commit a0819bbd36c200141787f8a98ecdfd6902290702
author Austin Clements <austin@google.com> Thu Oct 20 17:37:50 2016 -0400
committer Austin Clements <austin@google.com> Fri Oct 21 19:51:15 2016 +0000
tree c95438c49d754a4947dbba4792f3e9de0f464ac2
parent e67f5eca87e1a46f5b154439b827d050b4e1da9f

salsa20/salsa: hide SP alignment from spadj

The spadj computation in the assembler can't handle SP alignment code
and will just get confused by how it's currently written. Do the
alignment in a scratch register to hide it from the assembler.

Change-Id: I8857f428d96717db29e3a56050f2381bd86807c6
Reviewed-on: https://go-review.googlesource.com/31586
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Adam Langley <agl@golang.org>

salsa20/salsa/salsa2020_amd64.s

diff --git a/salsa20/salsa/salsa2020_amd64.s b/salsa20/salsa/salsa2020_amd64.s
index 6e1df96..9c4ae96 100644
--- a/salsa20/salsa/salsa2020_amd64.s
+++ b/salsa20/salsa/salsa2020_amd64.s
@@ -16,10 +16,10 @@
 	MOVQ key+32(FP),R8
 
 	MOVQ SP,R11
-	MOVQ $31,R9
-	NOTQ R9
-	ANDQ R9,SP
-	ADDQ $32,SP
+	MOVQ SP,R9
+	ADDQ $31, R9
+	ANDQ $~31, R9
+	MOVQ R9, SP
 
 	MOVQ R11,352(SP)
 	MOVQ R12,360(SP)