[cfe-dev] improved vector bool/pixel support

[Douglas Gregor]

On Aug 5, 2010, at 1:52 AM, Anton Yartsev wrote:
> Added code for an implicit conversion between GCC and AltiVec vectors to Sema. Also attached tests with the relaxed vector conversions turned off. Please review.

Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp	(revision 110284)
+++ lib/Sema/SemaExpr.cpp	(working copy)
@@ -4751,13 +4751,18 @@
   }
 
   if (lhsType->isVectorType() || rhsType->isVectorType()) {
-    // If we are allowing lax vector conversions, and LHS and RHS are both
-    // vectors, the total size only needs to be the same. This is a bitcast;
-    // no bits are changed but the result type is different.
-    if (getLangOptions().LaxVectorConversions &&
-        lhsType->isVectorType() && rhsType->isVectorType()) {
-      if (Context.getTypeSize(lhsType) == Context.getTypeSize(rhsType))
+    if (lhsType->isVectorType() && rhsType->isVectorType()) {
+      // If we are allowing lax vector conversions, and LHS and RHS are both
+      // vectors, the total size only needs to be the same. This is a bitcast;
+      // no bits are changed but the result type is different.
+      if (getLangOptions().LaxVectorConversions &&
+         (Context.getTypeSize(lhsType) == Context.getTypeSize(rhsType)))
         return IncompatibleVectors;
+
+      // Allow assignments of an AltiVec vector type to an equivalent GCC
+      // vector type and vice versa
+      if (Context.areCompatibleVectorTypes(lhsType, rhsType))
+        return IncompatibleVectors;
     }

I don't think that you want a warning when converting between AltiVec and GCC vector types, do you? If no, the "return IncompatibleVectors;" should be "return Compatible;".

Why does the C++ test use __attribute__((overloadable))? Actually, why does the C test use it? It doesn't seem necessary in either case.

It might make sense to test the ? : operator, which often gives us trouble with conversions. 

	- Doug