[llvm] [VPlan] Add initial VPScalarEvolution, use to get trip count SCEV (NFC) (PR #94464)
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 12 02:34:06 PDT 2024
https://github.com/fhahn updated https://github.com/llvm/llvm-project/pull/94464
>From fcd41480cd1539e37e046c31a95062ba43633103 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Wed, 5 Jun 2024 12:59:47 +0100
Subject: [PATCH 1/2] [VPlan] Add initial VPScalarEvolution, use to get trip
count SCEV (NFC)
Add an initial version of VPScalarEvolution, which can be used to return
a SCEV expression for a VPValue. The initial implementation only returns
SCEVs for live-in IR values (by constructing a SCEV based on the live-in
IR value) and VPExpandSCEVRecipe. This is enough to serve its first
use, getting a SCEV for a VPlan's trip count, but will be extended in
the future.
---
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 5 +++--
llvm/lib/Transforms/Vectorize/VPlan.h | 3 ---
llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp | 13 +++++++++++++
llvm/lib/Transforms/Vectorize/VPlanAnalysis.h | 15 +++++++++++++++
llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp | 4 +---
5 files changed, 32 insertions(+), 8 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index c7c19ef456c7c..14197259a9f98 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -978,8 +978,9 @@ Value *getRuntimeVF(IRBuilderBase &B, Type *Ty, ElementCount VF) {
return B.CreateElementCount(Ty, VF);
}
-const SCEV *createTripCountSCEV(Type *IdxTy, PredicatedScalarEvolution &PSE,
- Loop *OrigLoop) {
+static const SCEV *createTripCountSCEV(Type *IdxTy,
+ PredicatedScalarEvolution &PSE,
+ Loop *OrigLoop) {
const SCEV *BackedgeTakenCount = PSE.getBackedgeTakenCount();
assert(!isa<SCEVCouldNotCompute>(BackedgeTakenCount) && "Invalid loop count");
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 943edc3520869..de37262d2c3de 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -79,9 +79,6 @@ Value *getRuntimeVF(IRBuilderBase &B, Type *Ty, ElementCount VF);
Value *createStepForVF(IRBuilderBase &B, Type *Ty, ElementCount VF,
int64_t Step);
-const SCEV *createTripCountSCEV(Type *IdxTy, PredicatedScalarEvolution &PSE,
- Loop *CurLoop = nullptr);
-
/// A range of powers-of-2 vectorization factors with fixed start and
/// adjustable end. The range includes start and excludes end, e.g.,:
/// [1, 16) = {1, 2, 4, 8}
diff --git a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
index 90bbf2d5d99fa..e9f01c1a334e1 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
@@ -9,6 +9,7 @@
#include "VPlanAnalysis.h"
#include "VPlan.h"
#include "llvm/ADT/TypeSwitch.h"
+#include "llvm/Analysis/ScalarEvolution.h"
using namespace llvm;
@@ -265,3 +266,15 @@ Type *VPTypeAnalysis::inferScalarType(const VPValue *V) {
CachedTypes[V] = ResultTy;
return ResultTy;
}
+
+const SCEV *VPScalarEvolution::getSCEV(VPValue *V) {
+ if (V->isLiveIn())
+ return SE.getSCEV(V->getLiveInIRValue());
+
+ // TODO: Support constructing SCEVs for more recipes as needed.
+ return TypeSwitch<const VPRecipeBase *, const SCEV *>(V->getDefiningRecipe())
+ .Case<VPExpandSCEVRecipe>(
+ [](const VPExpandSCEVRecipe *R) { return R->getSCEV(); })
+ .Default(
+ [this](const VPRecipeBase *) { return SE.getCouldNotCompute(); });
+}
diff --git a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h
index 7d310b1b31b6f..9d549778092c9 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h
@@ -23,6 +23,8 @@ class VPWidenIntOrFpInductionRecipe;
class VPWidenMemoryRecipe;
struct VPWidenSelectRecipe;
class VPReplicateRecipe;
+class SCEV;
+class ScalarEvolution;
class Type;
/// An analysis for type-inference for VPValues.
@@ -61,6 +63,19 @@ class VPTypeAnalysis {
LLVMContext &getContext() { return Ctx; }
};
+/// A light wrapper over ScalarEvolution to construct SCEV expressions for
+/// VPValues and recipes.
+class VPScalarEvolution {
+ ScalarEvolution &SE;
+
+public:
+ VPScalarEvolution(ScalarEvolution &SE) : SE(SE) {}
+
+ /// Return the SCEV expression for \p V. Returns SCEVCouldNotCompute if no
+ /// SCEV expression could be constructed.
