When evaluating a VarDecl as a constant or determining whether it is
an integral constant expression, maintain a cache of the value and the
is-an-ICE flag within the VarDecl itself. This eliminates
exponential-time behavior of the Fibonacci template metaprogram.
llvm-svn: 72428
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 34b0187..7651884 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -700,8 +700,17 @@
// In C, they can also be folded, although they are not ICEs.
if (E->getType().getCVRQualifiers() == QualType::Const) {
if (const VarDecl *D = dyn_cast<VarDecl>(E->getDecl())) {
- if (const Expr *Init = D->getInit())
- return Visit(const_cast<Expr*>(Init));
+ if (APValue *V = D->getEvaluatedValue())
+ return Success(V->getInt(), E);
+ if (const Expr *Init = D->getInit()) {
+ if (Visit(const_cast<Expr*>(Init))) {
+ // Cache the evaluated value in the variable declaration.
+ D->setEvaluatedValue(Info.Ctx, Result);
+ return true;
+ }
+
+ return false;
+ }
}
}