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commit a55e2da2702e235fa0ae66a116d304d1bffc060a
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Author: Lucas A. M. Magalhaes <lamm@linux.ibm.com>
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Date: Thu May 6 17:01:52 2021 -0300
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powerpc: Optimized memcmp for power10
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This patch was based on the __memcmp_power8 and the recent
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__strlen_power10.
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Improvements from __memcmp_power8:
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1. Don't need alignment code.
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On POWER10 lxvp and lxvl do not generate alignment interrupts, so
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they are safe for use on caching-inhibited memory. Notice that the
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comparison on the main loop will wait for both VSR to be ready.
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Therefore aligning one of the input address does not improve
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performance. In order to align both registers a vperm is necessary
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which add too much overhead.
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2. Uses new POWER10 instructions
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This code uses lxvp to decrease contention on load by loading 32 bytes
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per instruction.
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The vextractbm is used to have a smaller tail code for calculating the
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return value.
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3. Performance improvement
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This version has around 35% better performance on average. I saw no
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performance regressions for any length or alignment.
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Thanks Matheus for helping me out with some details.
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Co-authored-by: Matheus Castanho <msc@linux.ibm.com>
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Reviewed-by: Raphael M Zinsly <rzinsly@linux.ibm.com>
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diff --git a/sysdeps/powerpc/powerpc64/le/power10/memcmp.S b/sysdeps/powerpc/powerpc64/le/power10/memcmp.S
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new file mode 100644
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index 0000000000000000..52f244e7e77cbdf9
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--- /dev/null
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+++ b/sysdeps/powerpc/powerpc64/le/power10/memcmp.S
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@@ -0,0 +1,179 @@
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+/* Optimized memcmp implementation for POWER10.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <sysdep.h>
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+
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+/* TODO: Replace macros by the actual instructions when minimum binutils becomes
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+ >= 2.35. This is used to keep compatibility with older versions. */
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+#define VEXTRACTBM(rt,vrb) \
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+ .long(((4)<<(32-6)) \
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+ | ((rt)<<(32-11)) \
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+ | ((8)<<(32-16)) \
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+ | ((vrb)<<(32-21)) \
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+ | 1602)
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+
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+#define LXVP(xtp,dq,ra) \
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+ .long(((6)<<(32-6)) \
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+ | ((((xtp)-32)>>1)<<(32-10)) \
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+ | ((1)<<(32-11)) \
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+ | ((ra)<<(32-16)) \
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+ | dq)
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+
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+/* Compare 32 bytes. */
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+#define COMPARE_32(vr1,vr2,offset,tail_1,tail_2)\
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+ LXVP(32+vr1,offset,r3); \
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+ LXVP(32+vr2,offset,r4); \
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+ vcmpneb. v5,vr1+1,vr2+1; \
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+ bne cr6,L(tail_2); \
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+ vcmpneb. v4,vr1,vr2; \
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+ bne cr6,L(tail_1); \
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+
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+#define TAIL(v_res,s1,s2) \
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+ vctzlsbb r7,v_res; \
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+ vextubrx r8,r7,s1; \
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+ vextubrx r9,r7,s2; \
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+ subf r3,r9,r8; \
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+ blr; \
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+
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+/* int [r3] memcmp (const char *s1 [r3], const char *s2 [r4],
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+ size_t size [r5]) */
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+
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+#ifndef MEMCMP
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+# define MEMCMP memcmp
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+#endif
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+ .machine power9
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+ENTRY_TOCLESS (MEMCMP, 4)
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+ CALL_MCOUNT 3
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+
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+ cmpldi cr6,r5,64
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+ bgt cr6,L(loop_head)
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+
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+/* Compare 64 bytes. This section is used for lengths <= 64 and for the last
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+ bytes for larger lengths. */
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+L(last_compare):
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+ li r8,16
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+
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+ sldi r9,r5,56
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+ sldi r8,r8,56
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+ addi r6,r3,16
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+ addi r7,r4,16
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+
