[SimpleLoopUnswitch] Run LICM for nested unswitching tests.

When enabling freeze-loop-unswitch-cond the inserted freeze instruction
may block unswitching of parent loops if they get inserted in a bl

[SimpleLoopUnswitch] Run LICM for nested unswitching tests.

When enabling freeze-loop-unswitch-cond the inserted freeze instruction
may block unswitching of parent loops if they get inserted in a block in
the parent loop (as the llvm::Loop-based invariance check only checks
whether an instruction is in a loop block or not).

In the optimization pipeline, LICM is responsible to hoist out loop
invariant instructions to enable further unswitching. Also run LICM for
nested unswitching tests in preparation for flipping the default of
freeze-loop-unswitch-cond.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D124251

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[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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Revert "[SimpleLoopUnswitch] Fix introduction of UB when hoisted condition may be undef or poison"

.. due to performance regression.

This patch is reverted until infrastructore for CSE/LICM support

Revert "[SimpleLoopUnswitch] Fix introduction of UB when hoisted condition may be undef or poison"

.. due to performance regression.

This patch is reverted until infrastructore for CSE/LICM support for freeze is
added.

This reverts commit 181628b

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[SimpleLoopUnswitch] Fix introduction of UB when hoisted condition may be undef or poison

Summary:
Loop unswitch hoists branches on loop-invariant conditions. However, if this
condition is poison/un

[SimpleLoopUnswitch] Fix introduction of UB when hoisted condition may be undef or poison

Summary:
Loop unswitch hoists branches on loop-invariant conditions. However, if this
condition is poison/undef and the branch wasn't originally reachable, loop
unswitch introduces UB (since the optimized code will branch on poison/undef and
the original one didn't)).
We fix this problem by freezing the condition to ensure we don't introduce UB.

We will now transform the following:
while (...) {
if (C) { A }
else { B }
}

Into:
C' = freeze(C)
if (C') {
while (...) { A }
} else {
while (...) { B }
}

This patch fixes the root cause of the following bug reports (which use the old loop unswitch, but can be reproduced with minor changes in the code and -enable-nontrivial-unswitch):
- https://llvm.org/bugs/show_bug.cgi?id=27506
- https://llvm.org/bugs/show_bug.cgi?id=31652

Reviewers: reames, majnemer, chenli, sanjoy, hfinkel

Reviewed By: reames

Subscribers: hiraditya, jvesely, nhaehnle, filcab, regehr, trentxintong, nlopes, llvm-commits, mzolotukhin

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D29015

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[MemorySSA] Update for partial unswitch.

Update MSSA for blocks cloned when doing partial unswitching.
Enable additional testing with MSSA.
Resolves PR43641.

llvm-svn: 374850

[NewPM] Add Option handling for SimpleLoopUnswitch

This patch enables passing options to SimpleLoopUnswitch via the passes pipeline.

Reviewers: chandlerc, fedor.sergeev, leonardchan, philip.pfaffe

[NewPM] Add Option handling for SimpleLoopUnswitch

This patch enables passing options to SimpleLoopUnswitch via the passes pipeline.

Reviewers: chandlerc, fedor.sergeev, leonardchan, philip.pfaffe
Reviewed By: fedor.sergeev
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D60676

llvm-svn: 358880

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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

[test] Fix use of 'sort -b' in SimpleLoopUnswitch on NetBSD

Add '-k 1' to 'sort -b' calls in SimpleLoopUnswitch tests, as required
for sort implementation on NetBSD. The '-b' modifier is ineffectiv

[test] Fix use of 'sort -b' in SimpleLoopUnswitch on NetBSD

Add '-k 1' to 'sort -b' calls in SimpleLoopUnswitch tests, as required
for sort implementation on NetBSD. The '-b' modifier is ineffective
if specified without any key. Per the manpage:

Note that the -b option has no effect unless key fields are specified.

Differential Revision: https://reviews.llvm.org/D55168

llvm-svn: 348097

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[SimpleLoopUnswitch] adding cost multiplier to cap exponential unswitch with

We need to control exponential behavior of loop-unswitch so we do not get
run-away compilation.

Suggested solution is to

[SimpleLoopUnswitch] adding cost multiplier to cap exponential unswitch with

We need to control exponential behavior of loop-unswitch so we do not get
run-away compilation.

Suggested solution is to introduce a multiplier for an unswitch cost that
makes cost prohibitive as soon as there are too many candidates and too
many sibling loops (meaning we have already started duplicating loops
by unswitching).

It does solve the currently known problem with compile-time degradation
(PR 39544).

Tests are built on top of a recently implemented CHECK-COUNT-<num>
FileCheck directives.

Reviewed By: chandlerc, mkazantsev
Differential Revision: https://reviews.llvm.org/D54223

llvm-svn: 347097

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