PR45481:
https://bugs.llvm.org/show_bug.cgi?id=45481
SDAG has an identical transform to this, so there's little
chance of any real-world impact. OTOH, that means we are
effectively sweeping the bug out of sight because poison
exists in codegen too.
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
This is a follow-up to rL343482 / D52439.
This was a pattern that initially caused the commit to be reverted because
the transform requires a bitcast as shown here.
llvm-svn: 343794
These are candidates for the same fold that was implemented in
D52439, but FP types require bitcasting (and that changes the
extra uses profitability calculation).
llvm-svn: 343587
This was originally committed at rL343407, but reverted at
rL343458 because it crashed trying to handle a case where
the destination type is FP. This version of the patch adds
a check for that possibility. Tests added at rL343480.
Original commit message:
This transform is requested for the backend in:
https://bugs.llvm.org/show_bug.cgi?id=39016
...but I figured it was worth doing in IR too, and it's probably
easier to implement here, so that's this patch.
In the simplest case, we are just truncating a scalar value. If the
extract index doesn't correspond to the LSBs of the scalar, then we
have to shift-right before the truncate. Endian-ness makes this tricky,
but hopefully the ASCII-art helps visualize the transform.
Differential Revision: https://reviews.llvm.org/D52439
llvm-svn: 343482
The first attempt at this transform:
rL343407
...was reverted:
rL343458
...because it did not handle the case where we bitcast to FP.
The patch was already limited to avoid the case where we
bitcast from FP, but we might want to transform that too.
llvm-svn: 343480
This caused Chromium builds to fail with "Illegal Trunc" assertion.
See https://crbug.com/890723 for repro.
> This transform is requested for the backend in:
> https://bugs.llvm.org/show_bug.cgi?id=39016
> ...but I figured it was worth doing in IR too, and it's probably
> easier to implement here, so that's this patch.
>
> In the simplest case, we are just truncating a scalar value. If the
> extract index doesn't correspond to the LSBs of the scalar, then we
> have to shift-right before the truncate. Endian-ness makes this tricky,
> but hopefully the ASCII-art helps visualize the transform.
>
> Differential Revision: https://reviews.llvm.org/D52439
llvm-svn: 343458
This transform is requested for the backend in:
https://bugs.llvm.org/show_bug.cgi?id=39016
...but I figured it was worth doing in IR too, and it's probably
easier to implement here, so that's this patch.
In the simplest case, we are just truncating a scalar value. If the
extract index doesn't correspond to the LSBs of the scalar, then we
have to shift-right before the truncate. Endian-ness makes this tricky,
but hopefully the ASCII-art helps visualize the transform.
Differential Revision: https://reviews.llvm.org/D52439
llvm-svn: 343407
In one case, we were handling out of bounds, but not undef indices. In the other, we were handling undef (with the comment making the analogy to out of bounds), but not out of bounds. Be consistent and treat both undef and constant out of bounds indices as producing undefined results.
As a side effect, this also protects instcombine from having to handle large constant indices as we always simplify first.
llvm-svn: 321575
Went to reduce another fuzzer failure to find it's already been fixed, but the test case is slightly different so it's worth adding anyways.
Reduced from oss-fuzz #4768 test case
llvm-svn: 321573
Sanjay Patel