Make bitsize_mode_for_mode return an opt_mode

2017-09-05  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* machmode.h (bitwise_mode_for_mode): Return opt_mode.
	* stor-layout.c (bitwise_mode_for_mode): Likewise.
	(bitwise_type_for_mode): Update accordingly.

From-SVN: r251733

gcc/ChangeLog

 2017-09-05  Richard Sandiford  <richard.sandiford@linaro.org>
 
+	* machmode.h (bitwise_mode_for_mode): Return opt_mode.
+	* stor-layout.c (bitwise_mode_for_mode): Likewise.
+	(bitwise_type_for_mode): Update accordingly.
+
+2017-09-05  Richard Sandiford  <richard.sandiford@linaro.org>
+
 	* stor-layout.h (mode_for_size_tree): Return an opt_mode.
 	* stor-layout.c (mode_for_size_tree): Likewise.
 	(mode_for_array): Update accordingly.

gcc/machmode.h

@@ -694,7 +694,7 @@ smallest_int_mode_for_size (unsigned int size)
 }
 
 extern opt_scalar_int_mode int_mode_for_mode (machine_mode);
-extern machine_mode bitwise_mode_for_mode (machine_mode);
+extern opt_machine_mode bitwise_mode_for_mode (machine_mode);
 extern opt_machine_mode mode_for_vector (scalar_mode, unsigned);
 extern opt_machine_mode mode_for_int_vector (unsigned int, unsigned int);
 

gcc/stor-layout.c

@@ -404,10 +404,10 @@ int_mode_for_mode (machine_mode mode)
     }
 }
 
-/* Find a mode that can be used for efficient bitwise operations on MODE.
-   Return BLKmode if no such mode exists.  */
+/* Find a mode that can be used for efficient bitwise operations on MODE,
+   if one exists.  */
 
-machine_mode
+opt_machine_mode
 bitwise_mode_for_mode (machine_mode mode)
 {
   /* Quick exit if we already have a suitable mode.  */
@@ -445,7 +445,7 @@ bitwise_mode_for_mode (machine_mode mode)
     }
 
   /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE.  */
-  return mode_for_size (bitsize, MODE_INT, true).else_blk ();
+  return mode_for_size (bitsize, MODE_INT, true);
 }
 
 /* Find a type that can be used for efficient bitwise operations on MODE.
@@ -454,8 +454,7 @@ bitwise_mode_for_mode (machine_mode mode)
 tree
 bitwise_type_for_mode (machine_mode mode)
 {
-  mode = bitwise_mode_for_mode (mode);
-  if (mode == BLKmode)
+  if (!bitwise_mode_for_mode (mode).exists (&mode))
     return NULL_TREE;
 
   unsigned int inner_size = GET_MODE_UNIT_BITSIZE (mode);