Re: [PATCH][RTL-ifcvt] PR rtl-optimization/68506: Fix emitting order of insns in IF-THEN-JOIN case

[Kyrill Tkachov <kyrylo dot tkachov at arm dot com>]

On 26/11/15 16:54, Kyrill Tkachov wrote:
> On 26/11/15 16:49, Bernd Schmidt wrote:
> > On 11/26/2015 05:45 PM, Kyrill Tkachov wrote:
> > >          that doesn't help, punt.  */
> > >
> > > -  modified_in_a = emit_a != NULL_RTX && modified_in_p (orig_b, emit_a);
> > >     if (tmp_b && then_bb)
> > >       {
> > These bits I thought would be part of a followup patch (which would also guard against single_set problems), and as I mentioned I'd rather have a checking assert.
> Yes, you're right. I have the checking_assert statement in the followup that I've been testing.
> I'll move the deletion of these two statements there as well to minimise the changes to this patch.
>
> I'll move these bits to that patch, re-build cc1 and commit.

Here it is.
I'm committing this to trunk.

Thanks,
Kyrill

2015-11-26  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

    PR rtl-optimization/68506
    * ifcvt.c (noce_try_cmove_arith): Try emitting the else basic block
    first if emit_a exists or then_bb modifies 'b'.  Reindent if-else
    blocks.

2015-11-26  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

    PR rtl-optimization/68506
    * gcc.c-torture/execute/pr68506.c: New test.

> Thanks for your guidance,
> Kyrill
>
> > So take these deletions out and leave them for the followup, and the patch is ok everywhere. No need for a full retest given that practically the same patch has been tested already, just make sure you can build cc1.
> >
> >
> > Bernd

commit ba7633ec30e8e25d7dc1975893bf56eadf223404
Author: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date:   Tue Nov 24 11:49:30 2015 +0000

    PR rtl-optimization/68506: Fix emitting order of insns in IF-THEN-JOIN case

diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
index af7a3b9..3ce9fe6 100644
--- a/gcc/ifcvt.c
+++ b/gcc/ifcvt.c
@@ -2220,40 +2220,38 @@ noce_try_cmove_arith (struct noce_if_info *if_info)
 	  }
 
     }
-    if (emit_a && modified_in_a)
-      {
-	modified_in_b = emit_b != NULL_RTX && modified_in_p (orig_a, emit_b);
-	if (tmp_b && else_bb)
-	  {
-	    FOR_BB_INSNS (else_bb, tmp_insn)
-	    /* Don't check inside insn_b.  We will have changed it to emit_b
-	       with a destination that doesn't conflict.  */
-	      if (!(insn_b && tmp_insn == insn_b)
-		  && modified_in_p (orig_a, tmp_insn))
-		{
-		  modified_in_b = true;
-		  break;
-		}
-
-	  }
-	if (modified_in_b)
-	  goto end_seq_and_fail;
-
-	if (!noce_emit_bb (emit_b, else_bb, b_simple))
-	  goto end_seq_and_fail;
+  if (emit_a || modified_in_a)
+    {
+      modified_in_b = emit_b != NULL_RTX && modified_in_p (orig_a, emit_b);
+      if (tmp_b && else_bb)
+	{
+	  FOR_BB_INSNS (else_bb, tmp_insn)
+	  /* Don't check inside insn_b.  We will have changed it to emit_b
+	     with a destination that doesn't conflict.  */
+	  if (!(insn_b && tmp_insn == insn_b)
+	      && modified_in_p (orig_a, tmp_insn))
+	    {
+	      modified_in_b = true;
+	      break;
+	    }
+	}
+      if (modified_in_b)
+	goto end_seq_and_fail;
 
-	if (!noce_emit_bb (emit_a, then_bb, a_simple))
-	  goto end_seq_and_fail;
-      }
-    else
-      {
-	if (!noce_emit_bb (emit_a, then_bb, a_simple))
-	  goto end_seq_and_fail;
+      if (!noce_emit_bb (emit_b, else_bb, b_simple))
+	goto end_seq_and_fail;
 
-	if (!noce_emit_bb (emit_b, else_bb, b_simple))
-	  goto end_seq_and_fail;
+      if (!noce_emit_bb (emit_a, then_bb, a_simple))
+	goto end_seq_and_fail;
+    }
+  else
+    {
+      if (!noce_emit_bb (emit_a, then_bb, a_simple))
+	goto end_seq_and_fail;
 
-      }
+      if (!noce_emit_bb (emit_b, else_bb, b_simple))
+	goto end_seq_and_fail;
+    }
 
   target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
 			    XEXP (if_info->cond, 1), a, b);
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr68506.c b/gcc/testsuite/gcc.c-torture/execute/pr68506.c
new file mode 100644
index 0000000..15984ed
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr68506.c
@@ -0,0 +1,63 @@
+/* { dg-options "-fno-builtin-abort" } */
+
+int a, b, m, n, o, p, s, u, i;
+char c, q, y;
+short d;
+unsigned char e;
+static int f, h;
+static short g, r, v;
+unsigned t;
+
+extern void abort ();
+
+int
+fn1 (int p1)
+{
+  return a ? p1 : p1 + a;
+}
+
+unsigned char
+fn2 (unsigned char p1, int p2)
+{
+  return p2 >= 2 ? p1 : p1 >> p2;
+}
+
+static short
+fn3 ()
+{
+  int w, x = 0;
+  for (; p < 31; p++)
+    {
+      s = fn1 (c | ((1 && c) == c));
+      t = fn2 (s, x);
+      c = (unsigned) c > -(unsigned) ((o = (m = d = t) == p) <= 4UL) && n;
+      v = -c;
+      y = 1;
+      for (; y; y++)
+	e = v == 1;
+      d = 0;
+      for (; h != 2;)
+	{
+	  for (;;)
+	    {
+	      if (!m)
+		abort ();
+	      r = 7 - f;
+	      x = e = i | r;
+	      q = u * g;
+	      w = b == q;
+	      if (w)
+		break;
+	    }
+	  break;
+	}
+    }
+  return x;
+}
+
+int
+main ()
+{
+  fn3 ();
+  return 0;
+}