[SimpleLoopUnswitch] Convert tests to opaque pointers (NFC)

[NewPM] Rename 'unswitch' to 'simple-loop-unswitch' in PassRegistry

It is confusing to have two ways of specifying the same pass
('simple-loop-unswitch' and 'unswitch'). This patch replaces
'unswitc

[NewPM] Rename 'unswitch' to 'simple-loop-unswitch' in PassRegistry

It is confusing to have two ways of specifying the same pass
('simple-loop-unswitch' and 'unswitch'). This patch replaces
'unswitch' by 'simple-loop-unswitch' to get a unique identifier.

Using 'simple-loop-unswitch' instead of 'unswitch' also has the
advantage of matching how the pass is named in DEBUG_TYPE etc. So
this makes it a bit more consistent how we refer to the pass in
options such as -passes, -print-after and -debug-only.

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D105628

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[LoopSimplifyCFG][NewPM] Rename simplify-cfg -> loop-simplifycfg

This matches the legacy PM name and makes all tests in
Transforms/LoopSimplifyCFG pass under NPM.

Reviewed By: arsenm

Differential

[LoopSimplifyCFG][NewPM] Rename simplify-cfg -> loop-simplifycfg

This matches the legacy PM name and makes all tests in
Transforms/LoopSimplifyCFG pass under NPM.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D87948

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[LoopPassManager + MemorySSA] Only enable use of MemorySSA for LPMs known to preserve it.

Summary:
Add a flag to the FunctionToLoopAdaptor that allows enabling MemorySSA only for the loop pass manag

[LoopPassManager + MemorySSA] Only enable use of MemorySSA for LPMs known to preserve it.

Summary:
Add a flag to the FunctionToLoopAdaptor that allows enabling MemorySSA only for the loop pass managers that are known to preserve it.

If an LPM is known to have only loop transforms that *all* preserve MemorySSA, then use MemorySSA if `EnableMSSALoopDependency` is set.
If an LPM has loop passes that do not preserve MemorySSA, then the flag passed is `false`, regardless of the value of `EnableMSSALoopDependency`.

When using a custom loop pass pipeline via `passes=...`, use keyword `loop` vs `loop-mssa` to use MemorySSA in that LPM. If a loop that does not preserve MemorySSA is added while using the `loop-mssa` keyword, that's an error.

Add the new `loop-mssa` keyword to a few tests where a difference occurs when enabling MemorySSA.

Reviewers: chandlerc

Subscribers: mehdi_amini, Prazek, george.burgess.iv, sanjoy.google, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66376

llvm-svn: 369548

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Revert "Temporarily Revert "Add basic loop fusion pass.""

The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552

Update MemorySSA in SimpleLoopUnswitch.

Summary:
Teach SimpleLoopUnswitch to preserve MemorySSA.

Subscribers: sanjoy, jlebar, Prazek, george.burgess.iv, llvm-commits

Differential Revision: https:/

Update MemorySSA in SimpleLoopUnswitch.

Summary:
Teach SimpleLoopUnswitch to preserve MemorySSA.

Subscribers: sanjoy, jlebar, Prazek, george.burgess.iv, llvm-commits

Differential Revision: https://reviews.llvm.org/D47022

llvm-svn: 348263

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Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred.

Summary:
Two utils methods have essentially the same functionality. This is an attempt to merge them into one.
1. l

Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred.

Summary:
Two utils methods have essentially the same functionality. This is an attempt to merge them into one.
1. lib/Transforms/Utils/Local.cpp : MergeBasicBlockIntoOnlyPred
2. lib/Transforms/Utils/BasicBlockUtils.cpp : MergeBlockIntoPredecessor

Prior to the patch:
1. MergeBasicBlockIntoOnlyPred
Updates either DomTree or DeferredDominance
Moves all instructions from Pred to BB, deletes Pred
Asserts BB has single predecessor
If address was taken, replace the block address with constant 1 (?)

2. MergeBlockIntoPredecessor
Updates DomTree, LoopInfo and MemoryDependenceResults
Moves all instruction from BB to Pred, deletes BB
Returns if doesn't have a single predecessor
Returns if BB's address was taken

After the patch:
Method 2. MergeBlockIntoPredecessor is attempting to become the new default:
Updates DomTree or DeferredDominance, and LoopInfo and MemoryDependenceResults
Moves all instruction from BB to Pred, deletes BB
Returns if doesn't have a single predecessor
Returns if BB's address was taken

Uses of MergeBasicBlockIntoOnlyPred that need to be replaced:

1. lib/Transforms/Scalar/LoopSimplifyCFG.cpp
Updated in this patch. No challenges.

2. lib/CodeGen/CodeGenPrepare.cpp
Updated in this patch.
i. eliminateFallThrough is straightforward, but I added using a temporary array to avoid the iterator invalidation.
ii. eliminateMostlyEmptyBlock(s) methods also now use a temporary array for blocks
Some interesting aspects:
- Since Pred is not deleted (BB is), the entry block does not need updating.
- The entry block was being updated with the deleted block in eliminateMostlyEmptyBlock. Added assert to make obvious that BB=SinglePred.
- isMergingEmptyBlockProfitable assumes BB is the one to be deleted.
- eliminateMostlyEmptyBlock(BB) does not delete BB on one path, it deletes its unique predecessor instead.
- adding some test owner as subscribers for the interesting tests modified:
test/CodeGen/X86/avx-cmp.ll
test/CodeGen/AMDGPU/nested-loop-conditions.ll
test/CodeGen/AMDGPU/si-annotate-cf.ll
test/CodeGen/X86/hoist-spill.ll
test/CodeGen/X86/2006-11-17-IllegalMove.ll

3. lib/Transforms/Scalar/JumpThreading.cpp
Not covered in this patch. It is the only use case using the DeferredDominance.
I would defer to Brian Rzycki to make this replacement.

Reviewers: chandlerc, spatel, davide, brzycki, bkramer, javed.absar

Subscribers: qcolombet, sanjoy, nemanjai, nhaehnle, jlebar, tpr, kbarton, RKSimon, wmi, arsenm, llvm-commits

Differential Revision: https://reviews.llvm.org/D48202

llvm-svn: 335183

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[PM/LoopUnswitch] When using the new SimpleLoopUnswitch pass, schedule
loop-cleanup passes at the beginning of the loop pass pipeline, and
re-enqueue loops after even trivial unswitching.

This will

[PM/LoopUnswitch] When using the new SimpleLoopUnswitch pass, schedule
loop-cleanup passes at the beginning of the loop pass pipeline, and
re-enqueue loops after even trivial unswitching.

This will allow us to much more consistently avoid simplifying code
while doing trivial unswitching. I've also added a test case that
specifically shows effective iteration using this technique.

I've unconditionally updated the new PM as that is always using the
SimpleLoopUnswitch pass, and I've made the pipeline changes for the old
PM conditional on using this new unswitch pass. I added a bunch of
comments to the loop pass pipeline in the old PM to make it more clear
what is going on when reviewing.

Hopefully this will unblock doing *partial* unswitching instead of just
full unswitching.

Differential Revision: https://reviews.llvm.org/D47408

llvm-svn: 333493

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