ARM: Optimsisation of ECMA ToInt32.

ARM: Optimsisation of ECMA ToInt32.

BUG=none
TEST=none

Committed: https://code.google.com/p/v8/source/detail?r=13912

[danno, 2013-03-11 09:56:03]

Ulan, can you please review this for Rodolph?

[danno, 2013-03-11 09:56:04]

Ulan, can you please review this for Rodolph?

[ulan, 2013-03-11 15:11:03]

LGTM!

https://codereview.chromium.org/12567004/diff/1/src/arm/code-stubs-arm.cc
File src/arm/code-stubs-arm.cc (right):

https://codereview.chromium.org/12567004/diff/1/src/arm/code-stubs-arm.cc#new...
src/arm/code-stubs-arm.cc:2300: // Allocate a new heap number without zapping
r0, which we need if it fails.
This comment is no longer valid.

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.cc
File src/arm/macro-assembler-arm.cc (right):

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.c...
src/arm/macro-assembler-arm.cc:2652: orr(result, result, Operand(1 <<
HeapNumber::kMantissaBitsInTopWord));
Maybe restore the comment about implicit 1?
// Set the implicit 1 before the mantissa part in input_high.

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.c...
src/arm/macro-assembler-arm.cc:2673: eor(result, result, Operand(input_high,
ASR, 31));
This is an awesome trick :)

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.h
File src/arm/macro-assembler-arm.h (right):

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.h...
src/arm/macro-assembler-arm.h:1365: // Helper for ECMAToInt32VFP and
ECMAToInt32NoVFP.
Description of preconditions for inputs would be helpful, like scratch contains
exponent - 1, 21 <= exponent <= 83

[Rodolph Perfetta, 2013-03-12 11:24:45]

https://codereview.chromium.org/12567004/diff/1/src/arm/code-stubs-arm.cc
File src/arm/code-stubs-arm.cc (right):

https://codereview.chromium.org/12567004/diff/1/src/arm/code-stubs-arm.cc#new...
src/arm/code-stubs-arm.cc:2300: // Allocate a new heap number without zapping
r0, which we need if it fails.
On 2013/03/11 15:11:03, ulan wrote:
> This comment is no longer valid.

Done.

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.cc
File src/arm/macro-assembler-arm.cc (right):

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.c...
src/arm/macro-assembler-arm.cc:2652: orr(result, result, Operand(1 <<
HeapNumber::kMantissaBitsInTopWord));
On 2013/03/11 15:11:03, ulan wrote:
> Maybe restore the comment about implicit 1?
> // Set the implicit 1 before the mantissa part in input_high.

Done.

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.h
File src/arm/macro-assembler-arm.h (right):

https://codereview.chromium.org/12567004/diff/1/src/arm/macro-assembler-arm.h...
src/arm/macro-assembler-arm.h:1365: // Helper for ECMAToInt32VFP and
ECMAToInt32NoVFP.
On 2013/03/11 15:11:03, ulan wrote:
> Description of preconditions for inputs would be helpful, like scratch
contains
> exponent - 1, 21 <= exponent <= 83

Done.

[Rodolph Perfetta, 2013-03-12 11:25:58]

Committed patchset #1 manually as r13912 (presubmit successful).