http://sourceware.org/ml/gdb-patches/2012-11/msg00312.html

gdb/ChangeLog
        * valarith.c (value_vector_widen): New function for replicating a
        scalar into a vector.
        (value_binop): Use value_vector_widen to widen scalar to vector
        rather than casting, this better matches gcc C behaviour.
        * valops.c (value_casst): Update logic for casting between vector
        types, and for casting from scalar to vector, try to match gcc C
        behaviour.
        * value.h (value_vector_widen): Declare.
        * opencl-lang.c (opencl_value_cast): New opencl specific casting
        function, handle special case for casting scalar to vector.
        (opencl_relop): Use opencl_value_cast.
        (evaluate_subexp_opencl): Use opencl_value_cast instead of
        value_cast, and handle BINOP_ASSIGN, UNOP_CAST, and UNOP_CAST_TYPE
        in order to use opencl_value_cast.

gdb/testsuite/ChangeLog
        * gdb.base/gnu_vector.c: New variable for use in tests.
        * gdb.base/gnu_vector.exp: Update and extend tests to reflect
        changes in scalar to vector casting and widening.
        * gdb.python/py-type.c: New variables for use in tests.
        * gdb.python/py-type.exp: Update vector related tests to reflect
        changes in scalar to vector casting and widening.

1 files changed, 46 insertions, 1 deletions

diff --git a/gdb/valarith.c b/gdb/valarith.c
index 074cf36..894a87a 100644
--- a/gdb/valarith.c
+++ b/gdb/valarith.c
@@ -1346,6 +1346,49 @@ scalar_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
   return val;
 }
 
+/* Widen a scalar value SCALAR_VALUE to vector type VECTOR_TYPE by
+   replicating SCALAR_VALUE for each element of the vector.  Only scalar
+   types that can be cast to the type of one element of the vector are
+   acceptable.  The newly created vector value is returned upon success,
+   otherwise an error is thrown.  */
+
+struct value *
+value_vector_widen (struct value *scalar_value, struct type *vector_type)
+{
+  /* Widen the scalar to a vector.  */
+  struct type *eltype, *scalar_type;
+  struct value *val, *elval;
+  LONGEST low_bound, high_bound;
+  int i;
+
+  CHECK_TYPEDEF (vector_type);
+
+  gdb_assert (TYPE_CODE (vector_type) == TYPE_CODE_ARRAY
+	      && TYPE_VECTOR (vector_type));
+
+  if (!get_array_bounds (vector_type, &low_bound, &high_bound))
+    error (_("Could not determine the vector bounds"));
+
+  eltype = check_typedef (TYPE_TARGET_TYPE (vector_type));
+  elval = value_cast (eltype, scalar_value);
+
+  scalar_type = check_typedef (value_type (scalar_value));
+
+  /* If we reduced the length of the scalar then check we didn't loose any
+     important bits.  */
+  if (TYPE_LENGTH (eltype) < TYPE_LENGTH (scalar_type)
+      && !value_equal (elval, scalar_value))
+    error (_("conversion of scalar to vector involves truncation"));
+
+  val = allocate_value (vector_type);
+  for (i = 0; i < high_bound - low_bound + 1; i++)
+    /* Duplicate the contents of elval into the destination vector.  */
+    memcpy (value_contents_writeable (val) + (i * TYPE_LENGTH (eltype)),
+	    value_contents_all (elval), TYPE_LENGTH (eltype));
+
+  return val;
+}
+
 /* Performs a binary operation on two vector operands by calling scalar_binop
    for each pair of vector components.  */
 
@@ -1425,7 +1468,9 @@ value_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
 	  && !is_integral_type (t))
 	error (_("Argument to operation not a number or boolean."));
 
-      *v = value_cast (t1_is_vec ? type1 : type2, *v);
+      /* Replicate the scalar value to make a vector value.  */
+      *v = value_vector_widen (*v, t1_is_vec ? type1 : type2);
+
       val = vector_binop (arg1, arg2, op);
     }