+ const SCEV *getSCEV(VPValue *V);
+};
+
} // end namespace llvm
#endif // LLVM_TRANSFORMS_VECTORIZE_VPLANANALYSIS_H
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index ab3b5cf2b9dab..541246266e1d5 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -674,10 +674,8 @@ void VPlanTransforms::optimizeForVFAndUF(VPlan &Plan, ElementCount BestVF,
m_BranchOnCond(m_Not(m_ActiveLaneMask(m_VPValue(), m_VPValue())))))
return;
- Type *IdxTy =
- Plan.getCanonicalIV()->getStartValue()->getLiveInIRValue()->getType();
- const SCEV *TripCount = createTripCountSCEV(IdxTy, PSE);
ScalarEvolution &SE = *PSE.getSE();
+ const SCEV *TripCount = VPScalarEvolution(SE).getSCEV(Plan.getTripCount());
ElementCount NumElements = BestVF.multiplyCoefficientBy(BestUF);
const SCEV *C = SE.getElementCount(TripCount->getType(), NumElements);
if (TripCount->isZero() ||
>From d7d389e7a072799989e94dad1e440e1826bbe0ab Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Fri, 12 Jul 2024 10:33:19 +0100
Subject: [PATCH 2/2] !fixup move logic to single getSCEVExprForVPValue
function
---
llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp | 5 ++---
llvm/lib/Transforms/Vectorize/VPlanAnalysis.h | 16 ++++++----------
.../lib/Transforms/Vectorize/VPlanTransforms.cpp | 3 ++-
3 files changed, 10 insertions(+), 14 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
index d3f4c18d98fb4..245b26e4ce22c 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
@@ -318,7 +318,7 @@ void llvm::collectEphemeralRecipesForVPlan(
}
}
-const SCEV *VPScalarEvolution::getSCEV(VPValue *V) {
+const SCEV *vputils::getSCEVExprForVPValue(VPValue *V, ScalarEvolution &SE) {
if (V->isLiveIn())
return SE.getSCEV(V->getLiveInIRValue());
@@ -326,6 +326,5 @@ const SCEV *VPScalarEvolution::getSCEV(VPValue *V) {
return TypeSwitch<const VPRecipeBase *, const SCEV *>(V->getDefiningRecipe())
.Case<VPExpandSCEVRecipe>(
[](const VPExpandSCEVRecipe *R) { return R->getSCEV(); })
- .Default(
- [this](const VPRecipeBase *) { return SE.getCouldNotCompute(); });
+ .Default([&SE](const VPRecipeBase *) { return SE.getCouldNotCompute(); });
}
diff --git a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h
index 51eaa0f702018..ef2012a32e66b 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.h
@@ -70,18 +70,14 @@ class VPTypeAnalysis {
void collectEphemeralRecipesForVPlan(VPlan &Plan,
DenseSet<VPRecipeBase *> &EphRecipes);
-/// A light wrapper over ScalarEvolution to construct SCEV expressions for
-/// VPValues and recipes.
-class VPScalarEvolution {
- ScalarEvolution &SE;
+namespace vputils {
-public:
- VPScalarEvolution(ScalarEvolution &SE) : SE(SE) {}
+/// Return the SCEV expression for \p V. Returns SCEVCouldNotCompute if no
+/// SCEV expression could be constructed.
+const SCEV *getSCEVExprForVPValue(VPValue *V, ScalarEvolution &SE);
+
+} // namespace vputils
- /// Return the SCEV expression for \p V. Returns SCEVCouldNotCompute if no
- /// SCEV expression could be constructed.
- const SCEV *getSCEV(VPValue *V);
-};
} // end namespace llvm
#endif // LLVM_TRANSFORMS_VECTORIZE_VPLANANALYSIS_H
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 734ab96a4a68a..b55e716fbff37 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -684,7 +684,8 @@ void VPlanTransforms::optimizeForVFAndUF(VPlan &Plan, ElementCount BestVF,
return;
ScalarEvolution &SE = *PSE.getSE();
- const SCEV *TripCount = VPScalarEvolution(SE).getSCEV(Plan.getTripCount());
+ const SCEV *TripCount =
+ vputils::getSCEVExprForVPValue(Plan.getTripCount(), SE);
ElementCount NumElements = BestVF.multiplyCoefficientBy(BestUF);
const SCEV *C = SE.getElementCount(TripCount->getType(), NumElements);
if (TripCount->isZero() ||
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