powerpc: Optimized st{r,p}cpy for POWER8/PPC64

This patch adds an optimized POWER8 strcpy using unaligned accesses.
For strings up to 16 bytes the implementation first calculate the
string size, like strlen, and issues a memcpy.  For larger strings,
source is first aligned to 16 bytes and then tested over a loop that
reads 16 bytes am combine the cmpb results for speedup.  Special case is
added for page cross reads.

It shows 30%-60% improvement over the optimized POWER7 one that uses
only aligned accesses.

ChangeLog

@@ -1,3 +1,22 @@
+2015-01-13  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
+	* sysdeps/powerpc/powerpc64/multiarch/Makefile [sysdep_routines]: Add
+	strcpy-power8 and stpcpy-power8 objects.
+	* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+	(__libc_ifunc_impl_list): Add __strcpy_power8 and __stpcpy_power8
+	implementations.
+	* sysdeps/powerpc/powerpc64/multiarch/stpcpy-power8.S: New file:
+	multiarch stpcpy implementation for POWER8.
+	* sysdeps/powerpc/powerpc64/multiarch/strcpy-power8.S: New file;
+	multiarch strcpy implementation for POWER8.
+	* sysdeps/powerpc/powerpc64/multiarch/strcpy.c (strcpy): Add
+	__strcpy_power8 function.
+	* sysdeps/powerpc/powerpc64/power8/stpcpy.S: New file: optimized
+	stpcpy for POWER8.
+	* sysdeps/powerpc/powerpc64/power8/strcpy.S: New file: optimized
+	strcpy for POWER8.
+	* NEWS: Update.
+
 2015-01-13  Leonhard Holz  <leonhard.holz@web.de>
 
 	[BZ #16009]

NEWS

@@ -19,6 +19,8 @@ Version 2.21
   17744, 17745, 17746, 17747, 17748, 17775, 17777, 17780, 17781, 17782,
   17791, 17793, 17796, 17797, 17803, 17806, 17834
 
+* Optimized strcpy and stpcpy implementations for powerpc64/powerpc64le.
+
 * Added support for TSX lock elision of pthread mutexes on powerpc32, powerpc64
   and powerpc64le.  This may improve lock scaling of existing programs on
   HTM capable systems.  The lock elision code is only enabled with

sysdeps/powerpc/powerpc64/multiarch/Makefile

@@ -13,7 +13,8 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   wcschr-power6 wcschr-ppc64 wcsrchr-power7 wcsrchr-power6 \
 		   wcsrchr-ppc64 wcscpy-power7 wcscpy-power6 wcscpy-ppc64 \
 		   wordcopy-power7 wordcopy-power6 wordcopy-ppc64 \
-		   strcpy-power7 strcpy-ppc64 stpcpy-power7 stpcpy-ppc64 \
+		   strcpy-power8 strcpy-power7 strcpy-ppc64 stpcpy-power8 \
+		   stpcpy-power7 stpcpy-ppc64 \
 		   strrchr-power7 strrchr-ppc64 strncat-power7 strncat-ppc64 \
 		   strncpy-power7 strncpy-ppc64 \
 		   stpncpy-power7 stpncpy-ppc64 strcmp-power7 strcmp-ppc64 \

sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c

@@ -83,6 +83,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/strcpy.c.  */
   IFUNC_IMPL (i, name, strcpy,
+	      IFUNC_IMPL_ADD (array, i, strcpy, hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __strcpy_power8)
 	      IFUNC_IMPL_ADD (array, i, strcpy, hwcap & PPC_FEATURE_HAS_VSX,
 			      __strcpy_power7)
 	      IFUNC_IMPL_ADD (array, i, strcpy, 1,
@@ -90,6 +92,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/stpcpy.c.  */
   IFUNC_IMPL (i, name, stpcpy,
+	      IFUNC_IMPL_ADD (array, i, stpcpy, hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __stpcpy_power8)
 	      IFUNC_IMPL_ADD (array, i, stpcpy, hwcap & PPC_FEATURE_HAS_VSX,
 			      __stpcpy_power7)
 	      IFUNC_IMPL_ADD (array, i, stpcpy, 1,

sysdeps/powerpc/powerpc64/multiarch/stpcpy-power8.S

@@ -0,0 +1,40 @@
+/* Optimized stpcpy implementation for POWER8/PPC64.
+   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>
+
+#undef EALIGN
+#define EALIGN(name, alignt, words)				\
+  .section ".text";						\
+  ENTRY_2(__stpcpy_power8)					\
+  .align ALIGNARG(alignt);					\
+  EALIGN_W_##words;						\
+  BODY_LABEL(__stpcpy_power8):					\
+  cfi_startproc;						\
+  LOCALENTRY(__stpcpy_power8)
+
+#undef END
+#define END(name)						\
+  cfi_endproc;							\
+  TRACEBACK(__stpcpy_power8)					\
+  END_2(__stpcpy_power8)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#include <sysdeps/powerpc/powerpc64/power8/stpcpy.S>

