[LLVM][IR] Use splat syntax when printing Constant[Data]Vector. (#112548)

[InstCombine] Remove some of the complexity-based canonicalization (#91185)

The idea behind this canonicalization is that it allows us to handle less
patterns, because we know that some will be can

[InstCombine] Remove some of the complexity-based canonicalization (#91185)

The idea behind this canonicalization is that it allows us to handle less
patterns, because we know that some will be canonicalized away. This is
indeed very useful to e.g. know that constants are always on the right.

However, this is only useful if the canonicalization is actually
reliable. This is the case for constants, but not for arguments: Moving
these to the right makes it look like the "more complex" expression is
guaranteed to be on the left, but this is not actually the case in
practice. It fails as soon as you replace the argument with another
instruction.

The end result is that it looks like things correctly work in tests,
while they actually don't. We use the "thwart complexity-based
canonicalization" trick to handle this in tests, but it's often a
challenge for new contributors to get this right, and based on the
regressions this PR originally exposed, we clearly don't get this right
in many cases.

For this reason, I think that it's better to remove this complexity
canonicalization. It will make it much easier to write tests for
commuted cases and make sure that they are handled.

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[InstCombine] Infer nsw/nuw for trunc (#87910)

This patch adds support for inferring trunc's nsw/nuw flags.

[InstCombine] integrate `N{U,S}WAddLike` into existing folds

Just went a quick replacement of `N{U,S}WAdd` with the `Like` variant
that old matches `or disjoint`

Closes #86082

[InstCombine] Add tests for integrating `N{U,S}WAddLike`; NFC

[InstCombine] Preserve nuw/nsw/exact flags when transforming (C shift (A add nuw C1)) --> ((C shift C1) shift A). (#79490)

If we weren't shifting out any non-zero bits or changing the sign before th

[InstCombine] Preserve nuw/nsw/exact flags when transforming (C shift (A add nuw C1)) --> ((C shift C1) shift A). (#79490)

If we weren't shifting out any non-zero bits or changing the sign before the transform, we
shouldn't be after.

Alive2: https://alive2.llvm.org/ce/z/mB-rWz

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[InstCombine] Replace non-demanded undef vector with poison

If an operand (esp to shufflevector or insertelement) is not
demanded, canonicalize it from undef to poison.

[InstCombine] Canonicalize splat shuffles to use poison operand

If the splat shuffle is represented using an undef RHS, replace it
with poison.

[InstCombine] Infer nneg flag from shift users (#71947)

This patch sets `nneg` flag when the zext is only used by a shift.

Alive2: https://alive2.llvm.org/ce/z/h3xKjP
Compile-time impact:
https

[InstCombine] Infer nneg flag from shift users (#71947)

This patch sets `nneg` flag when the zext is only used by a shift.

Alive2: https://alive2.llvm.org/ce/z/h3xKjP
Compile-time impact:
https://llvm-compile-time-tracker.com/compare.php?from=bd611264993f64decbce178d460caf1d1cb05f59&to=26bc473b239010bb24ff1bc39d58b42ecbbc4730&stat=instructions:u

This is an alternative to #71906.

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[InstCombine] Combine lshr of add -> (a + b < a)

Tries to perform
(lshr (add (zext X), (zext Y)), K)
-> (icmp ult (add X, Y), X)
where
- The add's operands are zexts from a K-bits integer

[InstCombine] Combine lshr of add -> (a + b < a)

Tries to perform
(lshr (add (zext X), (zext Y)), K)
-> (icmp ult (add X, Y), X)
where
- The add's operands are zexts from a K-bits integer to a bigger type.
- The add is only used by the shr, or by iK (or narrower) truncates.
- The lshr type has more than 2 bits (other types are boolean math).
- K > 1

This seems to be a pattern that just comes from OpenCL front-ends, so adding DAG/GISel combines doesn't seem to be worth the complexity.

Original patch D107552 by @abinavpp - adapted to use (a + b < a) instead of uaddo following discussion on the review.
See this issue https://github.com/RadeonOpenCompute/ROCm/issues/488

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D138814

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[InstCombine] Precommit D138814 tests

Separate commit for D138814's testcases to make review easier.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D139011

[InstCombine] add nuw to any (1<<x)

https://alive2.llvm.org/ce/z/9EjDKE

This was mentioned as a missing fold in D139598.

It can unlock follow-on folds in some cases.
This verifies one of the chang

[InstCombine] add nuw to any (1<<x)

https://alive2.llvm.org/ce/z/9EjDKE

This was mentioned as a missing fold in D139598.

