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1999-05-18  Richard Henderson  <rth@twiddle.net>

	* sysdeps/alpha/memchr.S: Zap high byte of length.  Reschedule.
This commit is contained in:
Ulrich Drepper 1999-05-18 08:57:29 +00:00
parent 05cc5bd9dc
commit 2a269cd083
2 changed files with 92 additions and 84 deletions
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ChangeLog
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@ -1,3 +1,7 @@
1999-05-18 Richard Henderson <rth@twiddle.net>
* sysdeps/alpha/memchr.S: Zap high byte of length. Reschedule.
1999-05-04 Zack Weinberg <zack@rabi.phys.columbia.edu>
* argp/argp.h, assert/assert.h, misc/sys/cdefs.h,

172
sysdeps/alpha/memchr.S
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@ -17,8 +17,7 @@
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* Finds characters in a memory area. Optimized for the Alpha
architecture:
/* Finds characters in a memory area. Optimized for the Alpha:
- memory accessed as aligned quadwords only
- uses cmpbge to compare 8 bytes in parallel
@ -48,119 +47,124 @@ ENTRY(memchr)
.prologue 0
#endif
beq a2, $not_found
ldq_u t0, 0(a0) # load first quadword (a0 may be misaligned)
addq a0, a2, t4
and a1, 0xff, a1 # a1 = 00000000000000ch
sll a1, 8, t1 # t1 = 000000000000ch00
cmpult a2, 9, t3
or t1, a1, a1 # a1 = 000000000000chch
sll a1, 16, t1 # t1 = 00000000chch0000
lda t2, -1(zero)
or t1, a1, a1 # a1 = 00000000chchchch
sll a1, 32, t1 # t1 = chchchch00000000
extql t0, a0, t6
or t1, a1, a1 # a1 = chchchchchchchch
# Hack -- if someone passes in (size_t)-1, hoping to just
# search til the end of the address space, we will overflow
# below when we find the address of the last byte. Given
# that we will never have a 56-bit address space, cropping
# the length is the easiest way to avoid trouble.
zap a2, 0x80, t4 #-e0 :
beq t3, $first_quad
beq a2, $not_found # .. e1 :
ldq_u t0, 0(a0) # e1 : load first quadword
insbl a1, 1, t1 # .. e0 : t1 = 000000000000ch00
and a1, 0xff, a1 #-e0 : a1 = 00000000000000ch
cmpult a2, 9, t3 # .. e1 :
or t1, a1, a1 # e0 : a1 = 000000000000chch
lda t2, -1(zero) # .. e1 :
sll a1, 16, t1 #-e0 : t1 = 00000000chch0000
addq a0, t4, t4 # .. e1 :
or t1, a1, a1 # e1 : a1 = 00000000chchchch
unop # :
sll a1, 32, t1 #-e0 : t1 = chchchch00000000
or t1, a1, a1 # e1 : a1 = chchchchchchchch
extql t0, a0, t6 # e0 :
beq t3, $first_quad # .. e1 :
ldq_u t5, -1(t4)
extqh t5, a0, t5
mov a0, v0
or t6, t5, t0 # t0 = quadword starting at a0
ldq_u t5, -1(t4) #-e1 : eight or less bytes to search
extqh t5, a0, t5 # .. e0 :
mov a0, v0 # e0 :
or t6, t5, t0 # .. e1 : t0 = quadword starting at a0
#
# Deal with the case where at most 8 bytes remain to be searched
# in t0. E.g.:
# a2 = 6
# t0 = ????c6c5c4c3c2c1
$last_quad:
negq a2, t5
srl t2, t5, t5 # t5 = mask of a2 bits set
xor a1, t0, t0
cmpbge zero, t0, t1
and t1, t5, t1
beq t1, $not_found
negq a2, t5 #-e0 :
xor a1, t0, t0 # .. e1 :
srl t2, t5, t5 # e0 : t5 = mask of a2 bits set
cmpbge zero, t0, t1 # .. e1 :
and t1, t5, t1 #-e0 :
beq t1, $not_found # .. e1 :
$found_it:
# now, determine which byte matched:
negq t1, t2
and t1, t2, t1
# Now, determine which byte matched:
negq t1, t2 # e0 :
and t1, t2, t1 # e1 :
and t1, 0x0f, t0
addq v0, 4, t2
cmoveq t0, t2, v0
and t1, 0x0f, t0 #-e0 :
addq v0, 4, t2 # .. e1 :
cmoveq t0, t2, v0 # e0 :
and t1, 0x33, t0
addq v0, 2, t2
cmoveq t0, t2, v0
addq v0, 2, t2 # .. e1 :
and t1, 0x33, t0 #-e0 :
cmoveq t0, t2, v0 # .. e1 :
and t1, 0x55, t0
addq v0, 1, t2
cmoveq t0, t2, v0
and t1, 0x55, t0 # e0 :
addq v0, 1, t2 # .. e1 :
cmoveq t0, t2, v0 #-e0 :
$done: ret
$done: ret # .. e1 :
