ifcvt.c (noce_process_if_block): Correctly detect X modified with INSN_B before COND_EARLIEST.

        * ifcvt.c (noce_process_if_block): Correctly detect X modified
        with INSN_B before COND_EARLIEST.  Don't check A and B for
        modification in condition range.  Reorder INSN_B for A==B properly.
        (if_convert): Iterate until no matches for a block.

	* gcc.c-torture/execute/20020916-1.c: New.

From-SVN: r57294

gcc/ChangeLog

 2002-09-18  Richard Henderson  <rth@redhat.com>
 
+	* ifcvt.c (noce_process_if_block): Correctly detect X modified
+	with INSN_B before COND_EARLIEST.  Don't check A and B for 
+	modification in condition range.  Reorder INSN_B for A==B properly.
+	(if_convert): Iterate until no matches for a block.
+
+2002-09-18  Richard Henderson  <rth@redhat.com>
+
 	* calls.c (store_one_arg): Rename default_align to parm_align;
 	always adjust parm_align for downward padding.
 

gcc/ifcvt.c

@@ -1700,7 +1700,7 @@ noce_process_if_block (ce_info)
   rtx insn_a, insn_b;
   rtx set_a, set_b;
   rtx orig_x, x, a, b;
-  rtx jump, cond, insn;
+  rtx jump, cond;
 
   /* We're looking for patterns of the form
 
@@ -1776,24 +1776,12 @@ noce_process_if_block (ce_info)
 	  || ! rtx_equal_p (x, SET_DEST (set_b))
 	  || reg_overlap_mentioned_p (x, cond)
 	  || reg_overlap_mentioned_p (x, a)
-	  || reg_overlap_mentioned_p (x, SET_SRC (set_b)))
+	  || reg_overlap_mentioned_p (x, SET_SRC (set_b))
+	  || modified_between_p (x, if_info.cond_earliest, NEXT_INSN (jump)))
 	insn_b = set_b = NULL_RTX;
     }
   b = (set_b ? SET_SRC (set_b) : x);
 
-  /* X may not be mentioned in the range (cond_earliest, jump]. 
-     Note the use of reg_overlap_mentioned_p, which handles memories
-     properly, as opposed to reg_mentioned_p, which doesn't.  */
-  for (insn = jump; insn != if_info.cond_earliest; insn = PREV_INSN (insn))
-    if (INSN_P (insn) && reg_overlap_mentioned_p (x, PATTERN (insn)))
-      return FALSE;
-
-  /* A and B may not be modified in the range [cond_earliest, jump).  */
-  for (insn = if_info.cond_earliest; insn != jump; insn = NEXT_INSN (insn))
-    if (INSN_P (insn)
-	&& (modified_in_p (a, insn) || modified_in_p (b, insn)))
-      return FALSE;
-
   /* Only operate on register destinations, and even then avoid extending
      the lifetime of hard registers on small register class machines.  */
   orig_x = x;
@@ -1839,7 +1827,7 @@ noce_process_if_block (ce_info)
 
 	  if (else_bb && insn_b == else_bb->end)
 	    else_bb->end = PREV_INSN (insn_b);
-	  reorder_insns (insn_b, insn_b, PREV_INSN (if_info.cond_earliest));
+	  reorder_insns (insn_b, insn_b, PREV_INSN (jump));
 
 	  /* If there was a REG_EQUAL note, delete it since it may have been
 	     true due to this insn being after a jump.  */
@@ -1894,9 +1882,9 @@ noce_process_if_block (ce_info)
   if (insn_b && else_bb)
     delete_insn (insn_b);
 
-  /* The new insns will have been inserted before cond_earliest.  We should
-     be able to remove the jump with impunity, but the condition itself may
-     have been modified by gcse to be shared across basic blocks.  */
+  /* The new insns will have been inserted immediately before the jump.  We
+     should be able to remove the jump with impunity, but the condition itself
+     may have been modified by gcse to be shared across basic blocks.  */
   delete_insn (jump);
 
   /* If we used a temporary, fix it up now.  */
@@ -3115,8 +3103,8 @@ if_convert (x_life_data_ok)
 
       FOR_EACH_BB (bb)
 	{
-	  basic_block new_bb = find_if_header (bb, pass);
-	  if (new_bb)
+	  basic_block new_bb;
+	  while ((new_bb = find_if_header (bb, pass)))
 	    bb = new_bb;
 	}
 

gcc/testsuite/gcc.c-torture/execute/20020916-1.c

+/* Distilled from try_pre_increment in flow.c.  If-conversion inserted
+   new instructions at the wrong place on ppc.  */
+
+int foo(int a)
+{
+  int x;
+  x = 0;
+  if (a > 0) x = 1;
+  if (a < 0) x = 1;
+  return x;
+}
+
+int main()
+{
+  if (foo(1) != 1)
+    abort();
+  return 0;
+}
+