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Reland mysterious cast that improves performance.

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BUG=499241
TEST=none
TBR=andrew

Review URL: https://codereview.webrtc.org/1206683002

Cr-Commit-Position: refs/heads/master@{#9492}
This commit is contained in:
Peter Kasting 2015-06-23 15:04:23 -07:00
parent 6bfc82aaf1
commit 084f3871b1
1 changed files with 4 additions and 2 deletions
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6
webrtc/common_audio/signal_processing/cross_correlation.c
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@ -22,9 +22,11 @@ void WebRtcSpl_CrossCorrelationC(int32_t* cross_correlation,
for (i = 0; i < dim_cross_correlation; i++) {
int32_t corr = 0;
/* Unrolling doesn't seem to improve performance. */
// Linux 64-bit performance is improved by the int16_t cast below.
// Presumably this is some sort of compiler bug, as there's no obvious
// reason why that should result in better code.
for (j = 0; j < dim_seq; j++)
corr += (seq1[j] * seq2[j]) >> right_shifts;
corr += (seq1[j] * seq2[j]) >> (int16_t)right_shifts;
seq2 += step_seq2;
*cross_correlation++ = corr;
}