This phi simplification transform was added with:
D45448
However as shown in PR43802:
https://bugs.llvm.org/show_bug.cgi?id=43802
...we must be careful not to propagate poison when we do the substitution.
There might be some more complicated analysis possible to retain the overflow flag,
but it should always be safe and easy to drop flags (we have similar behavior in
instcombine and other passes).
Differential Revision: https://reviews.llvm.org/D69442
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
We were previously using a DT in CVP through SimplifyQuery, but not requiring it in
the new pass manager. Hence it would crash if DT was not already available. This now
gets DT directly and plumbs it through to where it is used (instead of using it
through SQ).
llvm-svn: 332836
This is based on an example that was recently posted on llvm-dev:
void *propagate_null(void* b, int* g) {
if (!b) {
return 0;
}
(*g)++;
return b;
}
https://godbolt.org/g/xYk3qG
The original code or constant propagation in other passes has obscured the fact
that the phi can be removed completely.
Differential Revision: https://reviews.llvm.org/D45448
llvm-svn: 329755
Sanjay Patel