Re: [PATCH 0/7] block-sha1: improved SHA1 hashing

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, 6 Aug 2009, Artur Skawina wrote:
> 
> Oh, i noticed that '-mtune' makes quite a difference, it can change
> the relative performance of the functions significantly, in unobvious
> ways; depending on which cpu gcc tunes for (build config or -mtune);
> some implementations slow down, others become a bit faster.

That probably is mainly true for P4, although it's quite possible that it 
has an effect for just what the register allocator does, and then for 
spilling.

And it looks like _all_ the tweakability is in the spilling. Nothing else 
matters.

How does this patch work for you? It avoids doing that C-level register 
rotation, and instead rotates the register names with the preprocessor.

I realize it's ugly as hell, but it does make it easier for gcc to see 
what's going on.

The patch is against my git patches, but I think it should apply pretty 
much as-is to your sha1bench sources too. Does it make any difference for 
you?

		Linus

---
 block-sha1/sha1.c |  117 ++++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 90 insertions(+), 27 deletions(-)

diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c
index 78dcb0c..ac47162 100644
--- a/block-sha1/sha1.c
+++ b/block-sha1/sha1.c
@@ -101,20 +101,20 @@ void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
 #define SHA_SRC(t) htonl(data[t])
 #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) \
-	TEMP = input(t); W(t) = TEMP; \
-	TEMP += SHA_ROL(A,5) + (fn) + E + (constant); \
-	E = D; D = C; C = SHA_ROR(B, 2); B = A; A = TEMP
+#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)
 
-#define T_0_15(t)  SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999 )
-#define T_16_19(t) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999 )
-#define T_20_39(t) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1 )
-#define T_40_59(t) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc )
-#define T_60_79(t) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6 )
+#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 )
+#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
+#define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
+#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )
 
 static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned int *data)
 {
-	unsigned int A,B,C,D,E,TEMP;
+	unsigned int A,B,C,D,E;
 	unsigned int array[16];
 
 	A = ctx->H[0];
@@ -124,31 +124,94 @@ static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned int *data)
 	E = ctx->H[4];
 
 	/* Round 1 - iterations 0-16 take their input from 'data' */
-	T_0_15( 0); T_0_15( 1); T_0_15( 2); T_0_15( 3); T_0_15( 4);
-	T_0_15( 5); T_0_15( 6); T_0_15( 7); T_0_15( 8); T_0_15( 9);
-	T_0_15(10); T_0_15(11); T_0_15(12); T_0_15(13); T_0_15(14);
-	T_0_15(15);
+	T_0_15( 0, A, B, C, D, E);
+	T_0_15( 1, E, A, B, C, D);
+	T_0_15( 2, D, E, A, B, C);
+	T_0_15( 3, C, D, E, A, B);
+	T_0_15( 4, B, C, D, E, A);
+	T_0_15( 5, A, B, C, D, E);
+	T_0_15( 6, E, A, B, C, D);
+	T_0_15( 7, D, E, A, B, C);
+	T_0_15( 8, C, D, E, A, B);
+	T_0_15( 9, B, C, D, E, A);
+	T_0_15(10, A, B, C, D, E);
+	T_0_15(11, E, A, B, C, D);
+	T_0_15(12, D, E, A, B, C);
+	T_0_15(13, C, D, E, A, B);
+	T_0_15(14, B, C, D, E, A);
+	T_0_15(15, A, B, C, D, E);
 
 	/* Round 1 - tail. Input from 512-bit mixing array */
-	T_16_19(16); T_16_19(17); T_16_19(18); T_16_19(19);
+	T_16_19(16, E, A, B, C, D);
+	T_16_19(17, D, E, A, B, C);
+	T_16_19(18, C, D, E, A, B);
+	T_16_19(19, B, C, D, E, A);
 
