Commit Graph

7 Commits

Author SHA1 Message Date
Max Kazantsev e5fa7eb120 [SCEV] Add printout of symbolic max backedge-taken and block exit count
We do compute it and use in optimizations, but never print it out. We need
to do it in order to be able to track improvements in its computation.
2022-11-24 19:29:58 +07:00
Max Kazantsev 211d941188 [SCEV] Rename max backedge-taken count -> constant max backedge taken-count in printout
This is a preparatory step for introducing symbolic max backedge-taken count.
2022-11-24 18:43:42 +07:00
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