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memcmp: remove unreachable code from memcmp simd

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cppcheck:

src/util-memcmp.h:281:18: warning: Identical condition 'len-offset<16', second condition is always false [identicalConditionAfterEarlyExit]
        if (diff < 16) {
                 ^
src/util-memcmp.h:280:24: note: 'diff' is assigned value 'len-offset' here.
        int diff = len - offset;
                       ^
src/util-memcmp.h:269:33: note: If condition 'len-offset<16' is true, the function will return/exit
        if (likely(len - offset < 16)) {
                                ^
src/util-memcmp.h:281:18: note: Testing identical condition 'len-offset<16'
        if (diff < 16) {
                 ^
src/util-memcmp.h:344:18: warning: Identical condition 'len-offset<16', second condition is always false [identicalConditionAfterEarlyExit]
        if (diff < 16) {
                 ^
src/util-memcmp.h:343:24: note: 'diff' is assigned value 'len-offset' here.
        int diff = len - offset;
                       ^
src/util-memcmp.h:318:33: note: If condition 'len-offset<16' is true, the function will return/exit
        if (likely(len - offset < 16)) {
                                ^
src/util-memcmp.h:344:18: note: Testing identical condition 'len-offset<16'
        if (diff < 16) {
                 ^
src/util-memcmp.h:171:18: warning: Identical condition 'len-offset<16', second condition is always false [identicalConditionAfterEarlyExit]
        if (diff < 16) {
                 ^
src/util-memcmp.h:170:24: note: 'diff' is assigned value 'len-offset' here.
        int diff = len - offset;
                       ^
src/util-memcmp.h:159:33: note: If condition 'len-offset<16' is true, the function will return/exit
        if (likely(len - offset < 16)) {
                                ^
src/util-memcmp.h:171:18: note: Testing identical condition 'len-offset<16'
        if (diff < 16) {
                 ^
src/util-memcmp.h:233:18: warning: Identical condition 'len-offset<16', second condition is always false [identicalConditionAfterEarlyExit]
        if (diff < 16) {
                 ^
src/util-memcmp.h:232:24: note: 'diff' is assigned value 'len-offset' here.
        int diff = len - offset;
                       ^
src/util-memcmp.h:208:33: note: If condition 'len-offset<16' is true, the function will return/exit
        if (likely(len - offset < 16)) {
                                ^
src/util-memcmp.h:233:18: note: Testing identical condition 'len-offset<16'
        if (diff < 16) {
                 ^
pull/7391/head
Victor Julien 2 years ago
parent 9bdf18a3b0
commit ca97ed4436
1 changed files with 10 additions and 46 deletions
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56
src/util-memcmp.h
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@ -1,4 +1,4 @@
/* Copyright (C) 2007-2013 Open Information Security Foundation
/* Copyright (C) 2007-2022 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
@ -20,7 +20,7 @@
*
* \author Victor Julien <victor@inliniac.net>
*
* Memcmp implementations for SSE3, SSE4.1, SSE4.2 and TILE-Gx SIMD.
* Memcmp implementations for SSE3, SSE4.1, SSE4.2.
*
* Both SCMemcmp and SCMemcmpLowercase return 0 on a exact match,
* 1 on a failed match.
@ -167,17 +167,8 @@ static inline int SCMemcmp(const void *s1, const void *s2, size_t len)
b2 = _mm_loadu_si128((const __m128i *) s2);
c = _mm_cmpeq_epi8(b1, b2);
int diff = len - offset;
if (diff < 16) {
int rmask = ~(0xFFFFFFFF << diff);
if ((_mm_movemask_epi8(c) & rmask) != rmask) {
return 1;
}
} else {
if (_mm_movemask_epi8(c) != 0x0000FFFF) {
return 1;
}
if (_mm_movemask_epi8(c) != 0x0000FFFF) {
return 1;
}
offset += SCMEMCMP_BYTES;
@ -229,17 +220,8 @@ static inline int SCMemcmpLowercase(const void *s1, const void *s2, size_t len)
/* now all is lowercase, let's do the actual compare (reuse mask1 reg) */
mask1 = _mm_cmpeq_epi8(b1, b2);
int diff = len - offset;
if (diff < 16) {
int rmask = ~(0xFFFFFFFF << diff);
if ((_mm_movemask_epi8(mask1) & rmask) != rmask) {
return 1;
}
} else {
if (_mm_movemask_epi8(mask1) != 0x0000FFFF) {
return 1;
}
if (_mm_movemask_epi8(mask1) != 0x0000FFFF) {
return 1;
}
offset += SCMEMCMP_BYTES;
@ -277,17 +259,8 @@ static inline int SCMemcmp(const void *s1, const void *s2, size_t len)
b2 = _mm_loadu_si128((const __m128i *) s2);
c = _mm_cmpeq_epi8(b1, b2);
int diff = len - offset;
if (diff < 16) {
int rmask = ~(0xFFFFFFFF << diff);
if ((_mm_movemask_epi8(c) & rmask) != rmask) {
return 1;
}
} else {
if (_mm_movemask_epi8(c) != 0x0000FFFF) {
return 1;
}
if (_mm_movemask_epi8(c) != 0x0000FFFF) {
return 1;
}
offset += SCMEMCMP_BYTES;
@ -340,17 +313,8 @@ static inline int SCMemcmpLowercase(const void *s1, const void *s2, size_t len)
/* now all is lowercase, let's do the actual compare (reuse mask1 reg) */
mask1 = _mm_cmpeq_epi8(b1, b2);
int diff = len - offset;
if (diff < 16) {
int rmask = ~(0xFFFFFFFF << diff);
if ((_mm_movemask_epi8(mask1) & rmask) != rmask) {
return 1;
}
} else {
if (_mm_movemask_epi8(mask1) != 0x0000FFFF) {
return 1;
}
if (_mm_movemask_epi8(mask1) != 0x0000FFFF) {
return 1;
}
offset += SCMEMCMP_BYTES;

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