From: Heisenberg <lziqiang1@gmail.com>
Date: Thu, 11 Jun 2020 02:16:33 +0000 (+0800)
Subject: internal/bytealg: use CBZ instructions
X-Git-Tag: go1.16beta1~1309
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=99d6e3eec2cad4387b28759322273d774cc94fe5;p=gostls13.git

internal/bytealg: use CBZ instructions

Use CBZ to replace the comparison and jump to the zero instruction in the arm64 assembly file.

Change-Id: Ie16fb52e27b4d327343e119ebc0f0ca756437bc4
Reviewed-on: https://go-review.googlesource.com/c/go/+/237477
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---

diff --git a/src/internal/bytealg/compare_arm64.s b/src/internal/bytealg/compare_arm64.s
index 32e2ba200d..56d56f241e 100644
--- a/src/internal/bytealg/compare_arm64.s
+++ b/src/internal/bytealg/compare_arm64.s
@@ -36,8 +36,7 @@ TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0-0
 	CMP	R0, R1
 	CSEL	LT, R1, R0, R6    // R6 is min(R0, R1)
 
-	CMP	$0, R6
-	BEQ	samebytes
+	CBZ	R6, samebytes
 	BIC	$0xf, R6, R10
 	CBZ	R10, small        // length < 16
 	ADD	R2, R10           // end of chunk16