mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-25 10:43:34 +08:00
PowerPC LE strnlen
http://sourceware.org/ml/libc-alpha/2013-08/msg00098.html The existing strnlen code has a number of defects, so this patch is more than just adding little-endian support. The changes here are similar to those for memchr. * sysdeps/powerpc/powerpc64/power7/strnlen.S (strnlen): Add little-endian support. Remove unnecessary "are we done" tests. Handle "s" wrapping around zero and extremely large "size". Correct main loop count. Handle single left-over word from main loop inline rather than by using small_loop. Correct comments. Delete "zero" tail, use "end_max" instead. * sysdeps/powerpc/powerpc32/power7/strnlen.S: Likewise.
This commit is contained in:
Alan Modra
parent
db9b4570c5
commit
33ee81de05
10
ChangeLog
10
ChangeLog
@ -1,3 +1,13 @@
|
||||
2013-10-04 Alan Modra <amodra@gmail.com>
|
||||
|
||||
* sysdeps/powerpc/powerpc64/power7/strnlen.S (strnlen): Add
|
||||
little-endian support. Remove unnecessary "are we done" tests.
|
||||
Handle "s" wrapping around zero and extremely large "size".
|
||||
Correct main loop count. Handle single left-over word from main
|
||||
loop inline rather than by using small_loop. Correct comments.
|
||||
Delete "zero" tail, use "end_max" instead.
|
||||
* sysdeps/powerpc/powerpc32/power7/strnlen.S: Likewise.
|
||||
|
||||
2013-10-04 Alan Modra <amodra@gmail.com>
|
||||
|
||||
* sysdeps/powerpc/powerpc64/power7/strlen.S (strlen): Add little-endian
|
||||
|
||||
@ -28,51 +28,47 @@ ENTRY (__strnlen)
|
||||
add r7,r3,r4 /* Calculate the last acceptable address. */
|
||||
cmplwi r4,16
|
||||
li r0,0 /* Word with null chars. */
|
||||
addi r7,r7,-1
|
||||
ble L(small_range)
|
||||
|
||||
cmplw cr7,r3,r7 /* Is the address equal or less than r3? If
|
||||
it's equal or less, it means size is either 0
|
||||
or a negative number. */
|
||||
ble cr7,L(proceed)
|
||||
|
||||
li r7,-1 /* Make r11 the biggest if r4 <= 0. */
|
||||
L(proceed):
|
||||
rlwinm r6,r3,3,27,28 /* Calculate padding. */
|
||||
lwz r12,0(r8) /* Load word from memory. */
|
||||
cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */
|
||||
#ifdef __LITTLE_ENDIAN__
|
||||
srw r10,r10,r6
|
||||
slw r10,r10,r6
|
||||
#else
|
||||
slw r10,r10,r6
|
||||
srw r10,r10,r6
|
||||
#endif
|
||||
cmplwi cr7,r10,0 /* If r10 == 0, no null's have been found. */
|
||||
bne cr7,L(done)
|
||||
|
||||
/* Are we done already? */
|
||||
addi r9,r8,4
|
||||
cmplw cr6,r9,r7
|
||||
bge cr6,L(end_max)
|
||||
|
||||
clrrwi r7,r7,2 /* Address of last word. */
|
||||
mtcrf 0x01,r8
|
||||
/* Are we now aligned to a doubleword boundary? If so, skip to
|
||||
the main loop. Otherwise, go through the alignment code. */
|
||||
|
||||
bt 29,L(loop_setup)
|
||||
|
||||
/* Handle DWORD2 of pair. */
|
||||
/* Handle WORD2 of pair. */
|
||||
lwzu r12,4(r8)
|
||||
cmpb r10,r12,r0
|
||||
cmplwi cr7,r10,0
|
||||
bne cr7,L(done)
|
||||
|
||||
/* Are we done already? */
|
||||
addi r9,r8,4
|
||||
cmplw cr6,r9,r7
|
||||
bge cr6,L(end_max)
|
||||
|
||||
L(loop_setup):
|
||||
sub r5,r7,r9
|
||||
/* The last word we want to read in the loop below is the one
|
||||
containing the last byte of the string, ie. the word at
|
||||
