Move the debug output that prints out the selected VF from
selectVectorizationFactor -> computeBestVF. This means that the output
will still be written even after removing the assert for the legacy and
vplan cost models matching.
Update optimizeForVFAndUF to completely remove the vector loop region
when possible. At the moment, we cannot remove the region if it contains
* widened IVs: the recipe is needed to generate the step vector
* reductions: ComputeReductionResults requires the reduction phi recipe
for codegen.
Both cases can be addressed by more explicit modeling.
The patch also includes a number of updates to allow executing VPlans
without a vector loop region.
Depends on https://github.com/llvm/llvm-project/pull/110004
Check the VPlan directly to determine if a VPValue is an optimiziable IV
or IV use instead of checking the underlying IR instructions.
Split off from https://github.com/llvm/llvm-project/pull/112147. This
refactoring enables moving IV end value creation from the legacy
fixupIVUsers to a VPlan-based transform.
There is one case we now won't optimize, that is IVs with subtracts and
non-constant steps. But as this is a minor optimization and doesn't
impact correctness, the benefits of performing the check in VPlan should
outweigh the missed case.
Update wide induction increments to use the same step as the corresponding
wide induction. This enables detecting induction increments directly in
VPlan and removes redundant splats.
LoopVectorizationCostModel::needsExtract should recognise instructions
that have been widened by scalarizing as scalar instructions, and thus
not needing an extract when used by later scalarized instructions.
This fixes an incorrect cost calculation in computePredInstDiscount,
where we are adding a scalarization overhead cost when we shouldn't,
though I haven't come up with a test case where it makes a difference.
It will make a difference when the cost model switches to using the cost
kind TCK_CodeSize for optsize, as not doing this causes the test
LoopVectorize/X86/small-size.ll to get worse.
Move replacement of VPBBs for vector preheader, middle block and scalar
preheader from VPlan::execute to skeleton creation, which actually
creates the IR basic blocks.
For now, the vector preheader can only be replaced after
prepareToExecute as it may create new instructions in the vector
preheader.
This ensures that all blocks created during VPlan execution are properly
added to an enclosing loop, if present.
Split off from https://github.com/llvm/llvm-project/pull/108378 and also
needed once more of the skeleton blocks are created directly via VPlan.
This also allows removing the custom logic for early-exit loop
vectorization added as part of
https://github.com/llvm/llvm-project/pull/117008.
This patch changes the way blocks are managed by VPlan. Previously all
blocks reachable from entry would be cleaned up when a VPlan is
destroyed. With this patch, each VPlan keeps track of blocks created for
it in a list and this list is then used to delete all blocks in the list
when the VPlan is destroyed. To do so, block creation is funneled
through helpers in directly in VPlan.
The main advantage of doing so is it simplifies CFG transformations, as
those do not have to take care of deleting any blocks, just adjusting
the CFG. This helps to simplify
https://github.com/llvm/llvm-project/pull/108378 and
https://github.com/llvm/llvm-project/pull/106748.
This also simplifies handling of 'immutable' blocks a VPlan holds
references to, which at the moment only include the scalar header block.
PR: https://github.com/llvm/llvm-project/pull/120918
Currently available intrinsics are only ld2/st2, which don't support interleaving factor > 2.
This patch teaches the LV to use ld2/st2 recursively to support high
interleaving factors.
This re-lands the reverted #92418
When the VF is small enough so that dividing the VF by the scaling
factor results in 1, the reduction phi execution thinks the VF is scalar
and sets the reduction's output as a scalar value, tripping assertions
expecting a vector value. The latest commit in this PR fixes that by
using `State.VF` in the scalar check, rather than the divided VF.
---------
Co-authored-by: Nicholas Guy <nicholas.guy@arm.com>
Following on from https://github.com/llvm/llvm-project/pull/94499, this
patch adds support to the Loop Vectorizer to emit the partial reduction
intrinsics where they may be beneficial for the target.
---------
Co-authored-by: Samuel Tebbs <samuel.tebbs@arm.com>
Currently the addUsersInExitBlocks incorrectly assumes exit phis only
have a single operand, which may not be the case for loops with early
exits when they share a common exit block.
Also further relax the assertion in fixupIVUsers to allow exit values if
they come from theloop latch/middle.block.
PR: https://github.com/llvm/llvm-project/pull/120260
PR #112138 introduced initial support for dispatching to
multiple exit blocks via split middle blocks. This patch
fixes a few issues so that we can enable more tests to use
the new enable-early-exit-vectorization flag. Fixes are:
1. The code to bail out for any loop live-out values happens
too late. This is because collectUsersInExitBlocks ignores
induction variables, which get dealt with in fixupIVUsers.
I've moved the check much earlier in processLoop by looking
for outside users of loop-defined values.
2. We shouldn't yet be interleaving when vectorising loops
with uncountable early exits, since we've not added support
for this yet.
3. Similarly, we also shouldn't be creating vector epilogues.
4. Similarly, we shouldn't enable tail-folding.
5. The existing implementation doesn't yet support loops
that require scalar epilogues, although I plan to add that
as part of PR #88385.
6. The new split middle blocks weren't being added to the
parent loop.
