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
Upon further investigation and discussion,
this is actually the opposite direction from what we should be taking,
and this direction wouldn't solve the motivational problem anyway.
Additionally, some more (polly) tests have escaped being updated.
So, let's just take a step back here.
This reverts commit f3190dedeef9da2109ea57e4cb372f295ff53b88.
This reverts commit 749581d21f2b3f53e4fca4eb8728c942d646893b.
This reverts commit f3df87d57e096143670e0fd396e81d43393a2dd2.
This reverts commit ab1dbcecd6f0969976fafd62af34730436ad5944.
While we could emit such a tautological `select`,
it will stick around until the next instsimplify invocation,
which may happen after we count the cost of this redundant `select`.
Which is precisely what happens with loop vectorization legality checks,
and that artificially increases the cost of said checks,
which is bad.
There is prior art for this in `IRBuilderBase::CreateAnd()`/`IRBuilderBase::CreateOr()`.
Refs. https://reviews.llvm.org/D109368#3089809
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
The scalarization overhead was set deliberately high for MVE, whilst the
codegen was new. It helps protect us against the negative ramifications
of mixing scalar and vector instructions. This decreases that,
especially for floating point where the cost of extracting/inserting
lane elements can be low. For integer the cost is still fairly high due
to the cross-register-bank copy, but is no longer n^2 in the length of
the vector.
In general, this will decrease the cost of scalarizing floats and long
integer vectors. i64 increase in cost, having a high cost before and
after this patch. For floats this allows up to start doing things like
vectorizing fdiv instructions, even if they are scalarized.
Differential Revision: https://reviews.llvm.org/D98245
This patch updates IRBuilder to create insertelement/shufflevector using poison as a placeholder.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D93793
We currently collect the ICmp and Add from an induction variable,
marking them as dead so that vplan values are not created for them. This
extends that to include any single use trunk from the ICmp, which allows
the Add to more readily be removed too.
This can help with costing vplan nodes, as the ICmp and Add are more
reliably removed and are not double-counted.
Differential Revision: https://reviews.llvm.org/D88873
As part of D84741, this adds a target hook for the
preferPredicatedReductionSelect option and makes use
of it under MVE, allowing us to tail predicate most
reduction loops.
Differential Revision: https://reviews.llvm.org/D85980
It was getting difficult to see which test was in which file, so this
reorganises the test files so that now all filenames start with tail-folding-*
followed by a more descriptive name what that group of tests check.
