[PATCH] Avoid doing empty bb ehcleanup move if PHI on the landing pad has other uses (PR tree-optimization/47355, take 2)

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Jan 21, 2011 at 11:26:32AM +0100, Richard Guenther wrote:
> On Thu, Jan 20, 2011 at 5:29 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> > This patch fixes it by not moving the landing pad if there are other
> > uses of the old PHI result.
> >
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> Ok.

Actually, I've run another bootstrap/regtests with gathering statistics
and there were ~100 cases in which the !has_single_use test refused to move
something that was actually movable.  In particular if nop was used by more
than one PHI node on new_bb.  cleanup_empty_eh_merge_phis handles that
perfectly, so this patch allows those cases too.  With this patch
the only cases rejected by cleanup_empty_eh_merge_phis during x86_64-linux
and i686-linux bootstrap/regtests is the newly added testcase pr47355.C.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2011-01-21  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/47355
	* tree-eh.c (cleanup_empty_eh_merge_phis): Give up if
	NOP has non-debug uses beyond PHIs in new_bb.

	* g++.dg/opt/pr47355.C: New test.

--- gcc/tree-eh.c.jj	2011-01-18 18:16:11.000000000 +0100
+++ gcc/tree-eh.c	2011-01-21 13:22:41.000000000 +0100
@@ -3552,6 +3552,20 @@ cleanup_empty_eh_merge_phis (basic_block
       /* If we did find the corresponding PHI, copy those inputs.  */
       if (ophi)
 	{
+	  /* If NOP is used somewhere else beyond phis in new_bb, give up.  */
+	  if (!has_single_use (nop))
+	    {
+	      imm_use_iterator imm_iter;
+	      use_operand_p use_p;
+
+	      FOR_EACH_IMM_USE_FAST (use_p, imm_iter, nop)
+		{
+		  if (!gimple_debug_bind_p (USE_STMT (use_p))
+		      && (gimple_code (USE_STMT (use_p)) != GIMPLE_PHI
+			  || gimple_bb (USE_STMT (use_p)) != new_bb))
+		    goto fail;
+		}
+	    }
 	  bitmap_set_bit (ophi_handled, SSA_NAME_VERSION (nop));
 	  FOR_EACH_EDGE (e, ei, old_bb->preds)
 	    {
--- gcc/testsuite/g++.dg/opt/pr47355.C.jj	2011-01-20 11:29:54.000000000 +0100
+++ gcc/testsuite/g++.dg/opt/pr47355.C	2011-01-20 11:29:29.000000000 +0100
@@ -0,0 +1,39 @@
+// PR tree-optimization/47355
+// { dg-do compile }
+// { dg-options "-O -fipa-cp -fipa-cp-clone" }
+
+struct T
+{
+  T ();
+  void *p;
+  ~T ();
+};
+
+void foo (T *i);
+
+T *bar ();
+void baz (T *);
+
+struct V
+{
+  long q;
+  T *r;
+  ~V ()
+  {
+    while (q)
+      {
+	foo (r);
+	++r;
+	--q;
+      }
+    baz (r);
+  }
+};
+
+void
+foo ()
+{
+  V v;
+  T t;
+  v.r = bar ();
+}

	Jakub