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Undefined shifts.

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* replaces a left shift with multiplication, because the shiftee can
  be negative.

* replaces a right shift (a >> b) with the expression (b >= 32 ? 0 : a >> b)
  because a is a 32-bit value, and b can be >= 32.

cppreference quote relating to the second change:
"In any case, if the value of the right operand is
negative or is greater or equal to the number of bits in the promoted
left operand, the behavior is undefined."


Bug: chromium:805832 chromium:803078
Change-Id: I67db0c3fedb0af197b2205d424414a84f8fde474
Reviewed-on: https://webrtc-review.googlesource.com/43761
Reviewed-by: Oskar Sundbom <ossu@webrtc.org>
Commit-Queue: Alex Loiko <aleloi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21760}
This commit is contained in:
Alex Loiko
2018-01-25 11:42:43 +01:00
committed by Commit Bot
parent beabdcb498
commit 600bdb4adc
2 changed files with 8 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
modules/audio_processing/aecm/aecm_core.cc
View File

@ -928,8 +928,14 @@ void WebRtcAecm_UpdateChannel(AecmCore* aecm,
{
// We need to shift down before multiplication
shiftChFar = 32 - zerosCh - zerosFar;
// If zerosCh == zerosFar == 0, shiftChFar is 32. A
// right shift of 32 is undefined. To avoid that, we
// do this check.
tmpU32no1 = rtc::dchecked_cast<uint32_t>(
aecm->channelAdapt32[i] >> shiftChFar) * far_spectrum[i];
shiftChFar >= 32
? 0
: aecm->channelAdapt32[i] >> shiftChFar) *
far_spectrum[i];
}
// Determine Q-domain of numerator
zerosNum = WebRtcSpl_NormU32(tmpU32no1);

2
modules/audio_processing/aecm/aecm_core_c.cc
View File

@ -491,7 +491,7 @@ WebRtcAecm_ProcessBlock(AecmCore* aecm,
RTC_DCHECK_GE(zeros16, 0); // |zeros16| is a norm, hence non-negative.
dfa_clean_q_domain_diff = aecm->dfaCleanQDomain - aecm->dfaCleanQDomainOld;
if (zeros16 < dfa_clean_q_domain_diff && aecm->nearFilt[i]) {
tmp16no1 = aecm->nearFilt[i] << zeros16;
tmp16no1 = aecm->nearFilt[i] * (1 << zeros16);
qDomainDiff = zeros16 - dfa_clean_q_domain_diff;
tmp16no2 = ptrDfaClean[i] >> -qDomainDiff;
} else {