powerpc64: strrchr optimization for power8

P7 code is used for <=32B strings and for > 32B vectorized loops are used.
This shows as an average 25% improvement depending on the position of search
character.  The performance is same for shorter strings.
Tested on ppc64 and ppc64le.

6 files changed, 521 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index bfda0e1..13579e1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2017-04-18  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>
+
+	* sysdeps/powerpc/powerpc64/multiarch/Makefile
+	(sysdep_routines): Add strrchr-power8.
+	* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+	(strrchr): Add __strrchr_power8 to list of strrchr functions.
+	* sysdeps/powerpc/powerpc64/multiarch/strrchr-power8.S: New file.
+	* sysdeps/powerpc/powerpc64/multiarch/strrchr.c
+	(strrchr): Add __strrchr_power8 to ifunc list.
+	* sysdeps/powerpc/powerpc64/power8/strrchr.S: New file.
+
 2017-04-17  Rabin Vincent  <rabinv@axis.com>
 
 	[BZ #21357]
diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index 0eb3d07..7d4f35c 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -15,7 +15,7 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   strchrnul-power8 strchrnul-power7 strchrnul-ppc64 \
 		   strcpy-power8 strcpy-power7 strcpy-ppc64 stpcpy-power8 \
 		   stpcpy-power7 stpcpy-ppc64 \
-		   strrchr-power7 strrchr-ppc64 \
+		   strrchr-power8 strrchr-power7 strrchr-ppc64 \
 		   strncat-power8 strncat-power7 strncat-ppc64 \
 		   strncpy-power7 strncpy-ppc64 \
 		   stpncpy-power8 stpncpy-power7 stpncpy-ppc64 \
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index bddec1a..107ffe6 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -284,6 +284,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/powerpc/powerpc64/multiarch/strrchr.c.  */
   IFUNC_IMPL (i, name, strrchr,
 	      IFUNC_IMPL_ADD (array, i, strrchr,
+			      hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __strrchr_power8)
+	      IFUNC_IMPL_ADD (array, i, strrchr,
 			      hwcap & PPC_FEATURE_HAS_VSX,
 			      __strrchr_power7)
 	      IFUNC_IMPL_ADD (array, i, strrchr, 1,
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strrchr-power8.S b/sysdeps/powerpc/powerpc64/multiarch/strrchr-power8.S
new file mode 100644
index 0000000..23365a1
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strrchr-power8.S
@@ -0,0 +1,39 @@
+/* Optimized strrchr implementation for POWER8.
+   Copyright (C) 2017 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 ENTRY
+#define ENTRY(name)						\
+  .section ".text";						\
+  ENTRY_2(__strrchr_power8)					\
+  .align ALIGNARG(2);						\
+  BODY_LABEL(__strrchr_power8):					\
+  cfi_startproc;						\
+  LOCALENTRY(__strrchr_power8)
+
+#undef END
+#define END(name)						\
+  cfi_endproc;							\
+  TRACEBACK(__strrchr_power8)					\
+  END_2(__strrchr_power8)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#include <sysdeps/powerpc/powerpc64/power8/strrchr.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strrchr.c b/sysdeps/powerpc/powerpc64/multiarch/strrchr.c
index dc1d3d0..0f94c9d 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/strrchr.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/strrchr.c
@@ -25,11 +25,14 @@
 
 extern __typeof (strrchr) __strrchr_ppc attribute_hidden;
 extern __typeof (strrchr) __strrchr_power7 attribute_hidden;
+extern __typeof (strrchr) __strrchr_power8 attribute_hidden;
 #undef strrchr
 
 /* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
    ifunc symbol properly.  */
 libc_ifunc_redirected (__redirect_strrchr, strrchr,
+		       (hwcap2 & PPC_FEATURE2_ARCH_2_07)
+		       ? __strrchr_power8 :
 		       (hwcap & PPC_FEATURE_HAS_VSX)
 		       ? __strrchr_power7
 		       : __strrchr_ppc);
diff --git a/sysdeps/powerpc/powerpc64/power8/strrchr.S b/sysdeps/powerpc/powerpc64/power8/strrchr.S
new file mode 100644
index 0000000..8eb7485
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power8/strrchr.S
@@ -0,0 +1,464 @@
+/* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn.
