This reverts the revert commit 58326f1d5b5b379590af92dd129b2f3b3e96af46.
The build failure in sanitizer stage2 builds has been fixed with
0d39fe6f5bb3edf0bddec09a8c6417377390aeac.
Original commit message:
Model updating IV users directly in VPlan, replace fixupIVUsers.
Now simple extracts are created for all phis in the exit block during
initial VPlan construction. A later VPlan transform
(optimizeInductionExitUsers) replaces extracts of inductions with
their pre-computed values if possible.
This completes the transition towards modeling all live-outs directly in
VPlan.
There are a few follow-ups:
* emit extracts initially also for resume phis, and optimize them
tougher with IV exit users
* support for VPlans with multiple exits in optimizeInductionExitUsers.
Depends on https://github.com/llvm/llvm-project/pull/110004,
https://github.com/llvm/llvm-project/pull/109975 and
https://github.com/llvm/llvm-project/pull/112145.
Model updating IV users directly in VPlan, replace fixupIVUsers.
Now simple extracts are created for all phis in the exit block during
initial VPlan construction. A later VPlan transform
(optimizeInductionExitUsers) replaces extracts of inductions with
their pre-computed values if possible.
This completes the transition towards modeling all live-outs directly in
VPlan.
There are a few follow-ups:
* emit extracts initially also for resume phis, and optimize them
tougher with IV exit users
* support for VPlans with multiple exits in optimizeInductionExitUsers.
Depends on https://github.com/llvm/llvm-project/pull/110004,
https://github.com/llvm/llvm-project/pull/109975 and
https://github.com/llvm/llvm-project/pull/112145.
In each class which calculates instruction costs (VPCostContext,
LoopVectorizationCostModel, GeneratedRTChecks) set the CostKind once in
the constructor instead of in each function that calculates a cost. This
is in preparation for potentially changing the CostKind when compiling
for optsize.
This commit relands the changes from "[LV]: Teach LV to recursively
(de)interleave. #89018"
Reason for revert:
- The patch exposed a bug in the IA pass, the bug is now fixed and landed by commit: #122643
This patch is split off #120567, adding asserts in
addScalarResumePhis and addExitUsersForFirstOrderRecurrences
that the loop does not contain an uncountable early exit,
since the code cannot yet handle them correctly.
Currently we fail to detect the case where BTC + 1 wraps, i.e. the
vector trip count is 0, In those cases, the minimum iteration count
check will fail, and the vector code will never be executed.
Explicitly check for this condition in computeMaxVF and avoid trying to
vectorize alltogether.
Note that a number of tests needed to be updated, because the vector
loop would never be executed given the input IR.
Fixes https://github.com/llvm/llvm-project/issues/122558.
I've been exploring verifying the VPlan before and after the EVL
transformation steps, and noticed that the VPlan comes out in an invalid
state between construction and optimisation.
In adjustRecipesForReductions, we leave behind some dead recipes which
are invalid:
1) When we replace a link with a reduction recipe, the old link ends up
becoming a use-before-def:
WIDEN ir<%l7> = add ir<%sum.02>, ir<%indvars.iv>.1
WIDEN ir<%l8> = add ir<%l7>.1, ir<%l3>
WIDEN ir<%l9> = add ir<%l8>.1, ir<%l5>
...
REDUCE ir<%l7>.1 = ir<%sum.02> + reduce.add (ir<%indvars.iv>.1)
REDUCE ir<%l8>.1 = ir<%l7>.1 + reduce.add (ir<%l3>)
REDUCE ir<%l9>.1 = ir<%l8>.1 + reduce.add (ir<%l5>)
2) When transforming an AnyOf reduction phi to a boolean, we leave
behind a select with mismatching operand types, which will trigger the
assertions in VTypeAnalysis after #122679
This adds an extra verification step and deletes the dead recipes
eagerly to keep the plan valid.
Following 0e528ac404e13ed2d952a2d83aaf8383293c851e, this patch adjusts
the resume value of VPReductionPHIRecipe for FindLastIV reductions.
Replacing the resume value with:
ResumeValue = ResumeValue == StartValue ? SentinelValue : ResumeValue;
This addressed the correctness issue when the start value might not be
less than the minimum value of a monotonically increasing induction
variable.
Thanks Florian Hahn for the help.
---------
Co-authored-by: Florian Hahn <flo@fhahn.com>
This relands the reverted #120721 with a fix for cases where neither
reduction operand are the reduction phi. Only
63114239cc8d26225a0ef9920baacfc7cc00fc58 and
63114239cc8d26225a0ef9920baacfc7cc00fc58 are new on top of the reverted
PR.
---------
Co-authored-by: Nicholas Guy <nicholas.guy@arm.com>
This is a split-off from #109833 and only adds code relating to checking
if a struct-returning call can be vectorized.
This initial patch only allows the case where all users of the struct
return are `extractvalue` operations that can be widened.
```
%call = tail call { float, float } @foo(float %in_val)
%extract_a = extractvalue { float, float } %call, 0
%extract_b = extractvalue { float, float } %call, 1
```
Note: The tests require the VFABI changes from #119000 to pass.
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
