[PATCH] D135541: [TargetLowering][RISCV][X86] Support even divisors in expandDIVREMByConstant.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D135541#3880648 <https://reviews.llvm.org/D135541#3880648>, @mstorsjo wrote:

> In D135541#3879320 <https://reviews.llvm.org/D135541#3879320>, @mstorsjo wrote:
>
>> Thanks for the revert!
>>
>> I didn’t have time to narrow it down further yet, but it can be reproduced with these steps:
>>
>>   git clone git://source.ffmpeg.org/ffmpeg
>>   cd ffmpeg
>>   ./configure --cc=“clang -target …” --samples=$(pwd)/../samples
>>   make -j$(nproc)
>>   make fate-rsync
>>   make fate-sub-lrc-remux
>>
>> I don’t know yet which object files contain the breakage here.
>
> For this particular testcase, the changed behaviour is in `libavformat/lrcenc.o`.
>
> The changed behaviour can be seen in https://martin.st/temp/lrcenc-preproc.c, compiled with `clang -target i686-w64-mingw32 -c lrcenc-preproc.c -O2`. (I haven't traced the code to see exactly what inputs makes what difference in behaviour though.)

Thanks. I found one bug in how the remainder was calculated. I inadvertently copied the LSBs from after a shift instead of from before it. I recommited that earlier today. Hopefully it hasn't caused any additional failures?


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