[PATCH] Fix devirtualization ICE (PR tree-optimization/59622, take 5)

Jakub Jelinek jakub@redhat.com
Thu Jan 9 18:23:00 GMT 2014


On Thu, Jan 09, 2014 at 02:27:40PM +0100, Richard Biener wrote:
> > Perhaps, if you don't like the !gimple_in_ssa_p (cfun) in the condition
> > we can just drop the lhs always in that case, just doing what we do for
> > __builtin_unreachable if lhs is SSA_NAME:
> >   tree var = create_tmp_var (TREE_TYPE (lhs), NULL);
> >   tree def = get_or_create_ssa_default_def (cfun, var);
> >   gsi_insert_after (gsi, gimple_build_assign (lhs, def), GSI_NEW_STMT);
> 
> That works for me.

So like this?

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

2014-01-09  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/59622
	* gimple-fold.c (gimple_fold_call): Fix a typo in message.  For
	__builtin_unreachable replace the OBJ_TYPE_REF call with a call to
	__builtin_unreachable and add if needed a setter of the lhs SSA_NAME.
	Don't devirtualize for inplace at all.  For targets.length () == 1,
	if the call is noreturn and cfun isn't in SSA form yet, clear lhs.

	* g++.dg/opt/pr59622-2.C: New test.
	* g++.dg/opt/pr59622-3.C: New test.
	* g++.dg/opt/pr59622-4.C: New test.
	* g++.dg/opt/pr59622-5.C: New test.

--- gcc/gimple-fold.c.jj	2014-01-08 17:44:57.690582374 +0100
+++ gcc/gimple-fold.c	2014-01-09 14:34:40.816149806 +0100
@@ -1167,7 +1167,7 @@ gimple_fold_call (gimple_stmt_iterator *
                                                  (OBJ_TYPE_REF_EXPR (callee)))))
 	    {
 	      fprintf (dump_file,
-		       "Type inheritnace inconsistent devirtualization of ");
+		       "Type inheritance inconsistent devirtualization of ");
 	      print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
 	      fprintf (dump_file, " to ");
 	      print_generic_expr (dump_file, callee, TDF_SLIM);
@@ -1177,24 +1177,45 @@ gimple_fold_call (gimple_stmt_iterator *
 	  gimple_call_set_fn (stmt, OBJ_TYPE_REF_EXPR (callee));
 	  changed = true;
 	}
-      else if (flag_devirtualize && virtual_method_call_p (callee))
+      else if (flag_devirtualize && !inplace && virtual_method_call_p (callee))
 	{
 	  bool final;
 	  vec <cgraph_node *>targets
 	    = possible_polymorphic_call_targets (callee, &final);
 	  if (final && targets.length () <= 1)
 	    {
+	      tree lhs = gimple_call_lhs (stmt);
 	      if (targets.length () == 1)
 		{
 		  gimple_call_set_fndecl (stmt, targets[0]->decl);
 		  changed = true;
+		  /* If the call becomes noreturn, remove the lhs.  */
+		  if (lhs && (gimple_call_flags (stmt) & ECF_NORETURN))
+		    {
+		      if (TREE_CODE (lhs) == SSA_NAME)
+			{
+			  tree var = create_tmp_var (TREE_TYPE (lhs), NULL);
+			  tree def = get_or_create_ssa_default_def (cfun, var);
+			  gimple new_stmt = gimple_build_assign (lhs, def);
+			  gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
+			}
+		      gimple_call_set_lhs (stmt, NULL_TREE);
+		    }
 		}
-	      else if (!inplace)
+	      else
 		{
 		  tree fndecl = builtin_decl_implicit (BUILT_IN_UNREACHABLE);
 		  gimple new_stmt = gimple_build_call (fndecl, 0);
 		  gimple_set_location (new_stmt, gimple_location (stmt));
-		  gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
+		  if (lhs && TREE_CODE (lhs) == SSA_NAME)
+		    {
+		      tree var = create_tmp_var (TREE_TYPE (lhs), NULL);
+		      tree def = get_or_create_ssa_default_def (cfun, var);
+		      gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
+		      update_call_from_tree (gsi, def);
+		    }
+		  else
+		    gsi_replace (gsi, new_stmt, true);
 		  return true;
 		}
 	    }
--- gcc/testsuite/g++.dg/opt/pr59622-2.C.jj	2014-01-09 10:57:46.246694025 +0100
+++ gcc/testsuite/g++.dg/opt/pr59622-2.C	2014-01-09 10:57:46.246694025 +0100
@@ -0,0 +1,21 @@
+// PR tree-optimization/59622
+// { dg-do compile }
+// { dg-options "-O2" }
+
+namespace
+{
+  struct A
+  {
+    A () {}
+    virtual A *bar (int) = 0;
+    A *baz (int x) { return bar (x); }
+  };
+}
+
+A *a;
+
+void
+foo ()
+{
+  a->baz (0);
+}
--- gcc/testsuite/g++.dg/opt/pr59622-3.C.jj	2014-01-09 10:57:46.247694040 +0100
+++ gcc/testsuite/g++.dg/opt/pr59622-3.C	2014-01-09 10:57:46.247694040 +0100
@@ -0,0 +1,21 @@
+// PR tree-optimization/59622
+// { dg-do compile }
+// { dg-options "-O2" }
+
+struct C { int a; int b; };
+
+namespace
+{
+  struct A
+  {
+    virtual C foo ();
+    C bar () { return foo (); }
+  };
+}
+
+C
+baz ()
+{
+  A a;
+  return a.bar ();
+}
--- gcc/testsuite/g++.dg/opt/pr59622-4.C.jj	2014-01-09 10:57:46.247694040 +0100
+++ gcc/testsuite/g++.dg/opt/pr59622-4.C	2014-01-09 10:57:46.247694040 +0100
@@ -0,0 +1,23 @@
+// PR tree-optimization/59622
+// { dg-do compile }
+// { dg-options "-O2" }
+
+struct C { int a; int b; };
+
+namespace
+{
+  struct A
+  {
+    A () {}
+    virtual C bar (int) = 0;
+    C baz (int x) { return bar (x); }
+  };
+}
+
+A *a;
+
+C
+foo ()
+{
+  return a->baz (0);
+}
--- gcc/testsuite/g++.dg/opt/pr59622-5.C.jj	2014-01-09 11:06:11.862133398 +0100
+++ gcc/testsuite/g++.dg/opt/pr59622-5.C	2014-01-09 10:54:04.000000000 +0100
@@ -0,0 +1,26 @@
+// PR tree-optimization/59622
+// { dg-do compile }
+// { dg-options "-O2" }
+
+namespace
+{
+  struct A
+  {
+    A () {}
+    virtual A *bar (int);
+    A *baz (int x) { return bar (x); }
+  };
+
+  __attribute__((noreturn)) A *A::bar (int)
+  {
+    __builtin_exit (0);
+  }
+}
+
+A *a;
+
+void
+foo ()
+{
+  a->baz (0);
+}


	Jakub



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