sysdeps/powerpc/powerpc64/multiarch/strcpy-power8.S

@@ -0,0 +1,40 @@
+/* Optimized strcpy implementation for POWER8/PPC64.
+   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>
+
+#undef EALIGN
+#define EALIGN(name, alignt, words)				\
+  .section ".text";						\
+  ENTRY_2(__strcpy_power8)					\
+  .align ALIGNARG(alignt);					\
+  EALIGN_W_##words;						\
+  BODY_LABEL(__strcpy_power8):					\
+  cfi_startproc;						\
+  LOCALENTRY(__strcpy_power8)
+
+#undef END
+#define END(name)						\
+  cfi_endproc;							\
+  TRACEBACK(__strcpy_power8)					\
+  END_2(__strcpy_power8)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#include <sysdeps/powerpc/powerpc64/power8/strcpy.S>

sysdeps/powerpc/powerpc64/multiarch/strcpy.c

@@ -23,9 +23,12 @@
 
 extern __typeof (strcpy) __strcpy_ppc attribute_hidden;
 extern __typeof (strcpy) __strcpy_power7 attribute_hidden;
+extern __typeof (strcpy) __strcpy_power8 attribute_hidden;
 
 libc_ifunc (strcpy,
-            (hwcap & PPC_FEATURE_HAS_VSX)
+            (hwcap2 & PPC_FEATURE2_ARCH_2_07)
-            ? __strcpy_power7
+            ? __strcpy_power8 :
+              (hwcap & PPC_FEATURE_HAS_VSX)
+              ? __strcpy_power7
             : __strcpy_ppc);
 #endif

sysdeps/powerpc/powerpc64/power8/stpcpy.S

@@ -0,0 +1,24 @@
+/* Optimized stpcpy implementation for PowerPC64/POWER8.
+   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/>.  */
+
+#define USE_AS_STPCPY
+#include <sysdeps/powerpc/powerpc64/power8/strcpy.S>
+
+weak_alias (__stpcpy, stpcpy)
+libc_hidden_def (__stpcpy)
+libc_hidden_builtin_def (stpcpy)

