A better-scheduled PPC SHA-1 implementation.

This is about 15% faster that the current sha1ppc.S on a G4, and
5% faster on a G5 when hashing 10 million bytes, unaligned.
(The G5 ratio seems to get better as the sizes fall.)

It's also somewhat smaller, due to using load-multiple instructions.

No copyright is claimed on the changes to Paul Mackerras' work below.
maint
Unknown 2006-06-24 02:31:20 -07:00 committed by Junio C Hamano
parent b57cbbf8a8
commit 84702995f8
1 changed files with 183 additions and 144 deletions

View File

@ -3,183 +3,222 @@
* *
* Copyright (C) 2005 Paul Mackerras <paulus@samba.org> * Copyright (C) 2005 Paul Mackerras <paulus@samba.org>
*/ */
#define FS 80


/* /*
* We roll the registers for T, A, B, C, D, E around on each * PowerPC calling convention:
* iteration; T on iteration t is A on iteration t+1, and so on. * %r0 - volatile temp
* We use registers 7 - 12 for this. * %r1 - stack pointer.
* %r2 - reserved
* %r3-%r12 - Incoming arguments & return values; volatile.
* %r13-%r31 - Callee-save registers
* %lr - Return address, volatile
* %ctr - volatile
*
* Register usage in this routine:
* %r0 - temp
* %r3 - argument (pointer to 5 words of SHA state)
* %r4 - argument (pointer to data to hash)
* %r5 - Contant K in SHA round (initially number of blocks to hash)
* %r6-%r10 - Working copies of SHA variables A..E (actually E..A order)
* %r11-%r26 - Data being hashed W[].
* %r27-%r31 - Previous copies of A..E, for final add back.
* %ctr - loop count
*/ */
#define RT(t) ((((t)+5)%6)+7)
#define RA(t) ((((t)+4)%6)+7)
#define RB(t) ((((t)+3)%6)+7)
#define RC(t) ((((t)+2)%6)+7)
#define RD(t) ((((t)+1)%6)+7)
#define RE(t) ((((t)+0)%6)+7)


/* We use registers 16 - 31 for the W values */
#define W(t) (((t)%16)+16)


#define STEPD0(t) \ /*
and %r6,RB(t),RC(t); \ * We roll the registers for A, B, C, D, E around on each
andc %r0,RD(t),RB(t); \ * iteration; E on iteration t is D on iteration t+1, and so on.
rotlwi RT(t),RA(t),5; \ * We use registers 6 - 10 for this. (Registers 27 - 31 hold
rotlwi RB(t),RB(t),30; \ * the previous values.)
or %r6,%r6,%r0; \ */
add %r0,RE(t),%r15; \ #define RA(t) (((t)+4)%5+6)
add RT(t),RT(t),%r6; \ #define RB(t) (((t)+3)%5+6)
add %r0,%r0,W(t); \ #define RC(t) (((t)+2)%5+6)
add RT(t),RT(t),%r0 #define RD(t) (((t)+1)%5+6)
#define RE(t) (((t)+0)%5+6)


#define STEPD1(t) \ /* We use registers 11 - 26 for the W values */
xor %r6,RB(t),RC(t); \ #define W(t) ((t)%16+11)
rotlwi RT(t),RA(t),5; \
rotlwi RB(t),RB(t),30; \
xor %r6,%r6,RD(t); \
add %r0,RE(t),%r15; \
add RT(t),RT(t),%r6; \
add %r0,%r0,W(t); \
add RT(t),RT(t),%r0


#define STEPD2(t) \ /* Register 5 is used for the constant k */
and %r6,RB(t),RC(t); \
and %r0,RB(t),RD(t); \
rotlwi RT(t),RA(t),5; \
rotlwi RB(t),RB(t),30; \
or %r6,%r6,%r0; \
and %r0,RC(t),RD(t); \
or %r6,%r6,%r0; \
add %r0,RE(t),%r15; \
add RT(t),RT(t),%r6; \
add %r0,%r0,W(t); \
add RT(t),RT(t),%r0


