* basic-block.h (find_sub_basic_block): Declare.

	* flow.c (make_edges): New arguments MIN and MAX;
	(find_sub_basic_blocks): Revamp to use make_edges
	and purge_dead_edges.
	(find_basic_blocks): Update call of find_sub_basic_block.

	* recog.c (split_all_insns): Always expect CFG to be consistent;
	call find_sub_basic_blocks in case something has changed.
	* toplev.c (rest_of_compilation): Always call split_all_insns once CFG
	has been built.

	* basic-block.h (delete_noop_moves): Declare.
	* combine.c (combine_instructions): Call it.
	(recog_for_combine): Tolerate noop moves
	(distribute_notes): Force refresh when register dies at noop move.
	* flow.c (delete_noop_moves): Use BB structure; delete JUMP insns
	too.
	(life_analysis): Update delete_noop_moves call.
	(set_noop_p): Move too ...
	* rtlanal.c (noop_move_p): ... here.
	* rtl.h (noop_move_p): Declare.

	* basic-block.h (purge_all_dead_edges, purge_dead_edges): New functions.
	* toplev.c (rest_of_compilation): Conditionally call purge_all_dead_edges
	after combine.
	* gcse.c (cprop_cc0_jump, cprop_insn): New argument "basic_block".
	(cprop_jump): Likewise; call purge_dead_edges if substitution suceeded.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@44267 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 39 insertions, 0 deletions

diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 2f9696cc1fc..c9152ab0f8e 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -1020,6 +1020,45 @@ set_noop_p (set)
   return (GET_CODE (src) == REG && GET_CODE (dst) == REG
 	  && REGNO (src) == REGNO (dst));
 }
+
+/* Return nonzero if an insn consists only of SETs, each of which only sets a
+   value to itself.  */
+
+int
+noop_move_p (insn)
+     rtx insn;
+{
+  rtx pat = PATTERN (insn);
+
+  /* Insns carrying these notes are useful later on.  */
+  if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
+    return 0;
+
+  if (GET_CODE (pat) == SET && set_noop_p (pat))
+    return 1;
+
+  if (GET_CODE (pat) == PARALLEL)
+    {
+      int i;
+      /* If nothing but SETs of registers to themselves,
+	 this insn can also be deleted.  */
+      for (i = 0; i < XVECLEN (pat, 0); i++)
+	{
+	  rtx tem = XVECEXP (pat, 0, i);
+
+	  if (GET_CODE (tem) == USE
+	      || GET_CODE (tem) == CLOBBER)
+	    continue;
+
+	  if (GET_CODE (tem) != SET || ! set_noop_p (tem))
+	    return 0;
+	}
+
+      return 1;
+    }
+  return 0;
+}
+
 
 /* Return the last thing that X was assigned from before *PINSN.  If VALID_TO
    is not NULL_RTX then verify that the object is not modified up to VALID_TO.