PowerPC: memset optimization for POWER8/PPC64

This patch adds an optimized memset implementation for POWER8.  For
sizes from 0 to 255 bytes, a word/doubleword algorithm similar to
POWER7 optimized one is used.

For size higher than 255 two strategies are used:

1. If the constant is different than 0, the memory is written with
   altivec vector instruction;

2. If constant is 0, dbcz instructions are used.  The loop is unrolled
   to clear 512 byte at time.

Using vector instructions increases throughput considerable, with a
double performance for sizes larger than 1024.  The dcbz loops unrolls
also shows performance improvement, by doubling throughput for sizes
larger than 8192 bytes.

6 files changed, 513 insertions, 9 deletions

diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index 0de3804c0c..abc9d2e973 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -2,7 +2,7 @@ ifeq ($(subdir),string)
 sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   memcpy-power4 memcpy-ppc64 memcmp-power7 memcmp-power4 \
 		   memcmp-ppc64 memset-power7 memset-power6 memset-power4 \
-		   memset-ppc64 \
+		   memset-ppc64 memset-power8 \
 		   mempcpy-power7 mempcpy-ppc64 memchr-power7 memchr-ppc64 \
 		   memrchr-power7 memrchr-ppc64 rawmemchr-power7 \
 		   rawmemchr-ppc64 strlen-power7 strlen-ppc64 strnlen-power7 \
diff --git a/sysdeps/powerpc/powerpc64/multiarch/bzero.c b/sysdeps/powerpc/powerpc64/multiarch/bzero.c
index ed83541fa5..298cf005a1 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/bzero.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/bzero.c
@@ -26,14 +26,17 @@ extern __typeof (bzero) __bzero_ppc attribute_hidden;
 extern __typeof (bzero) __bzero_power4 attribute_hidden;
 extern __typeof (bzero) __bzero_power6 attribute_hidden;
 extern __typeof (bzero) __bzero_power7 attribute_hidden;
+extern __typeof (bzero) __bzero_power8 attribute_hidden;
 
 libc_ifunc (__bzero,
-            (hwcap & PPC_FEATURE_HAS_VSX)
-            ? __bzero_power7 :
-	      (hwcap & PPC_FEATURE_ARCH_2_05)
+            (hwcap2 & PPC_FEATURE2_ARCH_2_07)
+            ? __bzero_power8 :
+	      (hwcap & PPC_FEATURE_HAS_VSX)
+	      ? __bzero_power7 :
+		(hwcap & PPC_FEATURE_ARCH_2_05)
 		? __bzero_power6 :
 		  (hwcap & PPC_FEATURE_POWER4)
-		? __bzero_power4
+		  ? __bzero_power4
             : __bzero_ppc);
 
 weak_alias (__bzero, bzero)
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index a574487f2f..06d5be9efb 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -34,6 +34,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   size_t i = 0;
 
