[PATCH] Fix devirtualization ICE (PR tree-optimization/59622, take 3)

[Jakub Jelinek]

Hi!

On Fri, Jan 03, 2014 at 11:33:50AM +0100, Jakub Jelinek wrote:
> On Fri, Jan 03, 2014 at 11:24:53AM +0100, Richard Biener wrote:

Anyway, back to the original patch, so do you prefer something like
this instead?  I.e. handle only __builtin_unreachable and
__cxa_pure_virtual specially, and not devirt for fold_stmt_inplace?

2014-01-07  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/59622
        * gimple-fold.c (gimple_fold_call): Fix a typo in message.  Handle
        __cxa_pure_virtual similarly to __builtin_unreachable.  Don't
        devirtualize for inplace at all.

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

--- gcc/gimple-fold.c.jj        2014-01-03 11:40:57.247320424 +0100
+++ gcc/gimple-fold.c   2014-01-07 18:15:00.352601812 +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);
@@ -1177,26 +1177,35 @@ 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 fndecl;
              if (targets.length () == 1)
+               fndecl = targets[0]->decl;
+             else
+               fndecl = builtin_decl_implicit (BUILT_IN_UNREACHABLE);
+
+             /* If fndecl (like __builtin_unreachable or
+                __cxa_pure_virtual) takes no arguments, doesn't have
+                return value and is noreturn, just add the call before
+                stmt and DCE will do it's job later on.  */
+             if (TREE_THIS_VOLATILE (fndecl)
+                 && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fndecl)))
+                 && TYPE_ARG_TYPES (TREE_TYPE (fndecl)) == void_list_node)
                {
-                 gimple_call_set_fndecl (stmt, targets[0]->decl);
-                 changed = true;
-               }
-             else if (!inplace)
-               {
-                 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);
                  return true;
                }
+
+             gimple_call_set_fndecl (stmt, fndecl);
+             changed = true;
            }
        }
     }
--- gcc/testsuite/g++.dg/opt/pr59622-2.C.jj     2014-01-07 18:10:45.435904909 
+0100
+++ gcc/testsuite/g++.dg/opt/pr59622-2.C        2014-01-07 18:10:45.435904909 
+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);
+}


        Jakub