diff options
Diffstat (limited to 'sysdeps/powerpc')
| -rw-r--r-- | sysdeps/powerpc/powerpc32/power7/strlen.S | 17 | ||||
| -rw-r--r-- | sysdeps/powerpc/powerpc32/strlen.S | 69 | ||||
| -rw-r--r-- | sysdeps/powerpc/powerpc64/power7/strlen.S | 17 | ||||
| -rw-r--r-- | sysdeps/powerpc/powerpc64/strlen.S | 75 |
4 files changed, 131 insertions, 47 deletions
diff --git a/sysdeps/powerpc/powerpc32/power7/strlen.S b/sysdeps/powerpc/powerpc32/power7/strlen.S index b71a10f5c7..b08d6c028c 100644 --- a/sysdeps/powerpc/powerpc32/power7/strlen.S +++ b/sysdeps/powerpc/powerpc32/power7/strlen.S @@ -29,7 +29,11 @@ ENTRY (strlen) li r0,0 /* Word with null chars to use with cmpb. */ li r5,-1 /* MASK = 0xffffffffffffffff. */ lwz r12,0(r4) /* Load word from memory. */ +#ifdef __LITTLE_ENDIAN__ + slw r5,r5,r6 +#else srw r5,r5,r6 /* MASK = MASK >> padding. */ +#endif orc r9,r12,r5 /* Mask bits that are not part of the string. */ cmpb r10,r9,r0 /* Check for null bytes in WORD1. */ cmpwi cr7,r10,0 /* If r10 == 0, no null's have been found. */ @@ -47,9 +51,6 @@ ENTRY (strlen) cmpb r10,r12,r0 cmpwi cr7,r10,0 bne cr7,L(done) - b L(loop) /* We branch here (rather than falling through) - to skip the nops due to heavy alignment - of the loop below. */ /* Main loop to look for the end of the string. Since it's a small loop (< 8 instructions), align it to 32-bytes. */ @@ -86,9 +87,15 @@ L(loop): 0xff in the same position as the null byte in the original word from the string. Use that to calculate the length. */ L(done): - cntlzw r0,r10 /* Count leading zeroes before the match. */ +#ifdef __LITTLE_ENDIAN__ + addi r9, r10, -1 /* Form a mask from trailing zeros. */ + andc r9, r9, r10 + popcntw r0, r9 /* Count the bits in the mask. */ +#else + cntlzw r0,r10 /* Count leading zeros before the match. */ +#endif subf r5,r3,r4 - srwi r0,r0,3 /* Convert leading zeroes to bytes. */ + srwi r0,r0,3 /* Convert leading zeros to bytes. */ add r3,r5,r0 /* Compute final length. */ blr END (strlen) diff --git a/sysdeps/powerpc/powerpc32/strlen.S b/sysdeps/powerpc/powerpc32/strlen.S index 9a6eafc382..a7153ed7a2 100644 --- a/sysdeps/powerpc/powerpc32/strlen.S +++ b/sysdeps/powerpc/powerpc32/strlen.S @@ -29,7 +29,12 @@ 1 is subtracted you get a value in the range 0x00-0x7f, none of which have their high bit set. The expression here is (x + 0xfefefeff) & ~(x | 0x7f7f7f7f), which gives 0x00000000 when - there were no 0x00 bytes in the word. + there were no 0x00 bytes in the word. You get 0x80 in bytes that + match, but possibly false 0x80 matches in the next more significant + byte to a true match due to carries. For little-endian this is + of no consequence since the least significant match is the one + we're interested in, but big-endian needs method 2 to find which + byte matches. 