+   Copyright (C) 2017 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>
+
+/* char *[r3] strrchr (char *s [r3], int c [r4])  */
+/* TODO: change these to the actual instructions when the minimum required
+   binutils allows it.  */
+#define MTVRD(v,r) .long (0x7c000167 | ((v)<<(32-11)) | ((r)<<(32-16)))
+#define MFVRD(r,v) .long (0x7c000067 | ((v)<<(32-11)) | ((r)<<(32-16)))
+#define VBPERMQ(t,a,b)  .long (0x1000054c \
+				| ((t)<<(32-11)) \
+				| ((a)<<(32-16)) \
+				| ((b)<<(32-21)) )
+#define VCLZD(r,v) .long (0x100007c2 | ((r)<<(32-11)) | ((v)<<(32-21)))
+#define VPOPCNTD(r,v) .long (0x100007c3 | ((r)<<(32-11)) | ((v)<<(32-21)))
+#define VADDUQM(t,a,b)  .long (0x10000100 \
+				| ((t)<<(32-11)) \
+				| ((a)<<(32-16)) \
+				| ((b)<<(32-21)) )
+#ifdef __LITTLE_ENDIAN__
+/* Find the match position from v6 and place result in r6.  */
+# define CALCULATE_MATCH() \
+	VBPERMQ(v6, v6, v10); \
+	vsldoi	v6, v6, v6, 6; \
+	MFVRD(r7, v6); \
+	cntlzd	r6, r7; \
+	subfic	r6, r6, 15;
+/*
+ * Find the first null position to mask bytes after null.
+ * (reg): vcmpequb result: v2 for 1st qw v3 for 2nd qw.
+ * Result placed at v2.
+ */
+# define FIND_NULL_POS(reg) \
+	vspltisb	v11, -1; \
+	VADDUQM(v11, reg, v11); \
+	vandc	v11, v11, reg; \
+	VPOPCNTD(v2, v11); \
+	vspltb	v11, v2, 15; \
+	vcmpequb.	v11, v11, v9; \
+	blt	cr6, 1f; \
+	vsldoi	v9, v0, v9, 1; \
+	vslo	v2, v2, v9; \
+1: \
+	vsumsws	v2, v2, v0;
+#else
+# define CALCULATE_MATCH() \
+	VBPERMQ(v6, v6, v10); \
+	MFVRD(r7, v6); \
+	addi	r6, r7, -1; \
+	andc	r6, r6, r7; \
+	popcntd	r6, r6; \
+	subfic	r6, r6, 15;
+# define FIND_NULL_POS(reg) \
+	VCLZD(v2, reg); \
+	vspltb	v11, v2, 7; \
+	vcmpequb.	v11, v11, v9; \
+	blt	cr6, 1f; \
+	vsldoi	v9, v0, v9, 1; \
+	vsro	v2, v2, v9; \
+1: \
+	vsumsws	v2, v2, v0;
+#endif	/* !__LITTLE_ENDIAN__  */
+	.machine  power7
+ENTRY (strrchr)
+	CALL_MCOUNT 2
+	dcbt	0,r3
+	clrrdi	r8,r3,3	      /* Align the address to doubleword boundary.  */
+	cmpdi	cr7,r4,0
+	ld	r12,0(r8)     /* Load doubleword from memory.  */
+	li	r9,0	      /* Used to store last occurence.  */
+	li	r0,0	      /* Doubleword with null chars to use
+				 with cmpb.  */
+
+	rlwinm	r6,r3,3,26,28 /* Calculate padding.  */
+
+	beq	cr7,L(null_match)
+
+	/* Replicate byte to doubleword.  */
+	insrdi	r4,r4,8,48
+	insrdi	r4,r4,16,32
+	insrdi	r4,r4,32,0
+
+	/* r4 is changed now.  If it's passed more chars, then
+	   check for null again.  */
+	cmpdi	cr7,r4,0
+	beq	cr7,L(null_match)
+	/* Now r4 has a doubleword of c bytes and r0 has
+	   a doubleword of null bytes.  */
+
+	cmpb	r10,r12,r4     /* Compare each byte against c byte.  */
+	cmpb	r11,r12,r0     /* Compare each byte against null byte.  */
+
+	/* Move the doublewords left and right to discard the bits that are
+	   not part of the string and bring them back as zeros.  */
+#ifdef __LITTLE_ENDIAN__
+	srd	r10,r10,r6
+	srd	r11,r11,r6
+	sld	r10,r10,r6
+	sld	r11,r11,r6
