commit ee67ca3fd8acbee79709b7ae2ec2de1af2cf577f
author Alex Loiko <aleloi@webrtc.org> Fri Jan 12 13:48:06 2018 +0100
committer Commit Bot <commit-bot@chromium.org> Fri Jan 12 15:29:59 2018 +0000
tree e768902301d8bfb203fd640ee2ca81b83bf3af71
parent d84b3d1f3d8ad6b1e1f2667e2d2d48cf5ca59227

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 <kwiberg@webrtc.org>
Commit-Queue: Alex Loiko <aleloi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21605}

common_audio/signal_processing/complex_fft.c

diff --git a/common_audio/signal_processing/complex_fft.c b/common_audio/signal_processing/complex_fft.c
index d4666f3..36689b3 100644
--- a/common_audio/signal_processing/complex_fft.c
+++ b/common_audio/signal_processing/complex_fft.c
@@ -134,8 +134,8 @@
                     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 @@
                     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));

modules/audio_processing/aecm/aecm_core_c.cc

diff --git a/modules/audio_processing/aecm/aecm_core_c.cc b/modules/audio_processing/aecm/aecm_core_c.cc
index 7fd6a49..fa5f15c 100644
--- a/modules/audio_processing/aecm/aecm_core_c.cc
+++ b/modules/audio_processing/aecm/aecm_core_c.cc
@@ -74,9 +74,9 @@
   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);
   }