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+ /* Align up to 16 bytes. */
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+ lxvl 32+v0,r3,r9
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+ lxvl 32+v2,r4,r9
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+
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+ /* The sub. and vcmpneb. results are concatenated by the crnand in order
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+ to do a single branch. It's doing a NOT(CR0.GT AND CR6.EQ) then
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+ loading to CR0.LT. That means r9 is not bigger than 0 and v4 is not
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+ all equal to 0. */
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+ sub. r9,r9,r8
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+ vcmpneb. v4,v0,v2
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+ crnand 4*cr0+lt,4*cr0+gt,4*cr6+eq
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+ bt 4*cr0+lt,L(tail1)
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+
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+ addi r3,r3,32
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+ addi r4,r4,32
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+
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+ lxvl 32+v1,r6,r9
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+ lxvl 32+v3,r7,r9
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+ sub. r9,r9,r8
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+ vcmpneb. v5,v1,v3
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+ crnand 4*cr0+lt,4*cr0+gt,4*cr6+eq
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+ bt 4*cr0+lt,L(tail2)
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+
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+ addi r6,r3,16
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+ addi r7,r4,16
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+
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+ lxvl 32+v6,r3,r9
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+ lxvl 32+v8,r4,r9
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+ sub. r9,r9,r8
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+ vcmpneb. v4,v6,v8
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+ crnand 4*cr0+lt,4*cr0+gt,4*cr6+eq
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+ bt 4*cr0+lt,L(tail3)
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+
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+ lxvl 32+v7,r6,r9
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+ lxvl 32+v9,r7,r9
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+ vcmpneb. v5,v7,v9
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+ bne cr6,L(tail4)
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+
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+L(finish):
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+ /* The contents are equal. */
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+ li r3,0
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+ blr
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+
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+L(loop_head):
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+ /* Calculate how many loops to run. */
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+ srdi. r8,r5,7
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+ beq L(loop_tail)
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+ mtctr r8
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+
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+/* Main loop. Compares 128 bytes each loop. */
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+ .p2align 5
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+L(loop_128):
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+ COMPARE_32(v0,v2,0,tail1,tail2)
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+ COMPARE_32(v6,v8,32,tail3,tail4)
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+ COMPARE_32(v10,v12,64,tail5,tail6)
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+ COMPARE_32(v14,v16,96,tail7,tail8)
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+
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+ addi r3,r3,128
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+ addi r4,r4,128
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+ bdnz L(loop_128)
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+
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+ /* Account loop comparisons. */
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+ clrldi. r5,r5,57
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+ beq L(finish)
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+
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+/* Compares 64 bytes if length is still bigger than 64 bytes. */
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+ .p2align 5
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+L(loop_tail):
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+ cmpldi r5,64
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+ ble L(last_compare)
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+ COMPARE_32(v0,v2,0,tail1,tail2)
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+ COMPARE_32(v6,v8,32,tail3,tail4)
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+ addi r3,r3,64
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+ addi r4,r4,64
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+ subi r5,r5,64
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+ b L(last_compare)
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+
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+L(tail1):
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+ TAIL(v4,v0,v2)
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+
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+L(tail2):
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+ TAIL(v5,v1,v3)
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+
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+L(tail3):
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+ TAIL(v4,v6,v8)
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+
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+L(tail4):
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+ TAIL(v5,v7,v9)
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+
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+L(tail5):
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+ TAIL(v4,v10,v12)
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+
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+L(tail6):
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+ TAIL(v5,v11,v13)
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+
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+L(tail7):
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+ TAIL(v4,v14,v16)
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+
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+L(tail8):
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+ TAIL(v5,v15,v17)
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+
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+END (MEMCMP)
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+libc_hidden_builtin_def (memcmp)
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+weak_alias (memcmp, bcmp)
