Make get_value_for_expr check for INTEGER_CSTs

CONSTANT lattice values are symbolic constants rather than
compile-time constants, so among other things can be POLY_INT_CSTs.
This patch fixes a case in which we assumed all CONSTANTs were either
ADDR_EXPRs or INTEGER_CSTs.

This is tested by later SVE patches.

2019-09-18  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-ssa-ccp.c (get_value_for_expr): Check whether CONSTANTs
	are INTEGER_CSTs.

From-SVN: r275871

gcc/ChangeLog

 2019-09-18  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* tree-ssa-ccp.c (get_value_for_expr): Check whether CONSTANTs
+	are INTEGER_CSTs.
+
+2019-09-18  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* gimplify.c (gimplify_decl_expr): Use poly_int_tree_p instead
 	of checking specifically for INTEGER_CST.
 

gcc/tree-ssa-ccp.c

@@ -615,9 +615,17 @@ get_value_for_expr (tree expr, bool for_bits_p)
 	  val.mask = -1;
 	}
       if (for_bits_p
-	  && val.lattice_val == CONSTANT
-	  && TREE_CODE (val.value) == ADDR_EXPR)
-	val = get_value_from_alignment (val.value);
+	  && val.lattice_val == CONSTANT)
+	{
+	  if (TREE_CODE (val.value) == ADDR_EXPR)
+	    val = get_value_from_alignment (val.value);
+	  else if (TREE_CODE (val.value) != INTEGER_CST)
+	    {
+	      val.lattice_val = VARYING;
+	      val.value = NULL_TREE;
+	      val.mask = -1;
+	    }
+	}
       /* Fall back to a copy value.  */
       if (!for_bits_p
 	  && val.lattice_val == VARYING