| commit | 06337823ef4d9c57b1b01f9b97a348a47277a9df | [log] [tgz] |
|---|---|---|
| author | Junchen Li <junchen.li@arm.com> | Fri Jul 10 11:39:23 2020 +0800 |
| committer | Keith Randall <khr@golang.org> | Tue Aug 18 04:09:13 2020 +0000 |
| tree | 1b12a842aa7e03ad816ba4083ef711f33886badf | |
| parent | 7fbd8c75c6c57e713069a3a405e5cde26cfae090 [diff] |
cmd/compile: optimize unsigned comparisons to 0/1 on arm64
For an unsigned integer, it's useful to convert its order test with 0/1
to its equality test with 0. We can save a comparison instruction that
followed by a conditional branch on arm64 since it supports
compare-with-zero-and-branch instructions. For example,
if x > 0 { ... } else { ... }
the original version:
CMP $0, R0
BLS 9
the optimized version:
CBZ R0, 8
Updates #21439
Change-Id: Id1de6f865f6aa72c5d45b29f7894818857288425
Reviewed-on: https://go-review.googlesource.com/c/go/+/246857
Reviewed-by: Keith Randall <khr@golang.org>
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