   unsigned long int hwcap = GLRO(dl_hwcap);
+  unsigned long int hwcap2 = GLRO(dl_hwcap2);
+
   /* hwcap contains only the latest supported ISA, the code checks which is
      and fills the previous supported ones.  */
   if (hwcap & PPC_FEATURE_ARCH_2_06)
@@ -69,6 +71,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/memset.c.  */
   IFUNC_IMPL (i, name, memset,
+	      IFUNC_IMPL_ADD (array, i, memset, hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __memset_power8)
 	      IFUNC_IMPL_ADD (array, i, memset, hwcap & PPC_FEATURE_HAS_VSX,
 			      __memset_power7)
 	      IFUNC_IMPL_ADD (array, i, memset, hwcap & PPC_FEATURE_ARCH_2_05,
@@ -134,6 +138,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/bzero.c.  */
   IFUNC_IMPL (i, name, bzero,
+	      IFUNC_IMPL_ADD (array, i, bzero, hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __bzero_power8)
 	      IFUNC_IMPL_ADD (array, i, bzero, hwcap & PPC_FEATURE_HAS_VSX,
 			      __bzero_power7)
 	      IFUNC_IMPL_ADD (array, i, bzero, hwcap & PPC_FEATURE_ARCH_2_05,
diff --git a/sysdeps/powerpc/powerpc64/multiarch/memset-power8.S b/sysdeps/powerpc/powerpc64/multiarch/memset-power8.S
new file mode 100644
index 0000000000..e8a604b000
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/memset-power8.S
@@ -0,0 +1,43 @@
+/* Optimized memset implementation for PowerPC64/POWER8.
+   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(__memset_power8)					\
+  .align ALIGNARG(alignt);					\
+  EALIGN_W_##words;						\
+  BODY_LABEL(__memset_power8):					\
+  cfi_startproc;						\
+  LOCALENTRY(__memset_power8)
+
+#undef END_GEN_TB
+#define END_GEN_TB(name, mask)					\
+  cfi_endproc;							\
+  TRACEBACK_MASK(__memset_power8,mask)				\
+  END_2(__memset_power8)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#undef __bzero
+#define __bzero __bzero_power8
+
+#include <sysdeps/powerpc/powerpc64/power8/memset.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/memset.c b/sysdeps/powerpc/powerpc64/multiarch/memset.c
index aa2ae7056e..9c7ed10c87 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/memset.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/memset.c
@@ -32,16 +32,19 @@ extern __typeof (__redirect_memset) __memset_ppc attribute_hidden;
 extern __typeof (__redirect_memset) __memset_power4 attribute_hidden;
 extern __typeof (__redirect_memset) __memset_power6 attribute_hidden;
 extern __typeof (__redirect_memset) __memset_power7 attribute_hidden;
+extern __typeof (__redirect_memset) __memset_power8 attribute_hidden;
 
 /* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
    ifunc symbol properly.  */
 libc_ifunc (__libc_memset,
-            (hwcap & PPC_FEATURE_HAS_VSX)
-            ? __memset_power7 :
-	      (hwcap & PPC_FEATURE_ARCH_2_05)
+            (hwcap2 & PPC_FEATURE2_ARCH_2_07)
+            ? __memset_power8 :
+	      (hwcap & PPC_FEATURE_HAS_VSX)
+	      ? __memset_power7 :
+		(hwcap & PPC_FEATURE_ARCH_2_05)
 		? __memset_power6 :
 		  (hwcap & PPC_FEATURE_POWER4)
-		? __memset_power4
+		  ? __memset_power4
             : __memset_ppc);
 
