize));
     51 }
     52 
     53 
     54 void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
     55                                           DebugBreakCallHelperMode mode) {
     56   __ RecordComment("Debug break");
     57 
     58   // Enter an internal frame.
     59   {
     60     FrameScope scope(masm, StackFrame::INTERNAL);
     61 
     62     // Load padding words on stack.
     63     for (int i = 0; i < LiveEdit::kFramePaddingInitialSize; i++) {
     64       __ push(Immediate(Smi::FromInt(LiveEdit::kFramePaddingValue)));
     65     }
     66     __ push(Immediate(Smi::FromInt(LiveEdit::kFramePaddingInitialSize)));
     67 
     68     if (mode == SAVE_RESULT_REGISTER) __ push(eax);
     69 
     70     __ Move(eax, Immediate(0));  // No arguments.
     71     __ mov(ebx,
     72            Immediate(ExternalReference(
     73                Runtime::FunctionForId(Runtime::kDebugBreak), masm->isolate())));
     74 
     75     CEntryStub ceb(masm->isolate(), 1);
     76     __ CallStub(&ceb);
     77 
     78     if (FLAG_debug_code) {
     79       for (int i = 0; i < kNumJSCallerSaved; ++i) {
     80         Register reg = {JSCallerSavedCode(i)};
     81         __ Move(reg, Immediate(kDebugZapValue));
     82       }
     83     }
     84 
     85     if (mode == SAVE_RESULT_REGISTER) __ pop(eax);
     86 
     87     __ pop(ebx);
     88     // We divide stored value by 2 (untagging) and multiply it by word's size.
     89     STATIC_ASSERT(kSmiTagSize == 1 && kSmiShiftSize == 0);
     90     __ lea(esp, Operand(esp, ebx, times_half_pointer_size, 0));
     91 
     92     // Get rid of the internal frame.
     93   }
     94 
     95   // This call did not replace a call , so there will be an unwanted
     96   // return address left on the stack. Here we get rid of that.
     97   __ add(esp, Immediate(kPointerSize));
     98 
     99   // Now that the break point has been handled, resume normal execution by
    100   // jumping to the target address intended by the caller and that was
    101   // overwritten by the address of DebugBreakXXX.
    102   ExternalReference after_break_target =
    103       ExternalReference::debug_after_break_target_address(masm->isolate());
    104   __ jmp(Operand::StaticVariable(after_break_target));
    105 }
    106 
    107 
    108 void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
    109   // We do not know our frame height, but set esp based on ebp.
    110   __ lea(esp, Operand(ebp, -1 * kPointerSize));
    111 
    112   __ pop(edi);  // Function.
    113   __ pop(ebp);
    114 
    115   ParameterCount dummy(0);
    116   __ FloodFunctionIfStepping(edi, no_reg, dummy, dummy);
    117 
    118   // Load context from the function.
    119   __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
    120 
    121   // Clear new.target register as a safety measure.
    122   __ mov(edx, masm->isolate()->factory()->undefined_value());
    123 
    124   // Get function code.
    125   __ mov(ebx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
    126   __ mov(ebx, FieldOperand(ebx, SharedFunctionInfo::kCodeOffset));
    127   __ lea(ebx, FieldOperand(ebx, Code::kHeaderSize));
    128 
    129   // Re-run JSFunction, edi is function, esi is context.
    130   __ jmp(ebx);
    131 }
    132 
    133 
    134 const bool LiveEdit::kFrameDropperSupported = true;
    135 
    136 #undef __
    137 
    138 }  // namespace internal
    139 }  // namespace v8
    140 
    141 #endif  // V8_TARGET_ARCH_X87
    142