Revert "[NFCI] Regenerate SROA/LoopVectorize test checks"

This reverts commit 14e3450fb57305aa9ff3e9e60687b458e43835c9.

[NFCI] Regenerate LoopVectorize test checks

[LV] Create & use VPScalarIVSteps for all scalar users.

This patch is a follow-up to D115953. It updates optimizeInductions
to also introduce new VPScalarIVStepsRecipes if an IV has both vector
and

[LV] Create & use VPScalarIVSteps for all scalar users.

This patch is a follow-up to D115953. It updates optimizeInductions
to also introduce new VPScalarIVStepsRecipes if an IV has both vector
and scalar uses.

It updates all uses that only need scalar values to use the newly
created recipe for the scalar steps.

This completes untangling of VPWidenIntOrFpInductionRecipe
code-generation. Now the recipe *only* creates the widened vector
values, as it says on the tin.

The code to genereate IR has been moved directly to
VPWidenIntOrFpInductionRecipe::execute.

Note that the recipe has been updated to hold a reference to
ScalarEvolution, which is needed to expand the step, until we can place
the corresponding SCEV expansion in the pre-header.

Depends on D120827.

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D120828

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[VPlan] Handle IV vector splat using VPWidenCanonicalIV.

This patch tries to use an existing VPWidenCanonicalIVRecipe
instead of creating another step-vector for canonical
induction recipes in widen

[VPlan] Handle IV vector splat using VPWidenCanonicalIV.

This patch tries to use an existing VPWidenCanonicalIVRecipe
instead of creating another step-vector for canonical
induction recipes in widenIntOrFpInduction.

This has the following benefits:

1. First step to avoid setting both vector and scalar values for the
same induction def.
2. Reducing complexity of widenIntOrFpInduction through making things
more explicit in VPlan
3. Only need to splat the vector IV for block in masks.

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D116123

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[LV] Mark increment of main vector loop induction variable as NUW.

This patch marks the induction increment of the main induction variable
of the vector loop as NUW when not folding the tail.

If th

[LV] Mark increment of main vector loop induction variable as NUW.

This patch marks the induction increment of the main induction variable
of the vector loop as NUW when not folding the tail.

If the tail is not folded, we know that End - Start >= Step (either
statically or through the minimum iteration checks). We also know that both
Start % Step == 0 and End % Step == 0. We exit the vector loop if %IV +
%Step == %End. Hence we must exit the loop before %IV + %Step unsigned
overflows and we can mark the induction increment as NUW.

This should make SCEV return more precise bounds for the created vector
loops, used by later optimizations, like late unrolling.

At the moment quite a few tests still need to be updated, but before
doing so I'd like to get initial feedback to make sure I am not missing
anything.

Note that this could probably be further improved by using information
from the original IV.

Attempt of modeling of the assumption in Alive2:
https://alive2.llvm.org/ce/z/H_DL_g

Part of a set of fixes required for PR50412.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D103255

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[SLP,LV] Use poison constant vector for shufflevector/initial insertelement

This patch makes SLP and LV emit operations with initial vectors set to poison constant instead of undef.
This is a part o

[SLP,LV] Use poison constant vector for shufflevector/initial insertelement

This patch makes SLP and LV emit operations with initial vectors set to poison constant instead of undef.
This is a part of efforts for using poison vector instead of undef to represent "doesn't care" vector.
The goal is to make nice shufflevector optimizations valid that is currently incorrect due to the tricky interaction between undef and poison (see https://bugs.llvm.org/show_bug.cgi?id=44185 ).

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D94061

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[IR] Let IRBuilder's CreateVectorSplat/CreateShuffleVector use poison as placeholder

This patch updates IRBuilder to create insertelement/shufflevector using poison as a placeholder.

Reviewed By: n

[IR] Let IRBuilder's CreateVectorSplat/CreateShuffleVector use poison as placeholder

This patch updates IRBuilder to create insertelement/shufflevector using poison as a placeholder.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D93793

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[LV] Tail folded inloop reductions.

This expands upon the inloop reductions added in e9761688e41cb9e976,
allowing them to be inserted into tail folded loops. Reductions are
generates with the form:

[LV] Tail folded inloop reductions.

This expands upon the inloop reductions added in e9761688e41cb9e976,
allowing them to be inserted into tail folded loops. Reductions are
generates with the form:

x = select(mask, vecop, zero)
v = vecreduce.add(x)
c = add chain, v

Where zero here is chosen as the identity value for add reductions. The
backend is then expected to fold the select and the vecreduce into a
single predicated instruction.

Most of the code is fairly straight forward, except for the creation of
blockmasks which need to ensure they are created in dominance order. The
order they are added is altered to be after any phis, keeping the
requirements for the underlying IR.

Differential Revision: https://reviews.llvm.org/D84451

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[LV] Vectorize without versioning-for-unit-stride under -Os/-Oz

If a loop is in a function marked OptSize, Loop Access Analysis should refrain
from generating runtime checks for unit strides that wi

[LV] Vectorize without versioning-for-unit-stride under -Os/-Oz

If a loop is in a function marked OptSize, Loop Access Analysis should refrain
from generating runtime checks for unit strides that will version the loop.

If a loop is in a function marked OptSize and its vectorization is enabled, it
should be vectorized w/o any versioning.