+#else
+	sld	r10,r10,r6
+	sld	r11,r11,r6
+	srd	r10,r10,r6
+	srd	r11,r11,r6
+#endif
+	or	r5,r10,r11    /* OR the results to speed things up.  */
+	cmpdi	cr7,r5,0      /* If r5 == 0, no c or null bytes
+				 have been found.  */
+	bne	cr7,L(done)
+
+L(align):
+	andi.	r12, r8, 15
+
+	/* Are we now aligned to a doubleword boundary?  If so, skip to
+	   the main loop.  Otherwise, go through the alignment code.  */
+
+	bne	cr0, L(loop)
+
+	/* Handle WORD2 of pair.  */
+	ldu	r12,8(r8)
+	cmpb	r10,r12,r4
+	cmpb	r11,r12,r0
+	or	r5,r10,r11
+	cmpdi	cr7,r5,0
+	bne	cr7,L(done)
+	b	L(loop)	      /* We branch here (rather than falling through)
+				 to skip the nops due to heavy alignment
+				 of the loop below.  */
+	.p2align  5
+L(loop):
+	/* Load two doublewords, compare and merge in a
+	   single register for speed.  This is an attempt
+	   to speed up the null-checking process for bigger strings.  */
+	ld	r12,8(r8)
+	ldu	r7,16(r8)
+	cmpb	r10,r12,r4
+	cmpb	r11,r12,r0
+	cmpb	r6,r7,r4
+	cmpb	r7,r7,r0
+	or	r12,r10,r11
+	or	r5,r6,r7
+	or	r5,r12,r5
+	cmpdi	cr7,r5,0
+	beq	cr7,L(vector)
+
+	/* OK, one (or both) of the doublewords contains a c/null byte.  Check
+	   the first doubleword and decrement the address in case the first
+	   doubleword really contains a c/null byte.  */
+	cmpdi	cr6,r12,0
+	addi	r8,r8,-8
+	bne	cr6,L(done)
+
+	/* The c/null byte must be in the second doubleword.  Adjust the
+	   address again and move the result of cmpb to r10 so we can calculate
+	   the pointer.  */
+
+	mr	r10,r6
+	mr	r11,r7
+	addi	r8,r8,8
+
+	/* r10/r11 have the output of the cmpb instructions, that is,
+	   0xff in the same position as the c/null byte in the original
+	   doubleword from the string.  Use that to calculate the pointer.  */
+
+L(done):
+	/* If there are more than one 0xff in r11, find the first position of
+	   0xff in r11 and fill r10 with 0 from that position.  */
+	cmpdi	cr7,r11,0
+	beq	cr7,L(no_null)
+#ifdef __LITTLE_ENDIAN__
+	addi	r3,r11,-1
+	andc	r3,r3,r11
+	popcntd r0,r3
+#else
+	cntlzd	r0,r11
+#endif
+	subfic	r0,r0,63
+	li	r6,-1
+#ifdef __LITTLE_ENDIAN__
+	srd	r0,r6,r0
+#else
+	sld	r0,r6,r0
+#endif
+	and	r10,r0,r10
+L(no_null):
+#ifdef __LITTLE_ENDIAN__
+	cntlzd	r0,r10		/* Count leading zeros before c matches.  */
+	addi	r3,r10,-1
+	andc	r3,r3,r10
+	addi	r10,r11,-1
+	andc	r10,r10,r11
+	cmpld	cr7,r3,r10
+	bgt	cr7,L(no_match)
+#else
+	addi	r3,r10,-1	/* Count trailing zeros before c matches.  */
+	andc	r3,r3,r10
+	popcntd	r0,r3
+	cmpld	cr7,r11,r10
+	bgt	cr7,L(no_match)
+#endif
+	srdi	r0,r0,3		/* Convert trailing zeros to bytes.  */
+	subfic	r0,r0,7
+	add	r9,r8,r0      /* Return address of the matching c byte
+				 or null in case c was not found.  */
+	li	r0,0
+	cmpdi	cr7,r11,0     /* If r11 == 0, no null's have been found.  */
+	beq	cr7,L(align)
+
+	.align	4
+L(no_match):
+	mr	r3,r9
+	blr
+
+/* Check the first 32B in GPR's and move to vectorized loop.  */
