[patch]: Implement PR104327 for avr

[Richard Biener]

On Tue, May 23, 2023 at 2:56 PM Georg-Johann Lay <avr@gjlay.de> wrote:
>
> PR target/104327 not only affects s390 but also avr:
> The avr backend pre-sets some options depending on optimization level.
> The inliner then thinks that always_inline functions are not eligible
> for inlining and terminates with an error.
>
> Proposing the following patch that implements TARGET_CAN_INLINE_P.
>
> Ok to apply?
>
> Johann
>
> --
>
> target/104327: Allow more inlining between different optimization levels.
>
> avr-common.cc introduces the following options that are set depending
> on optimization level: -mgas-isr-prologues, -mmain-is-OS-task and
> -fsplit-wide-types-early.  The inliner thinks that different options
> disallow cross-optimization inlining, so provide can_inline_p.
>
> gcc/
>         PR target/104327
>         * config/avr/avr.cc (avr_can_inline_p): New static function.
>         (TARGET_CAN_INLINE_P): Define to that function.
> diff --git a/gcc/config/avr/avr.cc b/gcc/config/avr/avr.cc
> index 9fa50ca230d..55b48f63865 100644
> --- a/gcc/config/avr/avr.cc
> +++ b/gcc/config/avr/avr.cc
> @@ -1018,6 +1018,22 @@ avr_no_gccisr_function_p (tree func)
>     return avr_lookup_function_attribute1 (func, "no_gccisr");
>   }
>
> +
> +/* Implement `TARGET_CAN_INLINE_P'.  */
> +/* Some options like -mgas_isr_prologues depend on optimization level,
> +   and the inliner might think that due to different options, inlining
> +   is not permitted; see PR104327.  */
> +
> +static bool
> +avr_can_inline_p (tree /* caller */, tree callee)
> +{
> +  // For now, dont't allow to inline ISRs.  If the user actually wants
> +  // to inline ISR code, they have to turn the body of the ISR into an
> +  // ordinary function.
> +
> +  return ! avr_interrupt_function_p (callee);

I'm not sure if AVR has ISA extensions but the above will likely break
things like

void __attribute__((target("-mX"))) foo () { asm ("isa X opcode");
stmt-that-generates-X-ISA; }

void bar ()
{
  if (cpu-has-X)
    foo ();
}

if always-inlines are the concern you can use

  bool always_inline
    = (DECL_DISREGARD_INLINE_LIMITS (callee)
       && lookup_attribute ("always_inline",
                            DECL_ATTRIBUTES (callee)));
  /* Do what the user says.  */
  if (always_inline)
    return true;

  return default_target_can_inline_p (caller, callee);



> +}
> +
>   /* Implement `TARGET_SET_CURRENT_FUNCTION'.  */
>   /* Sanity cheching for above function attributes.  */
>
> @@ -14713,6 +14729,9 @@ avr_float_lib_compare_returns_bool (machine_mode
> mode, enum rtx_code)
>   #undef  TARGET_MD_ASM_ADJUST
>   #define TARGET_MD_ASM_ADJUST avr_md_asm_adjust
>
> +#undef  TARGET_CAN_INLINE_P
> +#define TARGET_CAN_INLINE_P avr_can_inline_p
> +
>   struct gcc_target targetm = TARGET_INITIALIZER;
>
>
>