Subzero: x86-64: Allow immediates in 64-bit instructions.

Subzero: x86-64: Allow immediates in 64-bit instructions.

The original code legalized *all* i64 constants into a register move, creating unnecessary instructions and slightly higher register pressure in most cases.

Generally, immediates can be used in 64-bit instructions as long as the immediate can be represented as a sign-extended 32-bit value.

BUG= none
R=jpp@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=9c2c093f37106ab952a439fa098d862101bb5854

[Jim Stichnoth, 2016-06-14 14:06:43]

Description was changed from

==========
Subzero: x86-64: Allow immediates in 64-bit instructions.

BUG= none
==========

to

==========
Subzero: x86-64: Allow immediates in 64-bit instructions.

The original code legalized *all* i64 constants into a register move, creating
unnecessary instructions and slightly higher register pressure in most cases.

Generally, immediates can be used in 64-bit instructions as long as the
immediate can be represented as a sign-extended 32-bit value.

BUG= none
==========

[Jim Stichnoth, 2016-06-14 14:06:43]

stichnot@chromium.org changed reviewers:
+ eholk@chromium.org, jpp@chromium.org, kschimpf@google.com, manasijm@google.com

[Jim Stichnoth, 2016-06-14 14:08:14]

This doesn't really help spec2k performance, but the code does look slightly
better.

[John, 2016-06-14 14:21:35]

lgtm

[Jim Stichnoth, 2016-06-14 14:27:27]

Description was changed from

==========
Subzero: x86-64: Allow immediates in 64-bit instructions.

The original code legalized *all* i64 constants into a register move, creating
unnecessary instructions and slightly higher register pressure in most cases.

Generally, immediates can be used in 64-bit instructions as long as the
immediate can be represented as a sign-extended 32-bit value.

BUG= none
==========

to

==========
Subzero: x86-64: Allow immediates in 64-bit instructions.

The original code legalized *all* i64 constants into a register move, creating
unnecessary instructions and slightly higher register pressure in most cases.

Generally, immediates can be used in 64-bit instructions as long as the
immediate can be represented as a sign-extended 32-bit value.

BUG= none
R=jpp@chromium.org

Committed:
https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a...
==========

[Jim Stichnoth, 2016-06-14 14:27:29]

Committed patchset #2 (id:20001) manually as
9c2c093f37106ab952a439fa098d862101bb5854 (presubmit successful).