On Thu, 9 Jan 2014, Jakub Jelinek wrote:
> On Thu, Jan 09, 2014 at 09:46:11AM +0100, Richard Biener wrote:
> > > + /* 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.
>
> Well, then the __cxa_pure_virtual testcases ICE again, but the pr59622-5.C
> testcase ICEs anyway, so here is a different patch (untested so far except
> for the tests). The issue with the calls is that when fold_stmt is done
> during gimplification (or omp lowering), we don't have cfg nor SSA form and
> nothing performs fixup_noreturn_calls (that function requires CFG and SSA
> form anyway). So, we have to fix that up by hand, but as we aren't in SSA
> form yet, dropping lhs is always safe for the noreturn calls.
Don't we "fix this up" during CFG build? That is, I fail to see the
issue with noreturn and pre-CFG?
Richard.
> 2014-01-09 Jakub Jelinek <ja...@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 11:05:40.165287975 +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);
> @@ -1177,7 +1177,7 @@ 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
> @@ -1188,13 +1188,29 @@ gimple_fold_call (gimple_stmt_iterator *
> {
> gimple_call_set_fndecl (stmt, targets[0]->decl);
> changed = true;
> + /* If the call becomes noreturn and we aren't in SSA form
> + yet, just drop the lhs, because fixup_noreturn_call
> + isn't run at that point yet. */
> + if ((gimple_call_flags (stmt) & ECF_NORETURN)
> + && !gimple_in_ssa_p (cfun)
> + && gimple_call_lhs (stmt))
> + gimple_call_set_lhs (stmt, NULL_TREE);
> }
> - else if (!inplace)
> + else
> {
> + tree lhs = gimple_call_lhs (stmt);
> 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
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer
