Fixes ARM SIMD IL bug.

Fixes ARM SIMD IL bug.

Issue 14341

R=fschneider@google.com

Committed: https://code.google.com/p/dart/source/detail?r=29092

[Florian Schneider, 2013-10-23 15:36:02]

LGTM with a comment.

https://codereview.chromium.org/37413002/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language_arm.cc (right):

https://codereview.chromium.org/37413002/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language_arm.cc:3315: __ Vsqrtqs(result, left, temp);
It seems this instruction is only used here. I'd make the temp argument
mandatory, instead of optional. Otherwise, it is really confusing that in one
case left is overwritten, and when passing a temp it is preserved.

[zra, 2013-10-23 15:56:17]

https://codereview.chromium.org/37413002/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language_arm.cc (right):

https://codereview.chromium.org/37413002/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language_arm.cc:3315: __ Vsqrtqs(result, left, temp);
On 2013/10/23 15:36:02, Florian Schneider wrote:
> It seems this instruction is only used here. I'd make the temp argument
> mandatory, instead of optional. Otherwise, it is really confusing that in one
> case left is overwritten, and when passing a temp it is preserved.

Done.

[zra, 2013-10-23 15:56:39]

Committed patchset #2 manually as r29092 (presubmit successful).

[Florian Schneider, 2013-10-23 16:08:43]

On 2013/10/23 15:56:39, zra wrote:
> Committed patchset #2 manually as r29092 (presubmit successful).

I think you should also change the code in Assembler::Vsqrtqs to something like

void Assembler::Vsqrtqs(QRegister qd, QRegister qm, QRegister temp) {
  ASSERT(temp != QTMP);
  ASSERT(qm != QTMP);
  ASSERT(qd != QTMP);
  ASSERT(temp != kNoRegister);

  vmovq(temp, qm);
  VreciprocalSqrtqs(qd, temp);
  vmovq(temp, qd);
  Vreciprocalqs(qd, temp);
}