Fixes PR46228.

Differential Revision: https://reviews.llvm.org/D81345

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[LV] Either get invariant condition OR vector condition.

Currently we unconditionally get the first lane of the condition
operand, even if we later use the full vector condition. This can result
in

[LV] Either get invariant condition OR vector condition.

Currently we unconditionally get the first lane of the condition
operand, even if we later use the full vector condition. This can result
in some unnecessary instructions being generated.

Suggested as follow-up in D80219.

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Recommit #2: "[LV] Induction Variable does not remain scalar under tail-folding."

This was reverted because of a miscompilation. At closer inspection, the
problem was actually visible in a changed l

Recommit #2: "[LV] Induction Variable does not remain scalar under tail-folding."

This was reverted because of a miscompilation. At closer inspection, the
problem was actually visible in a changed llvm regression test too. This
one-line follow up fix/recommit will splat the IV, which is what we are trying
to avoid if unnecessary in general, if tail-folding is requested even if all
users are scalar instructions after vectorisation. Because with tail-folding,
the splat IV will be used by the predicate of the masked loads/stores
instructions. The previous version omitted this, which caused the
miscompilation. The original commit message was:

If tail-folding of the scalar remainder loop is applied, the primary induction
variable is splat to a vector and used by the masked load/store vector
instructions, thus the IV does not remain scalar. Because we now mark
that the IV does not remain scalar for these cases, we don't emit the vector IV
if it is not used. Thus, the vectoriser produces less dead code.

Thanks to Ayal Zaks for the direction how to fix this.

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Revert "Recommit "[LV] Induction Variable does not remain scalar under tail-folding.""

This reverts commit ae45b4dbe73ffde5fe3119835aa947d5a49635ed. It
causes miscompilations, test case on the maili

Revert "Recommit "[LV] Induction Variable does not remain scalar under tail-folding.""

This reverts commit ae45b4dbe73ffde5fe3119835aa947d5a49635ed. It
causes miscompilations, test case on the mailing list.

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Recommit "[LV] Induction Variable does not remain scalar under tail-folding."

With 3 llvm regr tests fixed/updated that I had missed.

Revert "[LV] Induction Variable does not remain scalar under tail-folding."

This reverts commit 617aa64c84146468b384453375d1d34f97eb57db.

while I investigate buildbot failures.

[LV] Induction Variable does not remain scalar under tail-folding.

If tail-folding of the scalar remainder loop is applied, the primary induction
variable is splat to a vector and used by the masked

[LV] Induction Variable does not remain scalar under tail-folding.

If tail-folding of the scalar remainder loop is applied, the primary induction
variable is splat to a vector and used by the masked load/store vector
instructions, thus the IV does not remain scalar. Because we now mark
that the IV does not remain scalar for these cases, we don't emit the vector IV
if it is not used. Thus, the vectoriser produces less dead code.

Thanks to Ayal Zaks for the direction how to fix this.

Differential Revision: https://reviews.llvm.org/D78911

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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

[LV] Avoid vectorizing loops under opt for size that involve SCEV checks

Fix PR39417, PR39497

The loop vectorizer may generate runtime SCEV checks for overflow and stride==1
cases, leading to execu

[LV] Avoid vectorizing loops under opt for size that involve SCEV checks

Fix PR39417, PR39497

The loop vectorizer may generate runtime SCEV checks for overflow and stride==1
cases, leading to execution of original scalar loop. The latter is forbidden
when optimizing for size. An assert introduced in r344743 triggered the above
PR's showing it does happen. This patch fixes this behavior by preventing
vectorization in such cases.

Differential Revision: https://reviews.llvm.org/D53612

llvm-svn: 345959

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[LV] Fold tail by masking to vectorize loops of arbitrary trip count under opt for size

When optimizing for size, a loop is vectorized only if the resulting vector loop
completely replaces the origi

[LV] Fold tail by masking to vectorize loops of arbitrary trip count under opt for size

When optimizing for size, a loop is vectorized only if the resulting vector loop
completely replaces the original scalar loop. This holds if no runtime guards
are needed, if the original trip-count TC does not overflow, and if TC is a
known constant that is a multiple of the VF. The last two TC-related conditions
can be overcome by
1. rounding the trip-count of the vector loop up from TC to a multiple of VF;
2. masking the vector body under a newly introduced "if (i <= TC-1)" condition.

The patch allows loops with arbitrary trip counts to be vectorized under -Os,
subject to the existing cost model considerations. It also applies to loops with
small trip counts (under -O2) which are currently handled as if under -Os.

The patch does not handle loops with reductions, live-outs, or w/o a primary
induction variable, and disallows interleave groups.

(Third, final and main part of -)
Differential Revision: https://reviews.llvm.org/D50480

llvm-svn: 344743

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[LV] Add test checks when vectorizing loops under opt for size; NFC

Landing this as a separate part of https://reviews.llvm.org/D50480, recording
current behavior more accurately, to clarify subsequ

[LV] Add test checks when vectorizing loops under opt for size; NFC

Landing this as a separate part of https://reviews.llvm.org/D50480, recording
current behavior more accurately, to clarify subsequent diff ([LV] Vectorizing
loops of arbitrary trip count without remainder under opt for size).

llvm-svn: 344606

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