(s + size - 1) & ~3, or r7. The first word read is at
|
||||
r8 + 4, we read 2 * cnt words, so the last word read will
|
||||
be at r8 + 4 + 8 * cnt - 4. Solving for cnt gives
|
||||
cnt = (r7 - r8) / 8 */
|
||||
sub r5,r7,r8
|
||||
srwi r6,r5,3 /* Number of loop iterations. */
|
||||
mtctr r6 /* Setup the counter. */
|
||||
b L(loop)
|
||||
/* Main loop to look for the null byte backwards in the string. Since
|
||||
|
||||
/* Main loop to look for the null byte in the string. Since
|
||||
it's a small loop (< 8 instructions), align it to 32-bytes. */
|
||||
.p2align 5
|
||||
L(loop):
|
||||
@ -88,15 +84,18 @@ L(loop):
|
||||
cmplwi cr7,r5,0
|
||||
bne cr7,L(found)
|
||||
bdnz L(loop)
|
||||
/* We're here because the counter reached 0, and that means we
|
||||
didn't have any matches for null in the whole range. Just return
|
||||
the original size. */
|
||||
addi r9,r8,4
|
||||
cmplw cr6,r9,r7
|
||||
blt cr6,L(loop_small)
|
||||
|
||||
/* We may have one more word to read. */
|
||||
cmplw cr6,r8,r7
|
||||
beq cr6,L(end_max)
|
||||
|
||||
lwzu r12,4(r8)
|
||||
cmpb r10,r12,r0
|
||||
cmplwi cr6,r10,0
|
||||
bne cr6,L(done)
|
||||
|
||||
L(end_max):
|
||||
sub r3,r7,r3
|
||||
mr r3,r4
|
||||
blr
|
||||
|
||||
/* OK, one (or both) of the words contains a null byte. Check
|
||||
@ -121,49 +120,56 @@ L(found):
|
||||
We need to make sure the null char is *before* the end of the
|
||||
range. */
|
||||
L(done):
|
||||
cntlzw r0,r10 /* Count leading zeroes before the match. */
|
||||
srwi r0,r0,3 /* Convert leading zeroes to bytes. */
|
||||
add r9,r8,r0
|
||||
sub r6,r9,r3 /* Length until the match. */
|
||||
cmplw r9,r7
|
||||
bgt L(end_max)
|
||||
mr r3,r6
|
||||
#ifdef __LITTLE_ENDIAN__
|
||||
addi r0,r10,-1
|
||||
andc r0,r0,r10
|
||||
popcntw r0,r0
|
||||
#else
|
||||
cntlzw r0,r10 /* Count leading zeros before the match. */
|
||||
#endif
|
||||
sub r3,r8,r3
|
||||
srwi r0,r0,3 /* Convert leading/trailing zeros to bytes. */
|
||||
add r3,r3,r0 /* Length until the match. */
|
||||
cmplw r3,r4
|
||||
blelr
|
||||
mr r3,r4
|
||||
blr
|
||||
|
||||
.align 4
|
||||
L(zero):
|
||||
li r3,0
|
||||
blr
|
||||
|
||||
/* Deals with size <= 32. */
|
||||
/* Deals with size <= 16. */
|
||||
.align 4
|
||||
L(small_range):
|
||||
cmplwi r4,0
|
||||
beq L(zero)
|
||||
beq L(end_max)
|
||||
|
||||
clrrwi r7,r7,2 /* Address of last word. */
|
||||
|
||||
rlwinm r6,r3,3,27,28 /* Calculate padding. */
|
||||
lwz r12,0(r8) /* Load word from memory. */
|
||||
cmpb r10,r12,r0 /* Check for null bytes in WORD1. */
|
||||
#ifdef __LITTLE_ENDIAN__
|
||||
srw r10,r10,r6
|
||||
slw r10,r10,r6
|
||||
#else
|
||||
slw r10,r10,r6
|
||||
srw r10,r10,r6
|
||||
#endif
|
||||
cmplwi cr7,r10,0
|
||||
bne cr7,L(done)
|
||||
|
||||
addi r9,r8,4
|
||||
cmplw r9,r7
|
||||
bge L(end_max)
|
||||
b L(loop_small)
|
||||
cmplw r8,r7
|
||||
beq L(end_max)
|
||||
|
||||
.p2align 5
|
||||
L(loop_small):
|
||||
lwzu r12,4(r8)
|
||||
cmpb r10,r12,r0
|
||||
addi r9,r8,4
|
||||
cmplwi cr6,r10,0
|
||||
bne cr6,L(done)
|
||||
cmplw r9,r7
|
||||
bge L(end_max)
|
||||
b L(loop_small)
|
||||
cmplw r8,r7
|
||||
bne L(loop_small)
|
||||
mr r3,r4
|
||||
blr
|
||||
|
||||
END (__strnlen)
|
||||
weak_alias (__strnlen, strnlen)
|
||||
libc_hidden_builtin_def (strnlen)
|
||||
|
