PowerPC: Optimized strcmp for PPC64/POWER7

Optimization is achieved on 8 byte aligned strings with double word
comparison using cmpb instruction. On unaligned strings loop unrolling
is applied for Power7 gain.

7 files changed, 329 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 85e631e1f1..4be5547f76 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2014-06-11  Vidya Ranganathan  <vidya@linux.vnet.ibm.com>
+
+	* sysdeps/powerpc/powerpc64/power7/strcmp.S: New file: Optimization.
+	* sysdeps/powerpc/powerpc64/multiarch/strcmp.c: New file:
+	multiarch strcmp for PPC64.
+	* sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S: New file.
+	* sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S: New file.
+	* sysdeps/powerpc/powerpc64/multiarch/Makefile: Add strcmp
+	multiarch optimizations.
+	* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c:
+	(__libc_ifunc_impl_list): Likewise.
+
 2014-06-11  Siddhesh Poyarekar  <siddhesh@redhat.com>
 
 	* benchtests/scripts/validate_benchout.py: New script.
diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index 35020a7b4c..05744e9081 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -17,7 +17,7 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   strrchr-power7 strrchr-ppc64 strncat-power7 strncat-ppc64 \
 		   strspn-power7 strspn-ppc64 strcspn-power7 strcspn-ppc64 \
 		   strpbrk-power7 strpbrk-ppc64 strncpy-power7 strncpy-ppc64 \
-		   stpncpy-power7 stpncpy-ppc64
+		   stpncpy-power7 stpncpy-ppc64 strcmp-power7 strcmp-ppc64
 
 CFLAGS-strncase-power7.c += -mcpu=power7 -funroll-loops
 CFLAGS-strncase_l-power7.c += -mcpu=power7 -funroll-loops
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index d8578fb722..b3933a52d9 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -294,5 +294,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 	      IFUNC_IMPL_ADD (array, i, stpncpy, 1,
 			     __stpncpy_ppc))
 
