diff options
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | sysdeps/alpha/memchr.S | 178 |
2 files changed, 95 insertions, 87 deletions
@@ -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, diff --git a/sysdeps/alpha/memchr.S b/sysdeps/alpha/memchr.S index 7456735aad..0ea4aa1b3d 100644 --- a/sysdeps/alpha/memchr.S +++ b/sysdeps/alpha/memchr.S @@ -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 - - beq t3, $first_quad - - ldq_u t5, -1(t4) - extqh t5, a0, t5 - mov a0, v0 - or t6, t5, t0 # t0 = quadword starting at a0 - - # + # 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 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) #-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 : $found_it: - # now, determine which byte matched: - negq t1, t2 - and t1, t2, t1 - - and t1, 0x0f, t0 - addq v0, 4, t2 - cmoveq t0, t2, v0 + # Now, determine which byte matched: + negq t1, t2 # e0 : + and t1, t2, t1 # e1 : - and t1, 0x33, t0 - addq v0, 2, t2 - cmoveq t0, t2, v0 + and t1, 0x0f, t0 #-e0 : + addq v0, 4, t2 # .. e1 : + cmoveq t0, t2, v0 # e0 : - and t1, 0x55, t0 - addq v0, 1, t2 - cmoveq t0, t2, v0 + addq v0, 2, t2 # .. e1 : + and t1, 0x33, t0 #-e0 : + cmoveq t0, t2, v0 # .. e1 : -$done: ret + and t1, 0x55, t0 # e0 : + addq v0, 1, t2 # .. e1 : + cmoveq t0, t2, v0 #-e0 : +$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. + + ldq t0, 8(v0) # e0 : + subq t4, 1, a2 # .. e1 : + addq v0, 8, v0 #-e0 : - /* at least one byte left to process */ + # Make a2 point to last quad to be accessed (the + # last quad may or may not be partial). - 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 + andnot a2, 0x7, a2 # .. e1 : + cmpult v0, a2, t1 # e0 : + beq t1, $final # .. e1 : - /* at least two quads remain to be accessed */ + # At least two quads remain to be accessed. - 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 + 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 : - /* at least three quads remain to be accessed */ + # At least three quads remain to be accessed - mov t0, t3 # move prefetched value into correct register + mov t0, t3 # e0 : move prefetched value to correct reg - .align 3 + .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) |