[InstCombine] Infer nusw + nneg -> nuw for getelementptr (#111144)

If the gep is nusw (usually via inbounds) and the offset is
non-negative, we can infer nuw.

Proof: https://alive2.llvm.org/ce/z

[InstCombine] Infer nusw + nneg -> nuw for getelementptr (#111144)

If the gep is nusw (usually via inbounds) and the offset is
non-negative, we can infer nuw.

Proof: https://alive2.llvm.org/ce/z/ihztLy

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[InstCombine] Canonicalize constant GEPs to i8 source element type (#68882)

This patch canonicalizes getelementptr instructions with constant
indices to use the `i8` source element type. This makes

[InstCombine] Canonicalize constant GEPs to i8 source element type (#68882)

This patch canonicalizes getelementptr instructions with constant
indices to use the `i8` source element type. This makes it easier for
optimizations to recognize that two GEPs are identical, because they
don't need to see past many different ways to express the same offset.

This is a first step towards
https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699.
This is limited to constant GEPs only for now, as they have a clear
canonical form, while we're not yet sure how exactly to deal with
variable indices.

The test llvm/test/Transforms/PhaseOrdering/switch_with_geps.ll gives
two representative examples of the kind of optimization improvement we
expect from this change. In the first test SimplifyCFG can now realize
that all switch branches are actually the same. In the second test it
can convert it into simple arithmetic. These are representative of
common optimization failures we see in Rust.

Fixes https://github.com/llvm/llvm-project/issues/69841.

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[InstCombine] Convert some tests to opaque pointers (NFC)

Check lines for these were regenerated, but without any
significant changes (mostly different GEP source element types).

Revert "[InstCombine] Convert some tests to opaque pointers (NFC)"

This reverts commit 66cea84681e16f3d4ebdc69031824b114a0d5681.

I did not intend to commit all the changes in here, but only the
one

Revert "[InstCombine] Convert some tests to opaque pointers (NFC)"

This reverts commit 66cea84681e16f3d4ebdc69031824b114a0d5681.

I did not intend to commit all the changes in here, but only the
ones with no significant differences.

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[InstCombine] Convert some tests to opaque pointers (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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Precommit test for D116683

Add test case from 356ada9

[instcombine] Allow sinking of calls with known writes to uses

If we have a call whose only side effect is a write to a location which is known to be dead, we can sink said call to the users of the

[instcombine] Allow sinking of calls with known writes to uses

If we have a call whose only side effect is a write to a location which is known to be dead, we can sink said call to the users of the call's result value. This is analogous to the recent changes to delete said calls if unused, but framed as a sinking transform instead.

Differential Revision: https://reviews.llvm.org/D116200

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precommit tests for a planned followon to D116200

precommit additional tests for D116200

Add test coverage for D109917 and variants

Autogen a test in advance of another change

Update sink instruction testcase

Add inferable writeonly attribute. Simplify testcase.

Update with additional tests for sinking calls to uses

Precommitted from D109917.
Note that the log call is already handled by instCombine.