On Tue, Jun 3, 2025 at 6:06 AM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> On Mon, Jun 2, 2025 at 4:45 PM Richard Sandiford
> <richard.sandif...@arm.com> wrote:
> >
> > "H.J. Lu" <hjl.to...@gmail.com> writes:
> > > On Mon, Jun 2, 2025 at 4:07 PM Richard Sandiford
> > > <richard.sandif...@arm.com> wrote:
> > >>
> > >> "H.J. Lu" <hjl.to...@gmail.com> writes:
> > >> > Since not all CALL instructions in RTL passes have a REG_CALL_DECL
> > >> > note,
> > >> > update get_call_fndecl to also check function symbol for function
> > >> > declaration so that it can be used on CALL instructions like
> > >> >
> > >> > (call_insn 39 38 61 7 (set (reg:SI 0 ax)
> > >> > (call (mem:QI (symbol_ref:DI ("foo") [flags 0x3]
> > >> > <function_decl 0x7fffe96da900 foo>) [0 foo S1 A8])
> > >> > (const_int 0 [0]))) "pr92080-15.c":24:9 1480 {*call_value}
> > >> > (expr_list:REG_DEAD (reg:SI 5 di)
> > >> > (expr_list:REG_DEAD (reg:SI 4 si)
> > >> > (expr_list:REG_EH_REGION (const_int 0 [0])
> > >> > (nil))))
> > >> > (expr_list:SI (use (reg:SI 5 di))
> > >> > (expr_list:SI (use (reg:SI 4 si))
> > >> > (nil))))
> > >> >
> > >> > PR other/120494
> > >> > * rtlanal.cc (get_call_fndecl): Also check function symbol to
> > >> > get function declaration.
> > >>
> > >> What's your use case for this? I think we should instead move to making
> > >> the notes more generally available, since looking at the call rtx won't
> > >> work for targets that need indirect calls (e.g. for -mlong-calls).
> > >
> > > I am working on a pass which needs to check if CALL insn is a recursive
> > > call.
> >
> > I assume false negatives are allowed? That is, "false" means "might be
> > recursive, might not"?
> >
> > > Currently I have
> > >
> > > * Get the declaration of the function called by INSN. If INDIRECT_P
> > > is true, also get indirect declaration. */
> > >
> > > static tree
> > > get_call_fndecl_from_rtx (const rtx_insn *insn, bool indirect_p = false)
> > > {
> > > rtx note = find_reg_note (insn, REG_CALL_DECL, NULL_RTX);
> > > if (note)
> > > {
> > > rtx datum = XEXP (note, 0);
> > > if (datum)
> > > return SYMBOL_REF_DECL (datum);
> > > }
> > > rtx call = get_call_rtx_from (insn);
> > > rtx fnaddr = XEXP (call, 0);
> > > rtx addr = XEXP (fnaddr, 0);
> > > if (GET_CODE (addr) == SYMBOL_REF)
> > > {
> > > tree fndecl = SYMBOL_REF_DECL (addr);
> > > if (fndecl && TREE_CODE (fndecl) == FUNCTION_DECL)
> > > return fndecl;
> > > }
> > > return indirect_p ? MEM_EXPR (fnaddr) : nullptr;
> > > }
> > >
> > > if (CALL_P (insn))
> > > {
> > > tree fndecl = get_call_fndecl_from_rtx (insn);
> > > if (fndecl == current_function_decl
> > > && decl_binds_to_current_def_p (fndecl))
> > > {
> > > recursive_call_p = true;
> > > break;
> > > }
> > > }
> > >
> > > If get_call_fndecl works without a REG_CALL_DECL note, I can use it
> > > instead of writing my own.
> >
> > I think we should consider removing the flag_ipa_ra guards around
> > the code that adds REG_CALL_DECLs.
> >
>
> Like this?
>
> Always add REG_CALL_DECL note for CALL so that get_call_fndecl works
> without -fipa-ra.
>
> PR other/120494
> * calls.cc (expand_call): Always add REG_CALL_DECL note.
> (emit_library_call_value_1): Likewise.
>
> Thanks.
>
>
> --
> H.J.
I found another way to check recursive function. I don't need this patch for
my pass.
--
H.J.
