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authorLuis Machado <luisgpm@br.ibm.com>2010-06-14 17:13:24 -0700
committerUlrich Drepper <drepper@redhat.com>2010-06-14 17:13:24 -0700
commit158db1226717c77f30ee2245e164f2e1f7721637 (patch)
tree6d7493e39ee07ca0384041b6455ed036d9f469ae /sysdeps/powerpc/powerpc32/power7/strncmp.S
parent4bc93b30337482a0ad1758b4ba069704d09c39da (diff)
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power7 string compare optimizations
Diffstat (limited to 'sysdeps/powerpc/powerpc32/power7/strncmp.S')
-rw-r--r--sysdeps/powerpc/powerpc32/power7/strncmp.S177
1 files changed, 177 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc32/power7/strncmp.S b/sysdeps/powerpc/powerpc32/power7/strncmp.S
new file mode 100644
index 0000000000..dd0f7099a8
--- /dev/null
+++ b/sysdeps/powerpc/powerpc32/power7/strncmp.S
@@ -0,0 +1,177 @@
+/* Optimized strcmp implementation for POWER7/PowerPC32.
+ Copyright (C) 2010 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA
+ 02110-1301 USA. */
+
+#include <sysdep.h>
+#include <bp-sym.h>
+#include <bp-asm.h>
+
+/* See strlen.s for comments on how the end-of-string testing works. */
+
+/* int [r3] strncmp (const char *s1 [r3],
+ const char *s2 [r4],
+ size_t size [r5]) */
+
+EALIGN (BP_SYM(strncmp),4,0)
+
+#define rTMP r0
+#define rRTN r3
+#define rSTR1 r3 /* first string arg */
+#define rSTR2 r4 /* second string arg */
+#define rN r5 /* max string length */
+/* Note: The Bounded pointer support in this code is broken. This code
+ was inherited from PPC32 and and that support was never completed.
+ Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */
+#define rWORD1 r6 /* current word in s1 */
+#define rWORD2 r7 /* current word in s2 */
+#define rWORD3 r10
+#define rWORD4 r11
+#define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */
+#define r7F7F r9 /* constant 0x7f7f7f7f */
+#define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f) */
+#define rBITDIF r11 /* bits that differ in s1 & s2 words */
+
+ dcbt 0,rSTR1
+ or rTMP,rSTR2,rSTR1
+ lis r7F7F,0x7f7f
+ dcbt 0,rSTR2
+ clrlwi. rTMP,rTMP,30
+ cmplwi cr1,rN,0
+ lis rFEFE,-0x101
+ bne L(unaligned)
+/* We are word alligned so set up for two loops. first a word
+ loop, then fall into the byte loop if any residual. */
+ srwi. rTMP,rN,2
+ clrlwi rN,rN,30
+ addi rFEFE,rFEFE,-0x101
+ addi r7F7F,r7F7F,0x7f7f
+ cmplwi cr1,rN,0
+ beq L(unaligned)
+
+ mtctr rTMP
+ lwz rWORD1,0(rSTR1)
+ lwz rWORD2,0(rSTR2)
+ b L(g1)
+
+L(g0):
+ lwzu rWORD1,4(rSTR1)
+ bne cr1,L(different)
+ lwzu rWORD2,4(rSTR2)
+L(g1): add rTMP,rFEFE,rWORD1
+ nor rNEG,r7F7F,rWORD1
+ bdz L(tail)
+ and. rTMP,rTMP,rNEG
+ cmpw cr1,rWORD1,rWORD2
+ beq L(g0)
+
+/* OK. We've hit the end of the string. We need to be careful that
+ we don't compare two strings as different because of gunk beyond
+ the end of the strings... */
+
+L(endstring):
+ and rTMP,r7F7F,rWORD1
+ beq cr1,L(equal)
+ add rTMP,rTMP,r7F7F
+ xor. rBITDIF,rWORD1,rWORD2
+
+ andc rNEG,rNEG,rTMP
+ blt L(highbit)
+ cntlzw rBITDIF,rBITDIF
+ cntlzw rNEG,rNEG
+ addi rNEG,rNEG,7
+ cmpw cr1,rNEG,rBITDIF
+ sub rRTN,rWORD1,rWORD2
+ blt cr1,L(equal)
+ srawi rRTN,rRTN,31
+ ori rRTN,rRTN,1
+ blr
+L(equal):
+ li rRTN,0
+ blr
+
+L(different):
+ lwzu rWORD1,-4(rSTR1)
+ xor. rBITDIF,rWORD1,rWORD2
+ sub rRTN,rWORD1,rWORD2
+ blt L(highbit)
+ srawi rRTN,rRTN,31
+ ori rRTN,rRTN,1
+ blr
+L(highbit):
+ srwi rWORD2,rWORD2,24
+ srwi rWORD1,rWORD1,24
+ sub rRTN,rWORD1,rWORD2
+ blr
+
+
+/* Oh well. In this case, we just do a byte-by-byte comparison. */
+ .align 4
+L(tail):
+ and. rTMP,rTMP,rNEG
+ cmpw cr1,rWORD1,rWORD2
+ bne L(endstring)
+ addi rSTR1,rSTR1,4
+ bne cr1,L(different)
+ addi rSTR2,rSTR2,4
+ cmplwi cr1,rN,0
+L(unaligned):
+ mtctr rN
+ ble cr1,L(ux)
+L(uz):
+ lbz rWORD1,0(rSTR1)
+ lbz rWORD2,0(rSTR2)
+ .align 4
+L(u1):
+ cmpwi cr1,rWORD1,0
+ bdz L(u4)
+ cmpw rWORD1,rWORD2
+ beq cr1,L(u4)
+ lbzu rWORD3,1(rSTR1)
+ lbzu rWORD4,1(rSTR2)
+ bne L(u4)
+ cmpwi cr1,rWORD3,0
+ bdz L(u3)
+ cmpw rWORD3,rWORD4
+ beq cr1,L(u3)
+ lbzu rWORD1,1(rSTR1)
+ lbzu rWORD2,1(rSTR2)
+ bne L(u3)
+ cmpwi cr1,rWORD1,0
+ bdz L(u4)
+ cmpw rWORD1,rWORD2
+ beq cr1,L(u4)
+ lbzu rWORD3,1(rSTR1)
+ lbzu rWORD4,1(rSTR2)
+ bne L(u4)
+ cmpwi cr1,rWORD3,0
+ bdz L(u3)
+ cmpw rWORD3,rWORD4
+ beq cr1,L(u3)
+ lbzu rWORD1,1(rSTR1)
+ lbzu rWORD2,1(rSTR2)
+ beq L(u1)
+
+L(u3): sub rRTN,rWORD3,rWORD4
+ blr
+L(u4): sub rRTN,rWORD1,rWORD2
+ blr
+L(ux):
+ li rRTN,0
+ blr
+END (BP_SYM (strncmp))
+libc_hidden_builtin_def (strncmp)