+	.p2align  5
+L(vector):
+	addi	r3, r8, 8
+	/* Make sure 32B aligned.  */
+	andi.	r10, r3, 31
+	bne	cr0, L(loop)
+	vspltisb	v0, 0
+	/* Precompute vbpermq constant.  */
+	vspltisb	v10, 3
+	lvsl	v11, r0, r0
+	vslb	v10, v11, v10
+	MTVRD(v1, r4)
+	li	r5, 16
+	vspltb	v1, v1, 7
+	/* Compare 32 bytes in each loop.  */
+L(continue):
+	lvx	v4, 0, r3
+	lvx	v5, r3, r5
+	vcmpequb	v2, v0, v4
+	vcmpequb	v3, v0, v5
+	vcmpequb	v6, v1, v4
+	vcmpequb	v7, v1, v5
+	vor	v8, v2, v3
+	vor	v9, v6, v7
+	vor	v11, v8, v9
+	vcmpequb.	v11, v0, v11
+	addi	r3, r3, 32
+	blt	cr6, L(continue)
+	vcmpequb.	v8, v0, v8
+	blt	cr6, L(match)
+
+	/* One (or both) of the quadwords contains c/null.  */
+	vspltisb	v8, 2
+	vspltisb	v9, 5
+	/* Precompute values used for comparison.  */
+	vsl	v9, v8, v9	/* v9 = 0x4040404040404040.  */
+	vaddubm	v8, v9, v9
+	vsldoi	v8, v0, v8, 1	/* v8 = 0x80.  */
+
+	/* Check if null is in second qw.  */
+	vcmpequb.	v11, v0, v2
+	blt	cr6, L(secondqw)
+
+	/* Null found in first qw.  */
+	addi	r8, r3, -32
+	/* Calculate the null position.  */
+	FIND_NULL_POS(v2)
+	/* Check if null is in the first byte.  */
+	vcmpequb.	v11, v0, v2
+	blt	cr6, L(no_match)
+	vsububm	v2, v8, v2
+	/* Mask unwanted bytes after null.  */
+#ifdef __LITTLE_ENDIAN__
+	vslo	v6, v6, v2
+	vsro	v6, v6, v2
+#else
+	vsro	v6, v6, v2
+	vslo	v6, v6, v2
+#endif
+	vcmpequb.	v11, v0, v6
+	blt	cr6, L(no_match)
+	/* Found a match before null.  */
+	CALCULATE_MATCH()
+	add	r3, r8, r6
+	blr
+
+L(secondqw):
+	addi	r8, r3, -16
+	FIND_NULL_POS(v3)
+	vcmpequb.	v11, v0, v2
+	blt	cr6, L(no_match1)
+	vsububm	v2, v8, v2
+	/* Mask unwanted bytes after null.  */
+#ifdef __LITTLE_ENDIAN__
+	vslo	v7, v7, v2
+	vsro	v7, v7, v2
+#else
+	vsro	v7, v7, v2
+	vslo	v7, v7, v2
+#endif
+	vcmpequb.	v11, v0, v7
+	blt	cr6, L(no_match1)
+	addi	r8, r8, 16
+	vor	v6, v0, v7
+L(no_match1):
+	addi	r8, r8, -16
+	vcmpequb.	v11, v0, v6
+	blt	cr6, L(no_match)
+	/* Found a match before null.  */
+	CALCULATE_MATCH()
+	add	r3, r8, r6
+	blr
+
+L(match):
+	/* One (or both) of the quadwords contains a match.  */
+	mr	r8, r3
+	vcmpequb.	v8, v0, v7
+	blt	cr6, L(firstqw)
+	/* Match found in second qw.  */
+	addi	r8, r8, 16
+	vor	v6, v0, v7
+L(firstqw):
+	addi	r8, r8, -32
+	CALCULATE_MATCH()
+	add	r9, r8, r6      /* Compute final length.  */
+	b	L(continue)
+/* We are here because strrchr was called with a null byte.  */
+	.align	4
+L(null_match):
+	/* r0 has a doubleword of null bytes.  */
+
+	cmpb	r5,r12,r0     /* Compare each byte against null bytes.  */
+
+	/* Move the doublewords left and right to discard the bits that are
+	   not part of the string and bring them back as zeros.  */
+#ifdef __LITTLE_ENDIAN__
+	srd	r5,r5,r6
+	sld	r5,r5,r6
+#else
+	sld	r5,r5,r6
+	srd	r5,r5,r6
+#endif
+	cmpdi	cr7,r5,0      /* If r5 == 0, no c or null bytes
+				 have been found.  */
+	bne	cr7,L(done_null)
+
+	andi.	r12, r8, 15
+
+	/* Are we now aligned to a quadword boundary?  If so, skip to
