powerpc: strcasestr optmization for power8

This patch optimizes strcasestr function for power >= 8 systems.  The average
improvement of this optimization is ~40% and compares 16 bytes at a time
using vector instructions.  This patch is tested on powerpc64 and powerpc64le.

1 files changed, 531 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/power8/strcasestr.S b/sysdeps/powerpc/powerpc64/power8/strcasestr.S
new file mode 100644
index 0000000000..24b2b76564
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power8/strcasestr.S
@@ -0,0 +1,531 @@
+/* Optimized strcasestr implementation for PowerPC64/POWER8.
+   Copyright (C) 2016 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>
+#include <locale-defines.h>
+
+/* Char * [r3] strcasestr (char *s [r3], char * pat[r4])  */
+
+/* The performance gain is obtained by comparing 16 bytes.  */
+
+/* When the first char of r4 is hit ITERATIONS times in r3
+   fallback to default.  */
+#define ITERATIONS	64
+
+#ifndef STRLEN
+/* For builds without 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 without 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
+
+/* Convert 16 bytes of v4 and reg to lowercase and compare.  */
+#define TOLOWER(reg)     \
+	vcmpgtub	v6, v4, v1; \
+	vcmpgtub	v7, v2, v4; \
+	vand	v8, v7, v6; \
+	vand	v8, v8, v3; \
+	vor	v4, v8, v4; \
+	vcmpgtub	v6, reg, v1; \
+	vcmpgtub	v7, v2, reg; \
+	vand	v8, v7, v6; \
+	vand	v8, v8, v3; \
+	vor	reg, v8, reg; \
+	vcmpequb.	v6, reg, v4;
+
+/* TODO: change these to the actual instructions when the minimum required
+   binutils allows it.  */
+#ifdef _ARCH_PWR8
+#define VCLZD_V8_v7	vclzd	v8, v7;
+#else
+#define VCLZD_V8_v7	.long	0x11003fc2
+#endif
+
+#define	FRAMESIZE	(FRAME_MIN_SIZE+48)
+/* TODO: change this to .machine power8 when the minimum required binutils
+   allows it.  */
+	.machine  power7
+EALIGN (strcasestr, 4, 0)
+	CALL_MCOUNT 2
+	mflr	r0			/* Load link register LR to r0.  */
+	std	r31, -8(r1)		/* Save callers register r31.  */
+	std	r30, -16(r1)		/* Save callers register r30.  */
+	std	r29, -24(r1)		/* Save callers register r29.  */
+	std	r28, -32(r1)		/* Save callers register r28.  */
+	std	r27, -40(r1)		/* Save callers register r27.  */
+	std	r0, 16(r1)		/* Store the link register.  */
+	cfi_offset(r31, -8)
+	cfi_offset(r30, -16)
+	cfi_offset(r29, -24)
+	cfi_offset(r28, -32)
+	cfi_offset(r27, -40)
+	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		/* Input validation.  */
+	beq	cr7, L(retnull)
+	cmpdi	cr7, r4, 0
+	beq	cr7, L(retnull)
+
+	mr	r29, r3
+	mr	r30, r4
+	/* Load first byte from r4 and check if its null.  */
+	lbz	r6, 0(r4)
+	cmpdi	cr7, r6, 0
+	beq	cr7, L(ret_r3)
+
+	ld	r10, __libc_tsd_LOCALE@got@tprel(r2)
+	add	r9, r10, __libc_tsd_LOCALE@tls
+	ld	r9, 0(r9)
+	ld	r9, LOCALE_CTYPE_TOUPPER(r9)
+	sldi	r10, r6, 2		/* Convert to upper case.  */
+	lwzx	r28, r9, r10
+
+	ld	r10, __libc_tsd_LOCALE@got@tprel(r2)
+	add	r11, r10, __libc_tsd_LOCALE@tls