sysdeps/powerpc/powerpc64/power8/strcpy.S

@@ -0,0 +1,262 @@
+/* Optimized strcpy/stpcpy implementation for PowerPC64/POWER8.
+   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>
+
+#ifdef USE_AS_STPCPY
+# define FUNC_NAME __stpcpy
+#else
+# define FUNC_NAME strcpy
+#endif
+
+/* Implements the function
+
+   char * [r3] strcpy (char *dest [r3], const char *src [r4])
+
+   or
+
+   char * [r3] stpcpy (char *dest [r3], const char *src [r4])
+
+   if USE_AS_STPCPY is defined.
+
+   The implementation uses unaligned doubleword access to avoid specialized
+   code paths depending of data alignment.  Although recent powerpc64 uses
+   64K as default, the page cross handling assumes minimum page size of
+   4k.  */
+
+	.machine  power7
+EALIGN (FUNC_NAME, 4, 0)
+        li      r0,0          /* Doubleword with null chars to use
+                                 with cmpb.  */
+
+	/* Check if the [src]+15 will cross a 4K page by checking if the bit
+	   indicating the page size changes.  Basically:
+
+	   uint64_t srcin = (uint64_t)src;
+	   uint64_t ob = srcin & 4096UL;
+	   uint64_t nb = (srcin+15UL) & 4096UL;
+	   if (ob ^ nb)
+	     goto pagecross;  */
+
+	addi	r9,r4,15
+	xor	r9,r9,r4
+	rlwinm.	r9,r9,0,19,19
+	bne	L(pagecross)
+
+	/* For short string (less than 16 bytes), just calculate its size as
+	   strlen and issues a memcpy if null is found.  */
+	mr	r7,r4
+        ld      r12,0(r7)     /* Load doubleword from memory.  */
+        cmpb    r10,r12,r0    /* Check for null bytes in DWORD1.  */
+        cmpdi   cr7,r10,0     /* If r10 == 0, no null's have been found.  */
+        bne     cr7,L(done)
+
+        ldu     r8,8(r7)
+        cmpb    r10,r8,r0
+        cmpdi   cr7,r10,0
+        bne     cr7,L(done)
+
+	b	L(loop_before)
+
+	.align	4
+L(pagecross):
+	clrrdi  r7,r4,3       /* Align the address to doubleword boundary.  */
+	rlwinm  r6,r4,3,26,28 /* Calculate padding.  */
+	li      r5,-1         /* MASK = 0xffffffffffffffff.  */
+        ld      r12,0(r7)     /* Load doubleword from memory.  */
+#ifdef __LITTLE_ENDIAN__
+        sld     r5,r5,r6
+#else
+        srd     r5,r5,r6      /* MASK = MASK >> padding.  */
+#endif
+        orc     r9,r12,r5     /* Mask bits that are not part of the string.  */
+        cmpb    r10,r9,r0     /* Check for null bytes in DWORD1.  */
+        cmpdi   cr7,r10,0     /* If r10 == 0, no null's have been found.  */
+        bne     cr7,L(done)
+
+        ldu     r6,8(r7)
+        cmpb    r10,r6,r0
+        cmpdi   cr7,r10,0
+        bne     cr7,L(done)
+
+        ld      r12,0(r7)
+        cmpb    r10,r12,r0
+        cmpdi   cr7,r10,0
+        bne     cr7,L(done)
+
+        ldu     r6,8(r7)
+        cmpb    r10,r6,r0
+        cmpdi   cr7,r10,0
+        bne     cr7,L(done)
+
+	/* We checked for 24 - x bytes, with x being the source alignment
+	   (0 <= x <= 16), and no zero has been found.  Start the loop
+	   copy with doubleword aligned address.  */
+	mr	r7,r4
+	ld	r12, 0(r7)
+	ldu	r8, 8(r7)
+
+L(loop_before):
+	/* Save the two doublewords readed from source and align the source
+	   to 16 bytes for the loop.  */
+	mr	r11,r3
+	std	r12,0(r11)
+	std	r8,8(r11)
+	addi	r11,r11,16
+	rldicl	r9,r4,0,60
+	subf	r7,r9,r7
+	subf	r11,r9,r11
+	b	L(loop_start)
+
+        .align  5
+L(loop):
+        std     r12, 0(r11)
+        std     r6, 8(r11)
+	addi	r11,r11,16
+L(loop_start):
+        /* 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(r7)
+        ldu     r6, 16(r7)
+        cmpb    r10,r12,r0
+        cmpb    r9,r6,r0
+        or      r8,r9,r10     /* Merge everything in one doubleword.  */
+        cmpdi   cr7,r8,0
+        beq     cr7,L(loop)
+
+
+        /* 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.  */
+
+	addi	r4,r7,-8
+        cmpdi   cr6,r10,0
+        addi    r7,r7,-8
+        bne     cr6,L(done2)
+
+        /* 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
+           length.  */
+
+        mr      r10,r9
+        addi    r7,r7,8
+	b	L(done2)
+
+        /* r10 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 length.  */
+L(done):
+	mr	r11,r3
+L(done2):
+#ifdef __LITTLE_ENDIAN__
+        addi    r9, r10, -1   /* Form a mask from trailing zeros.  */
+        andc    r9, r9, r10
+        popcntd r6, r9        /* Count the bits in the mask.  */
+#else
+        cntlzd  r6,r10        /* Count leading zeros before the match.  */
+#endif
+        subf    r5,r4,r7
+        srdi    r6,r6,3       /* Convert leading/trailing zeros to bytes.  */
+        add     r8,r5,r6      /* Compute final length.  */
+#ifdef USE_AS_STPCPY
+	/* stpcpy returns the dest address plus the size not counting the
+	   final '\0'.  */
+	add	r3,r11,r8
+#endif
+	addi	r8,r8,1       /* Final '/0'.  */
+
+	cmpldi	cr6,r8,8
+	mtocrf	0x01,r8
+	ble	cr6,L(copy_LE_8)
+
+	cmpldi	cr1,r8,16
+	blt	cr1,8f
+
+	/* Handle copies of 0~31 bytes.  */
+	.align	4
+L(copy_LT_32):
+	/* At least 6 bytes to go.  */
+	blt	cr1,8f
+
+	/* Copy 16 bytes.  */
+	ld	r6,0(r4)
+	ld	r8,8(r4)
+	addi	r4,r4,16
+	std	r6,0(r11)
+	std	r8,8(r11)
+	addi	r11,r11,16
+8:	/* Copy 8 bytes.  */
+	bf	28,L(tail4)
+	ld	r6,0(r4)
+	addi	r4,r4,8
+	std	r6,0(r11)
+	addi	r11,r11,8
+
+	.align	4
+/* Copies 4~7 bytes.  */
+L(tail4):
+	bf	29,L(tail2)
+	lwz	r6,0(r4)
+	stw	r6,0(r11)
+	bf	30,L(tail5)
+	lhz	r7,4(r4)
+	sth	r7,4(r11)
+	bflr	31
+	lbz	r8,6(r4)
+	stb	r8,6(r11)
+	blr
+
+	.align	4
+/* Copies 2~3 bytes.  */
+L(tail2):
+	bf	30,1f
+	lhz	r6,0(r4)
+	sth	r6,0(r11)
+	bflr	31
+	lbz	r7,2(r4)
+	stb	r7,2(r11)
+	blr
+
+	.align	4
+L(tail5):
+	bf	31,1f
+	lbz	r6,4(r4)
+	stb	r6,4(r11)
+	blr
+
+	.align	4
+1:
+	bflr	31
+	lbz	r6,0(r4)
+	stb	r6,0(r11)
+	blr
+
+/* Handles copies of 0~8 bytes.  */
+	.align	4
+L(copy_LE_8):
+	bne	cr6,L(tail4)
+	ld	r6,0(r4)
+	std	r6,0(r11)
+	blr
+END (FUNC_NAME)
+
+#ifndef USE_AS_STPCPY
+libc_hidden_builtin_def (strcpy)
+#endif