+  /* Support sysdeps/powerpc/powerpc64/multiarch/strcmp.c.  */
+  IFUNC_IMPL (i, name, strcmp,
+	      IFUNC_IMPL_ADD (array, i, strcmp,
+			      hwcap & PPC_FEATURE_HAS_VSX,
+			      __strcmp_power7)
+	      IFUNC_IMPL_ADD (array, i, strcmp, 1,
+			     __strcmp_ppc))
   return i;
 }
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S b/sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S
new file mode 100644
index 0000000000..790ce8dbd5
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S
@@ -0,0 +1,40 @@
+/* Optimized strcmp implementation for POWER7.
+   Copyright (C) 2014 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, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#undef EALIGN
+#define EALIGN(name, alignt, words)				\
+  .section ".text";						\
+  ENTRY_2(__strcmp_power7)					\
+  .align ALIGNARG(alignt);					\
+  EALIGN_W_##words;						\
+  BODY_LABEL(__strcmp_power7):					\
+  cfi_startproc;						\
+  LOCALENTRY(__strcmp_power7)
+
+#undef END
+#define END(name)						\
+  cfi_endproc;							\
+  TRACEBACK(__strcmp_power7)					\
+  END_2(__strcmp_power7)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#include <sysdeps/powerpc/powerpc64/power7/strcmp.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S b/sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S
new file mode 100644
index 0000000000..93d12771f0
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S
@@ -0,0 +1,43 @@
+/* Default strcmp implementation for PowerPC64.
+   Copyright (C) 2014 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, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#if defined SHARED && !defined NOT_IN_libc
+# undef EALIGN
+# define EALIGN(name, alignt, words)				\
+  .section ".text";						\
+  ENTRY_2(__strcmp_ppc)						\
+  .align ALIGNARG(alignt);					\
+  EALIGN_W_##words;						\
+  BODY_LABEL(__strcmp_ppc):					\
+  cfi_startproc;						\
+  LOCALENTRY(__strcmp_ppc)
+
+# undef END
+# define END(name)						\
+  cfi_endproc;							\
+  TRACEBACK(__strcmp_ppc)					\
+  END_2(__strcmp_ppc)
+
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(name)				\
+    .globl __GI_strcmp; __GI_strcmp = __strcmp_ppc
+#endif
+
+#include <sysdeps/powerpc/powerpc64/strcmp.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp.c b/sysdeps/powerpc/powerpc64/multiarch/strcmp.c
new file mode 100644
index 0000000000..2013301aa1
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp.c
@@ -0,0 +1,31 @@
+/* Multiple versions of strcmp. PowerPC64 version.
+   Copyright (C) 2014 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, see
+   <http://www.gnu.org/licenses/>.  */
+
+#if defined SHARED && !defined NOT_IN_libc
+# include <string.h>
+# include <shlib-compat.h>
+# include "init-arch.h"
+
+extern __typeof (strcmp) __strcmp_ppc attribute_hidden;
+extern __typeof (strcmp) __strcmp_power7 attribute_hidden;
+
+libc_ifunc (strcmp,
+            (hwcap & PPC_FEATURE_HAS_VSX)
+            ? __strcmp_power7
+            : __strcmp_ppc);
+#endif
diff --git a/sysdeps/powerpc/powerpc64/power7/strcmp.S b/sysdeps/powerpc/powerpc64/power7/strcmp.S
new file mode 100644
index 0000000000..f16a9d8a88
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power7/strcmp.S
@@ -0,0 +1,195 @@
+/* Optimized strcmp implementation for Power7 using 'cmpb' instruction
+   Copyright (C) 2014 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, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* The optimization is achieved here through cmpb instruction.
+   8byte aligned strings are processed with double word comparision
+   and unaligned strings are handled effectively with loop unrolling
+   technique  */
+
+#include <sysdep.h>
+
+/* int [r3] strcmp (const char *s1 [r3], const char *s2 [r4])  */
+
+EALIGN (strcmp, 4, 0)
+	CALL_MCOUNT 2
+
+	or r9, r3, r4
+	rldicl. r10, r9, 0, 61	/* are s1 and s2 8 byte aligned..?  */
+	bne cr0, L(process_unaligned_bytes)
+
+/* process input parameters on double word aligned boundary  */
+	ld r9, 0(r4)		/* load s2 at offset=0  */
+	li r10, 0		/* load mask=0  */
+	cmpb r10, r9, r10	/* compare bytes at s2 with mask  */
+	cmpdi cr7, r10, 0	/* is NULL found ..? is end of string HIT  */
+	bne cr7, L(process_unaligned_bytes)	/* process byte by byte  */
+
+	ld r10, 0(r3)		/* load s1 at offset=0  */
+	li r8, 0		/* load mask=0  */
+	cmpb r8, r10, r8	/* compare bytes at s1 with mask  */
+	cmpdi cr7, r8, 0	/* is NULL found ..? is end of string HIT  */
+	bne cr7, L(process_unaligned_bytes)	/* process byte by byte  */
+
+/*s1 and s2 does not contain NULL now , so compare all 8 bytes in a GO  */
+	cmpb r9, r10, r9	/* compare s1 and s2  */