+	ld	r11, 0(r11)
+	ld	r11, LOCALE_CTYPE_TOLOWER(r11)
+	sldi	r10, r6, 2              /* Convert to lower case.  */
+	lwzx	r27, r11, r10
+
+	/* Check if the first char is present.  */
+	mr	r4, r27
+	bl	STRCHR
+	nop
+	mr	r5, r3
+	mr	r3, r29
+	mr	r29, r5
+	mr	r4, r28
+	bl	STRCHR
+	nop
+	cmpdi	cr7, r29, 0
+	beq	cr7, L(firstpos)
+	cmpdi	cr7, r3, 0
+	beq	cr7, L(skipcheck)
+	cmpw	cr7, r3, r29
+	ble 	cr7, L(firstpos)
+	/* Move r3 to the first occurence.  */
+L(skipcheck):
+	mr	r3, r29
+L(firstpos):
+	mr	r29, r3
+
+	sldi	r9, r27, 8
+	or	r28, r9, r28
+	/* Reg r27 is used to count the number of iterations.  */
+	li	r27, 0
+	/* If first char of search str is not present.  */
+	cmpdi	cr7, r3, 0
+	ble	cr7, L(end)
+
+	/* Find the length of pattern.  */
+	mr	r3, r30
+	bl	STRLEN
+	nop
+
+	cmpdi	cr7, r3, 0	/* If search str is null.  */
+	beq	cr7, L(ret_r3)
+
+	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
+
+	/* Locales not matching ASCII for single bytes.  */
+	ld	r10, __libc_tsd_LOCALE@got@tprel(r2)
+	add	r9, r10, __libc_tsd_LOCALE@tls
+	ld	r9, 0(r9)
+	ld	r7, 0(r9)
+	addi	r7, r7, LOCALE_DATA_VALUES+_NL_CTYPE_NONASCII_CASE*SIZEOF_VALUES
+	lwz	r8, 0(r7)
+	cmpdi	cr7, r8, 1
+	beq	cr7, L(bytebybyte)
+
+	/* If len(r4) < 16 handle byte by byte.  */
+	/* For shorter strings we will not use vector registers.  */
+	cmpdi	cr7, r31, 16
+	blt	cr7, L(bytebybyte)
+
+	/* Comparison values used for TOLOWER.  */
+	/* Load v1 = 64('A' - 1), v2 = 91('Z' + 1), v3 = 32 in each byte.  */
+	vspltish	v0, 0
+	vspltisb	v5, 2
+	vspltisb	v4, 4
+	vsl	v3, v5, v4
+	vaddubm	v1, v3, v3
+	vspltisb	v5, 15
+	vaddubm	v2, v5, v5
+	vaddubm	v2, v1, v2
+	vspltisb	v4, -3
+	vaddubm	v2, v2, v4
+
+	/*
+	1. Load 16 bytes from r3 and r4
+	2. Check if there is null, If yes, proceed byte by byte path.
+	3. Else,Convert both to lowercase and compare.
+	4. If they are same proceed to 1.
+	5. If they dont match, find if first char of r4 is present in the
+	   loaded 16 byte of r3.
+	6. If yes, move position, load next 16 bytes of r3 and proceed to 2.
+	*/
+
+	mr	r8, r3		/* Save r3 for future use.  */
+	mr	r4, r30		/* Restore r4.  */
+	clrldi	r10, r4, 60
+	lvx	v5, 0, r4	/* Load 16 bytes from r4.  */
+	cmpdi	cr7, r10, 0
+	beq	cr7, L(begin2)
+	/* If r4 is unaligned, load another 16 bytes.  */
+#ifdef __LITTLE_ENDIAN__
+	lvsr	v7, 0, r4
+#else
+	lvsl	v7, 0, r4
+#endif
+	addi	r5, r4, 16
+	lvx	v9, 0, r5
+#ifdef __LITTLE_ENDIAN__
+	vperm	v5, v9, v5, v7
+#else
+	vperm	v5, v5, v9, v7
+#endif
+L(begin2):
+	lvx	v4, 0, r3
+	vcmpequb.	v7, v0, v4	/* Check for null.  */
+	beq	cr6, L(nullchk6)
+	b	L(trailcheck)
+
+        .align  4
+L(nullchk6):
+	clrldi	r10, r3, 60
+	cmpdi	cr7, r10, 0
+	beq	cr7, L(next16)
+#ifdef __LITTLE_ENDIAN__
+	lvsr	v7, 0, r3
+#else
+	lvsl	v7, 0, r3
+#endif
+	addi	r5, r3, 16
+	/* If r3 is unaligned, load another 16 bytes.  */
+	lvx	v10, 0, r5
+#ifdef __LITTLE_ENDIAN__
+	vperm	v4, v10, v4, v7
+#else
+	vperm	v4, v4, v10, v7
