Commit Graph

5 Commits

Author SHA1 Message Date
Roman Lebedev 503541fa93
[SCEV] Recognize binary `and` as bit-wise `umin`
https://alive2.llvm.org/ce/z/aKAr94

We could transparently handle wider bitwidths,
by effectively casting iN to <N x i1> and performing the `umin`
bit/element -wise, the expression will be rather large,
so let's not do that for now.
2022-02-10 17:42:54 +03:00
Roman Lebedev e7e0834f07
[SCEV] Recognize binary `or` as bit-wise `umax`
https://alive2.llvm.org/ce/z/SMEaoc

We could transparently handle wider bitwidths,
by effectively casting iN to <N x i1> and performing the `umax`
bit/element -wise, the expression will be rather large,
so let's not do that for now.
2022-02-10 17:42:54 +03:00
Arthur Eubanks 50153213c8 [test][NewPM] Remove RUN lines using -analyze
Only tests in llvm/test/Analysis.

-analyze is legacy PM-specific.

This only touches files with `-passes`.

I looked through everything and made sure that everything had a new PM equivalent.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D109040
2021-09-02 11:38:14 -07:00
Max Kazantsev 48d7cc6ae2 [SCEV] Fix incorrect treatment of max taken count. PR48225
SCEV makes a logical mistake when handling EitherMayExit in
case when both conditions must be met to exit the loop. The
mistake looks like follows: "if condition `A` fails within at most `X` first
iterations, and `B` fails within at most `Y` first iterations, then `A & B`
fails at most within `min (X, Y)` first iterations". This is wrong, because
both of them must fail at the same time.

Simple example illustrating this is following: we have an IV with step 1,
condition `A` = "IV is even", condition `B` = "IV is odd". Both `A` and `B`
will fail within first two iterations. But it doesn't mean that both of them
will fail within first two first iterations at the same time, which would mean
that IV is neither even nor odd at the same time within first 2 iterations.

We can only do so for known exact BE counts, but not for max.

Differential Revision: https://reviews.llvm.org/D91942
Reviewed By: nikic
2020-11-23 16:52:39 +07:00
Max Kazantsev 0c101c9cbc [Test] Add tests demonstrating a bug in SCEV, PR48225
Slightly simplified version of original test reported by Congzhe Cao.
2020-11-20 15:59:22 +07:00