+	cmpdi cr7, r9, -1	/* compare result with 0xFFFFFFFFFFFFFFFF  */
+	bne cr7, L(process_unaligned_bytes)	/* s1,s2 mismatch found  */
+
+	addi r5, r3, 8		/* save next offset of s2  */
+	addi r11, r4, 8		/* save next offset of s1  */
+	ld r8, 8(r4)		/* load s2 at offset=8  */
+	li r9, 0		/* load mask=0  */
+	cmpb r9, r8, r9		/* compare bytes at s2 with mask  */
+	cmpdi cr7, r9, 0	/* NULL found ..?  */
+	bne cr7, L(processBytes)/* update input and process bytes one by one  */
+
+	mr r9, r4		/* save s2  */
+	li r10, 0		/* load mask=0  */
+
+	ld r7, 8(r3)		/* load s1 at offset=8  */
+	cmpb r6, r7, r10	/* compare bytes at s1 with mask  */
+	cmpdi cr7, r6, 0	/* is NULL found  */
+	bne cr7, L(processBytes)/* mismatch, so process one by one  */
+
+L(unrollDword):
+	cmpb r8, r7, r8		/* compare s1 and s2  */
+	cmpdi cr7, r8, -1	/* compare result with 0xFFFFFFFFFFFFFFFF  */
+	bne cr7, L(processBytes)/* mismatch with s1 and s2  */
+
+	addi r5, r3, 16		/* save offset=16 of s1  */
+	addi r4, r9, 16		/* save offset=16 of s2  */
+	ld r8, 16(r9)		/* load s2 at offset=16  */
+	cmpb r7, r8, r10	/* compare bytes at s2 with mask  */
+	cmpdi cr7, r7, 0	/* NULL found  ..?  */
+	bne cr7, L(update2processBytes)
+
+	ld r7, 16(r3)		/* load s1 at offset=16  */
+	cmpb r6, r7, r10	/* check s1 for end of string  */
+	cmpdi cr7, r6, 0	/* end of s1 ?,then handle byte by byte  */
+	bne 7,L(update2processBytes)
+
+	cmpb r8, r7, r8		/* compare s1 and s2 double words  */
+	cmpdi cr7, r8, -1	/* compare results with 0xFFFFFFFFFFFFFFFF  */
+	bne cr7,L(update2processBytes)
+
+	addi r5, r3, 24		/* update s1 to offset=24  */
+	addi r4, r9, 24		/* update s2 to offset=24  */
+
+	ld r8, 24(r9)		/* load s2  */
+	cmpb r7, r8, r10	/* compare s2 for NULL  */
+	cmpdi cr7, r7, 0	/* verify if s2 is ending now  */
+	bne cr7,L(update2processBytes)
+
+	ld r7, 24(r3)		/* load s1 at offset=24  */
+	cmpb r6, r7, r10	/* verify for NULL  */
+	cmpdi cr7, r6, 0	/* is NULL found  */
+	bne cr7, L(update2processBytes)
+
+	cmpb r8, r7, r8		/* compare s1 and s2  */
+	cmpdi cr7, r8, -1	/* are s1 and s2 same ..?  */
+	bne cr7, L(update2processBytes)
+
+	addi r7, r9, 32		/* update s2 to next double word  */
+	addi r3, r3, 32		/* update s1 to next double word  */
+
+	ld r8, 32(r9)		/* load s2  */
+	mr r4, r7		/* save s2  */
+	cmpb r6, r8, r10	/* compare s2 with NULL  */
+	cmpdi cr7, r6, 0	/* end of s2 ..? */
+	bne cr7, L(process_unaligned_bytes)
+
+	ld r6, 0(r3)		/* load and compare s1 for NULL  */
+	cmpb r5, r6, r10
+	cmpdi cr7, r5, 0
+	bne cr7, L(process_unaligned_bytes)
+
+	cmpb r8, r6, r8		/* compare s1 and s2  */
+	cmpdi cr7, r8, -1
+	bne cr7, L(process_unaligned_bytes)
+
+	addi r5, r3, 8		/* increment s1 and d2 here  */
+	addi r11, r9, 40
+
+	ld r8, 40(r9)		/* process s2 now  */
+	cmpb r9, r8, r10
+	cmpdi cr7, r9, 0
+	bne cr7, L(processBytes)
+
+	mr r9, r7
+	ld r7, 8(r3)		/* process s1 now  */
+	cmpb r6, r7, r10
+	cmpdi cr7, r6, 0
+	beq cr7, L(unrollDword)	/* unroll to compare s1 and s2  */
+
+L(processBytes):
+	mr r4, r11		/* update input params  */
+	mr r3, r5
+
+	.p2align 4
+L(process_unaligned_bytes):
+	lbz r9, 0(r3)		/* load byte from s1  */
+	lbz r10, 0(r4)		/* load byte from s2  */
+	cmpdi cr7, r9, 0	/* compare *s1 with NULL  */
+	beq cr7, L(diffOfNULL)	/* if *s1 is NULL , return *s1 - *s2  */
+	cmplw cr7, r9, r10	/* compare *s1 and *s2  */
+	bne cr7, L(ComputeDiff)	/* branch to compute difference and return  */
+
+	lbz r9, 1(r3)		/* load next byte from s1  */
+	lbz r10, 1(r4)		/* load next byte from s2  */
+	cmpdi cr7, r9, 0	/* compare *s1 with NULL  */
+	beq cr7, L(diffOfNULL)	/* if *s1 is NULL , return *s1 - *s2  */
+	cmplw cr7, r9, r10	/* compare *s1 and *s2  */
+	bne cr7, L(ComputeDiff)	/* branch to compute difference and return  */
+
+	lbz r9, 2(r3)		/* unroll 3rd byte here  */
+	lbz r10, 2(r4)
+	cmpdi cr7, r9, 0
+	beq cr7, L(diffOfNULL)
+	cmplw cr7, r9, r10
+	bne 7, L(ComputeDiff)
+
+	lbz r9, 3(r3)		/* unroll 4th byte now  */
+	lbz r10, 3(r4)
+	addi r3, r3, 4		/* increment s1 by unroll factor  */
+	cmpdi cr7, r9, 0
+	cmplw cr6, 9, r10
+	beq cr7, L(diffOfNULL)
+	addi r4, r4, 4		/* increment s2 by unroll factor  */
+	beq cr6, L(process_unaligned_bytes)	/* unroll byte processing  */
+
+	.p2align 4
+L(ComputeDiff):
+	extsw r9, r9
+	subf r10, r10, r9	/* compute s1 - s2  */
+	extsw r3, r10
+	blr			/* return  */
+
+	.p2align 4
+L(diffOfNULL):
+	li r9, 0
+	subf r10, r10, r9	/* compute s1 - s2  */
+	extsw r3, r10		/* sign extend result  */
+	blr			/* return  */
+
+	.p2align 4
+L(update2processBytes):
+	mr r3, r5		/* update and proceed  */
+	b L(process_unaligned_bytes)
+
+END (strcmp)
+libc_hidden_builtin_def (strcmp)