--- /dev/null
+/* Optimized memchr implementation for POWER8.
+ Copyright (C) 2017 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>
+
+/* void *[r3] memchr (const void *s [r3], int c [r4], size_t n [r5]) */
+
+/* TODO: change these to the actual instructions when the minimum required
+ binutils allows it. */
+#define MTVRD(v, r) .long (0x7c000167 | ((v)<<(32-11)) | ((r)<<(32-16)))
+#define MFVRD(r, v) .long (0x7c000067 | ((v)<<(32-11)) | ((r)<<(32-16)))
+#define VBPERMQ(t, a, b) .long (0x1000054c \
+ | ((t)<<(32-11)) \
+ | ((a)<<(32-16)) \
+ | ((b)<<(32-21)) )
+
+#ifndef MEMCHR
+# define MEMCHR __memchr
+#endif
+/* TODO: change this to .machine power8 when the minimum required binutils
+ allows it. */
+ .machine power7
+ENTRY_TOCLESS (MEMCHR)
+ CALL_MCOUNT 3
+ dcbt 0, r3
+ clrrdi r8, r3, 3
+ insrdi r4, r4, 8, 48
+
+ /* Calculate the last acceptable address and check for possible
+ addition overflow by using satured math:
+ r7 = r3 + r5
+ r7 |= -(r7 < x) */
+ add r7, r3, r5
+ subfc r6, r3, r7
+ subfe r9, r9, r9
+ extsw r6, r9
+ or r7, r7, r6
+
+ insrdi r4, r4, 16, 32
+ cmpldi r5, 32
+ li r9, -1
+ rlwinm r6, r3, 3, 26, 28 /* Calculate padding. */
+ insrdi r4, r4, 32, 0
+ mr r10, r7
+ addi r7, r7, -1
+#ifdef __LITTLE_ENDIAN__
+ sld r9, r9, r6
+#else
+ srd r9, r9, r6
+#endif
+ ble L(small_range)
+ andi. r11, r3, 63
+ beq cr0, L(align_qw)
+ clrldi r11, r3, 61
+ ld r12, 0(r8) /* Load doubleword from memory. */
+ cmpb r3, r12, r4 /* Check for BYTEs in DWORD1. */
+ and r3, r3, r9
+ clrldi r6, r7, 61 /* Byte count - 1 in last dword. */
+ clrrdi r7, r7, 3 /* Address of last doubleword. */
+ cmpldi cr7, r3, 0 /* Does r3 indicate we got a hit? */
+ bne cr7, L(done)
+ addi r8, r8, 8
+ addi r5, r5, -8
+ add r5, r5, r11
+
+ /* Are we now aligned to a quadword boundary? */
+ andi. r11, r8, 15
+ beq cr0, L(align_qw)
+
+ /* Handle DWORD to make it QW aligned. */
+ ld r12, 0(r8)
+ cmpb r3, r12, r4
+ cmpldi cr7, r3, 0
+ bne cr7, L(done)
+ addi r5, r5, -8
+ addi r8, r8, 8
+ /* At this point, r8 is 16B aligned. */
+L(align_qw):
+ vspltisb v0, 0
+ /* Precompute vbpermq constant. */
+ vspltisb v10, 3
+ li r0, 0
+ lvsl v11, r0, r0
+ vslb v10, v11, v10
+ MTVRD(v1, r4)
+ vspltb v1, v1, 7
+ cmpldi r5, 64
+ ble L(tail64)
+ /* Are we 64-byte aligned? If so, jump to the vectorized loop.
