Re: [PATCH RFA] ubsan: default to trap on unreachable at -O0 and -Og [PR104642]

[Jakub Jelinek <jakub@redhat.com>]

On Tue, Jun 21, 2022 at 11:59:56PM -0400, Jason Merrill wrote:
> 	PR c++/104642
> 
> gcc/ChangeLog:
> 
> 	* common.opt: Add -funreachable-traps.
> 	* doc/invoke.texi (-funreachable-traps): Document it.
> 	* opts.cc (finish_options): Enable at -O0 or -Og.
> 	* tree.cc (build_common_builtin_nodes): Add __builtin_trap.
> 	(builtin_decl_unreachable, build_builtin_unreachable): New.
> 	* tree.h: Declare them.
> 	* ubsan.cc (sanitize_unreachable_fn): Factor out.
> 	(ubsan_instrument_unreachable): Use
> 	gimple_build_builtin_unreachable.
> 	* ubsan.h (sanitize_unreachable_fn): Declare.
> 	* gimple.cc (gimple_build_builtin_unreachable): New.
> 	* gimple.h: Declare it.
> 	* builtins.cc (expand_builtin_unreachable): Add assert.
> 	(fold_builtin_0): Call build_builtin_unreachable.
> 	* sanopt.cc: Don't run for just SANITIZE_RETURN
> 	or SANITIZE_UNREACHABLE when trapping.
> 	* cgraphunit.cc (walk_polymorphic_call_targets): Use new
> 	unreachable functions.
> 	* gimple-fold.cc (gimple_fold_call)
> 	(gimple_get_virt_method_for_vtable)
> 	* ipa-fnsummary.cc (redirect_to_unreachable)
> 	* ipa-prop.cc (ipa_make_edge_direct_to_target)
> 	(ipa_impossible_devirt_target)
> 	* ipa.cc (walk_polymorphic_call_targets)
> 	* tree-cfg.cc (pass_warn_function_return::execute)
> 	(execute_fixup_cfg)
> 	* tree-ssa-loop-ivcanon.cc (remove_exits_and_undefined_stmts)
> 	(unloop_loops)
> 	* tree-ssa-sccvn.cc (eliminate_dom_walker::eliminate_stmt):
> 	Likewise.
> 
> gcc/cp/ChangeLog:
> 
> 	* constexpr.cc (cxx_eval_builtin_function_call): Handle
> 	unreachable/trap earlier.
> 	* cp-gimplify.cc (cp_maybe_instrument_return): Use
> 	build_builtin_unreachable.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/ubsan/return-8a.C: New test.
> 	* g++.dg/ubsan/return-8b.C: New test.
> 	* g++.dg/ubsan/return-8d.C: New test.
> 	* g++.dg/ubsan/return-8e.C: New test.

LGTM, thanks.

	Jakub