powerpc: strstr optimization

This patch optimizes strstr function for power >= 7 systems.  Performance
gain is obtained using aligned memory access and usage of cmpb
instruction for quicker comparison.  The average improvement of this
optimization is ~40%.  Tested on ppc64 and ppc64le.

2015-07-16  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>

	* sysdeps/powerpc/powerpc64/multiarch/Makefile: Add strstr().
	* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c: Likewise.
	* sysdeps/powerpc/powerpc64/power7/strstr.S: New File.
	* sysdeps/powerpc/powerpc64/multiarch/strstr-power7.S: New File.
	* sysdeps/powerpc/powerpc64/multiarch/strstr-ppc64.c: New File.
	* sysdeps/powerpc/powerpc64/multiarch/strstr.c: New File.

1 files changed, 509 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/power7/strstr.S b/sysdeps/powerpc/powerpc64/power7/strstr.S
new file mode 100644
index 0000000000..8dca31ce35
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power7/strstr.S
@@ -0,0 +1,509 @@
+/* Optimized strstr implementation for PowerPC64/POWER7.
+   Copyright (C) 2015 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] strstr (char *s [r3], char * pat[r4])  */
+
+/* The performance gain is obtained using aligned memory access, load
+ * doubleword and usage of cmpb instruction for quicker comparison.  */
+
+#ifndef STRLEN
+/* For builds with no IFUNC support, local calls should be made to internal
+   GLIBC symbol (created by libc_hidden_builtin_def).  */
+# ifdef SHARED
+#  define STRLEN   __GI_strlen
+# else
+#  define STRLEN   strlen
+# endif
+#endif
+
+#ifndef STRNLEN
+/* For builds with no IFUNC support, local calls should be made to internal
+   GLIBC symbol (created by libc_hidden_builtin_def).  */
+# ifdef SHARED
+#  define STRNLEN   __GI_strnlen
+# else
+#  define STRNLEN   strnlen
+# endif
+#endif
+
+#ifndef STRCHR
+# ifdef SHARED
+#  define STRCHR   __GI_strchr
+# else
+#  define STRCHR   strchr
+# endif
+#endif
+
+#define	FRAMESIZE	(FRAME_MIN_SIZE+32)
+	.machine  power7
+EALIGN (strstr, 4, 0)
+	CALL_MCOUNT 2
+	mflr	r0			/* Load link register LR to r0.  */
+	std	r31, -8(r1)		/* Save callers register r31.  */
+	cfi_offset(r31, -8)
+	std	r30, -16(r1)		/* Save callers register r30.  */
+	cfi_offset(r30, -16)
+	std	r29, -24(r1)		/* Save callers register r29.  */
+	cfi_offset(r29, -24)
+	std	r0, 16(r1)		/* Store the link register.  */
+	cfi_offset(lr, 16)
+	stdu	r1, -FRAMESIZE(r1)	/* Create the stack frame.  */
+	cfi_adjust_cfa_offset(FRAMESIZE)
+
+	dcbt	0, r3
+	dcbt	0, r4
+
+	cmpdi	cr7, r3, 0
+	beq	cr7, L(retnull)
+	cmpdi	cr7, r4, 0
+	beq	cr7, L(retnull)
+
+	mr	r29, r3
+	mr	r30, r4
+	mr	r3, r4
+	bl	STRLEN
+	nop
+
+	cmpdi	cr7, r3, 0	/* If search str is null.  */
+	beq	cr7, L(ret_r3)
+
+	/* Call __strstr_ppc if needle len > 2048 */
+	cmpdi	cr7, r3, 2048
+	bgt	cr7, L(default)
+
+	mr	r31, r3
+	mr	r4, r3
+	mr	r3, r29
+	bl	STRNLEN
+	nop
+
+	cmpd	cr7, r3, r31 	/* If len(r3) < len(r4).  */
