Home | History | Annotate | Download | only in ia32 
      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_IA32
      6 
      7 #include "src/codegen.h"
      8 #include "src/debug/debug.h"
      9 #include "src/ia32/frames-ia32.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(code->is_debug_stub());
     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 bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
     54   return !Assembler::IsNop(pc);
     55 }
     56 
     57 void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
     58                                           DebugBreakCallHelperMode mode) {
     59   __ RecordComment("Debug break");
     60 
     61   // Enter an internal frame.
     62   {
     63     FrameScope scope(masm, StackFrame::INTERNAL);
     64 
     65     // Load padding words on stack.
     66     for (int i = 0; i < LiveEdit::kFramePaddingInitialSize; i++) {
     67       __ push(Immediate(Smi::FromInt(LiveEdit::kFramePaddingValue)));
     68     }
     69     __ push(Immediate(Smi::FromInt(LiveEdit::kFramePaddingInitialSize)));
     70 
     71     // Push arguments for DebugBreak call.
     72     if (mode == SAVE_RESULT_REGISTER) {
     73       // Break on return.
     74       __ push(eax);
     75     } else {
     76       // Non-return breaks.
     77       __ Push(masm->isolate()->factory()->the_hole_value());
     78     }
     79     __ Move(eax, Immediate(1));
     80     __ mov(ebx,
     81            Immediate(ExternalReference(
     82                Runtime::FunctionForId(Runtime::kDebugBreak), masm->isolate())));
     83 
     84     CEntryStub ceb(masm->isolate(), 1);
     85     __ CallStub(&ceb);
     86 
     87     if (FLAG_debug_code) {
     88       for (int i = 0; i < kNumJSCallerSaved; ++i) {
     89         Register reg = {JSCallerSavedCode(i)};
     90         // Do not clobber eax if mode is SAVE_RESULT_REGISTER. It will
     91         // contain return value of the function.
     92         if (!(reg.is(eax) && (mode == SAVE_RESULT_REGISTER))) {
     93           __ Move(reg, Immediate(kDebugZapValue));
     94         }
     95       }
     96     }
     97 
     98     __ pop(ebx);
     99     // We divide stored value by 2 (untagging) and multiply it by word's size.
    100     STATIC_ASSERT(kSmiTagSize == 1 && kSmiShiftSize == 0);
    101     __ lea(esp, Operand(esp, ebx, times_half_pointer_size, 0));
    102 
    103     // Get rid of the internal frame.
    104   }
    105 
    106   // This call did not replace a call , so there will be an unwanted
    107   // return address left on the stack. Here we get rid of that.
    108   __ add(esp, Immediate(kPointerSize));
    109 
    110   // Now that the break point has been handled, resume normal execution by
    111   // jumping to the target address intended by the caller and that was
    112   // overwritten by the address of DebugBreakXXX.
    113   ExternalReference after_break_target =
    114       ExternalReference::debug_after_break_target_address(masm->isolate());
    115   __ jmp(Operand::StaticVariable(after_break_target));
    116 }
    117 
    118 
    119 void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
    120   // We do not know our frame height, but set esp based on ebp.
    121   __ lea(esp, Operand(ebp, FrameDropperFrameConstants::kFunctionOffset));
    122   __ pop(edi);  // Function.
    123   __ add(esp, Immediate(-FrameDropperFrameConstants::kCodeOffset));  // INTERNAL
    124                                                                      // frame
    125                                                                      // marker
    126                                                                      // and code
    127   __ pop(ebp);
    128 
    129   ParameterCount dummy(0);
    130   __ FloodFunctionIfStepping(edi, no_reg, dummy, dummy);
    131 
    132   // Load context from the function.
    133   __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
    134 
    135   // Clear new.target register as a safety measure.
    136   __ mov(edx, masm->isolate()->factory()->undefined_value());
    137 
    138   // Get function code.
    139   __ mov(ebx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
    140   __ mov(ebx, FieldOperand(ebx, SharedFunctionInfo::kCodeOffset));
    141   __ lea(ebx, FieldOperand(ebx, Code::kHeaderSize));
    142 
    143   // Re-run JSFunction, edi is function, esi is context.
    144   __ jmp(ebx);
    145 }
    146 
    147 
    148 const bool LiveEdit::kFrameDropperSupported = true;
    149 
    150 #undef __
    151 
    152 }  // namespace internal
    153 }  // namespace v8
    154 
    155 #endif  // V8_TARGET_ARCH_IA32
    156