re PR rtl-optimization/12826 (Optimizer removes reference through volatile pointer)

	PR opt/12826
	* loop.c (insert_loop_mem): Preffer VOLATILE memory references to be
	stored.

	PR opt/12863
	* cfgcleanup.c (label_is_jump_target_p): Move to...
	* rtlanal.c (label_is_jump_target_p): ... here.
	* cfgrtl.c (cfg_layout_redirect_edge_and_branch):  Fix redirecting of fallthru
	edges unified with branch edges.

From-SVN: r75733

gcc/ChangeLog

+2004-01-12  Jan Hubicka  <jh@suse.cz>
+
+	PR opt/12826
+	* loop.c (insert_loop_mem): Preffer VOLATILE memory references to be
+	stored.
+
+	PR opt/12863
+	* cfgcleanup.c (label_is_jump_target_p): Move to...
+	* rtlanal.c (label_is_jump_target_p): ... here.
+	* cfgrtl.c (cfg_layout_redirect_edge_and_branch):  Fix redirecting of fallthru
+	edges unified with branch edges.
+
 2004-01-12  Richard Earnshaw  <rearnsha@arm.com>
 
 	* simplify-rtx.c (simplify_immed_subreg): Correctly extract the

gcc/cfgcleanup.c

@@ -73,7 +73,6 @@ static bool outgoing_edges_match (int, basic_block, basic_block);
 static int flow_find_cross_jump (int, basic_block, basic_block, rtx *, rtx *);
 static bool insns_match_p (int, rtx, rtx);
 
-static bool label_is_jump_target_p (rtx, rtx);
 static bool tail_recursion_label_p (rtx);
 static void merge_blocks_move_predecessor_nojumps (basic_block, basic_block);
 static void merge_blocks_move_successor_nojumps (basic_block, basic_block);
@@ -646,33 +645,6 @@ try_forward_edges (int mode, basic_block b)
   return changed;
 }
 
-/* Return true if LABEL is a target of JUMP_INSN.  This applies only
-   to non-complex jumps.  That is, direct unconditional, conditional,
-   and tablejumps, but not computed jumps or returns.  It also does
-   not apply to the fallthru case of a conditional jump.  */
-
-static bool
-label_is_jump_target_p (rtx label, rtx jump_insn)
-{
-  rtx tmp = JUMP_LABEL (jump_insn);
-
-  if (label == tmp)
-    return true;
-
-  if (tablejump_p (jump_insn, NULL, &tmp))
-    {
-      rtvec vec = XVEC (PATTERN (tmp),
-			GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC);
-      int i, veclen = GET_NUM_ELEM (vec);
-
-      for (i = 0; i < veclen; ++i)
-	if (XEXP (RTVEC_ELT (vec, i), 0) == label)
-	  return true;
-    }
-
-  return false;
-}
-
 /* Return true if LABEL is used for tail recursion.  */
 
 static bool

gcc/cfgrtl.c

@@ -2463,10 +2463,18 @@ cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
     {
       /* Redirect any branch edges unified with the fallthru one.  */
       if (GET_CODE (BB_END (src)) == JUMP_INSN
-	  && JUMP_LABEL (BB_END (src)) == BB_HEAD (e->dest))
+	  && label_is_jump_target_p (BB_HEAD (e->dest),
+				     BB_END (src)))
 	{
-          if (!redirect_jump (BB_END (src), block_label (dest), 0))
+	  if (rtl_dump_file)
+	    fprintf (rtl_dump_file, "Fallthru edge unified with branch "
+		     "%i->%i redirected to %i\n",
+		     e->src->index, e->dest->index, dest->index);
+	  e->flags &= ~EDGE_FALLTHRU;
+	  if (!redirect_branch_edge (e, dest))
 	    abort ();
+	  e->flags |= EDGE_FALLTHRU;
+	  return true;
 	}
       /* In case we are redirecting fallthru edge to the branch edge
          of conditional jump, remove it.  */

gcc/loop.c

@@ -9561,6 +9561,8 @@ insert_loop_mem (rtx *mem, void *data ATTRIBUTE_UNUSED)
   for (i = 0; i < loop_info->mems_idx; ++i)
     if (rtx_equal_p (m, loop_info->mems[i].mem))
       {
+	if (MEM_VOLATILE_P (m) && !MEM_VOLATILE_P (loop_info->mems[i].mem))
+	  loop_info->mems[i].mem = m;
 	if (GET_MODE (m) != GET_MODE (loop_info->mems[i].mem))
 	  /* The modes of the two memory accesses are different.  If
 	     this happens, something tricky is going on, and we just

gcc/rtl.h

@@ -1725,6 +1725,7 @@ extern int insns_safe_to_move_p (rtx, rtx, rtx *);
 extern int loc_mentioned_in_p (rtx *, rtx);
 extern rtx find_first_parameter_load (rtx, rtx);
 extern bool keep_with_call_p (rtx);
+extern bool label_is_jump_target_p (rtx, rtx);
 
 /* flow.c */
 

gcc/rtlanal.c

@@ -3709,3 +3709,31 @@ hoist_insn_to_edge (rtx insn, edge e, rtx val, rtx new)
   end_sequence ();
   return new_insn;
 }
+
+/* Return true if LABEL is a target of JUMP_INSN.  This applies only
+   to non-complex jumps.  That is, direct unconditional, conditional,
+   and tablejumps, but not computed jumps or returns.  It also does
+   not apply to the fallthru case of a conditional jump.  */
+
+bool
+label_is_jump_target_p (rtx label, rtx jump_insn)
+{
+  rtx tmp = JUMP_LABEL (jump_insn);
+
+  if (label == tmp)
+    return true;
+
+  if (tablejump_p (jump_insn, NULL, &tmp))
+    {
+      rtvec vec = XVEC (PATTERN (tmp),
+			GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC);
+      int i, veclen = GET_NUM_ELEM (vec);
+
+      for (i = 0; i < veclen; ++i)
+	if (XEXP (RTVEC_ELT (vec, i), 0) == label)
+	  return true;
+    }
+
+  return false;
+}
+