 #undef memset
diff --git a/sysdeps/powerpc/powerpc64/power8/memset.S b/sysdeps/powerpc/powerpc64/power8/memset.S
new file mode 100644
index 0000000000..191a4df0a9
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power8/memset.S
@@ -0,0 +1,449 @@
+/* Optimized memset implementation for PowerPC64/POWER8.
+   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>
+
+/* __ptr_t [r3] memset (__ptr_t s [r3], int c [r4], size_t n [r5]));
+   Returns 's'.  */
+
+	.machine power8
+EALIGN (memset, 5, 0)
+	CALL_MCOUNT 3
+
+L(_memset):
+	cmpldi	cr7,r5,31
+	neg	r0,r3
+	mr	r10,r3
+
+	insrdi	r4,r4,8,48
+	insrdi	r4,r4,16,32	/* Replicate byte to word.  */
+	ble	cr7,L(write_LT_32)
+
+	andi.	r11,r10,15	/* Check alignment of DST.  */
+	insrdi	r4,r4,32,0	/* Replicate word to double word.  */
+
+	beq	L(big_aligned)
+
+	mtocrf	0x01,r0
+	clrldi	r0,r0,60
+
+	/* Get DST aligned to 16 bytes.  */
+1:	bf	31,2f
+	stb	r4,0(r10)
+	addi	r10,r10,1
+
+2:	bf	30,4f
+	sth	r4,0(r10)
+	addi	r10,r10,2
+
+4:	bf	29,8f
+	stw	r4,0(r10)
+	addi	r10,r10,4
+
+8:	bf      28,16f
+	std     r4,0(r10)
+	addi    r10,r10,8
+
+16:	subf	r5,r0,r5
+
+	.align	4
+L(big_aligned):
+	/* For sizes larger than 255 two possible paths:
+	   - if constant is '0', zero full cache lines with dcbz
+	   - otherwise uses vector instructions.  */
+	cmpldi	cr5,r5,255
+	dcbtst	0,r10
+	cmpldi	cr6,r4,0
+	crand	27,26,21
+	bt	27,L(huge_dcbz)
+	bge	cr5,L(huge_vector)
+
+
+	/* Size between 32 and 255 bytes with constant different than 0, use
+	   doubleword store instruction to achieve best throughput.  */
+	srdi    r8,r5,5
+	clrldi  r11,r5,59
+	cmpldi  cr6,r11,0
+	cmpdi	r8,0
+	beq     L(tail_bytes)
+	mtctr   r8
+
+	/* Main aligned write loop, writes 32-bytes at a time.  */
+	.align  4
+L(big_loop):
+	std     r4,0(r10)
+	std     r4,8(r10)
+	std     r4,16(r10)
+	std     r4,24(r10)
+	addi    r10,r10,32
+	bdz     L(tail_bytes)
+
+	std     r4,0(r10)
+	std     r4,8(r10)
+	std     r4,16(r10)
+	std     r4,24(r10)
+	addi    r10,10,32
+	bdnz    L(big_loop)
+
+	b       L(tail_bytes)
+
+	/* Write remaining 1~31 bytes.  */
+	.align  4
+L(tail_bytes):
+	beqlr   cr6
+
+	srdi    r7,r11,4
+	clrldi  r8,r11,60
+	mtocrf  0x01,r7
+
+	.align	4
+	bf	31,8f
+	std	r4,0(r10)
+	std	r4,8(r10)
+	addi	r10,r10,16
+
+	.align	4
+8:	mtocrf	0x1,r8
+	bf	28,4f
+	std	r4,0(r10)
+	addi	r10,r10,8
+
+	.align	4
+4:	bf      29,2f
+	stw     4,0(10)
+	addi    10,10,4
+
+	.align 	4
+2:	bf      30,1f
+	sth     4,0(10)
+	addi    10,10,2
+
+	.align  4
+1:      bflr    31
+	stb     4,0(10)
+	blr
+
+	/* Size larger than 255 bytes with constant different than 0, use
