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authorLinus Torvalds <torvalds@linux-foundation.org>2009-08-08 04:16:46 (GMT)
committerJunio C Hamano <gitster@pobox.com>2009-08-08 05:32:46 (GMT)
commit66c9c6c0fbba0894ebce3da572f62eb05162e547 (patch)
tree44ca7ad4f2ae1ac18e8f03d2746d791fcec51c32
parent30d12d4c16abc052e8961c07651f97bea2c061bd (diff)
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block-sha1: improved SHA1 hashing
I think I have found a way to avoid the gcc crazyness. Lookie here: # TIME[s] SPEED[MB/s] rfc3174 5.094 119.8 rfc3174 5.098 119.7 linus 1.462 417.5 linusas 2.008 304 linusas2 1.878 325 mozilla 5.566 109.6 mozillaas 5.866 104.1 openssl 1.609 379.3 spelvin 1.675 364.5 spelvina 1.601 381.3 nettle 1.591 383.6 notice? I outperform all the hand-tuned asm on 32-bit too. By quite a margin, in fact. Now, I didn't try a P4, and it's possible that it won't do that there, but the 32-bit code generation sure looks impressive on my Nehalem box. The magic? I force the stores to the 512-bit hash bucket to be done in order. That seems to help a lot. The diff is trivial (on top of the "rename registers with cpp" patch), as appended. And it does seem to fix the P4 issues too, although I can obviously (once again) only test Prescott, and only in 64-bit mode: # TIME[s] SPEED[MB/s] rfc3174 1.662 36.73 rfc3174 1.64 37.22 linus 0.2523 241.9 linusas 0.4367 139.8 linusas2 0.4487 136 mozilla 0.9704 62.9 mozillaas 0.9399 64.94 that's some really impressive improvement. All from just saying "do the stores in the order I told you to, dammit!" to the compiler. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--block-sha1/sha1.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c
index b715916..886bcf2 100644
--- a/block-sha1/sha1.c
+++ b/block-sha1/sha1.c
@@ -93,6 +93,7 @@ void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
/* This "rolls" over the 512-bit array */
#define W(x) (array[(x)&15])
+#define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))
/*
* Where do we get the source from? The first 16 iterations get it from
@@ -102,9 +103,9 @@ void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
#define SHA_MIX(t) SHA_ROL(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
- unsigned int TEMP = input(t); W(t) = TEMP; \
- TEMP += E + SHA_ROL(A,5) + (fn) + (constant); \
- B = SHA_ROR(B, 2); E = TEMP; } while (0)
+ unsigned int TEMP = input(t); setW(t, TEMP); \
+ E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
+ B = SHA_ROR(B, 2); } while (0)
#define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )