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[delinearize] use DataLayout index type in getIndexExpressionsFromGEP
Use SE.getEffectiveSCEVType(GEP->getPointerOperandType()) to get the correct pointer index sized integer type for the SCEV constant sizes, instead of using the type of the expression. This ensures the sizes have the correct type for the target's address space.
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‎0001-delinearize-use-SCEV-exprs-in-getIndexExpressionsFro.patch‎

Lines changed: 200 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,200 @@
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From 7f9239030a10aa26d7002cc05ec92d935c43c45a Mon Sep 17 00:00:00 2001
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From: Sebastian Pop <[email protected]>
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Date: Fri, 10 Oct 2025 12:01:57 -0500
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Subject: [PATCH] [delinearize] use SCEV exprs in getIndexExpressionsFromGEP
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---
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llvm/include/llvm/Analysis/Delinearization.h | 14 +++++-----
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llvm/lib/Analysis/Delinearization.cpp | 7 ++---
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llvm/lib/Analysis/DependenceAnalysis.cpp | 27 +++++++++-----------
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llvm/lib/Analysis/LoopCacheAnalysis.cpp | 5 ++--
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polly/lib/Analysis/ScopBuilder.cpp | 10 +++-----
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5 files changed, 28 insertions(+), 35 deletions(-)
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diff --git a/llvm/include/llvm/Analysis/Delinearization.h b/llvm/include/llvm/Analysis/Delinearization.h
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index 434cfb61699d..9c729b5cf18c 100644
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--- a/llvm/include/llvm/Analysis/Delinearization.h
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+++ b/llvm/include/llvm/Analysis/Delinearization.h
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@@ -145,15 +145,15 @@ bool delinearizeFixedSizeArray(ScalarEvolution &SE, const SCEV *Expr,
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///
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/// This function optimistically assumes the GEP references into a fixed size
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/// array. If this is actually true, this function returns a list of array
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-/// subscript expressions in \p Subscripts and a list of integers describing
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-/// the size of the individual array dimensions in \p Sizes. Both lists have
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-/// either equal length or the size list is one element shorter in case there
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-/// is no known size available for the outermost array dimension. Returns true
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-/// if successful and false otherwise.
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+/// subscript expressions in \p Subscripts and a list of SCEV expressions
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+/// describing the size of the individual array dimensions in \p Sizes. Both
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+/// lists have either equal length or the size list is one element shorter in
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+/// case there is no known size available for the outermost array dimension.
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+/// Returns true if successful and false otherwise.
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bool getIndexExpressionsFromGEP(ScalarEvolution &SE,
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const GetElementPtrInst *GEP,
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SmallVectorImpl<const SCEV *> &Subscripts,
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- SmallVectorImpl<int> &Sizes);
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+ SmallVectorImpl<const SCEV *> &Sizes);
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/// Implementation of fixed size array delinearization. Try to delinearize
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/// access function for a fixed size multi-dimensional array, by deriving
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@@ -164,7 +164,7 @@ bool getIndexExpressionsFromGEP(ScalarEvolution &SE,
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bool tryDelinearizeFixedSizeImpl(ScalarEvolution *SE, Instruction *Inst,
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const SCEV *AccessFn,
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SmallVectorImpl<const SCEV *> &Subscripts,
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- SmallVectorImpl<int> &Sizes);
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+ SmallVectorImpl<const SCEV *> &Sizes);
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struct DelinearizationPrinterPass
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: public PassInfoMixin<DelinearizationPrinterPass> {
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diff --git a/llvm/lib/Analysis/Delinearization.cpp b/llvm/lib/Analysis/Delinearization.cpp
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index 4064b25d9d4e..f438a9bd9ecd 100644
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--- a/llvm/lib/Analysis/Delinearization.cpp
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+++ b/llvm/lib/Analysis/Delinearization.cpp
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@@ -659,7 +659,7 @@ bool llvm::delinearizeFixedSizeArray(ScalarEvolution &SE, const SCEV *Expr,
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bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
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const GetElementPtrInst *GEP,
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SmallVectorImpl<const SCEV *> &Subscripts,
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- SmallVectorImpl<int> &Sizes) {
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+ SmallVectorImpl<const SCEV *> &Sizes) {
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assert(Subscripts.empty() && Sizes.empty() &&
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"Expected output lists to be empty on entry to this function.");
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assert(GEP && "getIndexExpressionsFromGEP called with a null GEP");
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@@ -690,7 +690,8 @@ bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
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Subscripts.push_back(Expr);
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if (!(DroppedFirstDim && i == 2))
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- Sizes.push_back(ArrayTy->getNumElements());
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+ Sizes.push_back(SE.getConstant(Expr->getType(),
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+ ArrayTy->getNumElements()));
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Ty = ArrayTy->getElementType();
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}
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@@ -706,7 +707,7 @@ bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
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bool llvm::tryDelinearizeFixedSizeImpl(
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ScalarEvolution *SE, Instruction *Inst, const SCEV *AccessFn,
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- SmallVectorImpl<const SCEV *> &Subscripts, SmallVectorImpl<int> &Sizes) {
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+ SmallVectorImpl<const SCEV *> &Subscripts, SmallVectorImpl<const SCEV *> &Sizes) {
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Value *SrcPtr = getLoadStorePointerOperand(Inst);
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// Check the simple case where the array dimensions are fixed size.