+#endif
+L(next16):
+	vcmpequb.	v6, v0, v5	/* Check for null.  */
+	beq	cr6, L(nullchk)
+	b	L(trailcheck)
+
+	.align	4
+L(nullchk):
+	vcmpequb.	v6, v0, v4
+	beq	cr6, L(nullchk1)
+	b	L(retnull)
+
+	.align	4
+L(nullchk1):
+	/* Convert both v3 and v4 to lower.  */
+	TOLOWER(v5)
+	/* If both are same, branch to match.  */
+	blt	cr6, L(match)
+	/* Find if the first char is present in next 15 bytes.  */
+#ifdef __LITTLE_ENDIAN__
+	vspltb	v6, v5, 15
+	vsldoi	v7, v0, v4, 15
+#else
+	vspltb	v6, v5, 0
+	vspltisb	v7, 8
+	vslo	v7, v4, v7
+#endif
+	vcmpequb	v7, v6, v7
+	vcmpequb.	v6, v0, v7
+	/* Shift r3 by 16 bytes and proceed.  */
+	blt	cr6, L(shift16)
+	VCLZD_V8_v7
+#ifdef __LITTLE_ENDIAN__
+	vspltb	v6, v8, 15
+#else
+	vspltb	v6, v8, 7
+#endif
+	vcmpequb.	v6, v6, v1
+	/* Shift r3 by 8  bytes and proceed.  */
+	blt	cr6, L(shift8)
+	b	L(begin)
+
+	.align	4
+L(match):
+	/* There is a match of 16 bytes, check next bytes.  */
+	cmpdi	cr7, r31, 16
+	mr	r29, r3
+	beq	cr7, L(ret_r3)
+
+L(secondmatch):
+	addi	r3, r3, 16
+	addi	r4, r4, 16
+	/* Load next 16 bytes of r3 and r4 and compare.  */
+	clrldi	r10, r4, 60
+	cmpdi	cr7, r10, 0
+	beq	cr7, L(nextload)
+	/* Handle unaligned case.  */
+	vor	v6, v9, v9
+	vcmpequb.	v7, v0, v6
+	beq	cr6, L(nullchk2)
+	b	L(trailcheck)
+
+	.align	4
+L(nullchk2):
+#ifdef __LITTLE_ENDIAN__
+	lvsr	v7, 0, r4
+#else
+	lvsl	v7, 0, r4
+#endif
+	addi	r5, r4, 16
+	/* If r4 is unaligned, load another 16 bytes.  */
+	lvx	v9, 0, r5
+#ifdef __LITTLE_ENDIAN__
+	vperm	v11, v9, v6, v7
+#else
+	vperm	v11, v6, v9, v7
+#endif
+	b	L(compare)
+
+	.align	4
+L(nextload):
+	lvx	v11, 0, r4
+L(compare):
+	vcmpequb.	v7, v0, v11
+	beq	cr6, L(nullchk3)
+	b	L(trailcheck)
+
+	.align	4
+L(nullchk3):
+	clrldi	r10, r3, 60
+	cmpdi 	cr7, r10, 0
+	beq 	cr7, L(nextload1)
+	/* Handle unaligned case.  */
+	vor	v4, v10, v10
+	vcmpequb.	v7, v0, v4
+	beq	cr6, L(nullchk4)
+	b	L(retnull)
+
+	.align	4
+L(nullchk4):
+#ifdef __LITTLE_ENDIAN__
+	lvsr	v7, 0, r3
+#else
+	lvsl	v7, 0, r3
+#endif
+	addi	r5, r3, 16
+	/* If r3 is unaligned, load another 16 bytes.  */
+	lvx	v10, 0, r5
+#ifdef __LITTLE_ENDIAN__
+	vperm	v4, v10, v4, v7
+#else
+	vperm	v4, v4, v10, v7
+#endif
+	b	L(compare1)
+
+	.align	4
+L(nextload1):
+	lvx	v4, 0, r3
+L(compare1):
+	vcmpequb.	v7, v0, v4
+	beq	cr6, L(nullchk5)
+	b	L(retnull)
+
+	.align	4
+L(nullchk5):
+	/* Convert both v3 and v4 to lower.  */
+	TOLOWER(v11)
+	/* If both are same, branch to secondmatch.  */
+	blt 	cr6, L(secondmatch)
+	/* Continue the search.  */
+        b	L(begin)
+
+	.align	4
+L(trailcheck):
+	ld	r10, __libc_tsd_LOCALE@got@tprel(r2)
+	add	r11, r10, __libc_tsd_LOCALE@tls
+	ld	r11, 0(r11)
+	ld	r11, LOCALE_CTYPE_TOLOWER(r11)
+L(loop2):
+	lbz	r5, 0(r3)               /* Load byte from r3.  */
+	lbz	r6, 0(r4)               /* Load next byte from r4.  */
+	cmpdi 	cr7, r6, 0              /* Is it null?  */
+	beq 	cr7, L(updater3)
+	cmpdi 	cr7, r5, 0              /* Is it null?  */
