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[Delinearization] Modernize loops (NFC) #146151

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[Delinearization] Modernize loops (NFC) #146151

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28 changes: 13 additions & 15 deletions llvm/lib/Analysis/Delinearization.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -349,24 +349,22 @@ void llvm::computeAccessFunctions(ScalarEvolution &SE, const SCEV *Expr,
return;

const SCEV *Res = Expr;
int Last = Sizes.size() - 1;
for (int i = Last; i >= 0; i--) {
for (const auto &[Idx, Sz] : enumerate(reverse(Sizes))) {
const SCEV *Q, *R;
SCEVDivision::divide(SE, Res, Sizes[i], &Q, &R);
SCEVDivision::divide(SE, Res, Sz, &Q, &R);

LLVM_DEBUG({
dbgs() << "Res: " << *Res << "\n";
dbgs() << "Sizes[i]: " << *Sizes[i] << "\n";
dbgs() << "Sizes[i]: " << *Sz << "\n";
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@kasuga-fj kasuga-fj Jun 30, 2025

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Can you keep the variable name as it is? This is no longer Sizes[i].

dbgs() << "Res divided by Sizes[i]:\n";
dbgs() << "Quotient: " << *Q << "\n";
dbgs() << "Remainder: " << *R << "\n";
});

Res = Q;

// Do not record the last subscript corresponding to the size of elements in
// the array.
if (i == Last) {
// Do not record the last subscript.
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@kasuga-fj kasuga-fj Jun 30, 2025

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Why is this comment updated?

if (Idx == 0) {
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@kasuga-fj kasuga-fj Jun 30, 2025

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Hmm, I personally feel the previous one is more readable...


// Bail out if the byte offset is non-zero.
if (!R->isZero()) {
Expand Down Expand Up @@ -489,9 +487,9 @@ bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
assert(GEP && "getIndexExpressionsFromGEP called with a null GEP");
Type *Ty = nullptr;
bool DroppedFirstDim = false;
for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
const SCEV *Expr = SE.getSCEV(GEP->getOperand(i));
if (i == 1) {
for (const auto [Idx, Op] : drop_begin(enumerate(GEP->operands()))) {
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@kasuga-fj kasuga-fj Jun 30, 2025

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Suggested change
for (const auto [Idx, Op] : drop_begin(enumerate(GEP->operands()))) {
for (const auto &[Idx, Op] : drop_begin(enumerate(GEP->operands()))) {

In addition, this function should be removed because it uses the GEP source element type for its optimization heuristics. IMHO, such a function should not be modified unless it causes a serious issue.

const SCEV *Expr = SE.getSCEV(Op);
if (Idx == 1) {
Ty = GEP->getSourceElementType();
if (auto *Const = dyn_cast<SCEVConstant>(Expr))
if (Const->getValue()->isZero()) {
Expand All @@ -510,7 +508,7 @@ bool llvm::getIndexExpressionsFromGEP(ScalarEvolution &SE,
}

Subscripts.push_back(Expr);
if (!(DroppedFirstDim && i == 2))
if (!(DroppedFirstDim && Idx == 2))
Sizes.push_back(ArrayTy->getNumElements());

Ty = ArrayTy->getElementType();
Expand Down Expand Up @@ -596,13 +594,13 @@ void printDelinearization(raw_ostream &O, Function *F, LoopInfo *LI,
O << "Base offset: " << *BasePointer << "\n";
O << "ArrayDecl[UnknownSize]";
int Size = Subscripts.size();
for (int i = 0; i < Size - 1; i++)
O << "[" << *Sizes[i] << "]";
for (const SCEV *Sz : drop_end(Sizes))
O << "[" << *Sz << "]";
O << " with elements of " << *Sizes[Size - 1] << " bytes.\n";

O << "ArrayRef";
for (int i = 0; i < Size; i++)
O << "[" << *Subscripts[i] << "]";
for (const SCEV *Sub : Subscripts)
O << "[" << *Sub << "]";
O << "\n";
}
}
Expand Down
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