Remove `br i1 undef` from some regression tests [NFC] (#115130)

As defined in LangRef, branching on `undef` is undefined behavior.
This PR aims to remove undefined behavior from tests. As UB tests

Remove `br i1 undef` from some regression tests [NFC] (#115130)

As defined in LangRef, branching on `undef` is undefined behavior.
This PR aims to remove undefined behavior from tests. As UB tests break
Alive2 and may be the root cause of breaking future optimizations.

Here's an Alive2 proof for one of the examples:
https://alive2.llvm.org/ce/z/TncxhP

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[SCEV] Extend type hint in analysis output to all backedge kinds

This extends the work from 7755c26 to all of the different backend
taken count kinds that we print for the scev analysis printer. As

[SCEV] Extend type hint in analysis output to all backedge kinds

This extends the work from 7755c26 to all of the different backend
taken count kinds that we print for the scev analysis printer. As
before, the goal is to cut down on confusion as i4 -1 is a very
different (unsigned) value from i32 -1.

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[SCEV] Print predicate backedge count only if new information available

When printing the result of SCEV's analysis, we can avoid printing
the predicated backedge taken count and the predicates if t

[SCEV] Print predicate backedge count only if new information available

When printing the result of SCEV's analysis, we can avoid printing
the predicated backedge taken count and the predicates if the predicates
are empty and no new information is provided. This helps to reduce the
verbosity of the output.

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[SCEV] Include type when printing constant max backedge taken count

When printing the result of the analysis, i8 -1 and i64 -1 are quite
different in terms of analysis quality. In a recent conversi

[SCEV] Include type when printing constant max backedge taken count

When printing the result of the analysis, i8 -1 and i64 -1 are quite
different in terms of analysis quality. In a recent conversion with
a new contributor, we ran into exactly this confusion.

Adding the type for constant scevs more globally seems worthwhile, but
introduces a much larger test diff. I'm splitting this off first since
it addresses the immediate need, and then going to do some further
changes to clarify a few related bits of analysis result output.

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[SCEV] Regenerate test checks (NFC)

There have been some minor but pervasive changes to the generated
CHECK lines, so regenerate all of them, to minimize future diffs.

[ValueTracking] Directly use KnownBits shift functions

Make ValueTracking directly call the KnownBits shift helpers, which
provides more precise results.

Unfortunately, ValueTracking has a special

[ValueTracking] Directly use KnownBits shift functions

Make ValueTracking directly call the KnownBits shift helpers, which
provides more precise results.

Unfortunately, ValueTracking has a special case where sometimes we
determine non-zero shift amounts using isKnownNonZero(). I have my
doubts about the usefulness of that special-case (it is only tested
in a single unit test), but I've reproduced the special-case via an
extra parameter to the KnownBits methods.

Differential Revision: https://reviews.llvm.org/D151816

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[SCEV] Strengthen nowrap flags via ranges for ARs on construction.

At the moment, proveNoWrapViaConstantRanges is only used when creating
SCEV[Zero,Sign]ExtendExprs. We can get significant improveme

[SCEV] Strengthen nowrap flags via ranges for ARs on construction.

At the moment, proveNoWrapViaConstantRanges is only used when creating
SCEV[Zero,Sign]ExtendExprs. We can get significant improvements by
strengthening flags after creating the AddRec.

I'll also share a follow-up patch that removes the code to strengthen
flags when creating SCEV[Zero,Sign]ExtendExprs. Modifying AddRecs while
creating those can lead to surprising changes.

Compile-time looks neutral:
https://llvm-compile-time-tracker.com/compare.php?from=94676cf8a13c511a9acfc24ed53c98964a87bde3&to=aced434e8b103109104882776824c4136c90030d&stat=instructions:u

Reviewed By: mkazantsev, nikic

Differential Revision: https://reviews.llvm.org/D144050

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[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

[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.

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[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.

[SCEV] Use SCEVUnknown(poison) instead of SCEVUnknown(undef).

Use poison instead of undef for SCEVUnkown of unreachable values.
This should be in line with the movement to replace undef with poison

[SCEV] Use SCEVUnknown(poison) instead of SCEVUnknown(undef).

Use poison instead of undef for SCEVUnkown of unreachable values.
This should be in line with the movement to replace undef with poison
when possible.

Suggested in D114650.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D128586

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[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 t

[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

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[SCEV] Compute ranges for ashr recurrences

Straight forward extension to the recently added infrastructure which was pioneered with shl. This was originally posted as part of D99687, but split off f

[SCEV] Compute ranges for ashr recurrences

Straight forward extension to the recently added infrastructure which was pioneered with shl. This was originally posted as part of D99687, but split off for ease of review.

(I also decided to exclude the unknown start sign case explicitly for simplicity of understanding.)

Differential Revision: https://reviews.llvm.org/D101181

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[SCEV] Compute ranges for lshr recurrences

Straight forward extension to the recently added infrastructure which was pioneered with shl.

Differential Revision: https://reviews.llvm.org/D99687

[tests] Expand coverage for D99687

[test] Add a couple extra tests for recurrence matching in unreachable code

These are salvaged from D100004 as we took a different approach to the fix.

[tests] Exercise cases where SCEV can use trip counts to refine ashr/lshr recurrences

[SCEV] Handle unreachable binop when matching shift recurrence

This fixes an issue introduced with my change d4648e, and reported in pr49768.

The root problem is that dominance collapses in unreach

[SCEV] Handle unreachable binop when matching shift recurrence

This fixes an issue introduced with my change d4648e, and reported in pr49768.

The root problem is that dominance collapses in unreachable code, and that LoopInfo explicitly only models reachable code. Since the recurrence matcher doesn't filter by reachability (and can't easily because not all consumers have domtree), we need to bailout before assuming that finding a recurrence implies we found a loop.

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[SCEV] Use trip count information to improve shift recurrence ranges

This patch exploits the knowledge that we may be running many fewer than bitwidth iterations of the loop, and may be able to disa

[SCEV] Use trip count information to improve shift recurrence ranges

This patch exploits the knowledge that we may be running many fewer than bitwidth iterations of the loop, and may be able to disallow the overflow case. This patch specifically implements only the shl case, but this can be generalized to ashr and lshr without difficulty.

Differential Revision: https://reviews.llvm.org/D98222

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[tests] Cover a case brought up in review of D98222

[test] precommit tests from D98222