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Fix a crash in constant evaluation of ExtVectorElementExprs #136771

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Merged
merged 1 commit into from
Apr 24, 2025
Merged

Fix a crash in constant evaluation of ExtVectorElementExprs #136771

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5 changes: 4 additions & 1 deletion clang/lib/AST/ExprConstant.cpp
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Expand Up @@ -9197,7 +9197,10 @@ bool LValueExprEvaluator::VisitExtVectorElementExpr(

if (Success) {
Result.setFrom(Info.Ctx, Val);
const auto *VT = E->getBase()->getType()->castAs<VectorType>();
QualType BaseType = E->getBase()->getType();
if (E->isArrow())
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I'm a little surprised this isn't already handled in the AST. I would expect the sub-expression to be a dereference of the vector type in the AST instead to having to do this (for the same reason that I would expect *vecTyPtr to have one).

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Is sub-expression the base expression in this case? For ExtVectorElementExpr, the base expression is whatever the LHS of -> or . is and that decision was made a long time ago. I think MemberExpr's base expression can be a pointer type too.

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Ah, huh, I didn't realize that about MemberExpr, I guess this IS consistent. Odd choice that we made...

BaseType = BaseType->getPointeeType();
const auto *VT = BaseType->castAs<VectorType>();
HandleLValueVectorElement(Info, E, Result, VT->getElementType(),
VT->getNumElements(), Indices[0]);
}
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2 changes: 2 additions & 0 deletions clang/test/SemaCXX/constexpr-vectors-access-elements.cpp
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Expand Up @@ -43,4 +43,6 @@ static_assert(b.lo.lo == 1); // expected-error {{not an integral constant expres
// make sure clang rejects taking address of a vector element
static_assert(&b[1]); // expected-error {{address of vector element requested}}

constexpr const FourIntsExtVec *p = &b;
static_assert(p->x == 1);
}
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