Update VPReductionPHIRecipe::execute to use the start value from the
start value operand of the recipe. This is needed to make sure we resume
from the correct value during epilogue vectorization.
At the moment, the start value is set to the sentinel value in
adjustRecipesForReductions, as the original start value needs to be used
when creating ResumePhi recipes.
Fixes a mis-compile introduced by b3cba9be41bfa8 in SPEC2017 on AArch64.
Split off from https://github.com/llvm/llvm-project/pull/112145. This
ensures that getOrCreateVectorTripCount creates the trip count as needed
when induction resume value creation is moved to VPlan and no longer
creates the vector trip count early.
Update VPWidenPointerInduction to manage its debug location via recipe.
This makes sure we emit a proper debug location for
VPWidenPointerInductionRecipes.
Properly set VPWidenIntOrFpInductionRecipe's debug location in the
recipe and use it, instead of using the debug location of the underlying
IR instruction.
After 6c8f41d33674, DT adjustments for the skeleton are applied as VPBBs
are executed. Move input DT verification up before starting to execute
any VPBBs to avoid checking DT while the CFG and DT are in an incomplete
state.
This fixes a number of verification failures with expensive checks
enabled, including
https://lab.llvm.org/buildbot/#/builders/16/builds/10584
As a first step to move towards modeling the full skeleton in VPlan,
start by wrapping IR blocks created during legacy skeleton creation in
VPIRBasicBlocks and hook them into the VPlan. This means the skeleton
CFG is represented in VPlan, just before execute. This allows moving
parts of skeleton creation into recipes in the VPBBs gradually.
Note that this allows retiring some manual DT updates, as this will be
handled automatically during VPlan execution.
PR: https://github.com/llvm/llvm-project/pull/114292
Instead of going through getOrAddLiveIn to get a VPValue for the vector
trip count retrieve it directly from VPlan via getVectorTripCount.
Small simplification following 0e70289f373.
Consider the following loop:
```
int rdx = init;
for (int i = 0; i < n; ++i)
rdx = (a[i] > b[i]) ? i : rdx;
```
We can vectorize this loop if `i` is an increasing induction variable.
The final reduced value will be the maximum of `i` that the condition
`a[i] > b[i]` is satisfied, or the start value `init`.
This patch added new RecurKind enums - IFindLastIV and FFindLastIV.
---------
Co-authored-by: Alexey Bataev <5361294+alexey-bataev@users.noreply.github.com>
A more lightweight variant of
https://github.com/llvm/llvm-project/pull/109193,
which dispatches to multiple exit blocks via the middle blocks.
The patch also introduces a bit of required scaffolding to enable
early-exit vectorization, including an option. At the moment, early-exit
vectorization doesn't come with legality checks, and is only used if the
option is provided and the loop has metadata forcing vectorization. This
is only intended to be used for testing during bring-up, with @david-arm
enabling auto early-exit vectorization plugging in the changes from
https://github.com/llvm/llvm-project/pull/88385.
PR: https://github.com/llvm/llvm-project/pull/112138
Adjust the assertion in fixupIVUsers to only require a unique exit block
if there are any values to fix up. This enables the bring up of
multi-exit loop vectorization without requiring a scalar epilogue.
Split off as suggested from
https://github.com/llvm/llvm-project/pull/112138.
Use getUniqueLatchExitBlock instead of getUniqueExitBlock in preparation
for multi-exit vectorization *without* requiring a scalar epilogue.
Split off as suggested from
https://github.com/llvm/llvm-project/pull/112138
Update the code to create induction resume PHIs to also create a resume
phi for the canonical induction during epilogue vectorization. This
unifies the code for handling induction resume values and removes the
need to explicitly create manually resume PHI and return it during
epilogue creation.
Overall it helps to move the code for updating the canonical induction
resume value to the place where all other header phi resume values are
updated.
This is NFC, modulo order of the created phis.
This patch fixes:
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:2699:49: error:
captured structured bindings are a C++20 extension
[-Werror,-Wc++20-extensions]
When VF has a fixed width and equals the number of iterations, and we are not
tail folding by masking, comparison instruction and induction operation will be DCEed later.
Ignoring the costs of these instructions improves the cost model.
This moves printing of the final VPlan to ::execute. This ensures the
final VPlan is printed, including recipes that get introduced by late,
lowering transforms and skeleton construction.
Split off from https://github.com/llvm/llvm-project/pull/114292, to
simplify the diff.
This reverts commit f09b16e2671cbcdf7cb7dc7ed705db092a9deda1.
The crash when building llvm-test-suite with stage2 should have been
fixed by 1091fad31a83d5ab87eb6fa11fe3bdb3f0d152ea.
This reverts commit 0678e2058364ec10b94560d27ec7138dfa003287.
This reverts commit 1091fad31a83d5ab87eb6fa11fe3bdb3f0d152ea.
Causes crashes in llvm-test-suite when using stage 2 clang.
Updated ILV.createInductionResumeValues (now createInductionResumeVPValue)
to directly update the VPIRInstructions wrapping the original phis with the
created resume values.
This is the first step towards modeling them completely in VPlan.
Subsequent patches will move creation of the resume values completely
into VPlan.
Depends on https://github.com/llvm/llvm-project/pull/109975.
PR: https://github.com/llvm/llvm-project/pull/110577
