MIPS64: Improve and fix nan hole checks and canonicalization.

MIPS64: Improve and fix hole nan checks and canonicalization.

TEST=kraken-1.1 benchmark
BUG=

Committed: https://crrev.com/47e608ab5261c7c222dbef4fab83be43865f784b
Cr-Commit-Position: refs/heads/master@{#26861}

[dusmil.imgtec, 2015-02-25 15:09:24]

dusan.milosavljevic@imgtec.com changed reviewers:
+ akos.palfi@imgtec.com, balazs.kilvady@imgtec.com, paul.lind@imgtec.com

[dusmil.imgtec, 2015-02-25 15:09:25]

PTAL.

[balazs.kilvady, 2015-02-25 15:55:49]

lgtm

[paul.l..., 2015-02-25 16:21:38]

LGTM, with a nit (and a question).

https://codereview.chromium.org/952233002/diff/1/src/mips64/lithium-codegen-m...
File src/mips64/lithium-codegen-mips64.cc (right):

https://codereview.chromium.org/952233002/diff/1/src/mips64/lithium-codegen-m...
src/mips64/lithium-codegen-mips64.cc:2367:
Operand(static_cast<int32_t>(kHoleNanUpper32)));
this looks like nice solution to remove some instructions! Curious if this
changes the number of instructions emitted by the li() in the branch, though. Is
our li() clever enough to sign-extend without needing to explicitly load all 4
16-bit chunks?

https://codereview.chromium.org/952233002/diff/1/src/mips64/macro-assembler-m...
File src/mips64/macro-assembler-mips64.cc (right):

https://codereview.chromium.org/952233002/diff/1/src/mips64/macro-assembler-m...
src/mips64/macro-assembler-mips64.cc:3891: // scratch1 is now effective address
of the double element.
nit: It looks like this comment is now stale - scratch1 is only used in
CheckMap() above, and should have map pointer. Can you correct this as
necessary.

[dusmil.imgtec, 2015-02-25 16:35:38]

The CQ bit was checked by dusan.milosavljevic@imgtec.com

[commit-bot: I haz the power, 2015-02-25 16:36:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/952233002/1

[commit-bot: I haz the power, 2015-02-25 17:09:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-25 17:09:46]

Patchset 1 (id:??) landed as
https://crrev.com/47e608ab5261c7c222dbef4fab83be43865f784b
Cr-Commit-Position: refs/heads/master@{#26861}