2) Given a word 'x', we can test to see _which_ byte was zero by calculating ~(((x & 0x7f7f7f7f) + 0x7f7f7f7f) | x | 0x7f7f7f7f). @@ -72,7 +77,7 @@ ENTRY (strlen) -#define rTMP1 r0 +#define rTMP4 r0 #define rRTN r3 /* incoming STR arg, outgoing result */ #define rSTR r4 /* current string position */ #define rPADN r5 /* number of padding bits we prepend to the @@ -82,9 +87,9 @@ ENTRY (strlen) #define rWORD1 r8 /* current string word */ #define rWORD2 r9 /* next string word */ #define rMASK r9 /* mask for first string word */ -#define rTMP2 r10 -#define rTMP3 r11 -#define rTMP4 r12 +#define rTMP1 r10 +#define rTMP2 r11 +#define rTMP3 r12 clrrwi rSTR, rRTN, 2 @@ -93,15 +98,20 @@ ENTRY (strlen) lwz rWORD1, 0(rSTR) li rMASK, -1 addi r7F7F, r7F7F, 0x7f7f -/* That's the setup done, now do the first pair of words. - We make an exception and use method (2) on the first two words, to reduce - overhead. */ +/* We use method (2) on the first two words, because rFEFE isn't + required which reduces setup overhead. Also gives a faster return + for small strings on big-endian due to needing to recalculate with + method (2) anyway. */ +#ifdef __LITTLE_ENDIAN__ + slw rMASK, rMASK, rPADN +#else srw rMASK, rMASK, rPADN +#endif and rTMP1, r7F7F, rWORD1 or rTMP2, r7F7F, rWORD1 add rTMP1, rTMP1, r7F7F - nor rTMP1, rTMP2, rTMP1 - and. rWORD1, rTMP1, rMASK + nor rTMP3, rTMP2, rTMP1 + and. rTMP3, rTMP3, rMASK mtcrf 0x01, rRTN bne L(done0) lis rFEFE, -0x101 @@ -110,11 +120,12 @@ ENTRY (strlen) bt 29, L(loop) /* Handle second word of pair. */ +/* Perhaps use method (1) here for little-endian, saving one instruction? */ lwzu rWORD1, 4(rSTR) and rTMP1, r7F7F, rWORD1 or rTMP2, r7F7F, rWORD1 add rTMP1, rTMP1, r7F7F - nor. rWORD1, rTMP2, rTMP1 + nor. rTMP3, rTMP2, rTMP1 bne L(done0) /* The loop. */ @@ -128,28 +139,52 @@ L(loop): add rTMP3, rFEFE, rWORD2 nor rTMP4, r7F7F, rWORD2 bne L(done1) - and. rTMP1, rTMP3, rTMP4 + and. rTMP3, rTMP3, rTMP4 beq L(loop) +#ifndef __LITTLE_ENDIAN__ and rTMP1, r7F7F, rWORD2 add rTMP1, rTMP1, r7F7F - andc rWORD1, rTMP4, rTMP1 + andc rTMP3, rTMP4, rTMP1 b L(done0) L(done1): and rTMP1, r7F7F, rWORD1 subi rSTR, rSTR, 4 add rTMP1, rTMP1, r7F7F - andc rWORD1, rTMP2, rTMP1 + andc rTMP3, rTMP2, rTMP1 /* When we get to here, rSTR points to the first word in the string that - contains a zero byte, and the most significant set bit in rWORD1 is in that - byte. */ + contains a zero byte, and rTMP3 has 0x80 for bytes that are zero, + and 0x00 otherwise. */ L(done0): - cntlzw rTMP3, rWORD1 + cntlzw rTMP3, rTMP3 subf rTMP1, rRTN, rSTR srwi rTMP3, rTMP3, 3 add rRTN, rTMP1, rTMP3 blr +#else + +L(done0): + addi rTMP1, rTMP3, -1 /* Form a mask from trailing zeros. */ + andc rTMP1, rTMP1, rTMP3 + cntlzw rTMP1, rTMP1 /* Count bits not in the mask. */ + subf rTMP3, rRTN, rSTR + subfic rTMP1, rTMP1, 32-7 + srwi rTMP1, rTMP1, 3 + add rRTN, rTMP1, rTMP3 + blr + +L(done1): + addi rTMP3, rTMP1, -1 + andc rTMP3, rTMP3, rTMP1 + cntlzw rTMP3, rTMP3 + subf rTMP1, rRTN, rSTR + subfic rTMP3, rTMP3, 32-7-32 + srawi rTMP3, rTMP3, 3 + add rRTN, rTMP1, rTMP3 + blr +#endif + END (strlen) libc_hidden_builtin_def (strlen) diff --git a/sysdeps/powerpc/powerpc64/power7/strlen.S b/sysdeps/powerpc/powerpc64/power7/strlen.S index 343216952e..807ef1082e 100644 --- a/sysdeps/powerpc/powerpc64/power7/strlen.S +++ b/sysdeps/powerpc/powerpc64/power7/strlen.S @@ -30,7 +30,11 @@ ENTRY (strlen) with cmpb. */ li r5,-1 /* MASK = 0xffffffffffffffff. */ ld r12,0(r4) /* Load doubleword from memory. */ +#ifdef __LITTLE_ENDIAN__ + sld r5,r5,r6 +#else srd r5,r5,r6 /* MASK = MASK >> padding. */ +#endif orc r9,r12,r5 /* Mask bits that are not part of the string. */ cmpb r10,r9,r0 /* Check for null bytes in DWORD1. */ cmpdi cr7,r10,0 /* If r10 == 0, no null's have been found. */ @@ -48,9 +52,6 @@ ENTRY (strlen) cmpb r10,r12,r0 cmpdi cr7,r10,0 bne cr7,L(done) - b L(loop) /* We branch here (rather than falling through) - to skip the nops due to heavy alignment - of the loop below. */ /* Main loop to look for the end of the string. Since it's a small loop (< 8 instructions), align it to 32-bytes. */ @@ -87,9 +88,15 @@ L(loop): 0xff in the same position as the null byte in the original doubleword from the string. Use that to calculate the length. */ L(done): - cntlzd r0,r10 /* Count leading zeroes before the match. */ +#ifdef __LITTLE_ENDIAN__ + addi r9, r10, -1 /* Form a mask from trailing zeros. */ + andc r9, r9, r10 + popcntd r0, r9 /* Count the bits in the mask. */ +#else + cntlzd r0,r10 /* Count leading zeros before the match. */ +#endif subf r5,r3,r4 - srdi r0,r0,3 /* Convert leading zeroes to bytes. */ + srdi r0,r0,3 /* Convert leading/trailing zeros to bytes. */ add r3,r5,r0 /* Compute final length. */ blr END (strlen) diff --git a/sysdeps/powerpc/powerpc64/strlen.S b/sysdeps/powerpc/powerpc64/strlen.S index 0f9b5eea9f..4ed1ba3ad1 100644 --- a/sysdeps/powerpc/powerpc64/strlen.S +++ b/sysdeps/powerpc/powerpc64/strlen.S @@ -29,7 +29,12 @@ 1 is subtracted you get a value in the range 0x00-0x7f, none of which have their high bit set. The expression here is (x + 0xfefefeff) & ~(x | 0x7f7f7f7f), which gives 0x00000000 when - there were no 0x00 bytes in the word. + there were no 0x00 bytes in the word. You get 0x80 in bytes that + match, but possibly false 0x80 matches in the next more significant + byte to a true match due to carries. For little-endian this is + of no consequence since the least significant match is the one + we're interested in, but big-endian needs method 2 to find which + byte matches. 2) Given a word 'x', we can test to see _which_ byte was zero by calculating ~(((x & 0x7f7f7f7f) + 0x7f7f7f7f) | x | 0x7f7f7f7f). @@ -62,7 +67,7 @@ Answer: 1) Added a Data Cache Block Touch early to prefetch the first 128 byte cache line. Adding dcbt instructions to the loop would not be - effective since most strings will be shorter than the cache line.