[FFmpeg-cvslog] simple_idct_template: Fix strict aliasing violation

Michael Niedermayer git at videolan.org
Tue Jun 21 22:13:53 CEST 2016


ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun May  8 21:55:40 2016 +0300| [283226e11ccf50a71d25d150fbbf1743f74c6c49] | committer: Martin Storsjö

simple_idct_template: Fix strict aliasing violation

This fixes fate-wmv8-intrax8 in certain configurations, e.g.
gcc 4.4.

Signed-off-by: Martin Storsjö <martin at martin.st>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=283226e11ccf50a71d25d150fbbf1743f74c6c49
---

 libavcodec/simple_idct_template.c |   18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/libavcodec/simple_idct_template.c b/libavcodec/simple_idct_template.c
index 9a5e38a..171cdf6 100644
--- a/libavcodec/simple_idct_template.c
+++ b/libavcodec/simple_idct_template.c
@@ -91,7 +91,7 @@ static inline void FUNC(idctRowCondDC)(int16_t *row, int extra_shift)
 
 #if HAVE_FAST_64BIT
 #define ROW0_MASK (0xffffLL << 48 * HAVE_BIGENDIAN)
-    if (((((uint64_t *)row)[0] & ~ROW0_MASK) | ((uint64_t *)row)[1]) == 0) {
+    if (((AV_RN64A(row) & ~ROW0_MASK) | AV_RN64A(row+4)) == 0) {
         uint64_t temp;
         if (DC_SHIFT - extra_shift > 0) {
             temp = (row[0] * (1 << (DC_SHIFT - extra_shift))) & 0xffff;
@@ -100,14 +100,14 @@ static inline void FUNC(idctRowCondDC)(int16_t *row, int extra_shift)
         }
         temp += temp * (1 << 16);
         temp += temp * ((uint64_t) 1 << 32);
-        ((uint64_t *)row)[0] = temp;
-        ((uint64_t *)row)[1] = temp;
+        AV_WN64A(row, temp);
+        AV_WN64A(row + 4, temp);
         return;
     }
 #else
-    if (!(((uint32_t*)row)[1] |
-          ((uint32_t*)row)[2] |
-          ((uint32_t*)row)[3] |
+    if (!(AV_RN32A(row+2) |
+          AV_RN32A(row+4) |
+          AV_RN32A(row+6) |
           row[1])) {
         uint32_t temp;
         if (DC_SHIFT - extra_shift > 0) {
@@ -116,8 +116,10 @@ static inline void FUNC(idctRowCondDC)(int16_t *row, int extra_shift)
             temp = (row[0] >> (extra_shift - DC_SHIFT)) & 0xffff;
         }
         temp += temp * (1 << 16);
-        ((uint32_t*)row)[0]=((uint32_t*)row)[1] =
-            ((uint32_t*)row)[2]=((uint32_t*)row)[3] = temp;
+        AV_WN32A(row, temp);
+        AV_WN32A(row+2, temp);
+        AV_WN32A(row+4, temp);
+        AV_WN32A(row+6, temp);
         return;
     }
 #endif



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