||||
@ -28,29 +28,25 @@ ENTRY (__strnlen)
|
||||
add r7,r3,r4 /* Calculate the last acceptable address. */
|
||||
cmpldi r4,32
|
||||
li r0,0 /* Doubleword with null chars. */
|
||||
addi r7,r7,-1
|
||||
|
||||
/* If we have less than 33 bytes to search, skip to a faster code. */
|
||||
ble L(small_range)
|
||||
|
||||
cmpld cr7,r3,r7 /* Is the address equal or less than r3? If
|
||||
it's equal or less, it means size is either 0
|
||||
or a negative number. */
|
||||
ble cr7,L(proceed)
|
||||
|
||||
li r7,-1 /* Make r11 the biggest if r4 <= 0. */
|
||||
L(proceed):
|
||||
rlwinm r6,r3,3,26,28 /* Calculate padding. */
|
||||
ld r12,0(r8) /* Load doubleword from memory. */
|
||||
cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */
|
||||
#ifdef __LITTLE_ENDIAN__
|
||||
srd r10,r10,r6
|
||||
sld r10,r10,r6
|
||||
#else
|
||||
sld r10,r10,r6
|
||||
srd r10,r10,r6
|
||||
#endif
|
||||
cmpldi cr7,r10,0 /* If r10 == 0, no null's have been found. */
|
||||
bne cr7,L(done)
|
||||
|
||||
/* Are we done already? */
|
||||
addi r9,r8,8
|
||||
cmpld cr6,r9,r7
|
||||
bge cr6,L(end_max)
|
||||
|
||||
clrrdi r7,r7,3 /* Address of last doubleword. */
|
||||
mtcrf 0x01,r8
|
||||
/* Are we now aligned to a quadword boundary? If so, skip to
|
||||
the main loop. Otherwise, go through the alignment code. */
|
||||
@ -63,17 +59,18 @@ L(proceed):
|
||||
cmpldi cr7,r10,0
|
||||
bne cr7,L(done)
|
||||
|
||||
/* Are we done already? */
|
||||
addi r9,r8,8
|
||||
cmpld cr6,r9,r7
|
||||
bge cr6,L(end_max)
|
||||
|
||||
L(loop_setup):
|
||||
sub r5,r7,r9
|
||||
/* The last dword we want to read in the loop below is the one
|
||||
containing the last byte of the string, ie. the dword at
|
||||
(s + size - 1) & ~7, or r7. The first dword read is at
|
||||
r8 + 8, we read 2 * cnt dwords, so the last dword read will
|
||||
be at r8 + 8 + 16 * cnt - 8. Solving for cnt gives
|
||||
cnt = (r7 - r8) / 16 */
|
||||
sub r5,r7,r8
|
||||
srdi r6,r5,4 /* Number of loop iterations. */
|
||||
mtctr r6 /* Setup the counter. */
|
||||
b L(loop)
|
||||
/* Main loop to look for the null byte backwards in the string. Since
|
||||
|
||||
/* Main loop to look for the null byte in the string. Since
|
||||
it's a small loop (< 8 instructions), align it to 32-bytes. */
|
||||
.p2align 5
|
||||
L(loop):
|
||||
@ -89,15 +86,18 @@ L(loop):
|
||||
cmpldi cr7,r5,0
|
||||
bne cr7,L(found)
|
||||
bdnz L(loop)
|
||||
/* We're here because the counter reached 0, and that means we
|
||||
didn't have any matches for null in the whole range. Just return
|
||||
the original size. */
|
||||
addi r9,r8,8
|
||||
cmpld cr6,r9,r7
|
||||
blt cr6,L(loop_small)
|
||||
|
||||
/* We may have one more dword to read. */
|
||||
cmpld cr6,r8,r7
|
||||
beq cr6,L(end_max)
|
||||
|
||||
ldu r12,8(r8)
|
||||
cmpb r10,r12,r0
|
||||
cmpldi cr6,r10,0
|
||||
bne cr6,L(done)
|
||||
|
||||
L(end_max):
|
||||
sub r3,r7,r3
|
||||
mr r3,r4
|
||||
blr
|
||||
|
||||
/* OK, one (or both) of the doublewords contains a null byte. Check
|
||||
@ -119,52 +119,59 @@ L(found):
|
||||
/* r10 has the output of the cmpb instruction, that is, it contains
|
||||
0xff in the same position as the null byte in the original
|
||||
doubleword from the string. Use that to calculate the length.
