[59/77] Add a rtx_jump_table_data::get_data_mode helper

This patch adds a helper function to get the mode of the addresses
or offsets in a jump table.  It also changes the final.c code to use
rtx_jump_table_data over rtx or rtx_insn in cases where it needed
to use the new helper.  This in turn meant adding a safe_dyn_cast
equivalent of safe_as_a, to cope with null NEXT_INSNs.

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* is-a.h (safe_dyn_cast): New function.
	* rtl.h (rtx_jump_table_data::get_data_mode): New function.
	(jump_table_for_label): Likewise.
	* final.c (final_addr_vec_align): Take an rtx_jump_table_data *
	instead of an rtx_insn *.
	(shorten_branches): Use dyn_cast instead of LABEL_P and
	JUMP_TABLE_DATA_P.  Use jump_table_for_label and
	rtx_jump_table_data::get_data_mode.
	(final_scan_insn): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r251511

1 files changed, 14 insertions, 0 deletions

diff --git a/gcc/is-a.h b/gcc/is-a.h
index b4e5279..2adc740 100644
--- a/gcc/is-a.h
+++ b/gcc/is-a.h
@@ -103,6 +103,11 @@ TYPE dyn_cast <TYPE> (pointer)
     Note that we have converted two sets of assertions in the calls to varpool
     into safe and efficient use of a variable.
 
+TYPE safe_dyn_cast <TYPE> (pointer)
+
+    Like dyn_cast <TYPE> (pointer), except that it accepts null pointers
+    and returns null results for them.
+
 
 If you use these functions and get a 'inline function not defined' or a
 'missing symbol' error message for 'is_a_helper<....>::test', it means that
@@ -222,4 +227,13 @@ dyn_cast (U *p)
     return static_cast <T> (0);
 }
 
+/* Similar to dyn_cast, except that the pointer may be null.  */
+
+template <typename T, typename U>
+inline T
+safe_dyn_cast (U *p)
+{
+  return p ? dyn_cast <T> (p) : 0;
+}
+
 #endif  /* GCC_IS_A_H  */