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[SCEV] Improve code in SCEVLoopGuardRewriter (NFC) #139257

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Merged
merged 2 commits into from
May 11, 2025
Merged

[SCEV] Improve code in SCEVLoopGuardRewriter (NFC) #139257

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95dc5b8
[SCEV] Improve code in SCEVLoopGuardRewriter (NFC)
artagnon May 9, 2025
1d6841a
[SCEV] Fix nit
artagnon May 11, 2025
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60 changes: 28 additions & 32 deletions llvm/lib/Analysis/ScalarEvolution.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15867,49 +15867,45 @@ const SCEV *ScalarEvolution::LoopGuards::rewrite(const SCEV *Expr) const {
}

const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
auto I = Map.find(Expr);
if (I == Map.end()) {
// If we didn't find the extact ZExt expr in the map, check if there's
// an entry for a smaller ZExt we can use instead.
Type *Ty = Expr->getType();
const SCEV *Op = Expr->getOperand(0);
unsigned Bitwidth = Ty->getScalarSizeInBits() / 2;
while (Bitwidth % 8 == 0 && Bitwidth >= 8 &&
Bitwidth > Op->getType()->getScalarSizeInBits()) {
Type *NarrowTy = IntegerType::get(SE.getContext(), Bitwidth);
auto *NarrowExt = SE.getZeroExtendExpr(Op, NarrowTy);
auto I = Map.find(NarrowExt);
if (I != Map.end())
return SE.getZeroExtendExpr(I->second, Ty);
Bitwidth = Bitwidth / 2;
}
if (const SCEV *S = Map.lookup(Expr))
return S;

return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitZeroExtendExpr(
Expr);
// If we didn't find the extact ZExt expr in the map, check if there's
// an entry for a smaller ZExt we can use instead.
Type *Ty = Expr->getType();
const SCEV *Op = Expr->getOperand(0);
unsigned Bitwidth = Ty->getScalarSizeInBits() / 2;
while (Bitwidth % 8 == 0 && Bitwidth >= 8 &&
Bitwidth > Op->getType()->getScalarSizeInBits()) {
Type *NarrowTy = IntegerType::get(SE.getContext(), Bitwidth);
auto *NarrowExt = SE.getZeroExtendExpr(Op, NarrowTy);
auto I = Map.find(NarrowExt);
if (I != Map.end())
return SE.getZeroExtendExpr(I->second, Ty);
Bitwidth = Bitwidth / 2;
}
return I->second;

return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitZeroExtendExpr(
Expr);
}

const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
auto I = Map.find(Expr);
if (I == Map.end())
return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitSignExtendExpr(
Expr);
return I->second;
if (const SCEV *S = Map.lookup(Expr))
return S;
return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitSignExtendExpr(
Expr);
}

const SCEV *visitUMinExpr(const SCEVUMinExpr *Expr) {
auto I = Map.find(Expr);
if (I == Map.end())
return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitUMinExpr(Expr);
return I->second;
if (const SCEV *S = Map.lookup(Expr))
return S;
return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitUMinExpr(Expr);
}

const SCEV *visitSMinExpr(const SCEVSMinExpr *Expr) {
auto I = Map.find(Expr);
if (I == Map.end())
return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitSMinExpr(Expr);
return I->second;
if (const SCEV *S = Map.lookup(Expr))
return S;
return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitSMinExpr(Expr);
}

const SCEV *visitAddExpr(const SCEVAddExpr *Expr) {
Expand Down