A64: Truncate booleans to 0 or 1 in LTaggedToI.

A64: Truncate booleans to 0 or 1 in LTaggedToI.

R=m.m.capewell@googlemail.com

Committed: https://code.google.com/p/v8/source/detail?r=19120

[ulan, 2014-02-05 18:21:26]

PTAL

[m.m.capewell, 2014-02-05 18:43:23]

https://codereview.chromium.org/145973022/diff/1/src/a64/lithium-codegen-a64.cc
File src/a64/lithium-codegen-a64.cc (right):

https://codereview.chromium.org/145973022/diff/1/src/a64/lithium-codegen-a64....
src/a64/lithium-codegen-a64.cc:5132: __ JumpIfNotRoot(scratch1,
Heap::kTrueValueRootIndex, &check_false);
It may be better to load both roots at once and use conditional instructions.

Register true_root = output;
Register false_root = scratch2;
LoadTrueFalseRoots(true_root, false_root);
Cmp(scratch1, true_root);
Cset(output, eq);
Ccmp(scratch1, false_root, ZFlag, ne);
B(eq, &done);
// Fall through to check_undefined.

You can delete the Mov(output, 0) from check_undefined, if it can't be reached
from elsewhere.

[ulan, 2014-02-05 19:21:29]

Thanks, I uploaded new patch set.

https://codereview.chromium.org/145973022/diff/1/src/a64/lithium-codegen-a64.cc
File src/a64/lithium-codegen-a64.cc (right):

https://codereview.chromium.org/145973022/diff/1/src/a64/lithium-codegen-a64....
src/a64/lithium-codegen-a64.cc:5132: __ JumpIfNotRoot(scratch1,
Heap::kTrueValueRootIndex, &check_false);
On 2014/02/05 18:43:23, m.m.capewell wrote:
> It may be better to load both roots at once and use conditional instructions.
> 
> Register true_root = output;
> Register false_root = scratch2;
> LoadTrueFalseRoots(true_root, false_root);
> Cmp(scratch1, true_root);
> Cset(output, eq);
> Ccmp(scratch1, false_root, ZFlag, ne);
> B(eq, &done);
> // Fall through to check_undefined.
> 
> You can delete the Mov(output, 0) from check_undefined, if it can't be reached
> from elsewhere.

Nice! Done.

[m.m.capewell, 2014-02-05 19:35:54]

lgtm

[ulan, 2014-02-05 19:56:58]

Committed patchset #3 manually as r19120 (presubmit successful).