glibc/sysdeps/x86_64/memchr.S
Noah Goldstein 645a158978 x86: Fix overflow bug with wmemchr-sse2 and wmemchr-avx2 [BZ ]
This commit fixes the bug mentioned in the previous commit.

The previous implementations of wmemchr in these files relied
on n * sizeof(wchar_t) which was not guranteed by the standard.

The new overflow tests added in the previous commit now
pass (As well as all the other tests).

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2021-06-23 14:13:03 -04:00

374 lines
6.3 KiB
ArmAsm

/* Copyright (C) 2011-2021 Free Software Foundation, Inc.
Contributed by Intel Corporation.
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>
#ifdef USE_AS_WMEMCHR
# define MEMCHR wmemchr
# define PCMPEQ pcmpeqd
# define CHAR_PER_VEC 4
#else
# define MEMCHR memchr
# define PCMPEQ pcmpeqb
# define CHAR_PER_VEC 16
#endif
/* fast SSE2 version with using pmaxub and 64 byte loop */
.text
ENTRY(MEMCHR)
movd %esi, %xmm1
mov %edi, %ecx
#ifdef __ILP32__
/* Clear the upper 32 bits. */
movl %edx, %edx
#endif
#ifdef USE_AS_WMEMCHR
test %RDX_LP, %RDX_LP
jz L(return_null)
#else
punpcklbw %xmm1, %xmm1
test %RDX_LP, %RDX_LP
jz L(return_null)
punpcklbw %xmm1, %xmm1
#endif
and $63, %ecx
pshufd $0, %xmm1, %xmm1
cmp $48, %ecx
ja L(crosscache)
movdqu (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches_1)
sub $CHAR_PER_VEC, %rdx
jbe L(return_null)
add $16, %rdi
and $15, %ecx
and $-16, %rdi
#ifdef USE_AS_WMEMCHR
shr $2, %ecx
#endif
add %rcx, %rdx
sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
jmp L(loop_prolog)
.p2align 4
L(crosscache):
and $15, %ecx
and $-16, %rdi
movdqa (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
/* Check if there is a match. */
pmovmskb %xmm0, %eax
/* Remove the leading bytes. */
sar %cl, %eax
test %eax, %eax
je L(unaligned_no_match)
/* Check which byte is a match. */
bsf %eax, %eax
#ifdef USE_AS_WMEMCHR
mov %eax, %esi
shr $2, %esi
sub %rsi, %rdx
#else
sub %rax, %rdx
#endif
jbe L(return_null)
add %rdi, %rax
add %rcx, %rax
ret
.p2align 4
L(unaligned_no_match):
/* "rcx" is less than 16. Calculate "rdx + rcx - 16" by using
"rdx - (16 - rcx)" instead of "(rdx + rcx) - 16" to void
possible addition overflow. */
neg %rcx
add $16, %rcx
#ifdef USE_AS_WMEMCHR
shr $2, %ecx
#endif
sub %rcx, %rdx
jbe L(return_null)
add $16, %rdi
sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
.p2align 4
L(loop_prolog):
movdqa (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches)
movdqa 16(%rdi), %xmm2
PCMPEQ %xmm1, %xmm2
pmovmskb %xmm2, %eax
test %eax, %eax
jnz L(matches16)
movdqa 32(%rdi), %xmm3
PCMPEQ %xmm1, %xmm3
pmovmskb %xmm3, %eax
test %eax, %eax
jnz L(matches32)
movdqa 48(%rdi), %xmm4
PCMPEQ %xmm1, %xmm4
add $64, %rdi
pmovmskb %xmm4, %eax
test %eax, %eax
jnz L(matches0)
test $0x3f, %rdi
jz L(align64_loop)
sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
movdqa (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches)
movdqa 16(%rdi), %xmm2
PCMPEQ %xmm1, %xmm2
