v8/src/ia32/register-allocator-ia32.cc
fschneider@chromium.org 53bee811ad Re-enable using push instructions for syncing the virtual frame.
This change fixes the problem with the original version of this approach
(r3032) that may lead to a corrupted stack if we would invoke spilling during 
syncing a large SMI constant (unsafe SMIs) in the virtual frame.

The new code for storing unsafe SMI constants does not use an extra temporary 
register. This prevents the compiler from ever having to spill during a 
virutal frame sync operation.

For storing a large SMI constant we previously generated:

  mov ecx, (large_smi & 0x0000ffff)
  xor ecx, (large_smi & 0xffff0000)
  push ecx

we now generate:

  push (large_smi & 0x0000ffff)
  or   [esp], (large_smi & 0xffff0000)

Not using a temporary register avoids spilling within an nvocation 
of VirtualFrame::SyncRange.

Review URL: http://codereview.chromium.org/391079

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3313 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2009-11-16 23:11:19 +00:00

100 lines
3.8 KiB
C++

// Copyright 2008 the V8 project authors. 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.
#include "v8.h"
#include "codegen-inl.h"
#include "register-allocator-inl.h"
namespace v8 {
namespace internal {
// -------------------------------------------------------------------------
// Result implementation.
void Result::ToRegister() {
ASSERT(is_valid());
if (is_constant()) {
Result fresh = CodeGeneratorScope::Current()->allocator()->Allocate();
ASSERT(fresh.is_valid());
if (CodeGeneratorScope::Current()->IsUnsafeSmi(handle())) {
CodeGeneratorScope::Current()->MoveUnsafeSmi(fresh.reg(), handle());
} else {
CodeGeneratorScope::Current()->masm()->Set(fresh.reg(),
Immediate(handle()));
}
// This result becomes a copy of the fresh one.
*this = fresh;
}
ASSERT(is_register());
}
void Result::ToRegister(Register target) {
ASSERT(is_valid());
if (!is_register() || !reg().is(target)) {
Result fresh = CodeGeneratorScope::Current()->allocator()->Allocate(target);
ASSERT(fresh.is_valid());
if (is_register()) {
CodeGeneratorScope::Current()->masm()->mov(fresh.reg(), reg());
} else {
ASSERT(is_constant());
if (CodeGeneratorScope::Current()->IsUnsafeSmi(handle())) {
CodeGeneratorScope::Current()->MoveUnsafeSmi(fresh.reg(), handle());
} else {
CodeGeneratorScope::Current()->masm()->Set(fresh.reg(),
Immediate(handle()));
}
}
*this = fresh;
} else if (is_register() && reg().is(target)) {
ASSERT(CodeGeneratorScope::Current()->has_valid_frame());
CodeGeneratorScope::Current()->frame()->Spill(target);
ASSERT(CodeGeneratorScope::Current()->allocator()->count(target) == 1);
}
ASSERT(is_register());
ASSERT(reg().is(target));
}
// -------------------------------------------------------------------------
// RegisterAllocator implementation.
Result RegisterAllocator::AllocateByteRegisterWithoutSpilling() {
Result result = AllocateWithoutSpilling();
// Check that the register is a byte register. If not, unuse the
// register if valid and return an invalid result.
if (result.is_valid() && !result.reg().is_byte_register()) {
result.Unuse();
return Result();
}
return result;
}
} } // namespace v8::internal