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diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
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index ac2446aca62cc4ab..ee98417f4a383356 100644
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--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
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+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
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@@ -32,7 +32,7 @@ sysdep_routines += memcpy-power8-cached memcpy-power7 memcpy-a2 memcpy-power6 \
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strncase-power8
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ifneq (,$(filter %le,$(config-machine)))
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-sysdep_routines += memcpy-power10 memmove-power10 memset-power10 \
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+sysdep_routines += memcmp-power10 memcpy-power10 memmove-power10 memset-power10 \
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rawmemchr-power9 rawmemchr-power10 \
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strcmp-power9 strncmp-power9 strcpy-power9 stpcpy-power9 \
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strlen-power9 strncpy-power9 stpncpy-power9 strlen-power10
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diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
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index 127af84b32a8196f..5213abdf87c79c88 100644
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--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
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+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
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@@ -184,6 +184,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
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/* Support sysdeps/powerpc/powerpc64/multiarch/memcmp.c. */
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IFUNC_IMPL (i, name, memcmp,
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+#ifdef __LITTLE_ENDIAN__
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+ IFUNC_IMPL_ADD (array, i, memcmp,
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+ hwcap2 & PPC_FEATURE2_ARCH_3_1
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+ && hwcap & PPC_FEATURE_HAS_VSX,
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+ __memcmp_power10)
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+#endif
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IFUNC_IMPL_ADD (array, i, memcmp, hwcap2 & PPC_FEATURE2_ARCH_2_07,
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__memcmp_power8)
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IFUNC_IMPL_ADD (array, i, memcmp, hwcap & PPC_FEATURE_HAS_VSX,
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diff --git a/sysdeps/powerpc/powerpc64/multiarch/memcmp-power10.S b/sysdeps/powerpc/powerpc64/multiarch/memcmp-power10.S
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new file mode 100644
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6fe9d0 |
index 0000000000000000..73a0debd4a811d8e
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6fe9d0 |
--- /dev/null
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+++ b/sysdeps/powerpc/powerpc64/multiarch/memcmp-power10.S
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@@ -0,0 +1,26 @@
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+/* Optimized memcmp implementation for POWER10.
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+ Copyright (C) 2017-2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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6fe9d0 |
+ The GNU C Library is free software; you can redistribute it and/or
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6fe9d0 |
+ modify it under the terms of the GNU Lesser General Public
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6fe9d0 |
+ License as published by the Free Software Foundation; either
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6fe9d0 |
+ version 2.1 of the License, or (at your option) any later version.
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6fe9d0 |
+
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6fe9d0 |
+ The GNU C Library is distributed in the hope that it will be useful,
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6fe9d0 |
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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6fe9d0 |
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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6fe9d0 |
+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#define MEMCMP __memcmp_power10
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+
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+#undef libc_hidden_builtin_def
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+#define libc_hidden_builtin_def(name)
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+#undef weak_alias
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+#define weak_alias(name,alias)
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+
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+#include <sysdeps/powerpc/powerpc64/le/power10/memcmp.S>
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diff --git a/sysdeps/powerpc/powerpc64/multiarch/memcmp.c b/sysdeps/powerpc/powerpc64/multiarch/memcmp.c
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index 2c7a083a6560f920..0b8c0c1d8aa3f90a 100644
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--- a/sysdeps/powerpc/powerpc64/multiarch/memcmp.c
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+++ b/sysdeps/powerpc/powerpc64/multiarch/memcmp.c
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@@ -27,11 +27,17 @@ extern __typeof (memcmp) __memcmp_ppc attribute_hidden;
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extern __typeof (memcmp) __memcmp_power4 attribute_hidden;
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extern __typeof (memcmp) __memcmp_power7 attribute_hidden;
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extern __typeof (memcmp) __memcmp_power8 attribute_hidden;
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+extern __typeof (memcmp) __memcmp_power10 attribute_hidden;
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# undef memcmp
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/* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
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ifunc symbol properly. */
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libc_ifunc_redirected (__redirect_memcmp, memcmp,
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+#ifdef __LITTLE_ENDIAN__
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+ (hwcap2 & PPC_FEATURE2_ARCH_3_1
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+ && hwcap & PPC_FEATURE_HAS_VSX)
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+ ? __memcmp_power10 :
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+#endif
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(hwcap2 & PPC_FEATURE2_ARCH_2_07)
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? __memcmp_power8 :
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(hwcap & PPC_FEATURE_HAS_VSX)
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