It can unlock follow-on folds in some cases.
This verifies one of the changed tests:
https://alive2.llvm.org/ce/z/B_btDM

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[test][InstCombine] Update some test cases to use opaque pointers

These tests cases were converted using the script at
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34

Differential Re

[test][InstCombine] Update some test cases to use opaque pointers

These tests cases were converted using the script at
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34

Differential Revision: https://reviews.llvm.org/D135094

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[InstCombine] C0 >> (X - C1) --> (C0 << C1) >> X

With the right pre-conditions, we can fold the offset
into the shifted constant:
https://alive2.llvm.org/ce/z/drMRBU
https://alive2.llvm.org/ce/z/cUQ

[InstCombine] C0 >> (X - C1) --> (C0 << C1) >> X

With the right pre-conditions, we can fold the offset
into the shifted constant:
https://alive2.llvm.org/ce/z/drMRBU
https://alive2.llvm.org/ce/z/cUQv-_

Fixes #55016

Differential Revision: https://reviews.llvm.org/D124369

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[InstCombine] add tests for ashr/lshr of constant with shift amount offset; NFC

Baseline tests for D124369

[InstCombine] C0 <<{nsw, nuw} (X - C1) --> (C0 >> C1) << X (2nd try)

The first attempt at this missed a check to make sure the offset
constant was in range and caused many bot failures.

That was mi

[InstCombine] C0 <<{nsw, nuw} (X - C1) --> (C0 >> C1) << X (2nd try)

The first attempt at this missed a check to make sure the offset
constant was in range and caused many bot failures.

That was missed in the Alive2 proof because on overshift creates
poison rather than the assert from APInt. Here's an alternate
attempt at a proof using count-trailing-zeros:
https://alive2.llvm.org/ce/z/pnXQYR

Original commit message:

This is similar to an existing pre-shift-of-constant fold:
8a9c70fc01e6
...but in this case, we need no-wrap on the shl and a negative
offset:
https://alive2.llvm.org/ce/z/_RVz99

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[InstCombine] add more tests for a planned shift fold; NFC

These are reductions for a missed constraint (the offset
constant must be less than the bitwidth) that caused the
first version of the patc

[InstCombine] add more tests for a planned shift fold; NFC

These are reductions for a missed constraint (the offset
constant must be less than the bitwidth) that caused the
first version of the patch ( 5819f4a42286 ) to be reverted.

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Revert "[InstCombine] C0 <<{nsw, nuw} (X - C1) --> (C0 >> C1) << X"

This reverts commit 5819f4a422865fc9a8ea4dc772769e14010ff6a7.
This caused bots to fail with a crash/assert during the fold,
so som

Revert "[InstCombine] C0 <<{nsw, nuw} (X - C1) --> (C0 >> C1) << X"

This reverts commit 5819f4a422865fc9a8ea4dc772769e14010ff6a7.
This caused bots to fail with a crash/assert during the fold,
so some constraint was missed.

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[InstCombine] C0 <<{nsw, nuw} (X - C1) --> (C0 >> C1) << X

This is similar to an existing pre-shift-of-constant fold:
8a9c70fc01e6
...but in this case, we need no-wrap on the shl and a negative
offs

[InstCombine] C0 <<{nsw, nuw} (X - C1) --> (C0 >> C1) << X

This is similar to an existing pre-shift-of-constant fold:
8a9c70fc01e6
...but in this case, we need no-wrap on the shl and a negative
offset:
https://alive2.llvm.org/ce/z/_RVz99

Fixes #54890

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[InstCombine] add tests for C << (X - C1); NFC

[InstCombine] C0 shift (X add nuw C) --> (C0 shift C) shift X

With 'nuw' we can convert the increment of the shift amount
into a pre-shift (constant fold) of the shifted constant:
https://alive2.llv

[InstCombine] C0 shift (X add nuw C) --> (C0 shift C) shift X

With 'nuw' we can convert the increment of the shift amount
into a pre-shift (constant fold) of the shifted constant:
https://alive2.llvm.org/ce/z/FkTyR2

Fixes issue #41976

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[InstCombine] add tests for shift-of-add with constants; NFC

[test] Use -passes=instcombine instead of -instcombine in lots of tests. NFC

Another step moving away from the deprecated syntax of specifying
pass pipeline in opt.

Differential Revision: https://r

[test] Use -passes=instcombine instead of -instcombine in lots of tests. NFC

Another step moving away from the deprecated syntax of specifying
pass pipeline in opt.

Differential Revision: https://reviews.llvm.org/D119081

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[instcombine] Canonicalize constant index type to i64 for extractelement/insertelement

The basic idea to this is that a) having a single canonical type makes CSE easier, and b) many of our transform

[instcombine] Canonicalize constant index type to i64 for extractelement/insertelement

The basic idea to this is that a) having a single canonical type makes CSE easier, and b) many of our transforms are inconsistent about which types we end up with based on visit order.

I'm restricting this to constants as for non-constants, we'd have to decide whether the simplicity was worth extra instructions. For constants, there are no extra instructions.

We chose the canonical type as i64 arbitrarily. We might consider changing this to something else in the future if we have cause.

Differential Revision: https://reviews.llvm.org/D115387

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Reapply [ConstantFold] Fold more operations to poison

This was reverted to mitigate mitigate miscompiles caused by
the logical and/or to bitwise and/or fold. Reapply it now that
the underlying issue

Reapply [ConstantFold] Fold more operations to poison

This was reverted to mitigate mitigate miscompiles caused by
the logical and/or to bitwise and/or fold. Reapply it now that
the underlying issue has been fixed by D101191.

-----

This patch folds more operations to poison.

Alive2 proof: https://alive2.llvm.org/ce/z/mxcb9G (it does not contain tests about div/rem because they fold to poison when raising UB)

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D92270

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