pmovmskb %xmm2, %eax
test %eax, %eax
jnz L(matches16)
movdqa 32(%rdi), %xmm3
PCMPEQ %xmm1, %xmm3
pmovmskb %xmm3, %eax
test %eax, %eax
jnz L(matches32)
movdqa 48(%rdi), %xmm3
PCMPEQ %xmm1, %xmm3
pmovmskb %xmm3, %eax
add $64, %rdi
test %eax, %eax
jnz L(matches0)
mov %rdi, %rcx
and $-64, %rdi
and $63, %ecx
#ifdef USE_AS_WMEMCHR
shr $2, %ecx
#endif
add %rcx, %rdx
.p2align 4
L(align64_loop):
sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
movdqa (%rdi), %xmm0
movdqa 16(%rdi), %xmm2
movdqa 32(%rdi), %xmm3
movdqa 48(%rdi), %xmm4
PCMPEQ %xmm1, %xmm0
PCMPEQ %xmm1, %xmm2
PCMPEQ %xmm1, %xmm3
PCMPEQ %xmm1, %xmm4
pmaxub %xmm0, %xmm3
pmaxub %xmm2, %xmm4
pmaxub %xmm3, %xmm4
pmovmskb %xmm4, %eax
add $64, %rdi
test %eax, %eax
jz L(align64_loop)
sub $64, %rdi
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches)
pmovmskb %xmm2, %eax
test %eax, %eax
jnz L(matches16)
movdqa 32(%rdi), %xmm3
PCMPEQ %xmm1, %xmm3
PCMPEQ 48(%rdi), %xmm1
pmovmskb %xmm3, %eax
test %eax, %eax
jnz L(matches32)
pmovmskb %xmm1, %eax
bsf %eax, %eax
lea 48(%rdi, %rax), %rax
ret
.p2align 4
L(exit_loop):
add $(CHAR_PER_VEC * 2), %edx
jle L(exit_loop_32)
movdqa (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches)
movdqa 16(%rdi), %xmm2
PCMPEQ %xmm1, %xmm2
pmovmskb %xmm2, %eax
test %eax, %eax
jnz L(matches16)
movdqa 32(%rdi), %xmm3
PCMPEQ %xmm1, %xmm3
pmovmskb %xmm3, %eax
test %eax, %eax
jnz L(matches32_1)
sub $CHAR_PER_VEC, %edx
jle L(return_null)
PCMPEQ 48(%rdi), %xmm1
pmovmskb %xmm1, %eax
test %eax, %eax
jnz L(matches48_1)
xor %eax, %eax
ret
.p2align 4
L(exit_loop_32):
add $(CHAR_PER_VEC * 2), %edx
movdqa (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches_1)
sub $CHAR_PER_VEC, %edx
jbe L(return_null)
PCMPEQ 16(%rdi), %xmm1
pmovmskb %xmm1, %eax
test %eax, %eax
jnz L(matches16_1)
xor %eax, %eax
ret
.p2align 4
L(matches0):
bsf %eax, %eax
lea -16(%rax, %rdi), %rax
ret
.p2align 4
L(matches):
bsf %eax, %eax
add %rdi, %rax
ret
.p2align 4
L(matches16):
bsf %eax, %eax
lea 16(%rax, %rdi), %rax
ret
.p2align 4
L(matches32):
bsf %eax, %eax
lea 32(%rax, %rdi), %rax
ret
.p2align 4
L(matches_1):
bsf %eax, %eax
#ifdef USE_AS_WMEMCHR
mov %eax, %esi
shr $2, %esi
sub %rsi, %rdx
#else
sub %rax, %rdx
#endif
jbe L(return_null)
add %rdi, %rax
ret
.p2align 4
L(matches16_1):
bsf %eax, %eax
#ifdef USE_AS_WMEMCHR
mov %eax, %esi
shr $2, %esi
sub %rsi, %rdx
#else
sub %rax, %rdx
#endif
jbe L(return_null)
lea 16(%rdi, %rax), %rax
ret
.p2align 4
L(matches32_1):
bsf %eax, %eax
#ifdef USE_AS_WMEMCHR
mov %eax, %esi
shr $2, %esi
sub %rsi, %rdx
#else
sub %rax, %rdx
#endif
jbe L(return_null)
lea 32(%rdi, %rax), %rax
ret
.p2align 4
L(matches48_1):
bsf %eax, %eax
#ifdef USE_AS_WMEMCHR
mov %eax, %esi
shr $2, %esi
sub %rsi, %rdx
#else
sub %rax, %rdx
#endif
jbe L(return_null)
lea 48(%rdi, %rax), %rax
ret
.p2align 4
L(return_null):
xor %eax, %eax
ret
END(MEMCHR)
#ifndef USE_AS_WMEMCHR
strong_alias (memchr, __memchr)
libc_hidden_builtin_def(memchr)
#endif