[turbofan] Elide fp32 convert for const compares

[turbofan] Elide fp32 convert for const compares

Reduce operations of the form f64cmp(fp32to64(x), k) to f32cmp(x, k) when k
can be encoded as a 32-bit float.

Committed: https://crrev.com/809f6b15be82e3b85425b5d9a45fe981d487bf43
Cr-Commit-Position: refs/heads/master@{#30909}

[martyn.capewell, 2015-09-23 13:43:03]

martyn.capewell@arm.com changed reviewers:
+ bmeurer@chromium.org, ulan@chromium.org

[Benedikt Meurer, 2015-09-23 17:31:52]

LGTM with nit.

https://codereview.chromium.org/1365623002/diff/1/src/compiler/machine-operat...
File src/compiler/machine-operator-reducer.cc (right):

https://codereview.chromium.org/1365623002/diff/1/src/compiler/machine-operat...
src/compiler/machine-operator-reducer.cc:1013: bool
IsFloat64RepresentableAsFloat32(const Float64Matcher* m) {
Nit: Please pass by const reference instead of const pointer.

[martyn.capewell, 2015-09-24 11:02:18]

The CQ bit was checked by martyn.capewell@arm.com

[martyn.capewell, 2015-09-24 11:02:19]

The patchset sent to the CQ was uploaded after l-g-t-m from bmeurer@chromium.org
Link to the patchset: https://codereview.chromium.org/1365623002/#ps20001
(title: "Address pointer->reference nit")

[commit-bot: I haz the power, 2015-09-24 11:02:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1365623002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1365623002/20001

[commit-bot: I haz the power, 2015-09-24 11:24:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-24 11:24:59]

Patchset 2 (id:??) landed as
https://crrev.com/809f6b15be82e3b85425b5d9a45fe981d487bf43
Cr-Commit-Position: refs/heads/master@{#30909}