Add flag to tracing element kind transitions

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index fe1641c374bc769d2bbb1bde13d2b6a5e2ec1e56..569f7e36ca791a8fff4405dcfe0f2e6a14844516 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -7040,6 +7040,32 @@ void FastElementsConversionStub::GenerateSmiOnlyToObject(MacroAssembler* masm) {
                       kDontSaveFPRegs,
                       EMIT_REMEMBERED_SET,
                       OMIT_SMI_CHECK);
+
+  if (FLAG_trace_element_transitions) {
+    // Save registers and make sure return address is on top.
+    __ pop(esi);
+    __ push(eax);
+    __ push(ebx);
+    __ push(ecx);
+    __ push(edx);
+    __ push(esi);
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ push(edx);
+      __ push(Immediate(FAST_SMI_ONLY_ELEMENTS << kSmiTagSize));
+      __ push(FieldOperand(edx, JSObject::kElementsOffset));
+      __ push(Immediate(FAST_ELEMENTS << kSmiTagSize));
+      __ push(FieldOperand(edx, JSObject::kElementsOffset));
+      __ CallRuntime(Runtime::kTraceElementsKindTransition, 5);
+    }
+    // Restore registers and make sure return address is on top.
+    __ pop(esi);
+    __ pop(edx);
+    __ pop(ecx);
+    __ pop(ebx);
+    __ pop(eax);
+    __ push(esi);
+  }
 }
 
 
@@ -7053,6 +7079,8 @@ void FastElementsConversionStub::GenerateSmiOnlyToDouble(
   //  -- esp[0] : return address
   // -----------------------------------
   Label loop, entry, convert_hole, gc_required;
+  // Make sure to change the following when pushing more values on the stack.
+  static int registers_already_on_stack = 2;
   __ push(eax);
   __ push(ebx);
 
@@ -7085,6 +7113,44 @@ void FastElementsConversionStub::GenerateSmiOnlyToDouble(
 
   __ mov(edi, FieldOperand(esi, FixedArray::kLengthOffset));
 
+  if (FLAG_trace_element_transitions) {
+    static int registers_to_save = 6;
+    // Swizzle the stack so that all registers are saved below the return
+    // address, which must be at the top of stack when calling out.
+    int registers_slot_for_return_address =
+        registers_to_save + registers_already_on_stack;
+    __ sub(esp, Immediate(registers_to_save * kPointerSize));
+    __ mov(Operand(esp, 5 * kPointerSize), ebx);
+    __ mov(Operand(esp, 4 * kPointerSize), ecx);
+    __ mov(Operand(esp, 3 * kPointerSize), edx);
+    __ mov(Operand(esp, 2 * kPointerSize), esi);
+    __ mov(Operand(esp, 1 * kPointerSize), edi);
+    __ mov(ebx, Operand(esp, registers_slot_for_return_address * kPointerSize));
+    __ mov(Operand(esp, 0), ebx);
+    __ mov(Operand(esp, registers_slot_for_return_address * kPointerSize), eax);
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ push(edx);
+      __ push(Immediate(FAST_SMI_ONLY_ELEMENTS << kSmiTagSize));
+      __ push(esi);
+      __ push(Immediate(FAST_DOUBLE_ELEMENTS << kSmiTagSize));
+      __ push(eax);
+      __ CallRuntime(Runtime::kTraceElementsKindTransition, 5);
+    }
+    // Restore all the registers that were saved before the internal frame scope
+    // was created, ensuring that the return address remains on the top of
+    // stack.
+    __ mov(eax, Operand(esp, registers_slot_for_return_address * kPointerSize));
+    __ mov(ebx, Operand(esp, 0));
+    __ mov(Operand(esp, registers_slot_for_return_address * kPointerSize), ebx);
+    __ mov(ebx, Operand(esp, 5 * kPointerSize));
+    __ mov(ecx, Operand(esp, 4 * kPointerSize));
+    __ mov(edx, Operand(esp, 3 * kPointerSize));
+    __ mov(esi, Operand(esp, 2 * kPointerSize));
+    __ mov(edi, Operand(esp, 1 * kPointerSize));
+    __ add(esp, Immediate(registers_to_save * kPointerSize));
+  }
+
   // Prepare for conversion loop.
   ExternalReference canonical_the_hole_nan_reference =
       ExternalReference::address_of_the_hole_nan();
@@ -7257,6 +7323,42 @@ void FastElementsConversionStub::GenerateDoubleToObject(
                       kDontSaveFPRegs,
                       EMIT_REMEMBERED_SET,
                       OMIT_SMI_CHECK);
+
+  if (FLAG_trace_element_transitions) {
+    static int registers_already_on_stack = 1;
+    static int registers_to_save = 4;
+    // Swizzle the stack so that all registers are saved below the return
+    // address, which must be at the top of stack when calling out.
+    int registers_slot_for_return_address =
+        registers_to_save + registers_already_on_stack;
+    __ sub(esp, Immediate(registers_to_save * kPointerSize));
+    __ mov(Operand(esp, 3 * kPointerSize), edx);
+    __ mov(Operand(esp, 2 * kPointerSize), ecx);
+    __ mov(Operand(esp, 1 * kPointerSize), ebx);
+    __ mov(ebx, Operand(esp, registers_slot_for_return_address * kPointerSize));
+    __ mov(Operand(esp, 0), ebx);
+    __ mov(Operand(esp, registers_slot_for_return_address * kPointerSize), eax);
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ push(edx);
+      __ push(Immediate(FAST_DOUBLE_ELEMENTS << kSmiTagSize));
+      __ push(FieldOperand(edx, JSObject::kElementsOffset));
+      __ push(Immediate(FAST_ELEMENTS << kSmiTagSize));
+      __ push(eax);
+      __ CallRuntime(Runtime::kTraceElementsKindTransition, 5);
+    }
+    // Restore all the registers that were saved before the internal frame scope
+    // was created, ensuring that the return address remains on the top of
+    // stack.
+    __ mov(eax, Operand(esp, registers_slot_for_return_address * kPointerSize));
+    __ mov(ebx, Operand(esp, 0));
+    __ mov(Operand(esp, registers_slot_for_return_address * kPointerSize), ebx);
+    __ mov(edx, Operand(esp, 3 * kPointerSize));
+    __ mov(ecx, Operand(esp, 2 * kPointerSize));
+    __ mov(ebx, Operand(esp, 1 * kPointerSize));
+    __ add(esp, Immediate(registers_to_save * kPointerSize));
+  }
+
   // Replace receiver's backing store with newly created and filled FixedArray.
   __ mov(FieldOperand(edx, JSObject::kElementsOffset), eax);
   __ RecordWriteField(edx,