#define LOADW(t) \ /*
lwz W(t),(t)*4(%r4) * The basic SHA-1 round function is:
* E += ROTL(A,5) + F(B,C,D) + W[i] + K; B = ROTL(B,30)
* Then the variables are renamed: (A,B,C,D,E) = (E,A,B,C,D).
*
* Every 20 rounds, the function F() and the contant K changes:
* - 20 rounds of f0(b,c,d) = "bit wise b ? c : d" = (^b & d) + (b & c)
* - 20 rounds of f1(b,c,d) = b^c^d = (b^d)^c
* - 20 rounds of f2(b,c,d) = majority(b,c,d) = (b&d) + ((b^d)&c)
* - 20 more rounds of f1(b,c,d)
*
* These are all scheduled for near-optimal performance on a G4.
* The G4 is a 3-issue out-of-order machine with 3 ALUs, but it can only
* *consider* starting the oldest 3 instructions per cycle. So to get
* maximum performace out of it, you have to treat it as an in-order
* machine. Which means interleaving the computation round t with the
* computation of W[t+4].
*
* The first 16 rounds use W values loaded directly from memory, while the
* remianing 64 use values computed from those first 16. We preload
* 4 values before starting, so there are three kinds of rounds:
* - The first 12 (all f0) also load the W values from memory.
* - The next 64 compute W(i+4) in parallel. 8*f0, 20*f1, 20*f2, 16*f1.
* - The last 4 (all f1) do not do anything with W.
*
* Therefore, we have 6 different round functions:
* STEPD0_LOAD(t,s) - Perform round t and load W(s). s < 16
* STEPD0_UPDATE(t,s) - Perform round t and compute W(s). s >= 16.
* STEPD1_UPDATE(t,s)
* STEPD2_UPDATE(t,s)
* STEPD1(t) - Perform round t with no load or update.
*
* The G5 is more fully out-of-order, and can find the parallelism
* by itself. The big limit is that it has a 2-cycle ALU latency, so
* even though it's 2-way, the code has to be scheduled as if it's
* 4-way, which can be a limit. To help it, we try to schedule the
* read of RA(t) as late as possible so it doesn't stall waiting for
* the previous round's RE(t-1), and we try to rotate RB(t) as early
* as possible while reading RC(t) (= RB(t-1)) as late as possible.
*/


#define UPDATEW(t) \ /* the initial loads. */
xor %r0,W((t)-3),W((t)-8); \ #define LOADW(s) \
xor W(t),W((t)-16),W((t)-14); \ lwz W(s),(s)*4(%r4)
xor W(t),W(t),%r0; \
rotlwi W(t),W(t),1


#define STEP0LD4(t) \ /*
STEPD0(t); LOADW((t)+4); \ * Perform a step with F0, and load W(s). Uses W(s) as a temporary
STEPD0((t)+1); LOADW((t)+5); \ * before loading it.
STEPD0((t)+2); LOADW((t)+6); \ * This is actually 10 instructions, which is an awkward fit.
STEPD0((t)+3); LOADW((t)+7) * It can execute grouped as listed, or delayed one instruction.
* (If delayed two instructions, there is a stall before the start of the
* second line.) Thus, two iterations take 7 cycles, 3.5 cycles per round.
*/
#define STEPD0_LOAD(t,s) \
add RE(t),RE(t),W(t); andc %r0,RD(t),RB(t); and W(s),RC(t),RB(t); \
add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; rotlwi RB(t),RB(t),30; \
add RE(t),RE(t),W(s); add %r0,%r0,%r5; lwz W(s),(s)*4(%r4); \
add RE(t),RE(t),%r0


#define STEPUP4(t, fn) \ /*
STEP##fn(t); UPDATEW((t)+4); \ * This is likewise awkward, 13 instructions. However, it can also
STEP##fn((t)+1); UPDATEW((t)+5); \ * execute starting with 2 out of 3 possible moduli, so it does 2 rounds
STEP##fn((t)+2); UPDATEW((t)+6); \ * in 9 cycles, 4.5 cycles/round.
STEP##fn((t)+3); UPDATEW((t)+7) */
#define STEPD0_UPDATE(t,s,loadk...) \
add RE(t),RE(t),W(t); andc %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \
add RE(t),RE(t),%r0; and %r0,RC(t),RB(t); xor W(s),W(s),W((s)-8); \
add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; xor W(s),W(s),W((s)-14); \
add RE(t),RE(t),%r5; loadk; rotlwi RB(t),RB(t),30; rotlwi W(s),W(s),1; \
add RE(t),RE(t),%r0