+	blt	cr7, L(retnull)
+	mr	r3, r29
+	lbz	r4, 0(r30)
+	bl	STRCHR
+	nop
+
+	mr	r11, r3
+	/* If first char of search str is not present.  */
+	cmpdi	cr7, r3, 0
+	ble	cr7, L(end)
+
+	rldicl	r8, r3, 0, 52	/* Page cross check.  */
+	cmpldi	cr7, r8, 4096-16
+	bgt	cr7, L(bytebybyte)
+
+	rldicl	r8, r30, 0, 52
+	cmpldi	cr7, r8, 4096-16
+	bgt	cr7, L(bytebybyte)
+
+	/* If len(r4) < 8 handle in a different way.  */
+	/* Shift position based on null and use cmpb.  */
+	cmpdi	cr7, r31, 8
+	blt	cr7, L(lessthan8)
+
+	/* Len(r4) >= 8 reaches here.  */
+	mr	r8, r3		/* Save r3 for future use.  */
+	mr	r4, r30		/* Restore r4.  */
+	li	r0, 0
+	rlwinm	r10, r30, 3, 26, 28	/* Calculate padding in bits.  */
+	clrrdi	r4, r4, 3	/* Make r4 aligned to 8.  */
+	ld	r6, 0(r4)
+	addi	r4, r4, 8
+	cmpdi	cr7, r10, 0	/* Check if its already aligned?  */
+	beq	cr7, L(begin1)
+#ifdef __LITTLE_ENDIAN__
+	srd	r6, r6, r10	/* Discard unwanted bits.  */
+#else
+	sld	r6, r6, r10
+#endif
+	ld	r9, 0(r4)
+	subfic	r10, r10, 64
+#ifdef __LITTLE_ENDIAN__
+	sld	r9, r9, r10	/* Discard unwanted bits.  */
+#else
+	srd	r9, r9, r10
+#endif
+	or	r6, r6, r9	/* Form complete search str.  */
+L(begin1):
+	mr	r29, r6
+	rlwinm	r10, r3, 3, 26, 28
+	clrrdi	r3, r3, 3
+	ld	r5, 0(r3)
+	cmpb	r9, r0, r6	/* Check if input has null.  */
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(return3)
+	cmpb	r9, r0, r5	/* Check if input has null.  */
+#ifdef __LITTLE_ENDIAN__
+	srd	r9, r9, r10
+#else
+	sld	r9, r9, r10
+#endif
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(retnull)
+
+	li	r12, -8		/* Shift values.  */
+	li	r11, 72		/* Shift values.  */
+	cmpdi	cr7, r10, 0
+	beq	cr7, L(nextbyte1)
+	mr	r12, r10
+	addi	r12, r12, -8
+	subfic	r11, r12, 64
+
+L(nextbyte1):
+	ldu	r7, 8(r3) 	/* Load next dw.  */
+	addi	r12, r12, 8	/* Shift one byte and compare.  */
+	addi	r11, r11, -8
+#ifdef __LITTLE_ENDIAN__
+	srd	r9, r5, r12	/* Rotate based on mask.  */
+	sld	r10, r7, r11
+#else
+	sld	r9, r5, r12
+	srd	r10, r7, r11
+#endif
+	/* Form single dw from few bytes on first load and second load.  */
+	or	r10, r9, r10
+	/* Check for null in the formed dw.  */
+	cmpb	r9, r0, r10
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(retnull)
+	/* Cmpb search str and input str.  */
+	cmpb	r9, r10, r6
+	cmpdi	cr7, r9, -1
+	beq	cr7, L(match)
+	addi	r8, r8, 1
+	b	L(begin)
+
+	.align	4
+L(match):
+	/* There is a match of 8 bytes, check next bytes.  */
+	cmpdi	cr7, r31, 8
+	beq	cr7, L(return)
+	/* Update next starting point r8.  */
+	srdi	r9, r11, 3
+	subf	r9, r9, r3
+	mr	r8, r9
+
+L(secondmatch):
+	mr	r5, r7
+	rlwinm	r10, r30, 3, 26, 28	/* Calculate padding in bits.  */
+	ld	r6, 0(r4)
+	addi	r4, r4, 8
+	cmpdi	cr7, r10, 0	/* Check if its already aligned?  */
+	beq	cr7, L(proceed3)
+#ifdef __LITTLE_ENDIAN__
+	srd	r6, r6, r10	/* Discard unwanted bits.  */
+	cmpb	r9, r0, r6
+	sld	r9, r9, r10
+#else
+	sld	r6, r6, r10
+	cmpb	r9, r0, r6
+	srd	r9, r9, r10