 	/* Round 2 */
-	T_20_39(20); T_20_39(21); T_20_39(22); T_20_39(23); T_20_39(24);
-	T_20_39(25); T_20_39(26); T_20_39(27); T_20_39(28); T_20_39(29);
-	T_20_39(30); T_20_39(31); T_20_39(32); T_20_39(33); T_20_39(34);
-	T_20_39(35); T_20_39(36); T_20_39(37); T_20_39(38); T_20_39(39);
+	T_20_39(20, A, B, C, D, E);
+	T_20_39(21, E, A, B, C, D);
+	T_20_39(22, D, E, A, B, C);
+	T_20_39(23, C, D, E, A, B);
+	T_20_39(24, B, C, D, E, A);
+	T_20_39(25, A, B, C, D, E);
+	T_20_39(26, E, A, B, C, D);
+	T_20_39(27, D, E, A, B, C);
+	T_20_39(28, C, D, E, A, B);
+	T_20_39(29, B, C, D, E, A);
+	T_20_39(30, A, B, C, D, E);
+	T_20_39(31, E, A, B, C, D);
+	T_20_39(32, D, E, A, B, C);
+	T_20_39(33, C, D, E, A, B);
+	T_20_39(34, B, C, D, E, A);
+	T_20_39(35, A, B, C, D, E);
+	T_20_39(36, E, A, B, C, D);
+	T_20_39(37, D, E, A, B, C);
+	T_20_39(38, C, D, E, A, B);
+	T_20_39(39, B, C, D, E, A);
 
 	/* Round 3 */
-	T_40_59(40); T_40_59(41); T_40_59(42); T_40_59(43); T_40_59(44);
-	T_40_59(45); T_40_59(46); T_40_59(47); T_40_59(48); T_40_59(49);
-	T_40_59(50); T_40_59(51); T_40_59(52); T_40_59(53); T_40_59(54);
-	T_40_59(55); T_40_59(56); T_40_59(57); T_40_59(58); T_40_59(59);
+	T_40_59(40, A, B, C, D, E);
+	T_40_59(41, E, A, B, C, D);
+	T_40_59(42, D, E, A, B, C);
+	T_40_59(43, C, D, E, A, B);
+	T_40_59(44, B, C, D, E, A);
+	T_40_59(45, A, B, C, D, E);
+	T_40_59(46, E, A, B, C, D);
+	T_40_59(47, D, E, A, B, C);
+	T_40_59(48, C, D, E, A, B);
+	T_40_59(49, B, C, D, E, A);
+	T_40_59(50, A, B, C, D, E);
+	T_40_59(51, E, A, B, C, D);
+	T_40_59(52, D, E, A, B, C);
+	T_40_59(53, C, D, E, A, B);
+	T_40_59(54, B, C, D, E, A);
+	T_40_59(55, A, B, C, D, E);
+	T_40_59(56, E, A, B, C, D);
+	T_40_59(57, D, E, A, B, C);
+	T_40_59(58, C, D, E, A, B);
+	T_40_59(59, B, C, D, E, A);
 
 	/* Round 4 */
-	T_60_79(60); T_60_79(61); T_60_79(62); T_60_79(63); T_60_79(64);
-	T_60_79(65); T_60_79(66); T_60_79(67); T_60_79(68); T_60_79(69);
-	T_60_79(70); T_60_79(71); T_60_79(72); T_60_79(73); T_60_79(74);
-	T_60_79(75); T_60_79(76); T_60_79(77); T_60_79(78); T_60_79(79);
+	T_60_79(60, A, B, C, D, E);
+	T_60_79(61, E, A, B, C, D);
+	T_60_79(62, D, E, A, B, C);
+	T_60_79(63, C, D, E, A, B);
+	T_60_79(64, B, C, D, E, A);
+	T_60_79(65, A, B, C, D, E);
+	T_60_79(66, E, A, B, C, D);
+	T_60_79(67, D, E, A, B, C);
+	T_60_79(68, C, D, E, A, B);
+	T_60_79(69, B, C, D, E, A);
+	T_60_79(70, A, B, C, D, E);
+	T_60_79(71, E, A, B, C, D);
+	T_60_79(72, D, E, A, B, C);
+	T_60_79(73, C, D, E, A, B);
+	T_60_79(74, B, C, D, E, A);
+	T_60_79(75, A, B, C, D, E);
+	T_60_79(76, E, A, B, C, D);
+	T_60_79(77, D, E, A, B, C);
+	T_60_79(78, C, D, E, A, B);
+	T_60_79(79, B, C, D, E, A);
 
 	ctx->H[0] += A;
 	ctx->H[1] += B;