#define STEPUP20(t, fn) \ /* Nicely optimal. Conveniently, also the most common. */
STEPUP4(t, fn); \ #define STEPD1_UPDATE(t,s,loadk...) \
STEPUP4((t)+4, fn); \ add RE(t),RE(t),W(t); xor %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \
STEPUP4((t)+8, fn); \ add RE(t),RE(t),%r5; loadk; xor %r0,%r0,RC(t); xor W(s),W(s),W((s)-8); \
STEPUP4((t)+12, fn); \ add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; xor W(s),W(s),W((s)-14); \
STEPUP4((t)+16, fn) add RE(t),RE(t),%r0; rotlwi RB(t),RB(t),30; rotlwi W(s),W(s),1

/*
* The naked version, no UPDATE, for the last 4 rounds. 3 cycles per.
* We could use W(s) as a temp register, but we don't need it.
*/
#define STEPD1(t) \
add RE(t),RE(t),W(t); xor %r0,RD(t),RB(t); \
rotlwi RB(t),RB(t),30; add RE(t),RE(t),%r5; xor %r0,%r0,RC(t); \
add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; /* spare slot */ \
add RE(t),RE(t),%r0

/*
* 14 instructions, 5 cycles per. The majority function is a bit
* awkward to compute. This can execute with a 1-instruction delay,
* but it causes a 2-instruction delay, which triggers a stall.
*/
#define STEPD2_UPDATE(t,s,loadk...) \
add RE(t),RE(t),W(t); and %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \
add RE(t),RE(t),%r0; xor %r0,RD(t),RB(t); xor W(s),W(s),W((s)-8); \
add RE(t),RE(t),%r5; loadk; and %r0,%r0,RC(t); xor W(s),W(s),W((s)-14); \
add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; rotlwi W(s),W(s),1; \
add RE(t),RE(t),%r0; rotlwi RB(t),RB(t),30

#define STEP0_LOAD4(t,s) \
STEPD0_LOAD(t,s); \
STEPD0_LOAD((t+1),(s)+1); \
STEPD0_LOAD((t)+2,(s)+2); \
STEPD0_LOAD((t)+3,(s)+3)

#define STEPUP4(fn, t, s, loadk...) \
STEP##fn##_UPDATE(t,s,); \
STEP##fn##_UPDATE((t)+1,(s)+1,); \
STEP##fn##_UPDATE((t)+2,(s)+2,); \
STEP##fn##_UPDATE((t)+3,(s)+3,loadk)

#define STEPUP20(fn, t, s, loadk...) \
STEPUP4(fn, t, s,); \
STEPUP4(fn, (t)+4, (s)+4,); \
STEPUP4(fn, (t)+8, (s)+8,); \
STEPUP4(fn, (t)+12, (s)+12,); \
STEPUP4(fn, (t)+16, (s)+16, loadk)


.globl sha1_core .globl sha1_core
sha1_core: sha1_core:
stwu %r1,-FS(%r1) stwu %r1,-80(%r1)
stw %r15,FS-68(%r1) stmw %r13,4(%r1)
stw %r16,FS-64(%r1)
stw %r17,FS-60(%r1)
stw %r18,FS-56(%r1)
stw %r19,FS-52(%r1)
stw %r20,FS-48(%r1)
stw %r21,FS-44(%r1)
stw %r22,FS-40(%r1)
stw %r23,FS-36(%r1)
stw %r24,FS-32(%r1)
stw %r25,FS-28(%r1)
stw %r26,FS-24(%r1)
stw %r27,FS-20(%r1)
stw %r28,FS-16(%r1)
stw %r29,FS-12(%r1)
stw %r30,FS-8(%r1)
stw %r31,FS-4(%r1)