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diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
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index 8d20b0e10305..7dd0bea75c84 100644
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--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
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+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
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@@ -3504,8 +3504,8 @@ bool DependenceInfo::tryDelinearizeFixedSize(
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"expected src and dst scev unknowns to be equal");
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});
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- SmallVector<int, 4> SrcSizes;
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- SmallVector<int, 4> DstSizes;
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+ SmallVector<const SCEV *, 4> SrcSizes;
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+ SmallVector<const SCEV *, 4> DstSizes;
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if (!tryDelinearizeFixedSizeImpl(SE, Src, SrcAccessFn, SrcSubscripts,
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SrcSizes) ||
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!tryDelinearizeFixedSizeImpl(SE, Dst, DstAccessFn, DstSubscripts,
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@@ -3513,7 +3513,7 @@ bool DependenceInfo::tryDelinearizeFixedSize(
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return false;
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// Check that the two size arrays are non-empty and equal in length and
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- // value.
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+ // value. SCEV expressions are uniqued, so we can compare pointers.
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if (SrcSizes.size() != DstSizes.size() ||
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!std::equal(SrcSizes.begin(), SrcSizes.end(), DstSizes.begin())) {
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SrcSubscripts.clear();
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@@ -3535,7 +3535,7 @@ bool DependenceInfo::tryDelinearizeFixedSize(
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// iff the subscripts are positive and are less than the range of the
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// dimension.
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if (!DisableDelinearizationChecks) {
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- auto AllIndicesInRange = [&](SmallVector<int, 4> &DimensionSizes,
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+ auto AllIndicesInRange = [&](SmallVector<const SCEV *, 4> &DimensionSizes,
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SmallVectorImpl<const SCEV *> &Subscripts,
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Value *Ptr) {
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size_t SSize = Subscripts.size();
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@@ -3548,17 +3548,14 @@ bool DependenceInfo::tryDelinearizeFixedSize(
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});
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return false;
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}
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- if (auto *SType = dyn_cast<IntegerType>(S->getType())) {
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- const SCEV *Range = SE->getConstant(
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- ConstantInt::get(SType, DimensionSizes[I - 1], false));
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- if (!isKnownLessThan(S, Range)) {
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- LLVM_DEBUG({
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- dbgs() << "Check failed: !isKnownLessThan(S, Range)\n";
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- dbgs() << " S: " << *S << "\n"
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- << " Range: " << *Range << "\n";
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- });
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- return false;
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- }
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+ const SCEV *Range = DimensionSizes[I - 1];
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+ if (!isKnownLessThan(S, Range)) {
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+ LLVM_DEBUG({
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+ dbgs() << "Check failed: !isKnownLessThan(S, Range)\n";
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+ dbgs() << " S: " << *S << "\n"
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+ << " Range: " << *Range << "\n";
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+ });
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+ return false;
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}
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}
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return true;
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diff --git a/llvm/lib/Analysis/LoopCacheAnalysis.cpp b/llvm/lib/Analysis/LoopCacheAnalysis.cpp
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index 050c32707596..74bcce8f51a4 100644
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--- a/llvm/lib/Analysis/LoopCacheAnalysis.cpp
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+++ b/llvm/lib/Analysis/LoopCacheAnalysis.cpp
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@@ -356,15 +356,14 @@ CacheCostTy IndexedReference::computeRefCost(const Loop &L,
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bool IndexedReference::tryDelinearizeFixedSize(
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const SCEV *AccessFn, SmallVectorImpl<const SCEV *> &Subscripts) {
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- SmallVector<int, 4> ArraySizes;
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+ SmallVector<const SCEV *, 4> ArraySizes;
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if (!tryDelinearizeFixedSizeImpl(&SE, &StoreOrLoadInst, AccessFn, Subscripts,
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ArraySizes))
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return false;
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// Populate Sizes with scev expressions to be used in calculations later.
