[FFmpeg-devel] [PATCH] aacenc_utils: Use temporary variable.

[Reimar Döffinger]

This ensures gcc does not create unnecessary
loads or stores and possibly even does not vectorize
the negation.
Speeds up mp3 to aac transcoding with default settings
by 10% when using "gcc (Debian 5.3.1-10) 5.3.1 20160224".

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
---
 libavcodec/aacenc_utils.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libavcodec/aacenc_utils.h b/libavcodec/aacenc_utils.h
index b9bd6bf..41a6296 100644
--- a/libavcodec/aacenc_utils.h
+++ b/libavcodec/aacenc_utils.h
@@ -68,10 +68,11 @@ static inline void quantize_bands(int *out, const float *in, const float *scaled
     int i;
     for (i = 0; i < size; i++) {
         float qc = scaled[i] * Q34;
-        out[i] = (int)FFMIN(qc + rounding, (float)maxval);
+        int tmp = (int)FFMIN(qc + rounding, (float)maxval);
         if (is_signed && in[i] < 0.0f) {
-            out[i] = -out[i];
+            tmp = -tmp;
         }
+        out[i] = tmp;
     }
 }
 
-- 
2.7.0