--- /dev/null
+/* Optimized memchr implementation for POWER10 LE.
+ Copyright (C) 2021-2023 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+# ifndef MEMCHR
+# define MEMCHR __memchr
+# endif
+# define M_VREG_ZERO v20
+# define M_OFF_START_LOOP 256
+# define MEMCHR_SUBTRACT_VECTORS \
+ vsububm v4,v4,v18; \
+ vsububm v5,v5,v18; \
+ vsububm v6,v6,v18; \
+ vsububm v7,v7,v18;
+# define M_TAIL(vreg,increment) \
+ vctzlsbb r4,vreg; \
+ cmpld r5,r4; \
+ ble L(null); \
+ addi r4,r4,increment; \
+ add r3,r6,r4; \
+ blr
+
+/* TODO: Replace macros by the actual instructions when minimum binutils becomes
+ >= 2.35. This is used to keep compatibility with older versions. */
+#define M_VEXTRACTBM(rt,vrb) \
+ .long(((4)<<(32-6)) \
+ | ((rt)<<(32-11)) \
+ | ((8)<<(32-16)) \
+ | ((vrb)<<(32-21)) \
+ | 1602)
+
+#define M_LXVP(xtp,dq,ra) \
+ .long(((6)<<(32-6)) \
+ | ((((xtp)-32)>>1)<<(32-10)) \
+ | ((1)<<(32-11)) \
+ | ((ra)<<(32-16)) \
+ | dq)
+
+#define CHECK16B(vreg,offset,addr,label) \
+ lxv vreg+32,offset(addr); \
+ vcmpequb. vreg,vreg,v18; \
+ bne cr6,L(label); \
+ cmpldi r5,16; \
+ ble L(null); \
+ addi r5,r5,-16;
+
+/* Load 4 quadwords, merge into one VR for speed and check for NULLs. r6 has #
+ of bytes already checked. */
+#define CHECK64B(offset,addr,label) \
+ M_LXVP(v4+32,offset,addr); \
+ M_LXVP(v6+32,offset+32,addr); \
+ MEMCHR_SUBTRACT_VECTORS; \
+ vminub v14,v4,v5; \
+ vminub v15,v6,v7; \
+ vminub v16,v14,v15; \
+ vcmpequb. v0,v16,M_VREG_ZERO; \
+ beq cr6,$+12; \
+ li r7,offset; \
+ b L(label); \
+ cmpldi r5,64; \
+ ble L(null); \
+ addi r5,r5,-64
+
+/* Implements the function
+ void *[r3] memchr (const void *s [r3], int c [r4], size_t n [r5]). */
+
+ .machine power9
+
+ENTRY_TOCLESS (MEMCHR)
+ CALL_MCOUNT 3
+
+ cmpldi r5,0
+ beq L(null)
+ mr r0,r5
+ xori r6,r4,0xff
+
+ mtvsrd v18+32,r4 /* matching char in v18 */
+ mtvsrd v19+32,r6 /* non matching char in v19 */
+
+ vspltb v18,v18,7 /* replicate */
+ vspltb v19,v19,7 /* replicate */
+ vspltisb M_VREG_ZERO,0
+
+ /* Next 16B-aligned address. Prepare address for L(aligned). */
+ addi r6,r3,16
+ clrrdi r6,r6,4
+
+ /* Align data and fill bytes not loaded with non matching char. */
+ lvx v0,0,r3
+ lvsr v1,0,r3
+ vperm v0,v19,v0,v1
+
+ vcmpequb. v6,v0,v18
+ bne cr6,L(found)
+ sub r4,r6,r3
+ cmpld r5,r4
+ ble L(null)
+ sub r5,r5,r4
+
+ /* Test up to OFF_START_LOOP-16 bytes in 16B chunks. The main loop is
+ optimized for longer strings, so checking the first bytes in 16B
+ chunks benefits a lot small strings. */
+ .p2align 5
+L(aligned):
+ cmpldi r5,0
+ beq L(null)
+
+ CHECK16B(v0,0,r6,tail1)
+ CHECK16B(v1,16,r6,tail2)
+ CHECK16B(v2,32,r6,tail3)
+ CHECK16B(v3,48,r6,tail4)
+ CHECK16B(v4,64,r6,tail5)
+ CHECK16B(v5,80,r6,tail6)
+ CHECK16B(v6,96,r6,tail7)
+ CHECK16B(v7,112,r6,tail8)
+ CHECK16B(v8,128,r6,tail9)
+ CHECK16B(v9,144,r6,tail10)
+ CHECK16B(v10,160,r6,tail11)
+ CHECK16B(v0,176,r6,tail12)
+ CHECK16B(v1,192,r6,tail13)
+ CHECK16B(v2,208,r6,tail14)
+ CHECK16B(v3,224,r6,tail15)
+
+ cmpdi cr5,r4,0 /* Check if c == 0. This will be useful to
+ choose how we will perform the main loop. */
+
+ /* Prepare address for the loop. */
+ addi r4,r3,M_OFF_START_LOOP
+ clrrdi r4,r4,6
+ sub r6,r4,r3
+ sub r5,r0,r6
+ addi r6,r4,128