+	beq 	cr7, L(retnull)         /* If yes, return.  */
+	addi	r3, r3, 1
+	addi	r4, r4, 1               /* Increment r4.  */
+	sldi	r10, r5, 2              /* Convert to lower case.  */
+	lwzx	r10, r11, r10
+	sldi	r7, r6, 2               /* Convert to lower case.  */
+	lwzx	r7, r11, r7
+	cmpw	cr7, r7, r10            /* Compare with byte from r4.  */
+	bne	cr7, L(begin)
+	b	L(loop2)
+
+	.align	4
+L(shift8):
+	addi	r8, r8, 7
+	b	L(begin)
+	.align	4
+L(shift16):
+	addi	r8, r8, 15
+	.align	4
+L(begin):
+	addi	r8, r8, 1
+	mr	r3, r8
+	/* When our iterations exceed ITERATIONS,fall back to default.  */
+	addi	r27, r27, 1
+	cmpdi	cr7, r27, ITERATIONS
+	beq	cr7, L(default)
+	mr	r4, r30         /* Restore r4.  */
+	b	L(begin2)
+
+	/* Handling byte by byte.  */
+	.align	4
+L(loop1):
+	mr	r3, r8
+	addi	r27, r27, 1
+	cmpdi	cr7, r27, ITERATIONS
+	beq	cr7, L(default)
+	mr	r29, r8
+	srdi	r4, r28, 8
+	/* Check if the first char is present.  */
+	bl	STRCHR
+	nop
+	mr	r5, r3
+	mr	r3, r29
+	mr	r29, r5
+	sldi	r4, r28, 56
+	srdi	r4, r4, 56
+	bl	STRCHR
+	nop
+	cmpdi	cr7, r29, 0
+	beq	cr7, L(nextpos)
+	cmpdi	cr7, r3, 0
+	beq	cr7, L(skipcheck1)
+	cmpw	cr7, r3, r29
+	ble 	cr7, L(nextpos)
+	/* Move r3 to first occurence.  */
+L(skipcheck1):
+	mr	r3, r29
+L(nextpos):
+	mr	r29, r3
+	cmpdi 	cr7, r3, 0
+	ble 	cr7, L(retnull)
+L(bytebybyte):
+	ld	r10, __libc_tsd_LOCALE@got@tprel(r2)
+	add	r11, r10, __libc_tsd_LOCALE@tls
+	ld	r11, 0(r11)
+	ld	r11, LOCALE_CTYPE_TOLOWER(r11)
+	mr	r4, r30                 /* Restore r4.  */
+	mr	r8, r3                  /* Save r3.  */
+	addi	r8, r8, 1
+
+L(loop):
+	addi	r3, r3, 1
+	lbz	r5, 0(r3)               /* Load byte from r3.  */
+	addi	r4, r4, 1               /* Increment r4.  */
+	lbz	r6, 0(r4)               /* Load next byte from r4.  */
+	cmpdi 	cr7, r6, 0              /* Is it null?  */
+	beq 	cr7, L(updater3)
+	cmpdi 	cr7, r5, 0              /* Is it null?  */
+	beq 	cr7, L(retnull)         /* If yes, return.  */
+	sldi	r10, r5, 2              /* Convert to lower case.  */
+	lwzx	r10, r11, r10
+	sldi	r7, r6, 2               /* Convert to lower case.  */
+	lwzx	r7, r11, r7
+	cmpw	cr7, r7, r10            /* Compare with byte from r4.  */
+	bne 	cr7, L(loop1)
+	b	L(loop)
+
+	/* Handling return values.  */
+	.align	4
+L(updater3):
+	subf	r3, r31, r3	/* Reduce r31 (len of r4) from r3.  */
+	b	L(end)
+
+	.align	4
+L(ret_r3):
+	mr	r3, r29		/* Return point of match.  */
+	b	L(end)
+
+	.align	4
+L(retnull):
+	li	r3, 0		/* Substring was not found.  */
+	b	L(end)
+
+	.align	4
+L(default):
+	mr	r4, r30
+	bl	__strcasestr_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	r27, -40(r1)
+	ld	r28, -32(r1)
+	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.  */
+	cfi_restore(lr)
+	cfi_restore(r27)
+	cfi_restore(r28)
+	cfi_restore(r29)
+	cfi_restore(r30)
+	cfi_restore(r31)
+	mtlr	r0		/* Branch to link register.  */
+	blr
+END (strcasestr)
+libc_hidden_builtin_def (strcasestr)