+	   the main loop.  Otherwise, go through the alignment code.  */
+
+	bne	cr0, L(loop_null)
+
+	/* Handle WORD2 of pair.  */
+	ldu	r12,8(r8)
+	cmpb	r5,r12,r0
+	cmpdi	cr7,r5,0
+	bne	cr7,L(done_null)
+	b	L(loop_null)  /* We branch here (rather than falling through)
+				 to skip the nops due to heavy alignment
+				 of the loop below.  */
+
+	/* Main loop to look for the end of the string.  Since it's a
+	   small loop (< 8 instructions), align it to 32-bytes.  */
+	.p2align  5
+L(loop_null):
+	/* Load two doublewords, compare and merge in a
+	   single register for speed.  This is an attempt
+	   to speed up the null-checking process for bigger strings.  */
+	ld	r12,8(r8)
+	ldu	r11,16(r8)
+	cmpb	r5,r12,r0
+	cmpb	r10,r11,r0
+	or	r6,r5,r10
+	cmpdi	cr7,r6,0
+	beq	cr7,L(vector1)
+
+	/* OK, one (or both) of the doublewords contains a null byte.  Check
+	   the first doubleword and decrement the address in case the first
+	   doubleword really contains a null byte.  */
+
+	cmpdi	cr6,r5,0
+	addi	r8,r8,-8
+	bne	cr6,L(done_null)
+
+	/* The null byte must be in the second doubleword.  Adjust the address
+	   again and move the result of cmpb to r10 so we can calculate the
+	   pointer.  */
+
+	mr	r5,r10
+	addi	r8,r8,8
+
+	/* r5 has the output of the cmpb instruction, that is, it contains
+	   0xff in the same position as the null byte in the original
+	   doubleword from the string.  Use that to calculate the pointer.  */
+L(done_null):
+#ifdef __LITTLE_ENDIAN__
+	addi	r0,r5,-1
+	andc	r0,r0,r5
+	popcntd	r0,r0
+#else
+	cntlzd	r0,r5	      /* Count leading zeros before the match.  */
+#endif
+	srdi	r0,r0,3	      /* Convert trailing zeros to bytes.  */
+	add	r3,r8,r0      /* Return address of the matching null byte.  */
+	blr
+/* Check the first 32B in GPR's and move to vectorized loop.  */
+	.p2align  5
+L(vector1):
+	addi	r3, r8, 8
+	/* Make sure 32B aligned.  */
+	andi.	r10, r3, 31
+	bne	cr0, L(loop_null)
+	vspltisb	v0, 0
+	/* Precompute vbpermq constant.  */
+	vspltisb	v10, 3
+	lvsl	v11, r0, r0
+	vslb	v10, v11, v10
+	li	r5, 16
+	/* Compare 32 bytes in each loop.  */
+L(continue1):
+	lvx	v4, 0, r3
+	lvx	v5, r3, r5
+	vcmpequb	v2, v0, v4
+	vcmpequb	v3, v0, v5
+	vor	v8, v2, v3
+	vcmpequb.	v11, v0, v8
+	addi	r3, r3, 32
+	blt	cr6, L(continue1)
+	addi	r3, r3, -32
+	VBPERMQ(v2, v2, v10)
+	VBPERMQ(v3, v3, v10)
+	/* Shift each component into its correct position for merging.  */
+#ifdef __LITTLE_ENDIAN__
+	vsldoi	v3, v3, v3, 2
+#else
+	vsldoi	v2, v2, v2, 6
+	vsldoi	v3, v3, v3, 4
+#endif
+	/* Merge the results and move to a GPR.  */
+	vor	v4, v3, v2
+	MFVRD(r5, v4)
+#ifdef __LITTLE_ENDIAN__
+	addi	r6, r5, -1
+	andc	r6, r6, r5
+	popcntd	r6, r6
+#else
+	cntlzd	r6, r5  /* Count leading zeros before the match.  */
+#endif
+	add	r3, r3, r6      /* Compute final length.  */
+	blr
+END (strrchr)
+weak_alias (strrchr, rindex)
+libc_hidden_builtin_def (strrchr)