+	   vector instruction to achieve best throughput.  */
+L(huge_vector):
+	/* Replicate set byte to quadword in VMX register.  */
+	mtvsrd	 v1,r4
+	xxpermdi 32,v0,v1,0
+	vspltb	 v2,v0,15
+
+	/* Main aligned write loop: 128 bytes at a time.  */
+	li	r6,16
+	li	r7,32
+	li	r8,48
+	mtocrf	0x02,r5
+	srdi	r12,r5,7
+	cmpdi	r12,0
+	beq	L(aligned_tail)
+	mtctr	r12
+	b	L(aligned_128loop)
+
+	.align  4
+L(aligned_128loop):
+	stvx	v2,0,r10
+	stvx	v2,r10,r6
+	stvx	v2,r10,r7
+	stvx	v2,r10,r8
+	addi	r10,r10,64
+	stvx	v2,0,r10
+	stvx	v2,r10,r6
+	stvx	v2,r10,r7
+	stvx	v2,r10,r8
+	addi	r10,r10,64
+	bdnz	L(aligned_128loop)
+
+	/* Write remaining 1~127 bytes.  */
+L(aligned_tail):
+	mtocrf	0x01,r5
+	bf	25,32f
+	stvx	v2,0,r10
+	stvx	v2,r10,r6
+	stvx	v2,r10,r7
+	stvx	v2,r10,r8
+	addi	r10,r10,64
+
+32:	bf	26,16f
+	stvx	v2,0,r10
+	stvx	v2,r10,r6
+	addi	r10,r10,32
+
+16:	bf	27,8f
+	stvx	v2,0,r10
+	addi	r10,r10,16
+
+8:	bf	28,4f
+	std     r4,0(r10)
+	addi	r10,r10,8
+
+	/* Copies 4~7 bytes.  */
+4:	bf	29,L(tail2)
+	stw     r4,0(r10)
+	bf      30,L(tail5)
+	sth     r4,4(r10)
+	bflr	31
+	stb     r4,6(r10)
+	/* Return original DST pointer.  */
+	blr
+
+	/* Special case when value is 0 and we have a long length to deal
+	   with.  Use dcbz to zero out a full cacheline of 128 bytes at a time.
+	   Before using dcbz though, we need to get the destination 128-byte
+	   aligned.  */
+	.align	4
+L(huge_dcbz):
+	andi.	r11,r10,127
+	neg	r0,r10
+	beq	L(huge_dcbz_aligned)
+
+	clrldi	r0,r0,57
+	subf	r5,r0,r5
+	srdi	r0,r0,3
+	mtocrf	0x01,r0
+
+	/* Write 1~128 bytes until DST is aligned to 128 bytes.  */
+8:	bf	28,4f
+
+	std	r4,0(r10)
+	std	r4,8(r10)
+	std	r4,16(r10)
+	std	r4,24(r10)
+	std	r4,32(r10)
+	std	r4,40(r10)
+	std	r4,48(r10)
+	std	r4,56(r10)
+	addi	r10,r10,64
+
+	.align	4
+4:	bf	29,2f
+	std	r4,0(r10)
+	std	r4,8(r10)
+	std	r4,16(r10)
+	std	r4,24(r10)
+	addi	r10,r10,32
+
+	.align	4
+2:	bf	30,1f
+	std	r4,0(r10)
+	std	r4,8(r10)
+	addi	r10,r10,16
+
+	.align	4
+1:	bf	31,L(huge_dcbz_aligned)
+	std	r4,0(r10)
+	addi	r10,r10,8
+
+L(huge_dcbz_aligned):
+	/* Setup dcbz unroll offsets and count numbers.  */
+	srdi	r8,r5,9
+	clrldi	r11,r5,55
+	cmpldi	cr6,r11,0
+	li	r9,128
+	cmpdi	r8,0
+	beq     L(huge_tail)
+	li	r7,256
+	li	r6,384
+	mtctr	r8
+
+	.align	4
+L(huge_loop):
+	/* Sets 512 bytes to zero in each iteration, the loop unrolling shows
+	   a throughput boost for large sizes (2048 bytes or higher).  */
+	dcbz	0,r10
+	dcbz	r9,r10
+	dcbz	r7,r10
+	dcbz	r6,r10
+	addi	r10,r10,512
+	bdnz	L(huge_loop)
+
+	beqlr	cr6
+