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for (auto Idx : seq<unsigned>(1, Subscripts.size()))
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- Sizes.push_back(
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- SE.getConstant(Subscripts[Idx]->getType(), ArraySizes[Idx - 1]));
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+ Sizes.push_back(ArraySizes[Idx - 1]);
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LLVM_DEBUG({
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dbgs() << "Delinearized subscripts of fixed-size array\n"
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diff --git a/polly/lib/Analysis/ScopBuilder.cpp b/polly/lib/Analysis/ScopBuilder.cpp
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index 67a4c4345580..ec77b15ddd76 100644
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--- a/polly/lib/Analysis/ScopBuilder.cpp
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+++ b/polly/lib/Analysis/ScopBuilder.cpp
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@@ -1463,7 +1463,7 @@ bool ScopBuilder::buildAccessMultiDimFixed(MemAccInst Inst, ScopStmt *Stmt) {
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return false;
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SmallVector<const SCEV *, 4> Subscripts;
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- SmallVector<int, 4> Sizes;
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+ SmallVector<const SCEV *, 4> Sizes;
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getIndexExpressionsFromGEP(SE, GEP, Subscripts, Sizes);
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auto *BasePtr = GEP->getOperand(0);
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@@ -1475,8 +1475,6 @@ bool ScopBuilder::buildAccessMultiDimFixed(MemAccInst Inst, ScopStmt *Stmt) {
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if (BasePtr != BasePointer->getValue())
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return false;
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- std::vector<const SCEV *> SizesSCEV;
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-
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const InvariantLoadsSetTy &ScopRIL = scop->getRequiredInvariantLoads();
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Loop *SurroundingLoop = Stmt->getSurroundingLoop();
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@@ -1494,11 +1492,9 @@ bool ScopBuilder::buildAccessMultiDimFixed(MemAccInst Inst, ScopStmt *Stmt) {
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if (Sizes.empty())
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return false;
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+ std::vector<const SCEV *> SizesSCEV;
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SizesSCEV.push_back(nullptr);
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-
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- for (auto V : Sizes)
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- SizesSCEV.push_back(SE.getSCEV(
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- ConstantInt::get(IntegerType::getInt64Ty(BasePtr->getContext()), V)));
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+ SizesSCEV.insert(SizesSCEV.end(), Sizes.begin(), Sizes.end());
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addArrayAccess(Stmt, Inst, AccType, BasePointer->getValue(), ElementType,
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true, Subscripts, SizesSCEV, Val);
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--
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2.45.2
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‎llvm/lib/Analysis/Delinearization.cpp‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -830,6 +830,7 @@ bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
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assert(GEP && "getIndexExpressionsFromGEP called with a null GEP");
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LLVM_DEBUG(dbgs() << "\nGEP to delinearize: " << *GEP << "\n");
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Type *Ty = nullptr;
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Type *IndexTy = SE.getEffectiveSCEVType(GEP->getPointerOperandType());
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bool DroppedFirstDim = false;
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for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
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const SCEV *Expr = SE.getSCEV(GEP->getOperand(i));
@@ -855,8 +856,7 @@ bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
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856857
Subscripts.push_back(Expr);
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if (!(DroppedFirstDim && i == 2))
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Sizes.push_back(SE.getConstant(Expr->getType(),
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ArrayTy->getNumElements()));
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Sizes.push_back(SE.getConstant(IndexTy, ArrayTy->getNumElements()));
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Ty = ArrayTy->getElementType();
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}

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