On Tue, 7 Jan 2014, Jakub Jelinek wrote:
> 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);
I prefer to always do this, not do the fancy insertion-before. That
would do repeated folding for
fold_stmt (gsi);
fold_stmt (gsi);
fold_stmt (gsi);
where the last two should be a no-op.
Richard.
> + 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
>
>
--
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