#
# Deal with the case where a2 > 8 bytes remain to be
# searched. a0 may not be aligned.
#
.align 4
$first_quad:
andnot a0, 0x7, v0
insqh t2, a0, t1 # t1 = 0000ffffffffffff (a0<0:2> ff bytes)
xor t0, a1, t0
or t0, t1, t0 # t0 = ====ffffffffffff
cmpbge zero, t0, t1
bne t1, $found_it
andnot a0, 0x7, v0 #-e1 :
insqh t2, a0, t1 # .. e0 : t1 = 0000ffffffffffff (a0<0:2> ff)
xor t0, a1, t0 # e0 :
or t0, t1, t0 # e1 : t0 = ====ffffffffffff
cmpbge zero, t0, t1 #-e0 :
bne t1, $found_it # .. e1 :
/* at least one byte left to process */
# At least one byte left to process.
ldq t0, 8(v0)
addq v0, 8, v0
/*
* Make a2 point to last quad to be accessed (the
* last quad may or may not be partial).
*/
subq t4, 1, a2
andnot a2, 0x7, a2
cmpult v0, a2, t1
beq t1, $final
ldq t0, 8(v0) # e0 :
subq t4, 1, a2 # .. e1 :
addq v0, 8, v0 #-e0 :
/* at least two quads remain to be accessed */
# Make a2 point to last quad to be accessed (the
# last quad may or may not be partial).
subq a2, v0, t3 # t3 <- number of quads to be processed in loop
and t3, 8, t3 # odd number of quads?
bne t3, $odd_quad_count
andnot a2, 0x7, a2 # .. e1 :
cmpult v0, a2, t1 # e0 :
beq t1, $final # .. e1 :
/* at least three quads remain to be accessed */
# At least two quads remain to be accessed.
mov t0, t3 # move prefetched value into correct register
subq a2, v0, t3 #-e0 : t3 <- nr quads to be processed
and t3, 8, t3 # e1 : odd number of quads?
bne t3, $odd_quad_count # e1 :
.align 3
# At least three quads remain to be accessed
mov t0, t3 # e0 : move prefetched value to correct reg
.align 4
$unrolled_loop:
ldq t0, 8(v0) # prefetch t0
xor a1, t3, t1
cmpbge zero, t1, t1
bne t1, $found_it
ldq t0, 8(v0) #-e0 : prefetch t0
xor a1, t3, t1 # .. e1 :
cmpbge zero, t1, t1 # e0 :
bne t1, $found_it # .. e1 :
addq v0, 8, v0
addq v0, 8, v0 #-e0 :
$odd_quad_count:
xor a1, t0, t1
ldq t3, 8(v0) # prefetch t3
cmpbge zero, t1, t1
bne t1, $found_it
xor a1, t0, t1 # .. e1 :
ldq t3, 8(v0) # e0 : prefetch t3
cmpbge zero, t1, t1 # .. e1 :
addq v0, 8, t5 #-e0 :
bne t1, $found_it # .. e1 :
addq v0, 8, v0
cmpult v0, a2, t5
bne t5, $unrolled_loop
cmpult t5, a2, t5 # e0 :
addq v0, 8, v0 # .. e1 :
bne t5, $unrolled_loop #-e1 :
mov t3, t0 # move prefetched value into t0
$final: subq t4, v0, a2 # a2 <- number of bytes left to do
bne a2, $last_quad
mov t3, t0 # e0 : move prefetched value into t0
$final: subq t4, v0, a2 # .. e1 : a2 <- number of bytes left to do
bne a2, $last_quad # e1 :
$not_found:
mov zero, v0
ret
mov zero, v0 #-e0 :
ret # .. e1 :
END(memchr)