On Mon, Nov 8, 2021 at 8:04 AM Jan Hubicka via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > Hi, > for nested functions we output call to builtin_dwarf_cfa which > initializes frame entry used only for debugging. This however > prevents us from detecting functions containing nested functions > as const/pure or analyze side effects in modref. > > builtin_dwarf_cfa is not documented and I wonder if it should be turned to > internal function. But I think we could consider functions using it const even > if in theory one can do things like test the return address and see the > difference between different frame addreses. > > While doing so I also noticed that special_buitin_state handles quite few > builtins that are not special cased by ipa-modref. They do not make > user visible loads/stores and thus I think they shoul dbe annotated by > ".c" to make this explicit for both modref and PTA. > > Finally I aded dwarf_cfa and similar return_address to list of simple > bulitins since it compiles to simple stack frame load and we consider > several other builtins doing so simple. > > lto-bootstrapped/regtested all languages on x86_64-linux, seems sane?
LGTM. > Honza > > * builtins.c (is_simple_builtin): Add builitin_dwarf_cfa > and builtin_return_address. > (builtin_fnspec): Annotate builtin_return, > bulitin_eh_pointer, builtin_eh_filter, builtin_unwind_resume, > builtin_cxa_end_cleanup, builtin_eh_copy_values, > builtin_frame_address, builtin_apply_args, > builtin_asan_before_dynamic_init, builtin_asan_after_dynamic_init, > builtin_prefetch, builtin_dwarf_cfa, builtin_return_addrss > as ".c" > * ipa-pure-const.c (special_builtin_state): Add builtin_dwarf_cfa > and builtin_return_address. > diff --git a/gcc/builtins.c b/gcc/builtins.c > index 7d0f61fc98b..43433e8d6ce 100644 > --- a/gcc/builtins.c > +++ b/gcc/builtins.c > @@ -10711,6 +10711,8 @@ is_simple_builtin (tree decl) > case BUILT_IN_VA_END: > case BUILT_IN_STACK_SAVE: > case BUILT_IN_STACK_RESTORE: > + case BUILT_IN_DWARF_CFA: > + case BUILT_IN_RETURN_ADDRESS: > /* Exception state returns or moves registers around. */ > case BUILT_IN_EH_FILTER: > case BUILT_IN_EH_POINTER: > @@ -11099,6 +11099,19 @@ builtin_fnspec (tree callee) > CASE_BUILT_IN_TM_STORE (M256): > return ".cO "; > case BUILT_IN_STACK_SAVE: > + case BUILT_IN_RETURN: > + case BUILT_IN_EH_POINTER: > + case BUILT_IN_EH_FILTER: > + case BUILT_IN_UNWIND_RESUME: > + case BUILT_IN_CXA_END_CLEANUP: > + case BUILT_IN_EH_COPY_VALUES: > + case BUILT_IN_FRAME_ADDRESS: > + case BUILT_IN_APPLY_ARGS: > + case BUILT_IN_ASAN_BEFORE_DYNAMIC_INIT: > + case BUILT_IN_ASAN_AFTER_DYNAMIC_INIT: > + case BUILT_IN_PREFETCH: > + case BUILT_IN_DWARF_CFA: > + case BUILT_IN_RETURN_ADDRESS: > return ".c"; > case BUILT_IN_ASSUME_ALIGNED: > return "1cX "; > diff --git a/gcc/ipa-pure-const.c b/gcc/ipa-pure-const.c > index a84a4eb7ac0..e5048092939 100644 > --- a/gcc/ipa-pure-const.c > +++ b/gcc/ipa-pure-const.c > @@ -529,6 +529,8 @@ special_builtin_state (enum pure_const_state_e *state, > bool *looping, > case BUILT_IN_APPLY_ARGS: > case BUILT_IN_ASAN_BEFORE_DYNAMIC_INIT: > case BUILT_IN_ASAN_AFTER_DYNAMIC_INIT: > + case BUILT_IN_DWARF_CFA: > + case BUILT_IN_RETURN_ADDRESS: > *looping = false; > *state = IPA_CONST; > return true;