+#endif
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(proceed3)
+	ld	r9, 0(r4)
+	subfic	r10, r10, 64
+#ifdef __LITTLE_ENDIAN__
+	sld	r9, r9, r10	/* Discard unwanted bits.  */
+#else
+	srd	r9, r9, r10
+#endif
+	or	r6, r6, r9	/* Form complete search str.  */
+
+L(proceed3):
+	li	r7, 0
+	addi	r3, r3, 8
+	cmpb	r9, r0, r5
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(proceed4)
+	ld	r7, 0(r3)
+L(proceed4):
+#ifdef __LITTLE_ENDIAN__
+	srd	r9, r5, r12
+	sld	r10, r7, r11
+#else
+	sld	r9, r5, r12
+	srd	r10, r7, r11
+#endif
+	/* Form single dw with few bytes from first and second load.  */
+	or	r10, r9, r10
+	cmpb	r9, r0, r6
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(return4)
+	/* Check for null in the formed dw.  */
+	cmpb	r9, r0, r10
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(retnull)
+	/* If the next 8 bytes dont match, start search again.  */
+	cmpb	r9, r10, r6
+	cmpdi	cr7, r9, -1
+	bne	cr7, L(reset)
+	/* If the next 8 bytes match, load and compare next 8.  */
+	b	L(secondmatch)
+
+	.align	4
+L(reset):
+	/* Start the search again.  */
+	addi	r8, r8, 1
+	b	L(begin)
+
+	.align	4
+L(return3):
+	/* Count leading zeros and compare partial dw.  */
+#ifdef __LITTLE_ENDIAN__
+	addi	r7, r9, -1
+	andc	r7, r7, r9
+	popcntd	r7, r7
+	subfic	r7, r7, 64
+	sld	r10, r5, r7
+	sld	r6, r6, r7
+#else
+	cntlzd	r7, r9
+	subfic	r7, r7, 64
+	srd	r10, r5, r7
+	srd	r6, r6, r7
+#endif
+	cmpb	r9, r10, r6
+	cmpdi	cr7, r9, -1
+	addi	r8, r8, 1
+	/* Start search again if there is no match.  */
+	bne	cr7, L(begin)
+	/* If the words match, update return values.  */
+	subfic	r7, r7, 64
+	srdi	r7, r7, 3
+	add	r3, r3, r7
+	subf	r3, r31, r3
+	b	L(end)
+
+	.align	4
+L(return4):
+	/* Count leading zeros and compare partial dw.  */
+#ifdef __LITTLE_ENDIAN__
+	addi	r7, r9, -1
+	andc	r7, r7, r9
+	popcntd	r7, r7
+	subfic	r7, r7, 64
+	sld	r10, r10, r7
+	sld	r6, r6, r7
+#else
+	cntlzd	r7, r9
+	subfic	r7, r7, 64
+	srd	r10, r10, r7
+	srd	r6, r6, r7
+#endif
+	cmpb	r9, r10, r6
+	cmpdi	cr7, r9, -1
+	addi	r8, r8, 1
+	bne	cr7, L(begin)
+	subfic	r7, r7, 64
+	srdi	r11, r11, 3
+	subf	r3, r11, r3
+	srdi	r7, r7, 3
+	add	r3, r3, r7
+	subf	r3, r31, r3
+	b	L(end)
+
+	.align	4
+L(begin):
+	mr	r3, r8
+	lbz	r4, 0(r30)
+	bl	STRCHR
+	nop
+	/* If first char of search str is not present.  */
+	cmpdi	cr7, r3, 0
+	ble	cr7, L(end)
+	mr	r8, r3
+	mr	r4, r30		/* Restore r4.  */
+	li	r0, 0
+	mr	r6, r29
+	clrrdi	r4, r4, 3
+	addi	r4, r4, 8
+	b	L(begin1)
+
+	/* Handle less than 8 search string.  */
+	.align	4
+L(lessthan8):
+	mr	r4, r3
+	mr	r9, r30
+	li	r0, 0
+
+	rlwinm	r10, r9, 3, 26, 28	/* Calculate padding in bits.  */
+	srdi	r8, r10, 3	/* Padding in bytes.  */
+	clrrdi	r9, r9, 3	/* Make r4 aligned to 8.  */
+	ld	r6, 0(r9)
+	cmpdi	cr7, r10, 0	/* Check if its already aligned?  */
+	beq	cr7, L(proceed2)
+#ifdef __LITTLE_ENDIAN__
+	srd	r6, r6, r10	/* Discard unwanted bits.  */
+#else
+	sld	r6, r6, r10
+#endif
