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Change __ mov(eax, TOS) to

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__ pop(eax);
...
__ push(eax);
to enable push/pop eliminations.

__ push(eax) must happen before RecordWrite because RecordWrite may destroy 
eax value. To be safe, also moved __ push(r0) on ARM to above RecordWrite.

This only affects the case where a context variable is used in a inner scope.

Create a tests for it. It fails if __ push(eax) is after RecordWrite.



git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@111 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
feng.qian.v8 2008-09-02 21:47:45 +00:00
parent 786760039e
commit 6287c675d8
3 changed files with 40 additions and 2 deletions
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2
src/codegen-arm.cc
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@ -3238,6 +3238,7 @@ void ArmCodeGenerator::VisitSlot(Slot* node) {
// r2 may be loaded with context; used below in RecordWrite.
__ pop(r0);
__ str(r0, SlotOperand(node, r2));
__ push(r0);
if (node->type() == Slot::CONTEXT) {
// Skip write barrier if the written value is a smi.
Label exit;
@ -3249,7 +3250,6 @@ void ArmCodeGenerator::VisitSlot(Slot* node) {
__ RecordWrite(r2, r3, r1);
__ bind(&exit);
}
__ push(r0);
break;
}
}

3
src/codegen-ia32.cc
View File

@ -3440,8 +3440,9 @@ void Ia32CodeGenerator::VisitSlot(Slot* node) {
// Variable::CONST because of const declarations which will
// initialize consts to 'the hole' value and by doing so, end
// up calling this code.
__ mov(eax, TOS);
__ pop(eax);
__ mov(SlotOperand(node, ecx), eax);
__ push(eax); // RecordWrite may destroy the value in eax.
if (node->type() == Slot::CONTEXT) {
// ecx is loaded with context when calling SlotOperand above.
int offset = FixedArray::kHeaderSize + node->index() * kPointerSize;

37
test/mjsunit/context-variable-assignments.js Normal file
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@ -0,0 +1,37 @@
// Copyright 2008 Google Inc. All Rights Reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
function foo() {
var a, b;
var bar = function() {
a = b = "hello world";
}
bar();
return a;
}
assertEquals("hello world", foo());