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ARM: Change register allocation in armv6t2 memchr implementation.

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This commit is contained in:
Roland McGrath 2013-03-12 10:00:53 -07:00
parent 9967e003b3
commit 47c71d9323
2 changed files with 20 additions and 15 deletions
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5
ports/ChangeLog.arm
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@ -1,3 +1,8 @@
2013-03-12 Roland McGrath <roland@hack.frob.com>
* sysdeps/arm/armv6t2/memchr.S: Change register allocation so ldrd use
is r4,r5 rather than r5,r6; this way ARM mode will allow that ldrd.
2013-03-11 Joseph Myers <joseph@codesourcery.com>
* sysdeps/arm/preconfigure.in: Add comment about

30
ports/sysdeps/arm/armv6t2/memchr.S
View File

@ -83,20 +83,20 @@ ENTRY(memchr)
orr r1, r1, r1, lsl #8 @ expand the match word across to all bytes
orr r1, r1, r1, lsl #16
bic r4, r2, #7 @ Number of double words to work with * 8
bic r6, r2, #7 @ Number of double words to work with * 8
mvns r7, #0 @ all F's
movs r3, #0
15:
ldrd r5,r6, [r0],#8
subs r4, r4, #8
eor r5,r5, r1 @ Get it so that r5,r6 have 00's where the bytes match the target
eor r6,r6, r1
ldrd r4,r5, [r0],#8
subs r6, r6, #8
eor r4,r4, r1 @ Get it so that r4,r5 have 00's where the bytes match the target
eor r5,r5, r1
uadd8 r4, r4, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0
sel r4, r3, r7 @ bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
uadd8 r5, r5, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0
sel r5, r3, r7 @ bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
uadd8 r6, r6, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0
sel r6, r5, r7 @ chained....bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
cbnz r6, 60f
sel r5, r4, r7 @ chained....bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
cbnz r5, 60f
bne 15b @ (Flags from the subs above) If not run out of bytes then go around again
pop {r4,r5,r6,r7}
@ -129,22 +129,22 @@ ENTRY(memchr)
60: @ We're here because the fast path found a hit - now we have to track down exactly which word it was
@ r0 points to the start of the double word after the one that was tested
@ r5 has the 00/ff pattern for the first word, r6 has the chained value
@ r4 has the 00/ff pattern for the first word, r5 has the chained value
cfi_restore_state
cmp r5, #0
cmp r4, #0
itte eq
moveq r5, r6 @ the end is in the 2nd word
moveq r4, r5 @ the end is in the 2nd word
subeq r0,r0,#3 @ Points to 2nd byte of 2nd word
subne r0,r0,#7 @ or 2nd byte of 1st word
@ r0 currently points to the 2nd byte of the word containing the hit
tst r5, # CHARTSTMASK(0) @ 1st character
tst r4, # CHARTSTMASK(0) @ 1st character
bne 61f
adds r0,r0,#1
tst r5, # CHARTSTMASK(1) @ 2nd character
tst r4, # CHARTSTMASK(1) @ 2nd character
ittt eq
addeq r0,r0,#1
tsteq r5, # (3<<15) @ 2nd & 3rd character
tsteq r4, # (3<<15) @ 2nd & 3rd character
@ If not the 3rd must be the last one
addeq r0,r0,#1