X-Git-Url: https://git.openssl.org/gitweb/?a=blobdiff_plain;ds=sidebyside;f=crypto%2Fbn%2Fbn_lib.c;h=64c9fd9dc17a42fd5c6c0be45e305e476e72933c;hb=e14d4443a27816b05b044350ad39cd15668c55b8;hp=bd53124f1e103bdcc809a60494cb5418de694fae;hpb=257e206da6b42181b0dc8976792164c4d9cff89b;p=openssl.git diff --git a/crypto/bn/bn_lib.c b/crypto/bn/bn_lib.c index bd53124f1e..64c9fd9dc1 100644 --- a/crypto/bn/bn_lib.c +++ b/crypto/bn/bn_lib.c @@ -150,7 +150,7 @@ char *BN_options(void) int BN_num_bits_word(BN_ULONG l) { - static char bits[256]={ + static const char bits[256]={ 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4, 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5, 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6, @@ -343,8 +343,9 @@ void BN_CTX_free(BN_CTX *c) BIGNUM *bn_expand2(BIGNUM *b, int words) { - BN_ULONG *A,*B,*a; - int i,j; + BN_ULONG *A,*a; + const BN_ULONG *B; + int i; bn_check_top(b); @@ -362,15 +363,38 @@ BIGNUM *bn_expand2(BIGNUM *b, int words) BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE); return(NULL); } -memset(A,0x5c,sizeof(BN_ULONG)*(words+1)); #if 1 B=b->d; /* Check if the previous number needs to be copied */ if (B != NULL) { +#if 0 /* This lot is an unrolled loop to copy b->top * BN_ULONGs from B to A */ +/* + * I have nothing against unrolling but it's usually done for + * several reasons, namely: + * - minimize percentage of decision making code, i.e. branches; + * - avoid cache trashing; + * - make it possible to schedule loads earlier; + * Now let's examine the code below. The cornerstone of C is + * "programmer is always right" and that's what we love it for:-) + * For this very reason C compilers have to be paranoid when it + * comes to data aliasing and assume the worst. Yeah, but what + * does it mean in real life? This means that loop body below will + * be compiled to sequence of loads immediately followed by stores + * as compiler assumes the worst, something in A==B+1 style. As a + * result CPU pipeline is going to starve for incoming data. Secondly + * if A and B happen to share same cache line such code is going to + * cause severe cache trashing. Both factors have severe impact on + * performance of modern CPUs and this is the reason why this + * particulare piece of code is #ifdefed away and replaced by more + * "friendly" version found in #else section below. This comment + * also applies to BN_copy function. + * + * + */ for (i=b->top&(~7); i>0; i-=8) { A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3]; @@ -407,6 +431,30 @@ memset(A,0x5c,sizeof(BN_ULONG)*(words+1)); */ ; } +#else + for (i=b->top>>2; i>0; i--,A+=4,B+=4) + { + /* + * The fact that the loop is unrolled + * 4-wise is a tribute to Intel. It's + * the one that doesn't have enough + * registers to accomodate more data. + * I'd unroll it 8-wise otherwise:-) + * + * + */ + BN_ULONG a0,a1,a2,a3; + a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3]; + A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3; + } + switch (b->top&3) + { + case 3: A[2]=B[2]; + case 2: A[1]=B[1]; + case 1: A[0]=B[0]; + case 0: ; /* ultrix cc workaround, see above */ + } +#endif Free(b->d); } @@ -415,22 +463,19 @@ memset(A,0x5c,sizeof(BN_ULONG)*(words+1)); /* Now need to zero any data between b->top and b->max */ - B= &(b->d[b->top]); - j=(b->max - b->top) & ~7; - for (i=0; id[b->top]); + for (i=(b->max - b->top)>>3; i>0; i--,A+=8) { - B[0]=0; B[1]=0; B[2]=0; B[3]=0; - B[4]=0; B[5]=0; B[6]=0; B[7]=0; - B+=8; - } - j=(b->max - b->top) & 7; - for (i=0; imax - b->top)&7; i>0; i--,A++) + A[0]=0; #else - memcpy(a->d,b->d,sizeof(b->d[0])*b->top); + memset(A,0,sizeof(BN_ULONG)*(words+1)); + memcpy(A,b->d,sizeof(b->d[0])*b->top); + b->d=a; + b->max=words; #endif /* memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */ @@ -454,7 +499,8 @@ BIGNUM *BN_dup(BIGNUM *a) BIGNUM *BN_copy(BIGNUM *a, BIGNUM *b) { int i; - BN_ULONG *A,*B; + BN_ULONG *A; + const BN_ULONG *B; bn_check_top(b); @@ -464,47 +510,18 @@ BIGNUM *BN_copy(BIGNUM *a, BIGNUM *b) #if 1 A=a->d; B=b->d; - for (i=b->top&(~7); i>0; i-=8) + for (i=b->top>>2; i>0; i--,A+=4,B+=4) { - A[0]=B[0]; - A[1]=B[1]; - A[2]=B[2]; - A[3]=B[3]; - A[4]=B[4]; - A[5]=B[5]; - A[6]=B[6]; - A[7]=B[7]; - A+=8; - B+=8; + BN_ULONG a0,a1,a2,a3; + a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3]; + A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3; } - switch (b->top&7) + switch (b->top&3) { - case 7: - A[6]=B[6]; - case 6: - A[5]=B[5]; - case 5: - A[4]=B[4]; - case 4: - A[3]=B[3]; - case 3: - A[2]=B[2]; - case 2: - A[1]=B[1]; - case 1: - A[0]=B[0]; - case 0: - /* I need the 'case 0' entry for utrix cc. - * If the optimiser is turned on, it does the - * switch table by doing - * a=top&7 - * a--; - * goto jump_table[a]; - * If top is 0, this makes us jump to 0xffffffc which is - * rather bad :-(. - * eric 23-Apr-1998 - */ - ; + case 3: A[2]=B[2]; + case 2: A[1]=B[1]; + case 1: A[0]=B[0]; + case 0: ; /* ultrix cc workaround, see comments in bn_expand2 */ } #else memcpy(a->d,b->d,sizeof(b->d[0])*b->top); @@ -539,6 +556,8 @@ BN_ULONG BN_get_word(BIGNUM *a) #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */ ret<<=BN_BITS4; /* stops the compiler complaining */ ret<<=BN_BITS4; +#else + ret=0; #endif ret|=a->d[i]; } @@ -563,6 +582,8 @@ int BN_set_word(BIGNUM *a, BN_ULONG w) #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */ w>>=BN_BITS4; w>>=BN_BITS4; +#else + w=0; #endif a->d[i]=(BN_ULONG)w&BN_MASK2; if (a->d[i] != 0) a->top=i+1; @@ -699,7 +720,7 @@ int BN_set_bit(BIGNUM *a, int n) a->top=i+1; } - a->d[i]|=(1L<d[i]|=(((BN_ULONG)1)<top <= i) return(0); - a->d[i]&=(~(1L<d[i]&=(~(((BN_ULONG)1)<