[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, 19 insertions, 0 deletions

diff --git a/gcc/rtl.h b/gcc/rtl.h
index 8f4c1fa..736134f5 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -634,6 +634,7 @@ public:
      This method gets the underlying vec.  */
 
   inline rtvec get_labels () const;
+  inline scalar_int_mode get_data_mode () const;
 };
 
 class GTY(()) rtx_barrier : public rtx_insn
@@ -1477,6 +1478,24 @@ inline rtvec rtx_jump_table_data::get_labels () const
     return XVEC (pat, 1); /* presumably an ADDR_DIFF_VEC */
 }
 
+/* Return the mode of the data in the table, which is always a scalar
+   integer.  */
+
+inline scalar_int_mode
+rtx_jump_table_data::get_data_mode () const
+{
+  return as_a <scalar_int_mode> (GET_MODE (PATTERN (this)));
+}
+
+/* If LABEL is followed by a jump table, return the table, otherwise
+   return null.  */
+
+inline rtx_jump_table_data *
+jump_table_for_label (const rtx_code_label *label)
+{
+  return safe_dyn_cast <rtx_jump_table_data *> (NEXT_INSN (label));
+}
+
 #define RTX_FRAME_RELATED_P(RTX)					\
   (RTL_FLAG_CHECK6 ("RTX_FRAME_RELATED_P", (RTX), DEBUG_INSN, INSN,	\
 		    CALL_INSN, JUMP_INSN, BARRIER, SET)->frame_related)