[PATCH] powerpc: power7 strncmp optimization
Will Schmidt
will_schmidt@vnet.ibm.com
Thu Aug 4 14:23:00 GMT 2011
Hi,
The following code change provides a throughput boost to the 64-bit
power7 strncmp code of approx 15%. The 32-bit throughput is not notably
affected by this change, so the change to the 32-bit code is done to
keep the two files in sync with each other.
2011-08-04 Will Schmidt <will_schmidt@vnet.ibm.com>
* sysdeps/powerpc/powerpc32/power7/strncmp.S: Adjust the alignment
and add nop instructions for throughput optimization.
* sysdeps/powerpc/powerpc64/power7/strncmp.S: Adjust the alignment
and nop instructions for throughput optimization.
diff --git a/sysdeps/powerpc/powerpc32/power7/strncmp.S b/sysdeps/powerpc/powerpc32/power7/strncmp.S
index 6a1422a..bcd13b6 100644
--- a/sysdeps/powerpc/powerpc32/power7/strncmp.S
+++ b/sysdeps/powerpc/powerpc32/power7/strncmp.S
@@ -27,7 +27,7 @@
const char *s2 [r4],
size_t size [r5]) */
-EALIGN (BP_SYM(strncmp),4,0)
+EALIGN (BP_SYM(strncmp),5,0)
#define rTMP r0
#define rRTN r3
@@ -47,9 +47,11 @@ EALIGN (BP_SYM(strncmp),4,0)
#define rBITDIF r11 /* bits that differ in s1 & s2 words */
dcbt 0,rSTR1
+ nop
or rTMP,rSTR2,rSTR1
lis r7F7F,0x7f7f
dcbt 0,rSTR2
+ nop
clrlwi. rTMP,rTMP,30
cmplwi cr1,rN,0
lis rFEFE,-0x101
diff --git a/sysdeps/powerpc/powerpc64/power7/strncmp.S b/sysdeps/powerpc/powerpc64/power7/strncmp.S
index 498b19c..4c02b11 100644
--- a/sysdeps/powerpc/powerpc64/power7/strncmp.S
+++ b/sysdeps/powerpc/powerpc64/power7/strncmp.S
@@ -27,7 +27,7 @@
const char *s2 [r4],
size_t size [r5]) */
-EALIGN (BP_SYM(strncmp),4,0)
+EALIGN (BP_SYM(strncmp),5,0)
CALL_MCOUNT 3
#define rTMP r0
@@ -48,9 +48,11 @@ EALIGN (BP_SYM(strncmp),4,0)
#define rBITDIF r11 /* bits that differ in s1 & s2 words */
dcbt 0,rSTR1
+ nop
or rTMP,rSTR2,rSTR1
lis r7F7F,0x7f7f
dcbt 0,rSTR2
+ nop
clrldi. rTMP,rTMP,61
cmpldi cr1,rN,0
lis rFEFE,-0x101
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