From: Bernd Schmidt <bernds@redhat.co.uk>
Date: Wed, 20 Dec 2000 13:53:00 +0000 (+0000)
Subject: Backport a fix to the 2.95 branch
X-Git-Tag: prereleases/gcc-2.95.3-test1~23
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d750c728974471c46fdf057f11a86a32afa52f32;p=thirdparty%2Fgcc.git

Backport a fix to the 2.95 branch

From-SVN: r38397
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 49b0610895a2..3edb05f1b2a9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2000-12-20  Bernd Schmidt  <bernds@redhat.co.uk>
 
+	Sun Sep 19 09:03:40 1999  Mark Mitchell  <mark@codesourcery.com>
+	* rtl.h (insns_safe_to_move_p): New function.
+	* loop.c (find_and_verify_loops): Use it.
+	* rtlanal.c (insns_safe_to_move_p): Define it.
+
 	Thu Nov  2 19:20:12 2000  J"orn Rennecke <amylaar@redhat.com>
 	* reload.c (find_equiv_reg): Test all hard registers for membership
 	in the requested class.
diff --git a/gcc/loop.c b/gcc/loop.c
index 1aa56b75029a..a85e6d33d477 100644
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -2773,6 +2773,7 @@ find_and_verify_loops (f)
 	  {
 	    rtx p;
 	    rtx our_next = next_real_insn (insn);
+	    rtx last_insn_to_move = NEXT_INSN (insn);
 	    int dest_loop;
 	    int outer_loop = -1;
 
@@ -2824,7 +2825,11 @@ find_and_verify_loops (f)
 		&& INSN_UID (JUMP_LABEL (p)) != 0
 		&& condjump_p (p)
 		&& ! simplejump_p (p)
-		&& next_real_insn (JUMP_LABEL (p)) == our_next)
+		&& next_real_insn (JUMP_LABEL (p)) == our_next
+		/* If it's not safe to move the sequence, then we
+		   mustn't try.  */
+		&& insns_safe_to_move_p (p, NEXT_INSN (insn), 
+					 &last_insn_to_move))
 	      {
 		rtx target
 		  = JUMP_LABEL (insn) ? JUMP_LABEL (insn) : get_last_insn ();
@@ -2893,11 +2898,13 @@ find_and_verify_loops (f)
 
 		       /* Include the BARRIER after INSN and copy the
 			  block after LOC.  */
-		       new_label = squeeze_notes (new_label, NEXT_INSN (insn));
-		       reorder_insns (new_label, NEXT_INSN (insn), loc);
+		       new_label = squeeze_notes (new_label, 
+						  last_insn_to_move);
+		       reorder_insns (new_label, last_insn_to_move, loc);
 
 		       /* All those insns are now in TARGET_LOOP_NUM.  */
-		       for (q = new_label; q != NEXT_INSN (NEXT_INSN (insn));
+		       for (q = new_label; 
+			    q != NEXT_INSN (last_insn_to_move);
 			    q = NEXT_INSN (q))
 			 uid_loop_num[INSN_UID (q)] = target_loop_num;
 
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 8eba5eab5d9d..0f43e87dc751 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1084,6 +1084,7 @@ extern int for_each_rtx                 PROTO((rtx *, rtx_function, void *));
 extern rtx regno_use_in			PROTO((int, rtx));
 extern int auto_inc_p			PROTO((rtx));
 extern void remove_node_from_expr_list	PROTO((rtx, rtx *));
+extern int insns_safe_to_move_p         PROTO((rtx, rtx, rtx *));
 
 /* flow.c */
 
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index fb4f87c07de3..49131a4efedc 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -2289,3 +2289,82 @@ auto_inc_p (x)
     }
   return 0;
 }
+
+/* Return 1 if the sequence of instructions beginning with FROM and up
+   to and including TO is safe to move.  If NEW_TO is non-NULL, and
+   the sequence is not already safe to move, but can be easily
+   extended to a sequence which is safe, then NEW_TO will point to the
+   end of the extended sequence.  
+ 
+   For now, this function only checks that the region contains whole
+   exception regiongs, but it could be extended to check additional
+   conditions as well.  */
+
+int
+insns_safe_to_move_p (from, to, new_to)
+     rtx from;
+     rtx to;
+     rtx *new_to;
+{
+  int eh_region_count = 0;
+  int past_to_p = 0;
+  rtx r = from;
+
+  /* By default, assume the end of the region will be what was
+     suggested.  */
+  if (new_to)
+    *new_to = to;
+
+  while (r)
+    {
+      if (GET_CODE (r) == NOTE)
+	{
+	  switch (NOTE_LINE_NUMBER (r))
+	    {
+	    case NOTE_INSN_EH_REGION_BEG:
+	      ++eh_region_count;
+	      break;
+
+	    case NOTE_INSN_EH_REGION_END:
+	      if (eh_region_count == 0)
+		/* This sequence of instructions contains the end of
+		   an exception region, but not he beginning.  Moving
+		   it will cause chaos.  */
+		return 0;
+
+	      --eh_region_count;
+	      break;
+
+	    default:
+	      break;
+	    }
+	}
+      else if (past_to_p)
+	/* If we've passed TO, and we see a non-note instruction, we
+	   can't extend the sequence to a movable sequence.  */
+	return 0;
+
+      if (r == to)
+	{
+	  if (!new_to)
+	    /* It's OK to move the sequence if there were matched sets of
+	       exception region notes.  */
+	    return eh_region_count == 0;
+	  
+	  past_to_p = 1;
+	}
+
+      /* It's OK to move the sequence if there were matched sets of
+	 exception region notes.  */
+      if (past_to_p && eh_region_count == 0)
+	{
+	  *new_to = r;
+	  return 1;
+	}
+
+      /* Go to the next instruction.  */
+      r = NEXT_INSN (r);
+    }
+  
+  return 0;
+}