crypto: x86/sha512 - Use TEST %reg,%reg instead of CMP $0,%reg

CMP $0,%reg can't set overflow flag, so we can use shorter TEST %reg,%reg instruction when only zero and sign flags are checked (E,L,LE,G,GE conditions). Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
mariux64 · Dec 4, 2020 · 0b837f1 · 0b837f1
1 parent 032d049
commit 0b837f1
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diff --git a/arch/x86/crypto/sha512-avx-asm.S b/arch/x86/crypto/sha512-avx-asm.S
@@ -278,7 +278,7 @@ frame_size = frame_GPRSAVE + GPRSAVE_SIZE
 # "blocks" is the message length in SHA512 blocks
 ########################################################################
 SYM_FUNC_START(sha512_transform_avx)
-	cmp $0, msglen
+	test msglen, msglen
 	je nowork
 
 	# Allocate Stack Space

diff --git a/arch/x86/crypto/sha512-ssse3-asm.S b/arch/x86/crypto/sha512-ssse3-asm.S
@@ -280,7 +280,7 @@ frame_size = frame_GPRSAVE + GPRSAVE_SIZE
 ########################################################################
 SYM_FUNC_START(sha512_transform_ssse3)
 
-	cmp $0, msglen
+	test msglen, msglen
 	je nowork
 
 	# Allocate Stack Space