[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/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 82f055c..58103ea 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -1510,6 +1510,12 @@
E->setRParenLoc(ReadSourceLocation());
}
+void ASTStmtReader::VisitBuiltinBitCastExpr(BuiltinBitCastExpr *E) {
+ VisitExplicitCastExpr(E);
+ E->KWLoc = ReadSourceLocation();
+ E->RParenLoc = ReadSourceLocation();
+}
+
void ASTStmtReader::VisitUserDefinedLiteral(UserDefinedLiteral *E) {
VisitCallExpr(E);
E->UDSuffixLoc = ReadSourceLocation();
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 20a6b7d..486cc14 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -1451,6 +1451,12 @@
Code = serialization::EXPR_CXX_FUNCTIONAL_CAST;
}
+void ASTStmtWriter::VisitBuiltinBitCastExpr(BuiltinBitCastExpr *E) {
+ VisitExplicitCastExpr(E);
+ Record.AddSourceLocation(E->getBeginLoc());
+ Record.AddSourceLocation(E->getEndLoc());
+}
+
void ASTStmtWriter::VisitUserDefinedLiteral(UserDefinedLiteral *E) {
VisitCallExpr(E);
Record.AddSourceLocation(E->UDSuffixLoc);