[ConstraintElim] Remove dead compares after simplification.

Remove compares after replacing all uses. Cleaning dead compares can
enable additional simplifications when adjusting the position of the

[ConstraintElim] Remove dead compares after simplification.

Remove compares after replacing all uses. Cleaning dead compares can
enable additional simplifications when adjusting the position of the
pass slightly. In particular, it seems like the additional dead
instructions may prevent SimplifyCFG performing some folds.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D158760

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[ConstraintElim] Track and simplify conditions at use.

This patch updates ConstraintElimination to track uses of conditions in
the worklist. This allows simplifying conditions using the context that

[ConstraintElim] Track and simplify conditions at use.

This patch updates ConstraintElimination to track uses of conditions in
the worklist. This allows simplifying conditions using the context that
holds directly at the condition, instead of where the condition is
defined.

This allows us to catch more cases in practice: there are multiple
code-size changes for CTMark while compile-time remains unchanged:
https://llvm-compile-time-tracker.com/compare.php?from=4b020cca9363bebab4643f89cfa92ab2fcc7976c&to=7a6e84b8f029713c137814cd46eec775d24a54a1&stat=instructions:u

This should help to simplify D151799.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D153660

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[ConstraintElim] Fix sort order to not comparing insts in different bbs.

Update the sort order to make sure that comesBefore is never used from
conditional facts, which are instructions but may use

[ConstraintElim] Fix sort order to not comparing insts in different bbs.

Update the sort order to make sure that comesBefore is never used from
conditional facts, which are instructions but may use DFS numbers from
different blocks.

This fixes a crash in the added test on some platforms.

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[ConstraintElim] Queue facts and checks directly.

This allows interleaving facts and checks in a single block. In
particular this enables using facts from assumes for conditions in the
same block th

[ConstraintElim] Queue facts and checks directly.

This allows interleaving facts and checks in a single block. In
particular this enables using facts from assumes for conditions in the
same block that come after the assume.

This could be extended to only try to simplify checks at the point where
a condition is used.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D138452

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[ConstraintElimination] Add missing dominance check.

When dealing with an unconditional branch, the condition can only added
if BB properly dominates the successor.

[ConstraintElimination] Support BBs with single successor in CanAdd.

If BB has a single successor, conditions can be added safely.

[ConstraintElimination] Add additional tests with uncond branches.

[ConstraintElimination] Only add cond from assume to succs if valid.

Add missing CanAdd check before adding a condition from an assume
to the successor blocks. When adding information from assume to

[ConstraintElimination] Only add cond from assume to succs if valid.

Add missing CanAdd check before adding a condition from an assume
to the successor blocks. When adding information from assume to
successor blocks we need to perform the same CanAdd as we do for adding
a condition from a branch.

Fixes https://github.com/llvm/llvm-project/issues/54217

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[ConstraintElimination] Add test case for PR54217.

Adds test case for https://github.com/llvm/llvm-project/issues/54217.

[test] Use -passes syntax when specifying pipeline in some more tests

The legacy PM is deprecated, so update a bunch of lit tests running
opt to use the new PM syntax when specifying the pipeline.
I

[test] Use -passes syntax when specifying pipeline in some more tests

The legacy PM is deprecated, so update a bunch of lit tests running
opt to use the new PM syntax when specifying the pipeline.
In this patch focus has been put on test cases for ConstantMerge,
ConstraintElimination, CorrelatedValuePropagation, GlobalDCE,
GlobalOpt, SCCP, TailCallElim and PredicateInfo.

Differential Revision: https://reviews.llvm.org/D114516

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[ConstraintElimination] Initial support for using info from assumes.

This patch adds initial support to use facts from @llvm.assume calls. It
intentionally does not handle all possible cases to keep

[ConstraintElimination] Initial support for using info from assumes.

This patch adds initial support to use facts from @llvm.assume calls. It
intentionally does not handle all possible cases to keep things simple
initially.

For now, the condition from an assume is made available on entry to the
containing block, if the assume is guaranteed to execute. Otherwise it
is only made available in the successor blocks.

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[ConstraintElimination] Add more assume tests.

[ConstraintElimination] Add test cases with @llvm.assume.