tree-optimization/116057 - wrong code with CCP and vector CTORs

The following fixes an issue with CCPs likely_value when faced with
a vector CTOR containing undef SSA names and constants.  This should
be classified as CONSTANT and not UNDEFINED.

	PR tree-optimization/116057
	* tree-ssa-ccp.cc (likely_value): Also walk CTORs in stmt
	operands to look for constants.

	* gcc.dg/torture/pr116057.c: New testcase.

gcc/testsuite/gcc.dg/torture/pr116057.c

@@ -0,0 +1,20 @@
+/* { dg-do run } */
+/* { dg-additional-options "-Wno-psabi" } */
+
+#define vect8 __attribute__((vector_size(8)))
+
+vect8 int __attribute__((noipa))
+f(int a)
+{
+  int b;
+  vect8 int t={1,1};
+  if(a) return t;
+  return (vect8 int){0, b};
+}
+
+int main ()
+{
+  if (f(0)[0] != 0)
+    __builtin_abort ();
+  return 0;
+}

gcc/tree-ssa-ccp.cc

@@ -762,6 +762,17 @@ likely_value (gimple *stmt)
 	continue;
       if (is_gimple_min_invariant (op))
 	has_constant_operand = true;
+      else if (TREE_CODE (op) == CONSTRUCTOR)
+	{
+	  unsigned j;
+	  tree val;
+	  FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (op), j, val)
+	    if (CONSTANT_CLASS_P (val))
+	      {
+		has_constant_operand = true;
+		break;
+	      }
+	}
     }
 
   if (has_constant_operand)