[v8-dev] [v8 commit] r1620 - Change the arguments access stub to take both arguments in registers

[codesite-noreply]

Author: kmilli...@chromium.org
Date: Thu Mar 26 06:02:00 2009
New Revision: 1620

Modified:
    branches/bleeding_edge/src/codegen-ia32.cc

Log:
Change the arguments access stub to take both arguments in registers
rathern than one in a register and one on the stack.

Fix a stack height bug in the case that the arguments access stub hit
its slow case.
Review URL: http://codereview.chromium.org/49037

Modified: branches/bleeding_edge/src/codegen-ia32.cc
==============================================================================
--- branches/bleeding_edge/src/codegen-ia32.cc  (original)
+++ branches/bleeding_edge/src/codegen-ia32.cc  Thu Mar 26 06:02:00 2009
@@ -4351,9 +4351,12 @@
  void CodeGenerator::GenerateArgumentsAccess(ZoneList<Expression*>* args) {
    ASSERT(args->length() == 1);

-  // Load the key onto the stack and set register eax to the formal
-  // parameters count for the currently executing function.
+  // Load the key into edx and set eax to the formal parameters count
+  // for the currently executing function.
    Load(args->at(0));
+  Result key = frame_->Pop();
+  key.ToRegister(edx);
+
    Result parameters_count = allocator()->Allocate(eax);
    ASSERT(parameters_count.is_valid());
    __ Set(parameters_count.reg(),
@@ -4361,8 +4364,8 @@

    // Call the shared stub to get to arguments[key].
    ArgumentsAccessStub stub(ArgumentsAccessStub::READ_ELEMENT);
-  Result result = frame_->CallStub(&stub, &parameters_count, 0);
-  frame_->SetElementAt(0, &result);
+  Result result = frame_->CallStub(&stub, &parameters_count, &key, 0);
+  frame_->Push(&result);
  }


@@ -6259,6 +6262,8 @@


  void ArgumentsAccessStub::GenerateReadElement(MacroAssembler* masm) {
+  // The key is in edx and the parameter count is in eax.
+
    // The displacement is used for skipping the frame pointer on the
    // stack. It is the offset of the last parameter (if any) relative
    // to the frame pointer.
@@ -6266,48 +6271,50 @@

    // Check that the key is a smi.
    Label slow;
-  __ mov(ebx, Operand(esp, 1 * kPointerSize));  // skip return address
-  __ test(ebx, Immediate(kSmiTagMask));
+  __ test(edx, Immediate(kSmiTagMask));
    __ j(not_zero, &slow, not_taken);

    // Check if the calling frame is an arguments adaptor frame.
    Label adaptor;
-  __ mov(edx, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
-  __ mov(ecx, Operand(edx, StandardFrameConstants::kContextOffset));
+  __ mov(ebx, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
+  __ mov(ecx, Operand(ebx, StandardFrameConstants::kContextOffset));
    __ cmp(ecx, ArgumentsAdaptorFrame::SENTINEL);
    __ j(equal, &adaptor);

    // Check index against formal parameters count limit passed in
    // through register eax. Use unsigned comparison to get negative
    // check for free.
-  __ cmp(ebx, Operand(eax));
+  __ cmp(edx, Operand(eax));
    __ j(above_equal, &slow, not_taken);

    // Read the argument from the stack and return it.
    ASSERT(kSmiTagSize == 1 && kSmiTag == 0);  // shifting code depends on  
this
-  __ lea(edx, Operand(ebp, eax, times_2, 0));
-  __ neg(ebx);
-  __ mov(eax, Operand(edx, ebx, times_2, kDisplacement));
+  __ lea(ebx, Operand(ebp, eax, times_2, 0));
+  __ neg(edx);
+  __ mov(eax, Operand(ebx, edx, times_2, kDisplacement));
    __ ret(0);

    // Arguments adaptor case: Check index against actual arguments
    // limit found in the arguments adaptor frame. Use unsigned
    // comparison to get negative check for free.
    __ bind(&adaptor);
-  __ mov(ecx, Operand(edx, ArgumentsAdaptorFrameConstants::kLengthOffset));
-  __ cmp(ebx, Operand(ecx));
+  __ mov(ecx, Operand(ebx, ArgumentsAdaptorFrameConstants::kLengthOffset));
+  __ cmp(edx, Operand(ecx));
    __ j(above_equal, &slow, not_taken);

    // Read the argument from the stack and return it.
    ASSERT(kSmiTagSize == 1 && kSmiTag == 0);  // shifting code depends on  
this
-  __ lea(edx, Operand(edx, ecx, times_2, 0));
-  __ neg(ebx);
-  __ mov(eax, Operand(edx, ebx, times_2, kDisplacement));
+  __ lea(ebx, Operand(ebx, ecx, times_2, 0));
+  __ neg(edx);
+  __ mov(eax, Operand(ebx, edx, times_2, kDisplacement));
    __ ret(0);

    // Slow-case: Handle non-smi or out-of-bounds access to arguments
    // by calling the runtime system.
    __ bind(&slow);
+  __ pop(ebx);  // Return address.
+  __ push(edx);
+  __ push(ebx);
    __ TailCallRuntime(ExternalReference(Runtime::kGetArgumentsProperty), 1);
  }


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