Replace left shift with equivalent multiplication.

We have done changes to the Audio Processing fuzzer here https://webrtc-review.googlesource.com/c/src/+/36500/6. We ran the new version of the fuzzer locally. The UBSAN detector found these (minor) issues. We have used the Godbolt compiler explorer to check that similar changes produce identical compiled code. Bug: webrtc:7820 Change-Id: I9cc3b81e4be7cf691f878c37010ce105bc2f3e38 Reviewed-on: https://webrtc-review.googlesource.com/39264 Reviewed-by: Karl Wiberg <[email protected]> Commit-Queue: Alex Loiko <[email protected]> Cr-Commit-Position: refs/heads/master@{#21605}
czs100 · Jan 12, 2018 · ee67ca3 · ee67ca3
1 parent d84b3d1
commit ee67ca3
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Showing 2 changed files with 6 additions and 6 deletions.
diff --git a/common_audio/signal_processing/complex_fft.c b/common_audio/signal_processing/complex_fft.c
@@ -134,8 +134,8 @@ int WebRtcSpl_ComplexFFT(int16_t frfi[], int stages, int mode)
                     tr32 >>= 15 - CFFTSFT;
                     ti32 >>= 15 - CFFTSFT;
 
-                    qr32 = ((int32_t)frfi[2 * i]) << CFFTSFT;
-                    qi32 = ((int32_t)frfi[2 * i + 1]) << CFFTSFT;
+                    qr32 = ((int32_t)frfi[2 * i]) * (1 << CFFTSFT);
+                    qi32 = ((int32_t)frfi[2 * i + 1]) * (1 << CFFTSFT);
 
                     frfi[2 * j] = (int16_t)(
                         (qr32 - tr32 + CFFTRND2) >> (1 + CFFTSFT));
@@ -276,8 +276,8 @@ int WebRtcSpl_ComplexIFFT(int16_t frfi[], int stages, int mode)
                     tr32 >>= 15 - CIFFTSFT;
                     ti32 >>= 15 - CIFFTSFT;
 
-                    qr32 = ((int32_t)frfi[2 * i]) << CIFFTSFT;
-                    qi32 = ((int32_t)frfi[2 * i + 1]) << CIFFTSFT;
+                    qr32 = ((int32_t)frfi[2 * i]) * (1 << CIFFTSFT);
+                    qi32 = ((int32_t)frfi[2 * i + 1]) * (1 << CIFFTSFT);
 
                     frfi[2 * j] = (int16_t)(
                         (qr32 - tr32 + round2) >> (shift + CIFFTSFT));

diff --git a/modules/audio_processing/aecm/aecm_core_c.cc b/modules/audio_processing/aecm/aecm_core_c.cc
@@ -74,9 +74,9 @@ static void WindowAndFFT(AecmCore* aecm,
   for (i = 0; i < PART_LEN; i++) {
     // Window time domain signal and insert into real part of
     // transformation array |fft|
-    int16_t scaled_time_signal = time_signal[i] << time_signal_scaling;
+    int16_t scaled_time_signal = time_signal[i] * (1 << time_signal_scaling);
     fft[i] = (int16_t)((scaled_time_signal * WebRtcAecm_kSqrtHanning[i]) >> 14);
-    scaled_time_signal = time_signal[i + PART_LEN] << time_signal_scaling;
+    scaled_time_signal = time_signal[i + PART_LEN] * (1 << time_signal_scaling);
     fft[PART_LEN + i] = (int16_t)((
         scaled_time_signal * WebRtcAecm_kSqrtHanning[PART_LEN - i]) >> 14);
   }