+L(huge_tail):
+	srdi    r6,r11,8
+	srdi    r7,r11,4
+	clrldi  r8,r11,4
+	cmpldi  cr6,r8,0
+	mtocrf  0x01,r6
+
+	beq	cr6,L(tail)
+
+	/* We have 1~511 bytes remaining.  */
+	.align	4
+32:	bf	31,16f
+	dcbz	0,r10
+	dcbz	r9,r10
+	addi	r10,r10,256
+
+	.align	4
+16:	mtocrf  0x01,r7
+	bf	28,8f
+	dcbz	0,r10
+	addi	r10,r10,128
+
+	.align 	4
+8:	bf	29,4f
+	std	r4,0(r10)
+	std	r4,8(r10)
+	std	r4,16(r10)
+	std	r4,24(r10)
+	std	r4,32(r10)
+	std	r4,40(r10)
+	std	r4,48(r10)
+	std	r4,56(r10)
+	addi	r10,r10,64
+
+	.align	4
+4:	bf	30,2f
+	std	r4,0(r10)
+	std	r4,8(r10)
+	std	r4,16(r10)
+	std	r4,24(r10)
+	addi	r10,r10,32
+
+	.align	4
+2:	bf	31,L(tail)
+	std	r4,0(r10)
+	std	r4,8(r10)
+	addi	r10,r10,16
+	.align	4
+
+	/* Remaining 1~15 bytes.  */
+L(tail):
+	mtocrf  0x01,r8
+
+	.align
+8:	bf	28,4f
+	std	r4,0(r10)
+	addi	r10,r10,8
+
+	.align	4
+4:	bf	29,2f
+	stw	r4,0(r10)
+	addi	r10,r10,4
+
+	.align	4
+2:	bf	30,1f
+	sth	r4,0(r10)
+	addi	r10,r10,2
+
+	.align	4
+1:	bflr	31
+	stb	r4,0(r10)
+	blr
+
+	/* Handle short copies of 0~31 bytes.  Best throughput is achieved
+	   by just unrolling all operations.  */
+	.align	4
+L(write_LT_32):
+	cmpldi	cr6,5,8
+	mtocrf	0x01,r5
+	ble	cr6,L(write_LE_8)
+
+	/* At least 9 bytes to go.  */
+	neg	r8,r4
+	andi.	r0,r8,3
+	cmpldi	cr1,r5,16
+	beq	L(write_LT_32_aligned)
+
+	/* Force 4-byte alignment for SRC.  */
+	mtocrf	0x01,r0
+	subf	r5,r0,r5
+
+2:	bf	30,1f
+	sth	r4,0(r10)
+	addi	r10,r10,2
+
+1:	bf	31,L(end_4bytes_alignment)
+	stb	r4,0(r10)
+	addi	r10,r10,1
+
+	.align	4
+L(end_4bytes_alignment):
+	cmpldi	cr1,r5,16
+	mtocrf	0x01,r5
+
+L(write_LT_32_aligned):
+	blt	cr1,8f
+
+	stw	r4,0(r10)
+	stw	r4,4(r10)
+	stw	r4,8(r10)
+	stw	r4,12(r10)
+	addi	r10,r10,16
+
+8:	bf	28,L(tail4)
+	stw	r4,0(r10)
+	stw	r4,4(r10)
+	addi	r10,r10,8
+
+	.align	4
+	/* Copies 4~7 bytes.  */
+L(tail4):
+	bf	29,L(tail2)
+	stw	r4,0(r10)
+	bf	30,L(tail5)
+	sth	r4,4(r10)
+	bflr	31
+	stb	r4,6(r10)
+	blr
+
+	.align	4
+	/* Copies 2~3 bytes.  */
+L(tail2):
+	bf	30,1f
+	sth	r4,0(r10)
+	bflr	31
+	stb	r4,2(r10)
+	blr
+
+	.align	4
+L(tail5):
+	bflr	31
+	stb	r4,4(r10)
+	blr
+
+	.align	4
+1: 	bflr	31
+	stb	r4,0(r10)
+	blr
+
+	/* Handles copies of 0~8 bytes.  */
+	.align	4
+L(write_LE_8):
+	bne	cr6,L(tail4)
+
+	stw	r4,0(r10)
+	stw	r4,4(r10)
+	blr
+END_GEN_TB (memset,TB_TOCLESS)
+libc_hidden_builtin_def (memset)
+
+/* Copied from bzero.S to prevent the linker from inserting a stub
+   between bzero and memset.  */
+ENTRY (__bzero)
+	CALL_MCOUNT 3
+	mr	r5,r4
+	li	r4,0
+	b	L(_memset)
+END (__bzero)
+#ifndef __bzero
+weak_alias (__bzero, bzero)
+#endif