[LV][VPlan] Remove any-of reduction from precomputeCost. NFC #117109
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The any-of reduction contains phi and select instructions. The select instruction might be optimized and removed in the vplan which may cause VF difference between legacy and VPlan-based model. But if the select instruction be removed, `planContainsAdditionalSimplifications()` will catch it and disable the assertion. Therefore, we can just remove the ayn-of reduction calculation in the precomputeCost().
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@llvm/pr-subscribers-vectorizers @llvm/pr-subscribers-llvm-transforms Author: Elvis Wang (ElvisWang123) ChangesThe any-of reduction contains phi and select instructions. The select instruction might be optimized and removed in the vplan which may cause VF difference between legacy and VPlan-based model. But if the select instruction be removed, Therefore, we can just remove the ayn-of reduction calculation in the precomputeCost(). Full diff: https://github.com/llvm/llvm-project/pull/117109.diff 1 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 1ebc62f9843905..e2b76948cb6b19 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7278,34 +7278,14 @@ LoopVectorizationPlanner::precomputeCosts(VPlan &Plan, ElementCount VF,
// The legacy cost model has special logic to compute the cost of in-loop
// reductions, which may be smaller than the sum of all instructions involved
- // in the reduction. For AnyOf reductions, VPlan codegen may remove the select
- // which the legacy cost model uses to assign cost. Pre-compute their costs
- // for now.
+ // in the reduction.
// TODO: Switch to costing based on VPlan once the logic has been ported.
for (const auto &[RedPhi, RdxDesc] : Legal->getReductionVars()) {
if (ForceTargetInstructionCost.getNumOccurrences())
continue;
- if (!CM.isInLoopReduction(RedPhi) &&
- !RecurrenceDescriptor::isAnyOfRecurrenceKind(
- RdxDesc.getRecurrenceKind()))
- continue;
-
- // AnyOf reduction codegen may remove the select. To match the legacy cost
- // model, pre-compute the cost for AnyOf reductions here.
- if (RecurrenceDescriptor::isAnyOfRecurrenceKind(
- RdxDesc.getRecurrenceKind())) {
- auto *Select = cast<SelectInst>(*find_if(
- RedPhi->users(), [](User *U) { return isa<SelectInst>(U); }));
- assert(!CostCtx.SkipCostComputation.contains(Select) &&
- "reduction op visited multiple times");
- CostCtx.SkipCostComputation.insert(Select);
- auto ReductionCost = CostCtx.getLegacyCost(Select, VF);
- LLVM_DEBUG(dbgs() << "Cost of " << ReductionCost << " for VF " << VF
- << ":\n any-of reduction " << *Select << "\n");
- Cost += ReductionCost;
+ if (!CM.isInLoopReduction(RedPhi))
continue;
- }
const auto &ChainOps = RdxDesc.getReductionOpChain(RedPhi, OrigLoop);
SetVector<Instruction *> ChainOpsAndOperands(ChainOps.begin(),
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/137/builds/9080 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/185/builds/8966 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/65/builds/8196 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/9989 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/175/builds/8968 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/108/builds/6249 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/33/builds/6980 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/16/builds/9385 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/13412 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/56/builds/12827 Here is the relevant piece of the build log for the reference |
ElvisWang123
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Nov 28, 2024
#117109)" (#117289) Update the test cases contains `any-of` printings from the precomputeCost(). Origin message: The any-of reduction contains phi and select instructions. The select instruction might be optimized and removed in the vplan which may cause VF difference between legacy and VPlan-based model. But if the select instruction be removed, planContainsAdditionalSimplifications() will catch it and disable the assertion. Therefore, we can just remove the ayn-of reduction calculation in the precomputeCost(). Recommit "[LV][VPlan] Remove any-of reduction from precomputeCost. NFC (#117109)"
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The any-of reduction contains phi and select instructions.
The select instruction might be optimized and removed in the vplan which may cause VF difference between legacy and VPlan-based model. But if the select instruction be removed,
planContainsAdditionalSimplifications()will catch it and disable the assertion.Therefore, we can just remove the ayn-of reduction calculation in the precomputeCost().