+
+ /* If c == 0, use the loop without the vsububm. */
+ beq cr5,L(loop)
+
+ /* This is very similar to the block after L(loop), the difference is
+ that here MEMCHR_SUBTRACT_VECTORS is not empty, and we subtract
+ each byte loaded by the char we are looking for, this way we can keep
+ using vminub to merge the results and checking for nulls. */
+ .p2align 5
+L(memchr_loop):
+ CHECK64B(0,r4,pre_tail_64b)
+ CHECK64B(64,r4,pre_tail_64b)
+ addi r4,r4,256
+
+ CHECK64B(0,r6,tail_64b)
+ CHECK64B(64,r6,tail_64b)
+ addi r6,r6,256
+
+ CHECK64B(0,r4,pre_tail_64b)
+ CHECK64B(64,r4,pre_tail_64b)
+ addi r4,r4,256
+
+ CHECK64B(0,r6,tail_64b)
+ CHECK64B(64,r6,tail_64b)
+ addi r6,r6,256
+
+ b L(memchr_loop)
+ /* Switch to a more aggressive approach checking 64B each time. Use 2
+ pointers 128B apart and unroll the loop once to make the pointer
+ updates and usages separated enough to avoid stalls waiting for
+ address calculation. */
+ .p2align 5
+L(loop):
+#undef MEMCHR_SUBTRACT_VECTORS
+#define MEMCHR_SUBTRACT_VECTORS /* nothing */
+ CHECK64B(0,r4,pre_tail_64b)
+ CHECK64B(64,r4,pre_tail_64b)
+ addi r4,r4,256
+
+ CHECK64B(0,r6,tail_64b)
+ CHECK64B(64,r6,tail_64b)
+ addi r6,r6,256
+
+ CHECK64B(0,r4,pre_tail_64b)
+ CHECK64B(64,r4,pre_tail_64b)
+ addi r4,r4,256
+
+ CHECK64B(0,r6,tail_64b)
+ CHECK64B(64,r6,tail_64b)
+ addi r6,r6,256
+
+ b L(loop)
+
+ .p2align 5
+L(pre_tail_64b):
+ mr r6,r4
+L(tail_64b):
+ /* OK, we found a null byte. Let's look for it in the current 64-byte
+ block and mark it in its corresponding VR. lxvp vx,0(ry) puts the
+ low 16B bytes into vx+1, and the high into vx, so the order here is
+ v5, v4, v7, v6. */
+ vcmpequb v1,v5,M_VREG_ZERO
+ vcmpequb v2,v4,M_VREG_ZERO
+ vcmpequb v3,v7,M_VREG_ZERO
+ vcmpequb v4,v6,M_VREG_ZERO
+
+ /* Take into account the other 64B blocks we had already checked. */
+ add r6,r6,r7
+ /* Extract first bit of each byte. */
+ M_VEXTRACTBM(r8,v1)
+ M_VEXTRACTBM(r9,v2)
+ M_VEXTRACTBM(r10,v3)
+ M_VEXTRACTBM(r11,v4)
+
+ /* Shift each value into their corresponding position. */
+ sldi r9,r9,16
+ sldi r10,r10,32
+ sldi r11,r11,48
+
+ /* Merge the results. */
+ or r8,r8,r9
+ or r9,r10,r11
+ or r11,r9,r8
+
+ cnttzd r0,r11 /* Count trailing zeros before the match. */
+ cmpld r5,r0
+ ble L(null)
+ add r3,r6,r0 /* Compute final address. */
+ blr
+
+ .p2align 5
+L(tail1):
+ M_TAIL(v0,0)
+
+ .p2align 5
+L(tail2):
+ M_TAIL(v1,16)
+
+ .p2align 5
+L(tail3):
+ M_TAIL(v2,32)
+
+ .p2align 5
+L(tail4):
+ M_TAIL(v3,48)
+
+ .p2align 5
+L(tail5):
+ M_TAIL(v4,64)
+
+ .p2align 5
+L(tail6):
+ M_TAIL(v5,80)
+
+ .p2align 5
+L(tail7):
+ M_TAIL(v6,96)
+
+ .p2align 5
+L(tail8):
+ M_TAIL(v7,112)
+
+ .p2align 5
+L(tail9):
+ M_TAIL(v8,128)
+
+ .p2align 5
+L(tail10):
+ M_TAIL(v9,144)
+
+ .p2align 5
+L(tail11):
+ M_TAIL(v10,160)
+
+ .p2align 5
+L(tail12):
+ M_TAIL(v0,176)
+
+ .p2align 5
+L(tail13):
+ M_TAIL(v1,192)
+
+ .p2align 5
+L(tail14):
+ M_TAIL(v2,208)
+
+ .p2align 5
+L(tail15):
+ M_TAIL(v3,224)
+
+ .p2align 5
+L(found):
+ vctzlsbb r7,v6
+ cmpld r5,r7
+ ble L(null)
+ add r3,r3,r7
+ blr
+
+ .p2align 5
+L(null):
+ li r3,0
+ blr
+
+END (MEMCHR)
+
+weak_alias (__memchr, memchr)
+libc_hidden_builtin_def (memchr)
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