|
||||
We need to make sure the null char is *before* the start of the
|
||||
range (since we're going backwards). */
|
||||
We need to make sure the null char is *before* the end of the
|
||||
range. */
|
||||
L(done):
|
||||
cntlzd r0,r10 /* Count leading zeroes before the match. */
|
||||
srdi r0,r0,3 /* Convert leading zeroes to bytes. */
|
||||
add r9,r8,r0
|
||||
sub r6,r9,r3 /* Length until the match. */
|
||||
cmpld r9,r7
|
||||
bgt L(end_max)
|
||||
mr r3,r6
|
||||
blr
|
||||
|
||||
.align 4
|
||||
L(zero):
|
||||
li r3,0
|
||||
#ifdef __LITTLE_ENDIAN__
|
||||
addi r0,r10,-1
|
||||
andc r0,r0,r10
|
||||
popcntd r0,r0
|
||||
#else
|
||||
cntlzd r0,r10 /* Count leading zeros before the match. */
|
||||
#endif
|
||||
sub r3,r8,r3
|
||||
srdi r0,r0,3 /* Convert leading/trailing zeros to bytes. */
|
||||
add r3,r3,r0 /* Length until the match. */
|
||||
cmpld r3,r4
|
||||
blelr
|
||||
mr r3,r4
|
||||
blr
|
||||
|
||||
/* Deals with size <= 32. */
|
||||
.align 4
|
||||
L(small_range):
|
||||
cmpldi r4,0
|
||||
beq L(zero)
|
||||
beq L(end_max)
|
||||
|
||||
clrrdi r7,r7,3 /* Address of last doubleword. */
|
||||
|
||||
rlwinm r6,r3,3,26,28 /* Calculate padding. */
|
||||
ld r12,0(r8) /* Load word from memory. */
|
||||
ld r12,0(r8) /* Load doubleword from memory. */
|
||||
cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */
|
||||
#ifdef __LITTLE_ENDIAN__
|
||||
srd r10,r10,r6
|
||||
sld r10,r10,r6
|
||||
#else
|
||||
sld r10,r10,r6
|
||||
srd r10,r10,r6
|
||||
#endif
|
||||
cmpldi cr7,r10,0
|
||||
bne cr7,L(done)
|
||||
|
||||
addi r9,r8,8
|
||||
cmpld r9,r7
|
||||
bge L(end_max)
|
||||
b L(loop_small)
|
||||
cmpld r8,r7
|
||||
beq L(end_max)
|
||||
|
||||
.p2align 5
|
||||
L(loop_small):
|
||||
ldu r12,8(r8)
|
||||
cmpb r10,r12,r0
|
||||
addi r9,r8,8
|
||||
cmpldi cr6,r10,0
|
||||
bne cr6,L(done)
|
||||
cmpld r9,r7
|
||||
bge L(end_max)
|
||||
b L(loop_small)
|
||||
cmpld r8,r7
|
||||
bne L(loop_small)
|
||||
mr r3,r4
|
||||
blr
|
||||
|
||||
END (__strnlen)
|
||||
weak_alias (__strnlen, strnlen)
|
||||
libc_hidden_builtin_def (strnlen)
|
||||
|
||||
Loading…
Reference in New Issue
Block a user