+ Note: aligning to 64-byte will necessarily slow down performance for
+ strings around 64 bytes in length due to the extra comparisons
+ required to check alignment for the vectorized loop. This is a
+ necessary tradeoff we are willing to take in order to speed up the
+ calculation for larger strings. */
+ andi. r11, r8, 63
+ beq cr0, L(preloop_64B)
+ /* In order to begin the 64B loop, it needs to be 64
+ bytes aligned. So read until it is 64B aligned. */
+ lvx v4, 0, r8
+ vcmpequb v6, v1, v4
+ vcmpequb. v11, v0, v6
+ bnl cr6, L(found_16B)
+ addi r8, r8, 16
+ addi r5, r5, -16
+
+ andi. r11, r8, 63
+ beq cr0, L(preloop_64B)
+ lvx v4, 0, r8
+ vcmpequb v6, v1, v4
+ vcmpequb. v11, v0, v6
+ bnl cr6, L(found_16B)
+ addi r8, r8, 16
+ addi r5, r5, -16
+
+ andi. r11, r8, 63
+ beq cr0, L(preloop_64B)
+ lvx v4, 0, r8
+ vcmpequb v6, v1, v4
+ vcmpequb. v11, v0, v6
+ bnl cr6, L(found_16B)
+ addi r8, r8, 16
+ addi r5, r5, -16
+ /* At this point it should be 64B aligned.
+ Prepare for the 64B loop. */
+L(preloop_64B):
+ cmpldi r5, 64 /* Check if r5 < 64. */
+ ble L(tail64)
+ sub r6, r10, r8
+ srdi r9, r6, 6 /* Number of loop iterations. */
+ mtctr r9 /* Setup the counter. */
+ li r11, 16 /* Load required offsets. */
+ li r9, 32
+ li r7, 48
+
+ /* Handle r5 > 64. Loop over the bytes in strides of 64B. */
+ .align 4
+L(loop):
+ lvx v2, 0, r8 /* Load 4 quadwords. */
+ lvx v3, r8, r11
+ lvx v4, v8, r9
+ lvx v5, v8, r7
+ vcmpequb v6, v1, v2
+ vcmpequb v7, v1, v3
+ vcmpequb v8, v1, v4
+ vcmpequb v9, v1, v5
+ vor v11, v6, v7
+ vor v12, v8, v9
+ vor v11, v11, v12 /* Compare and merge into one VR for speed. */
+ vcmpequb. v11, v0, v11
+ bnl cr6, L(found)
+ addi r8, r8, 64 /* Adjust address for the next iteration. */
+ bdnz L(loop)
+ clrldi r5, r6, 58
+
+ /* Handle remainder of 64B loop or r5 > 64. */
+ .align 4
+L(tail64):
+ cmpldi r5, 0
+ beq L(null)
+ lvx v4, 0, r8
+ vcmpequb v6, v1, v4
+ vcmpequb. v11, v0, v6
+ bnl cr6, L(found_16B)
+ addi r8, r8, 16
+ cmpldi cr6, r5, 16
+ ble cr6, L(null)
+ addi r5, r5, -16
+
+ lvx v4, 0, r8
+ vcmpequb v6, v1, v4
+ vcmpequb. v11, v0, v6
+ bnl cr6, L(found_16B)
+ addi r8, r8, 16
+ cmpldi cr6, r5, 16
+ ble cr6, L(null)
+ addi r5, r5, -16
+
+ lvx v4, 0, r8
+ vcmpequb v6, v1, v4
+ vcmpequb. v11, v0, v6
+ bnl cr6, L(found_16B)
+ addi r8, r8, 16
+ cmpldi cr6, r5, 16
+ ble cr6, L(null)
+ addi r5, r5, -16
+
+ lvx v4, 0, r8
+ vcmpequb v6, v1, v4
+ vcmpequb. v11, v0, v6
+ bnl cr6, L(found_16B)
+ li r3, 0
+ blr
+
+ /* Found a match in 64B loop. */
+ .align 4
+L(found):
+ /* Permute the first bit of each byte into bits 48-63. */
+ VBPERMQ(v6, v6, v10)
+ VBPERMQ(v7, v7, v10)
+ VBPERMQ(v8, v8, v10)
+ VBPERMQ(v9, v9, v10)
+ /* Shift each component into its correct position for merging. */
+#ifdef __LITTLE_ENDIAN__
+ vsldoi v7, v7, v7, 2
+ vsldoi v8, v8, v8, 4
+ vsldoi v9, v9, v9, 6
+#else
+ vsldoi v6, v6, v6, 6
+ vsldoi v7, v7, v7, 4
+ vsldoi v8, v8, v8, 2
+#endif
+ /* Merge the results and move to a GPR. */
+ vor v11, v6, v7
+ vor v4, v9, v8
+ vor v4, v11, v4
+ MFVRD(r5, v4)
+#ifdef __LITTLE_ENDIAN__
+ addi r6, r5, -1
+ andc r6, r6, r5
+ popcntd r6, r6
+#else
+ cntlzd r6, r5 /* Count leading zeros before the match. */
+#endif
+ add r3, r8, r6 /* Compute final length. */
+ blr
+
+ /* Found a match in last 16 bytes. */
+ .align 4
+L(found_16B):
+ /* Permute the first bit of each byte into bits 48-63. */
+ VBPERMQ(v6, v6, v10)
+ /* Shift each component into its correct position for merging. */
+#ifdef __LITTLE_ENDIAN__
+ MFVRD(r7, v6)
+ addi r6, r7, -1
+ andc r6, r6, r7
+ popcntd r6, r6
+#else
+ vsldoi v6, v6, v6, 6
+ MFVRD(r7, v6)
+ cntlzd r6, r7 /* Count leading zeros before the match. */
+#endif
+ add r3, r8, r6 /* Compute final length. */
+ cmpld r6, r5
+ bltlr
+ li r3, 0
+ blr
+
+ .align 4
+ /* r3 has the output of the cmpb instruction, that is, it contains
+ 0xff in the same position as BYTE in the original
+ doubleword from the string. Use that to calculate the pointer.
+ We need to make sure BYTE is *before* the end of the range. */
+L(done):
+#ifdef __LITTLE_ENDIAN__
+ addi r0, r3, -1
+ andc r0, r0, r3
+ popcntd r0, r0 /* Count trailing zeros. */
+#else
+ cntlzd r0, r3 /* Count leading zeros before the match. */
+#endif
+ cmpld r8, r7 /* Are we on the last dword? */
+ srdi r0, r0, 3 /* Convert leading/trailing zeros to bytes. */
+ add r3, r8, r0
+ cmpld cr7, r0, r6 /* If on the last dword, check byte offset. */
+ bnelr
+ blelr cr7
+ li r3, 0
+ blr
+
+ .align 4
+L(null):
+ li r3, 0
+ blr
+
+/* Deals with size <= 32. */
+ .align 4
+L(small_range):
+ cmpldi r5, 0
+ beq L(null)
+ ld r12, 0(r8) /* Load word from memory. */
+ cmpb r3, r12, r4 /* Check for BYTE in DWORD1. */
+ and r3, r3, r9
+ cmpldi cr7, r3, 0
+ clrldi r6, r7, 61 /* Byte count - 1 in last dword. */
+ clrrdi r7, r7, 3 /* Address of last doubleword. */
+ cmpld r8, r7 /* Are we done already? */
+ bne cr7, L(done)
+ beqlr
+
+ ldu r12, 8(r8)
+ cmpb r3, r12, r4
+ cmpldi cr6, r3, 0
+ cmpld r8, r7
+ bne cr6, L(done) /* Found something. */
+ beqlr /* Hit end of string (length). */
+
+ ldu r12, 8(r8)
+ cmpb r3, r12, r4
+ cmpldi cr6, r3, 0
+ cmpld r8, r7
+ bne cr6, L(done)
+ beqlr
+
+ ldu r12, 8(r8)
+ cmpb r3, r12, r4
+ cmpldi cr6, r3, 0
+ cmpld r8, r7
+ bne cr6, L(done)
+ beqlr
+
+ ldu r12, 8(r8)
+ cmpb r3, r12, r4
+ cmpldi cr6, r3, 0
+ bne cr6, L(done)
+ blr
+
+END (MEMCHR)
+weak_alias (__memchr, memchr)
+libc_hidden_builtin_def (memchr)
projects / thirdparty / glibc.git / commitdiff
