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[clang][Sema] Fix PR47676: Handle dependent AltiVec C-style cast 

Fix premature decision in the presence of type-dependent expression
operands on whether AltiVec vector initializations from single
expressions are "splat" operations.

Verify that the instantiation is able to determine the correct cast
semantics for both the scalar type and the vector type case.

Note that, because the change only affects the single-expression
case (and the target type is an AltiVec-style vector type), the
replacement of a parenthesized list with a parenthesized expression
does not change the semantics of the program in a program-observable
manner.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D88526
This commit is contained in:
Hubert Tong 2020-10-01 15:46:26 -04:00
parent 88f2fe5cad
commit 35ecc7fe49
2 changed files with 39 additions and 1 deletions
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2
clang/lib/Sema/SemaExpr.cpp
View File

@ -7408,7 +7408,7 @@ Sema::ActOnCastExpr(Scope *S, SourceLocation LParenLoc,
}
if (PE || PLE->getNumExprs() == 1) {
Expr *E = (PE ? PE->getSubExpr() : PLE->getExpr(0));
if (!E->getType()->isVectorType())
if (!E->isTypeDependent() && !E->getType()->isVectorType())
isVectorLiteral = true;
}
else

38
clang/test/SemaTemplate/pr47676.cpp Normal file
View File

@ -0,0 +1,38 @@
// RUN: %clang_cc1 -triple=powerpc64le-unknown-linux-gnu \
// RUN: -target-feature +altivec -fsyntax-only -ast-dump \
// RUN: -xc++ < %s 2>&1 \
// RUN: | FileCheck %s
// Ensures that casts to AltiVec type with a dependent expression operand does
// not hit the assertion failure reported in PR47676. Further checks that casts
// to AltiVec type with a dependent expression operand is, on instantiation,
// able to correctly differentiate between a splat case and a bitcast case.
template <typename T> void f(T *tp) {
extern void g(int, ...);
g(0, (__vector int)(*tp));
g(0, (__vector int)*tp);
}
void g(void) {
f<__vector float>(nullptr);
// CHECK: | |-FunctionDecl {{.*}} f 'void (__vector float *)'
// CHECK: | | `-CStyleCastExpr {{.*}} '__vector int' <NoOp>
// CHECK-NEXT: | | `-ImplicitCastExpr {{.*}} '__vector int' <BitCast>
// CHECK-NEXT: | | `-ImplicitCastExpr {{.*}}'__vector float' <LValueToRValue>
// CHECK: | `-CStyleCastExpr {{.*}} '__vector int' <NoOp>
// CHECK-NEXT: | `-ImplicitCastExpr {{.*}} '__vector int' <BitCast>
// CHECK-NEXT: | `-ImplicitCastExpr {{.*}}'__vector float' <LValueToRValue>
f<double>(nullptr);
// CHECK: | `-FunctionDecl {{.*}} f 'void (double *)'
// CHECK: | | `-CStyleCastExpr {{.*}} '__vector int' <VectorSplat>
// CHECK-NEXT: | | `-ImplicitCastExpr {{.*}} 'int' <FloatingToIntegral>
// CHECK-NEXT: | | `-ImplicitCastExpr {{.*}}'double' <LValueToRValue>
// CHECK: | `-CStyleCastExpr {{.*}} '__vector int' <VectorSplat>
// CHECK-NEXT: | `-ImplicitCastExpr {{.*}} 'int' <FloatingToIntegral>
// CHECK-NEXT: | `-ImplicitCastExpr {{.*}}:'double' <LValueToRValue>
}