Move vector bitcast handling in constant expressions from the expression

evaluator into constant initializer handling / IRGen. The practical consequence
of this is that the bitcast now lives in the constant's definition, rather than
in its uses.

The code in the constant expression evaluator was producing vectors of the wrong
type and size (and possibly of the wrong value for a big-endian int-to-vector
bitcast). We were getting away with this only because we don't yet support
constant-folding of any expressions which inspect vector values.

llvm-svn: 145981

1 files changed, 13 insertions, 9 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index c2880a0ad13..08611c32c69 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -2541,23 +2541,27 @@ bool Expr::isConstantInitializer(ASTContext &Ctx, bool IsForRef) const {
   case CXXFunctionalCastExprClass:
   case CXXStaticCastExprClass:
   case ImplicitCastExprClass:
-  case CStyleCastExprClass:
+  case CStyleCastExprClass: {
+    const CastExpr *CE = cast<CastExpr>(this);
+
+    // Handle bitcasts of vector constants.
+    if (getType()->isVectorType() && CE->getCastKind() == CK_BitCast)
+      return CE->getSubExpr()->isConstantInitializer(Ctx, false);
+
     // Handle casts with a destination that's a struct or union; this
     // deals with both the gcc no-op struct cast extension and the
     // cast-to-union extension.
     if (getType()->isRecordType())
-      return cast<CastExpr>(this)->getSubExpr()
-        ->isConstantInitializer(Ctx, false);
-      
+      return CE->getSubExpr()->isConstantInitializer(Ctx, false);
+
     // Integer->integer casts can be handled here, which is important for
     // things like (int)(&&x-&&y).  Scary but true.
     if (getType()->isIntegerType() &&
-        cast<CastExpr>(this)->getSubExpr()->getType()->isIntegerType())
-      return cast<CastExpr>(this)->getSubExpr()
-        ->isConstantInitializer(Ctx, false);
-      
+        CE->getSubExpr()->getType()->isIntegerType())
+      return CE->getSubExpr()->isConstantInitializer(Ctx, false);
+
     break;
-      
+  }
   case MaterializeTemporaryExprClass:
     return cast<MaterializeTemporaryExpr>(this)->GetTemporaryExpr()
                                             ->isConstantInitializer(Ctx, false);