[ObjC] Emit a boxed expression as a compile-time constant if the
expression inside the parentheses is a valid UTF-8 string literal.
Previously clang emitted an expression like @("abc") as a message send
to stringWithUTF8String. This commit makes clang emit the boxed
expression as a compile-time constant instead.
This commit also has the effect of silencing the nullable-to-nonnull
conversion warning clang started emitting after r317727, which
originally motivated this commit (see https://oleb.net/2018/@keypath).
rdar://problem/42684601
Differential Revision: https://reviews.llvm.org/D58729
llvm-svn: 355662
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index 64ad582..102d21e 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -1613,6 +1613,7 @@
ConstantLValue VisitConstantExpr(const ConstantExpr *E);
ConstantLValue VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
ConstantLValue VisitStringLiteral(const StringLiteral *E);
+ ConstantLValue VisitObjCBoxedExpr(const ObjCBoxedExpr *E);
ConstantLValue VisitObjCEncodeExpr(const ObjCEncodeExpr *E);
ConstantLValue VisitObjCStringLiteral(const ObjCStringLiteral *E);
ConstantLValue VisitPredefinedExpr(const PredefinedExpr *E);
@@ -1775,10 +1776,24 @@
return CGM.GetAddrOfConstantStringFromObjCEncode(E);
}
+static ConstantLValue emitConstantObjCStringLiteral(const StringLiteral *S,
+ QualType T,
+ CodeGenModule &CGM) {
+ auto C = CGM.getObjCRuntime().GenerateConstantString(S);
+ return C.getElementBitCast(CGM.getTypes().ConvertTypeForMem(T));
+}
+
ConstantLValue
ConstantLValueEmitter::VisitObjCStringLiteral(const ObjCStringLiteral *E) {
- auto C = CGM.getObjCRuntime().GenerateConstantString(E->getString());
- return C.getElementBitCast(CGM.getTypes().ConvertTypeForMem(E->getType()));
+ return emitConstantObjCStringLiteral(E->getString(), E->getType(), CGM);
+}
+
+ConstantLValue
+ConstantLValueEmitter::VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
+ assert(E->isExpressibleAsConstantInitializer() &&
+ "this boxed expression can't be emitted as a compile-time constant");
+ auto *SL = cast<StringLiteral>(E->getSubExpr()->IgnoreParenCasts());
+ return emitConstantObjCStringLiteral(SL, E->getType(), CGM);
}
ConstantLValue