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[DenseMap] Fix constness issues with lookup_or #139247

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Merged
merged 2 commits into from
May 28, 2025
Merged

[DenseMap] Fix constness issues with lookup_or #139247

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c1d2731
[DenseMap] Fix constness issues with lookup_or
artagnon May 9, 2025
9f49a22
[DenseMapTest] Fix test
artagnon May 28, 2025
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3 changes: 1 addition & 2 deletions llvm/include/llvm/ADT/DenseMap.h
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Expand Up @@ -220,8 +220,7 @@ class DenseMapBase : public DebugEpochBase {
// Return the entry with the specified key, or \p Default. This variant is
// useful, because `lookup` cannot be used with non-default-constructible
// values.
ValueT lookup_or(const_arg_type_t<KeyT> Val,
const_arg_type_t<ValueT> Default) const {
ValueT lookup_or(const_arg_type_t<KeyT> Val, ValueT &&Default) const {
if (const BucketT *Bucket = doFind(Val))
return Bucket->getSecond();
return Default;
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5 changes: 1 addition & 4 deletions llvm/lib/Analysis/ScalarEvolution.cpp
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Expand Up @@ -15904,10 +15904,7 @@ const SCEV *ScalarEvolution::LoopGuards::rewrite(const SCEV *Expr) const {
const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { return Expr; }

const SCEV *visitUnknown(const SCEVUnknown *Expr) {
auto I = Map.find(Expr);
if (I == Map.end())
return Expr;
return I->second;
return Map.lookup_or(Expr, Expr);
}

const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
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7 changes: 7 additions & 0 deletions llvm/unittests/ADT/DenseMapTest.cpp
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Expand Up @@ -671,6 +671,13 @@ TEST(DenseMapCustomTest, LookupOr) {
EXPECT_EQ(M.lookup_or(2, 4u), 4u);
}

TEST(DenseMapCustomTest, LookupOrConstness) {
DenseMap<int, unsigned *> M;
unsigned Default = 3u;
unsigned *Ret = M.lookup_or(0, &Default);
EXPECT_EQ(Ret, &Default);
}

// Key traits that allows lookup with either an unsigned or char* key;
// In the latter case, "a" == 0, "b" == 1 and so on.
struct TestDenseMapInfo {
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