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webp: WEBP_OFFSET_PTR()

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Removes undefined behavior of offsetting NULL.

Change-Id: I7c83d0c913c631c091a5fb128f6d6b46b1d116db
This commit is contained in:
Yannis Guyon 2020-03-20 11:39:06 +01:00
parent 687ab00e6e
commit 47309ef52d
2 changed files with 22 additions and 14 deletions
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6
src/dsp/dsp.h
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@ -193,6 +193,12 @@ extern "C" {
#endif
#endif
// If 'ptr' is NULL, returns NULL. Otherwise returns 'ptr + off'.
// Prevents undefined behavior sanitizer nullptr-with-nonzero-offset warning.
#if !defined(WEBP_OFFSET_PTR)
#define WEBP_OFFSET_PTR(ptr, off) (((ptr) == NULL) ? NULL : ((ptr) + (off)))
#endif
// Regularize the definition of WEBP_SWAP_16BIT_CSP (backward compatibility)
#if !defined(WEBP_SWAP_16BIT_CSP)
#define WEBP_SWAP_16BIT_CSP 0

30
src/dsp/lossless_enc_sse2.c
View File

@ -460,20 +460,22 @@ static void PredictorSub0_SSE2(const uint32_t* in, const uint32_t* upper,
(void)upper;
}
#define GENERATE_PREDICTOR_1(X, IN) \
static void PredictorSub##X##_SSE2(const uint32_t* in, const uint32_t* upper, \
int num_pixels, uint32_t* out) { \
int i; \
for (i = 0; i + 4 <= num_pixels; i += 4) { \
const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]); \
const __m128i pred = _mm_loadu_si128((const __m128i*)&(IN)); \
const __m128i res = _mm_sub_epi8(src, pred); \
_mm_storeu_si128((__m128i*)&out[i], res); \
} \
if (i != num_pixels) { \
VP8LPredictorsSub_C[(X)](in + i, upper + i, num_pixels - i, out + i); \
} \
}
#define GENERATE_PREDICTOR_1(X, IN) \
static void PredictorSub##X##_SSE2(const uint32_t* const in, \
const uint32_t* const upper, \
int num_pixels, uint32_t* const out) { \
int i; \
for (i = 0; i + 4 <= num_pixels; i += 4) { \
const __m128i src = _mm_loadu_si128((const __m128i*)&in[i]); \
const __m128i pred = _mm_loadu_si128((const __m128i*)&(IN)); \
const __m128i res = _mm_sub_epi8(src, pred); \
_mm_storeu_si128((__m128i*)&out[i], res); \
} \
if (i != num_pixels) { \
VP8LPredictorsSub_C[(X)](in + i, WEBP_OFFSET_PTR(upper, i), \
num_pixels - i, out + i); \
} \
}
GENERATE_PREDICTOR_1(1, in[i - 1]) // Predictor1: L
GENERATE_PREDICTOR_1(2, upper[i]) // Predictor2: T