1 files changed, 8 insertions, 0 deletions
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index d55ac5ee833..6b20f59046d 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -5562,6 +5562,14 @@ static bool breakDownVectorType(QualType type, uint64_t &len,
 /// vector nor a real type.
 bool Sema::areLaxCompatibleVectorTypes(QualType srcTy, QualType destTy) {
   assert(destTy->isVectorType() || srcTy->isVectorType());
+  
+  // Disallow lax conversions between scalars and ExtVectors (these
+  // conversions are allowed for other vector types because common headers
+  // depend on them).  Most scalar OP ExtVector cases are handled by the
+  // splat path anyway, which does what we want (convert, not bitcast).
+  // What this rules out for ExtVectors is crazy things like char4*float.
+  if (srcTy->isScalarType() && destTy->isExtVectorType()) return false;
+  if (destTy->isScalarType() && srcTy->isExtVectorType()) return false;
 
   uint64_t srcLen, destLen;
   QualType srcElt, destElt;