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Update. 

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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4
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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> 1999-05-04 Zack Weinberg <zack@rabi.phys.columbia.edu>
* argp/argp.h, assert/assert.h, misc/sys/cdefs.h, * 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, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */ Boston, MA 02111-1307, USA. */
/* Finds characters in a memory area. Optimized for the Alpha /* Finds characters in a memory area. Optimized for the Alpha:
architecture:
- memory accessed as aligned quadwords only - memory accessed as aligned quadwords only
- uses cmpbge to compare 8 bytes in parallel - uses cmpbge to compare 8 bytes in parallel
@ -48,119 +47,124 @@ ENTRY(memchr)
.prologue 0 .prologue 0
#endif #endif
beq a2, $not_found # Hack -- if someone passes in (size_t)-1, hoping to just
ldq_u t0, 0(a0) # load first quadword (a0 may be misaligned) # search til the end of the address space, we will overflow
addq a0, a2, t4 # below when we find the address of the last byte. Given
and a1, 0xff, a1 # a1 = 00000000000000ch # that we will never have a 56-bit address space, cropping
sll a1, 8, t1 # t1 = 000000000000ch00 # the length is the easiest way to avoid trouble.
cmpult a2, 9, t3 zap a2, 0x80, t4 #-e0 :
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
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) ldq_u t5, -1(t4) #-e1 : eight or less bytes to search
extqh t5, a0, t5 extqh t5, a0, t5 # .. e0 :
mov a0, v0 mov a0, v0 # e0 :
or t6, t5, t0 # t0 = quadword starting at a0 or t6, t5, t0 # .. e1 : t0 = quadword starting at a0
#
# Deal with the case where at most 8 bytes remain to be searched # Deal with the case where at most 8 bytes remain to be searched
# in t0. E.g.: # in t0. E.g.:
# a2 = 6 # a2 = 6
# t0 = ????c6c5c4c3c2c1 # t0 = ????c6c5c4c3c2c1
$last_quad: $last_quad:
negq a2, t5 negq a2, t5 #-e0 :
srl t2, t5, t5 # t5 = mask of a2 bits set xor a1, t0, t0 # .. e1 :
xor a1, t0, t0 srl t2, t5, t5 # e0 : t5 = mask of a2 bits set
cmpbge zero, t0, t1 cmpbge zero, t0, t1 # .. e1 :
and t1, t5, t1 and t1, t5, t1 #-e0 :
beq t1, $not_found beq t1, $not_found # .. e1 :
$found_it: $found_it:
# now, determine which byte matched: # Now, determine which byte matched:
negq t1, t2 negq t1, t2 # e0 :
and t1, t2, t1 and t1, t2, t1 # e1 :
and t1, 0x0f, t0 and t1, 0x0f, t0 #-e0 :
addq v0, 4, t2 addq v0, 4, t2 # .. e1 :
cmoveq t0, t2, v0 cmoveq t0, t2, v0 # e0 :
and t1, 0x33, t0 addq v0, 2, t2 # .. e1 :
addq v0, 2, t2 and t1, 0x33, t0 #-e0 :
cmoveq t0, t2, v0 cmoveq t0, t2, v0 # .. e1 :
and t1, 0x55, t0 and t1, 0x55, t0 # e0 :
addq v0, 1, t2 addq v0, 1, t2 # .. e1 :
cmoveq t0, t2, v0 cmoveq t0, t2, v0 #-e0 :
$done: ret $done: ret # .. e1 :
#
# Deal with the case where a2 > 8 bytes remain to be # Deal with the case where a2 > 8 bytes remain to be
# searched. a0 may not be aligned. # searched. a0 may not be aligned.
# .align 4
$first_quad: $first_quad:
andnot a0, 0x7, v0 andnot a0, 0x7, v0 #-e1 :
insqh t2, a0, t1 # t1 = 0000ffffffffffff (a0<0:2> ff bytes) insqh t2, a0, t1 # .. e0 : t1 = 0000ffffffffffff (a0<0:2> ff)
xor t0, a1, t0 xor t0, a1, t0 # e0 :
or t0, t1, t0 # t0 = ====ffffffffffff or t0, t1, t0 # e1 : t0 = ====ffffffffffff
cmpbge zero, t0, t1 cmpbge zero, t0, t1 #-e0 :
bne t1, $found_it bne t1, $found_it # .. e1 :
/* at least one byte left to process */ # At least one byte left to process.
ldq t0, 8(v0) ldq t0, 8(v0) # e0 :
addq v0, 8, v0 subq t4, 1, a2 # .. e1 :
/* addq v0, 8, v0 #-e0 :
* 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
/* 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 andnot a2, 0x7, a2 # .. e1 :
and t3, 8, t3 # odd number of quads? cmpult v0, a2, t1 # e0 :
bne t3, $odd_quad_count 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: $unrolled_loop:
ldq t0, 8(v0) # prefetch t0 ldq t0, 8(v0) #-e0 : prefetch t0
xor a1, t3, t1 xor a1, t3, t1 # .. e1 :
cmpbge zero, t1, t1 cmpbge zero, t1, t1 # e0 :
bne t1, $found_it bne t1, $found_it # .. e1 :
addq v0, 8, v0 addq v0, 8, v0 #-e0 :
$odd_quad_count: $odd_quad_count:
xor a1, t0, t1 xor a1, t0, t1 # .. e1 :
ldq t3, 8(v0) # prefetch t3 ldq t3, 8(v0) # e0 : prefetch t3
cmpbge zero, t1, t1 cmpbge zero, t1, t1 # .. e1 :
bne t1, $found_it addq v0, 8, t5 #-e0 :
bne t1, $found_it # .. e1 :
addq v0, 8, v0 cmpult t5, a2, t5 # e0 :
cmpult v0, a2, t5 addq v0, 8, v0 # .. e1 :
bne t5, $unrolled_loop bne t5, $unrolled_loop #-e1 :
mov t3, t0 # move prefetched value into t0 mov t3, t0 # e0 : move prefetched value into t0
$final: subq t4, v0, a2 # a2 <- number of bytes left to do $final: subq t4, v0, a2 # .. e1 : a2 <- number of bytes left to do
bne a2, $last_quad bne a2, $last_quad # e1 :
$not_found: $not_found:
mov zero, v0 mov zero, v0 #-e0 :
ret ret # .. e1 :
END(memchr) END(memchr)