[turbofan][x64] Improve code generation for external reference access.

[turbofan][x64] Improve code generation for external reference access.

Properly fold external reference access into memory operands whenever
possible, i.e. for accessing the allocation top/limit, similar to what
we do in Crankshaft and hand-written native code. This only works when
the serializer is disabled, i.e. doesn't apply to the stubs in the
snapshot (for now). This reduces register pressure especially around
allocations where we'd currently need two registers to hold both the
allocation top and limit pointers in registers (on x64).

R=epertoso@chromium.org

Committed: https://crrev.com/7500e5077caaddf84e26a4c2356fb69f3edc7be5
Cr-Commit-Position: refs/heads/master@{#39993}

[Benedikt Meurer, 2016-10-05 12:13:38]

The CQ bit was checked by bmeurer@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-10-05 12:13:42]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[epertoso, 2016-10-05 12:26:40]

lgtm

[Benedikt Meurer, 2016-10-05 12:32:51]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2016-10-05 12:32:57]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-10-05 12:33:03]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-05 13:07:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-05 13:07:43]

Description was changed from

==========
[turbofan][x64] Improve code generation for external reference access.

Properly fold external reference access into memory operands whenever
possible, i.e. for accessing the allocation top/limit, similar to what
we do in Crankshaft and hand-written native code. This only works when
the serializer is disabled, i.e. doesn't apply to the stubs in the
snapshot (for now). This reduces register pressure especially around
allocations where we'd currently need two registers to hold both the
allocation top and limit pointers in registers (on x64).

R=epertoso@chromium.org
==========

to

==========
[turbofan][x64] Improve code generation for external reference access.

Properly fold external reference access into memory operands whenever
possible, i.e. for accessing the allocation top/limit, similar to what
we do in Crankshaft and hand-written native code. This only works when
the serializer is disabled, i.e. doesn't apply to the stubs in the
snapshot (for now). This reduces register pressure especially around
allocations where we'd currently need two registers to hold both the
allocation top and limit pointers in registers (on x64).

R=epertoso@chromium.org

Committed: https://crrev.com/7500e5077caaddf84e26a4c2356fb69f3edc7be5
Cr-Commit-Position: refs/heads/master@{#39993}
==========

[commit-bot: I haz the power, 2016-10-05 13:07:43]

Patchset 1 (id:??) landed as
https://crrev.com/7500e5077caaddf84e26a4c2356fb69f3edc7be5
Cr-Commit-Position: refs/heads/master@{#39993}