+	subfic	r8, r8, 8
+	cmpd	cr7, r8, r31	/* Next load needed?  */
+	bge	cr7, L(proceed2)
+	ld	r7, 8(r9)
+	subfic	r10, r10, 64
+#ifdef __LITTLE_ENDIAN__
+	sld	r7, r7, r10	/* Discard unwanted bits.  */
+#else
+	srd	r7, r7, r10
+#endif
+	or	r6, r6, r7	/* Form complete search str.  */
+L(proceed2):
+	mr	r29, r6
+	rlwinm	r10, r3, 3, 26, 28
+	clrrdi	r7, r3, 3	/* Make r3 aligned.  */
+	ld	r5, 0(r7)
+	sldi	r8, r31, 3
+	subfic	r8, r8, 64
+#ifdef __LITTLE_ENDIAN__
+	sld	r6, r6, r8
+	cmpb	r9, r0, r5
+	srd	r9, r9, r10
+#else
+	srd	r6, r6, r8
+	cmpb	r9, r0, r5
+	sld	r9, r9, r10
+#endif
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(noload)
+	cmpdi	cr7, r10, 0
+	beq	cr7, L(continue)
+	ld	r7, 8(r7)
+L(continue1):
+	mr	r12, r10
+	addi	r12, r12, -8
+	subfic	r11, r12, 64
+	b	L(nextbyte)
+
+	.align	4
+L(continue):
+	ld	r7, 8(r7)
+	li	r12, -8		/* Shift values.  */
+	li	r11, 72		/* Shift values.  */
+L(nextbyte):
+	addi	r12, r12, 8	/* Mask for rotation.  */
+	addi	r11, r11, -8
+#ifdef __LITTLE_ENDIAN__
+	srd	r9, r5, r12
+	sld	r10, r7, r11
+	or	r10, r9, r10
+	sld	r10, r10, r8
+	cmpb	r9, r0, r10
+	srd	r9, r9, r8
+#else
+	sld	r9, r5, r12
+	srd	r10, r7, r11
+	or	r10, r9, r10
+	srd	r10, r10, r8
+	cmpb	r9, r0, r10
+	sld	r9, r9, r8
+#endif
+	cmpdi	cr7, r9, 0
+	bne	cr7, L(retnull)
+	cmpb	r9, r10, r6
+	cmpdi	cr7, r9, -1
+	beq	cr7, L(end)
+	addi	r3, r4, 1
+	lbz	r4, 0(r30)
+	bl	STRCHR
+	nop
+	/* If first char of search str is not present.  */
+	cmpdi	cr7, r3, 0
+	ble	cr7, L(end)
+	mr	r4, r3
+	mr	r6, r29
+	li	r0, 0
+	b	L(proceed2)
+
+	.align	4
+L(noload):
+	/* Reached null in r3, so skip next load.  */
+	li 	r7, 0
+	b	L(continue1)
+
+	.align	4
+L(return):
+	/* Update return values.  */
+	srdi	r9, r11, 3
+	subf	r3, r9, r3
+	b	L(end)
+
+	/* Handling byte by byte.  */
+	.align	4
+L(bytebybyte):
+	mr	r8, r3
+	addi	r8, r8, -1
+L(loop1):
+	addi	r8, r8, 1
+	mr	r3, r8
+	mr	r4, r30
+	lbz	r6, 0(r4)
+	cmpdi	cr7, r6, 0
+	beq	cr7, L(updater3)
+L(loop):
+	lbz	r5, 0(r3)
+	cmpdi	cr7, r5, 0
+	beq	cr7, L(retnull)
+	cmpld	cr7, r6, r5
+	bne	cr7, L(loop1)
+	addi	r3, r3, 1
+	addi	r4, r4, 1
+	lbz	r6, 0(r4)
+	cmpdi	cr7, r6, 0
+	beq	cr7, L(updater3)
+	b	L(loop)
+
+	/* Handling return values.  */
+	.align	4
+L(updater3):
+	subf	r3, r31, r3	/* Reduce len of r4 from r3.  */
+	b	L(end)
+
+	.align	4
+L(ret_r3):
+	mr	r3, r29		/* Return r3.  */
+	b	L(end)
+
+	.align	4
+L(retnull):
+	li	r3, 0		/* Return NULL.  */
+	b	L(end)
+
+	.align	4
+L(default):
+	mr	r3, r29
+	mr	r4, r30
+	bl	__strstr_ppc
+	nop
+
+	.align	4
+L(end):
+	addi	r1, r1, FRAMESIZE	/* Restore stack pointer.  */
+	cfi_adjust_cfa_offset(-FRAMESIZE)
+	ld	r0, 16(r1)	/* Restore the saved link register.  */
+	ld	r29, -24(r1)	/* Restore callers save register r29.  */
+	ld	r30, -16(r1)	/* Restore callers save register r30.  */
+	ld	r31, -8(r1)	/* Restore callers save register r31.  */
+	mtlr	r0		/* Branch to link register.  */
+	blr
+END (strstr)
+libc_hidden_builtin_def (strstr)