Use combined_fn in tree-vect-patterns.c

Another patch to extend uses of built_in_function to combined_fn,
this time in tree-vect-patterns.c.  The old code didn't handle the
long double pow variants, but I think that's because noone had a target
that would benefit rather than because the code would mishandle them.

Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi.

gcc/
	* tree-vect-patterns.c: Include case-cfn-macros.h.
	(vect_recog_pow_pattern): Use combined_fn instead of built-in codes.

From-SVN: r230482

gcc/ChangeLog

 2015-11-17  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* tree-vect-patterns.c: Include case-cfn-macros.h.
+	(vect_recog_pow_pattern): Use combined_fn instead of built-in codes.
+
+2015-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* tree-ssa-math-opts.c: Include case-cfn-macros.h.
 	(execute_cse_sincos_1): Use combined_fn instead of built-in codes.
 	(pass_cse_sincos::execute): Likewise.

gcc/tree-vect-patterns.c

@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-vectorizer.h"
 #include "dumpfile.h"
 #include "builtins.h"
+#include "case-cfn-macros.h"
 
 /* Pattern recognition functions  */
 static gimple *vect_recog_widen_sum_pattern (vec<gimple *> *, tree *,
@@ -1009,23 +1010,17 @@ vect_recog_pow_pattern (vec<gimple *> *stmts, tree *type_in,
 			tree *type_out)
 {
   gimple *last_stmt = (*stmts)[0];
-  tree fn, base, exp = NULL;
+  tree base, exp = NULL;
   gimple *stmt;
   tree var;
 
   if (!is_gimple_call (last_stmt) || gimple_call_lhs (last_stmt) == NULL)
     return NULL;
 
-  fn = gimple_call_fndecl (last_stmt);
-  if (fn == NULL_TREE || DECL_BUILT_IN_CLASS (fn) != BUILT_IN_NORMAL)
-   return NULL;
-
-  switch (DECL_FUNCTION_CODE (fn))
+  switch (gimple_call_combined_fn (last_stmt))
     {
-    case BUILT_IN_POWIF:
-    case BUILT_IN_POWI:
-    case BUILT_IN_POWF:
-    case BUILT_IN_POW:
+    CASE_CFN_POW:
+    CASE_CFN_POWI:
       base = gimple_call_arg (last_stmt, 0);
       exp = gimple_call_arg (last_stmt, 1);
       if (TREE_CODE (exp) != REAL_CST