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fix new strncmp test on alpha
- From: Richard Henderson <rth at twiddle dot net>
- To: libc-alpha at sources dot redhat dot com
- Date: Sat, 26 Nov 2005 22:06:16 -0800
- Subject: fix new strncmp test on alpha
Committed.
r~
* sysdeps/alpha/strncmp.S: Don't read too much data when pointers
are co-aligned, and count is aligned with the end of the word.
Index: sysdeps/alpha/strncmp.S
===================================================================
RCS file: /cvs/glibc/libc/sysdeps/alpha/strncmp.S,v
retrieving revision 1.5
diff -u -p -d -r1.5 strncmp.S
--- sysdeps/alpha/strncmp.S 29 Apr 2003 22:47:20 -0000 1.5
+++ sysdeps/alpha/strncmp.S 27 Nov 2005 06:03:23 -0000
@@ -61,8 +61,10 @@ $aligned:
ornot t0, t3, t0 # .. e1 :
cmpbge zero, t1, t7 # e0 : bits set iff null found
beq a2, $eoc # .. e1 : check end of count
- subq a2, 1, a2 # e0 :
+ unop # e0 :
bne t7, $eos # .. e1 :
+ unop # e0 :
+ beq t10, $ant_loop # .. e1 :
/* Aligned compare main loop.
On entry to this basic block:
@@ -74,13 +76,30 @@ $a_loop:
bne t2, $wordcmp # .. e1 (zdb)
ldq_u t1, 8(a1) # e0 :
ldq_u t0, 8(a0) # .. e1 :
+ subq a2, 1, a2 # e0 :
+ addq a1, 8, a1 # .. e1 :
+ addq a0, 8, a0 # e0 :
+ beq a2, $eoc # .. e1 :
+ cmpbge zero, t1, t7 # e0 :
+ beq t7, $a_loop # .. e1 :
+ unop # e0 :
+ br $eos # .. e1 :
+
+ /* Alternate aligned compare loop, for when there's no trailing
+ bytes on the count. We have to avoid reading too much data. */
+$ant_loop:
+ xor t0, t1, t2 # e0 :
+ bne t2, $wordcmp # .. e1 (zdb)
+ subq a2, 1, a2 # e0 :
+ beq a2, $zerolength # .. e1 :
+ ldq_u t1, 8(a1) # e0 :
+ ldq_u t0, 8(a0) # .. e1 :
addq a1, 8, a1 # e0 :
addq a0, 8, a0 # .. e1 :
cmpbge zero, t1, t7 # e0 :
- beq a2, $eoc # .. e1 :
- subq a2, 1, a2 # e0 :
- beq t7, $a_loop # .. e1 :
- br $eos # e1 :
+ beq t7, $ant_loop # .. e1 :
+ unop # e0 :
+ br $eos # .. e1 :
/* The two strings are not co-aligned. Align s1 and cope. */
$unaligned:
@@ -184,6 +203,8 @@ $u_final:
$eoc:
mskql t0, t10, t0
mskql t1, t10, t1
+ unop
+ cmpbge zero, t1, t7
/* We've found a zero somewhere in a word we just read.
On entry to this basic block:
@@ -203,6 +224,7 @@ $eos:
/* Here we have two differing co-aligned words in t0 & t1.
Bytewise compare them and return (t0 > t1 ? 1 : -1). */
+ .align 3
$wordcmp:
cmpbge t0, t1, t2 # e0 : comparison yields bit mask of ge
cmpbge t1, t0, t3 # .. e1 :
@@ -216,6 +238,7 @@ $wordcmp:
$done:
ret # e1 :
+ .align 3
$zerolength:
clr v0
ret