*/ + effective since most strings will be shorter than the cache line. */ /* Some notes on register usage: Under the SVR4 ABI, we can use registers 0 and 3 through 12 (so long as we don't call any procedures) without @@ -78,7 +83,7 @@ ENTRY (strlen) CALL_MCOUNT 1 -#define rTMP1 r0 +#define rTMP4 r0 #define rRTN r3 /* incoming STR arg, outgoing result */ #define rSTR r4 /* current string position */ #define rPADN r5 /* number of padding bits we prepend to the @@ -88,9 +93,9 @@ ENTRY (strlen) #define rWORD1 r8 /* current string doubleword */ #define rWORD2 r9 /* next string doubleword */ #define rMASK r9 /* mask for first string doubleword */ -#define rTMP2 r10 -#define rTMP3 r11 -#define rTMP4 r12 +#define rTMP1 r10 +#define rTMP2 r11 +#define rTMP3 r12 dcbt 0,rRTN clrrdi rSTR, rRTN, 3 @@ -100,30 +105,36 @@ ENTRY (strlen) addi r7F7F, r7F7F, 0x7f7f li rMASK, -1 insrdi r7F7F, r7F7F, 32, 0 -/* That's the setup done, now do the first pair of doublewords. - We make an exception and use method (2) on the first two doublewords, - to reduce overhead. */ +/* We use method (2) on the first two doublewords, because rFEFE isn't + required which reduces setup overhead. Also gives a faster return + for small strings on big-endian due to needing to recalculate with + method (2) anyway. */ +#ifdef __LITTLE_ENDIAN__ + sld rMASK, rMASK, rPADN +#else srd rMASK, rMASK, rPADN +#endif and rTMP1, r7F7F, rWORD1 or rTMP2, r7F7F, rWORD1 lis rFEFE, -0x101 add rTMP1, rTMP1, r7F7F addi rFEFE, rFEFE, -0x101 - nor rTMP1, rTMP2, rTMP1 - and. rWORD1, rTMP1, rMASK + nor rTMP3, rTMP2, rTMP1 + and. rTMP3, rTMP3, rMASK mtcrf 0x01, rRTN bne L(done0) - sldi rTMP1, rFEFE, 32 - add rFEFE, rFEFE, rTMP1 + sldi rTMP1, rFEFE, 32 + add rFEFE, rFEFE, rTMP1 /* Are we now aligned to a doubleword boundary? */ bt 28, L(loop) /* Handle second doubleword of pair. */ +/* Perhaps use method (1) here for little-endian, saving one instruction? */ ldu rWORD1, 8(rSTR) and rTMP1, r7F7F, rWORD1 or rTMP2, r7F7F, rWORD1 add rTMP1, rTMP1, r7F7F - nor. rWORD1, rTMP2, rTMP1 + nor. rTMP3, rTMP2, rTMP1 bne L(done0) /* The loop. */ @@ -137,28 +148,52 @@ L(loop): add rTMP3, rFEFE, rWORD2 nor rTMP4, r7F7F, rWORD2 bne L(done1) - and. rTMP1, rTMP3, rTMP4 + and. rTMP3, rTMP3, rTMP4 beq L(loop) +#ifndef __LITTLE_ENDIAN__ and rTMP1, r7F7F, rWORD2 add rTMP1, rTMP1, r7F7F - andc rWORD1, rTMP4, rTMP1 + andc rTMP3, rTMP4, rTMP1 b L(done0) L(done1): and rTMP1, r7F7F, rWORD1 subi rSTR, rSTR, 8 add rTMP1, rTMP1, r7F7F - andc rWORD1, rTMP2, rTMP1 + andc rTMP3, rTMP2, rTMP1 /* When we get to here, rSTR points to the first doubleword in the string that - contains a zero byte, and the most significant set bit in rWORD1 is in that - byte. */ + contains a zero byte, and rTMP3 has 0x80 for bytes that are zero, and 0x00 + otherwise. */ L(done0): - cntlzd rTMP3, rWORD1 + cntlzd rTMP3, rTMP3 subf rTMP1, rRTN, rSTR srdi rTMP3, rTMP3, 3 add rRTN, rTMP1, rTMP3 blr +#else + +L(done0): + addi rTMP1, rTMP3, -1 /* Form a mask from trailing zeros. */ + andc rTMP1, rTMP1, rTMP3 + cntlzd rTMP1, rTMP1 /* Count bits not in the mask. */ + subf rTMP3, rRTN, rSTR + subfic rTMP1, rTMP1, 64-7 + srdi rTMP1, rTMP1, 3 + add rRTN, rTMP1, rTMP3 + blr + +L(done1): + addi rTMP3, rTMP1, -1 + andc rTMP3, rTMP3, rTMP1 + cntlzd rTMP3, rTMP3 + subf rTMP1, rRTN, rSTR + subfic rTMP3, rTMP3, 64-7-64 + sradi rTMP3, rTMP3, 3 + add rRTN, rTMP1, rTMP3 + blr +#endif + END (strlen) libc_hidden_builtin_def (strlen) |