MIPS: Support LiveEdit.

src/mips/debug-mips.cc

 // 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.
 
 
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_MIPS
 
@@ skipping 83 matching lines @@
 #define __ ACCESS_MASM(masm)
 
 
 
 static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
                                           RegList object_regs,
                                           RegList non_object_regs) {
   {
     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);
+
     // Store the registers containing live values on the expression stack to
     // make sure that these are correctly updated during GC. Non object values
     // are stored as a smi causing it to be untouched by GC.
     ASSERT((object_regs & ~kJSCallerSaved) == 0);
     ASSERT((non_object_regs & ~kJSCallerSaved) == 0);
     ASSERT((object_regs & non_object_regs) == 0);
     if ((object_regs | non_object_regs) != 0) {
       for (int i = 0; i < kNumJSCallerSaved; i++) {
         int r = JSCallerSavedCode(i);
         Register reg = { r };
@@ skipping 26 matching lines @@
         if ((non_object_regs & (1 << r)) != 0) {
           __ srl(reg, reg, kSmiTagSize);
         }
         if (FLAG_debug_code &&
             (((object_regs |non_object_regs) & (1 << r)) == 0)) {
           __ 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));
@@ skipping 123 matching lines @@
 
 
 void DebugCodegen::GenerateSlotDebugBreak(MacroAssembler* masm) {
   // In the places where a debug break slot is inserted no registers can contain
   // object pointers.
   Generate_DebugBreakCallHelper(masm, 0, 0);
 }
 
 
 void DebugCodegen::GeneratePlainReturnLiveEdit(MacroAssembler* masm) {
-  masm->Abort(kLiveEditFrameDroppingIsNotSupportedOnMips);
+  __ Ret();
 }
 
 
 void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
-  masm->Abort(kLiveEditFrameDroppingIsNotSupportedOnMips);
+  ExternalReference restarter_frame_function_slot =
+      ExternalReference::debug_restarter_frame_function_pointer_address(
+          masm->isolate());
+  __ li(at, Operand(restarter_frame_function_slot));
+  __ sw(zero_reg, MemOperand(at, 0));
+
+  // We do not know our frame height, but set sp based on fp.
+  __ Subu(sp, fp, Operand(kPointerSize));
+
+  __ Pop(ra, fp, a1);  // Return address, Frame, Function.
+
+  // Load context from the function.
+  __ lw(cp, FieldMemOperand(a1, JSFunction::kContextOffset));
+
+  // 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 = false;
+const bool LiveEdit::kFrameDropperSupported = true;
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS