1 /* Optimized strcmp implementation for PowerPC64/POWER9.
2 Copyright (C) 2016-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18 #ifdef __LITTLE_ENDIAN__
21 /* Implements the function
23 int [r3] strcmp (const char *s1 [r3], const char *s2 [r4])
25 The implementation uses unaligned doubleword access for first 32 bytes
26 as in POWER8 patch and uses vectorised loops after that. */
28 /* TODO: Change this to actual instructions when minimum binutils is upgraded
29 to 2.27. Macros are defined below for these newer instructions in order
30 to maintain compatibility. */
31 # define VCTZLSBB(r,v) .long (0x10010602 | ((r)<<(32-11)) | ((v)<<(32-21)))
33 # define VEXTUBRX(t,a,b) .long (0x1000070d \
38 # define VCMPNEZB(t,a,b) .long (0x10000507 \
43 /* Get 16 bytes for unaligned case.
44 reg1: Vector to hold next 16 bytes.
45 reg2: Address to read from.
46 reg3: Permute control vector. */
47 # define GET16BYTES(reg1, reg2, reg3) \
49 vperm v8, v2, reg1, reg3; \
50 vcmpequb. v8, v0, v8; \
59 vperm reg1, v9, reg1, reg3;
61 /* TODO: change this to .machine power9 when the minimum required binutils
68 /* Check if [s1]+16 or [s2]+16 will cross a 4K page boundary using
71 (((size_t) s1) % PAGE_SIZE > (PAGE_SIZE - ITER_SIZE))
73 with PAGE_SIZE being 4096 and ITER_SIZE begin 16. */
77 cmpldi cr7, r7, 4096-16
78 bgt cr7, L(pagecross_check)
79 cmpldi cr5, r9, 4096-16
80 bgt cr5, L(pagecross_check)
82 /* For short strings up to 16 bytes, load both s1 and s2 using
83 unaligned dwords and compare. */
89 bne cr0, L(different_nocmpb)
96 bne cr0, L(different_nocmpb)
102 /* Now it has checked for first 16 bytes. */
105 lvsr v6, 0, r4 /* Compute mask. */
111 lvsr v10, 0, r7 /* Compute mask. */
113 /* Both s1 and s2 are unaligned. */
114 GET16BYTES(v4, r7, v10)
115 GET16BYTES(v5, r4, v6)
120 /* Align s1 to qw and adjust s2 address. */
130 /* There are 2 loops depending on the input alignment.
131 Each loop gets 16 bytes from s1 and s2 and compares.
132 Loop until a mismatch or null occurs. */
135 GET16BYTES(v5, r4, v6)
139 bne cr6, L(different)
142 GET16BYTES(v5, r4, v6)
146 bne cr6, L(different)
149 GET16BYTES(v5, r4, v6)
153 bne cr6, L(different)
156 GET16BYTES(v5, r4, v6)
170 bne cr6, L(different)
177 bne cr6, L(different)
184 bne cr6, L(different)
193 /* Calculate and return the difference. */
210 rldicl r10, r10, 0, 56
221 bge cr7, L(pagecross)
224 /* If unaligned 16 bytes reads across a 4K page boundary, it uses
225 a simple byte a byte comparison until the page alignment for s1
234 /* Loads a byte from s1 and s2, compare if *s1 is equal to *s2
235 and if *s1 is '\0'. */
242 bne cr7, L(pagecross_ne)
243 beq cr5, L(pagecross_nullfound)
244 bdnz L(pagecross_loop)
251 L(pagecross_retdiff):
257 L(pagecross_nullfound):
259 b L(pagecross_retdiff)
261 libc_hidden_builtin_def (strcmp)
263 #include <sysdeps/powerpc/powerpc64/power8/strcmp.S>