[C++2a] Add __builtin_bit_cast, used to implement std::bit_cast
This commit adds a new builtin, __builtin_bit_cast(T, v), which performs a
bit_cast from a value v to a type T. This expression can be evaluated at
compile time under specific circumstances.
The compile time evaluation currently doesn't support bit-fields, but I'm
planning on fixing this in a follow up (some of the logic for figuring this out
is in CodeGen). I'm also planning follow-ups for supporting some more esoteric
types that the constexpr evaluator supports, as well as extending
__builtin_memcpy constexpr evaluation to use the same infrastructure.
rdar://44987528
Differential revision: https://reviews.llvm.org/D62825
llvm-svn: 364954
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 83c017f..46802d7 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -1703,6 +1703,14 @@
VisitCXXNamedCastExpr(Node);
}
+void StmtPrinter::VisitBuiltinBitCastExpr(BuiltinBitCastExpr *Node) {
+ OS << "__builtin_bit_cast(";
+ Node->getTypeInfoAsWritten()->getType().print(OS, Policy);
+ OS << ", ";
+ PrintExpr(Node->getSubExpr());
+ OS << ")";
+}
+
void StmtPrinter::VisitCXXTypeidExpr(CXXTypeidExpr *Node) {
OS << "typeid(";
if (Node->isTypeOperand()) {