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


On Wed, 8 Jan 2014, Jakub Jelinek wrote:

> On Wed, Jan 08, 2014 at 12:19:02PM +0100, Richard Biener wrote:
> > On Wed, 8 Jan 2014, Jakub Jelinek wrote:
> > 
> > > On Wed, Jan 08, 2014 at 12:15:40PM +0100, Richard Biener wrote:
> > > > > I start to think this is a too complex transform for stmt folding ...
> > > > 
> > > > Alternatively do update_call_from_tree (gsi, get_or_create_ssa_default_def 
> > > > (cfun, create_tmp_var (TREE_TYPE (lhs)))).
> > > 
> > > The lhs might not be is_gimple_reg_type though.  What to do in that case?
> > 
> > In that case you can remove the stmt.
> 
> Ok, so like this?  Unfortunately, I haven't been able to construct a
> testcase where this would be folded later than during gimplification where
> lhs is obviously not a SSA_NAME and we can safely replace the call.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux.

Ok, though if you are happy to do another change then ...

> 2014-01-08  Jakub Jelinek  <jakub@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, but replace
> 	the OBJ_TYPE_REF call with the noreturn and add if needed a setter
> 	of the lhs SSA_NAME.  Don't devirtualize for inplace at all.
> 
> 	* g++.dg/opt/pr59622-2.C: New test.
> 	* g++.dg/opt/pr59622-3.C: New test.
> 	* g++.dg/opt/pr59622-4.C: New test.
> 
> --- gcc/gimple-fold.c.jj	2014-01-08 10:23:24.536443566 +0100
> +++ gcc/gimple-fold.c	2014-01-08 17:02:40.356635177 +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 +1177,46 @@ 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, if the call doesn't have
> +		 lhs or lhs isn't SSA_NAME, replace the call with
> +		 the noreturn call, otherwise insert it before the call
> +		 and replace the call with setting of lhs to default def.  */
> +	      if (TREE_THIS_VOLATILE (fndecl)
> +		  && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fndecl)))
> +		  && TYPE_ARG_TYPES (TREE_TYPE (fndecl)) == void_list_node)

... restrict this to the targets.length () == 0 case.

Thanks,
Richard.

>  		{
> -		  gimple_call_set_fndecl (stmt, targets[0]->decl);
> -		  changed = true;
> -		}
> -	      else if (!inplace)
> -		{
> -		  tree fndecl = builtin_decl_implicit (BUILT_IN_UNREACHABLE);
> +		  tree lhs = gimple_call_lhs (stmt);
>  		  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;
>  		}
> +
> +	      gimple_call_set_fndecl (stmt, fndecl);
> +	      changed = true;
>  	    }
>  	}
>      }
> --- gcc/testsuite/g++.dg/opt/pr59622-2.C.jj	2014-01-08 16:42:49.588747876 +0100
> +++ gcc/testsuite/g++.dg/opt/pr59622-2.C	2014-01-08 16:42:49.588747876 +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	2014-01-08 17:00:20.944359961 +0100
> +++ gcc/testsuite/g++.dg/opt/pr59622-3.C	2014-01-08 17:00:44.558244745 +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	2014-01-08 17:00:54.332188462 +0100
> +++ gcc/testsuite/g++.dg/opt/pr59622-4.C	2014-01-08 17:01:41.113947431 +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);
> +}
> 
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer


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