/* Load up A - E */ /* Load up A - E */
lwz RA(0),0(%r3) /* A */ lmw %r27,0(%r3)
lwz RB(0),4(%r3) /* B */
lwz RC(0),8(%r3) /* C */
lwz RD(0),12(%r3) /* D */
lwz RE(0),16(%r3) /* E */


mtctr %r5 mtctr %r5


1: LOADW(0) 1:
LOADW(0)
lis %r5,0x5a82
mr RE(0),%r31
LOADW(1) LOADW(1)
mr RD(0),%r30
mr RC(0),%r29
LOADW(2) LOADW(2)
ori %r5,%r5,0x7999 /* K0-19 */
mr RB(0),%r28
LOADW(3) LOADW(3)
mr RA(0),%r27


lis %r15,0x5a82 /* K0-19 */ STEP0_LOAD4(0, 4)
ori %r15,%r15,0x7999 STEP0_LOAD4(4, 8)
STEP0LD4(0) STEP0_LOAD4(8, 12)
STEP0LD4(4) STEPUP4(D0, 12, 16,)
STEP0LD4(8) STEPUP4(D0, 16, 20, lis %r5,0x6ed9)
STEPUP4(12, D0)
STEPUP4(16, D0)


lis %r15,0x6ed9 /* K20-39 */ ori %r5,%r5,0xeba1 /* K20-39 */
ori %r15,%r15,0xeba1 STEPUP20(D1, 20, 24, lis %r5,0x8f1b)
STEPUP20(20, D1)


lis %r15,0x8f1b /* K40-59 */ ori %r5,%r5,0xbcdc /* K40-59 */
ori %r15,%r15,0xbcdc STEPUP20(D2, 40, 44, lis %r5,0xca62)
STEPUP20(40, D2)


lis %r15,0xca62 /* K60-79 */ ori %r5,%r5,0xc1d6 /* K60-79 */
ori %r15,%r15,0xc1d6 STEPUP4(D1, 60, 64,)
STEPUP4(60, D1) STEPUP4(D1, 64, 68,)
STEPUP4(64, D1) STEPUP4(D1, 68, 72,)
STEPUP4(68, D1) STEPUP4(D1, 72, 76,)
STEPUP4(72, D1) addi %r4,%r4,64
STEPD1(76) STEPD1(76)
STEPD1(77) STEPD1(77)
STEPD1(78) STEPD1(78)
STEPD1(79) STEPD1(79)


lwz %r20,16(%r3) /* Add results to original values */
lwz %r19,12(%r3) add %r31,%r31,RE(0)
lwz %r18,8(%r3) add %r30,%r30,RD(0)
lwz %r17,4(%r3) add %r29,%r29,RC(0)
lwz %r16,0(%r3) add %r28,%r28,RB(0)
add %r20,RE(80),%r20 add %r27,%r27,RA(0)
add RD(0),RD(80),%r19
add RC(0),RC(80),%r18
add RB(0),RB(80),%r17
add RA(0),RA(80),%r16
mr RE(0),%r20
stw RA(0),0(%r3)
stw RB(0),4(%r3)
stw RC(0),8(%r3)
stw RD(0),12(%r3)
stw RE(0),16(%r3)


addi %r4,%r4,64
bdnz 1b bdnz 1b


lwz %r15,FS-68(%r1) /* Save final hash, restore registers, and return */
lwz %r16,FS-64(%r1) stmw %r27,0(%r3)
lwz %r17,FS-60(%r1) lmw %r13,4(%r1)
lwz %r18,FS-56(%r1) addi %r1,%r1,80
lwz %r19,FS-52(%r1)
lwz %r20,FS-48(%r1)
lwz %r21,FS-44(%r1)
lwz %r22,FS-40(%r1)
lwz %r23,FS-36(%r1)
lwz %r24,FS-32(%r1)
lwz %r25,FS-28(%r1)
lwz %r26,FS-24(%r1)
lwz %r27,FS-20(%r1)
lwz %r28,FS-16(%r1)
lwz %r29,FS-12(%r1)
lwz %r30,FS-8(%r1)
lwz %r31,FS-4(%r1)
addi %r1,%r1,FS
blr blr