Commit Graph

5 Commits

Author SHA1 Message Date
Roman Lebedev 49d9acc242
[SCEV] Recognize logical `or` as `not umin_seq (not, not)`
By definition, `umin_seq` has the exact same
poison stopping properties the original `select` had:
https://alive2.llvm.org/ce/z/MUfbTL
2022-02-10 17:42:55 +03:00
Roman Lebedev 16bc24e7be
[SCEV] Recognize logical `and` as `umin_seq`
By definition, `umin_seq` has the exact same
poison stopping properties the original `select` had:
https://alive2.llvm.org/ce/z/59KuZZ
2022-02-10 17:42:55 +03:00
Roman Lebedev 6a563e2570
[NFC][SCEV][IndVars] Add more tests for exit count w/ `select`
See https://github.com/llvm/llvm-project/issues/53020
2022-01-07 01:30:21 +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
Juneyoung Lee 509fa8e02e [SCEV] recognize logical and/or pattern
This patch makes SCEV recognize 'select A, B, false' and 'select A, true, B'.
This is a performance improvement that will be helpful after unsound select -> and/or transformation is removed, as discussed in D93065.

SCEV's answers for the select form should be a bit more conservative than the equivalent `and A, B` / `or A, B`.
Take this example: https://alive2.llvm.org/ce/z/NsP9ue .
To check whether it is valid for SCEV's computeExitLimit to return min(n, m) as ExactNotTaken value, I put llvm.assume at tgt.
It fails because the exit limit becomes poison if n is zero and m is poison. This is problematic if e.g. the exit value of i is replaced with min(n, m).
If either n or m is constant, we can revive the analysis again. I added relevant tests and put alive2 links there.

If and is used instead, this is okay: https://alive2.llvm.org/ce/z/K9rbJk . Hence the existing analysis is sound.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D93882
2021-01-01 04:37:57 +09:00