Re: [PATCH] avr: Set param_min_pagesize to 0 [PR105523]

[Richard Biener <richard.guenther@gmail.com>]

On Wed, Apr 26, 2023 at 12:56 PM <SenthilKumar.Selvaraj@microchip.com> wrote:
>
> On Wed, Apr 26, 2023 at 3:15 PM Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> >
> > On Wed, Apr 26, 2023 at 11:42 AM Richard Biener
> > <richard.guenther@gmail.com> wrote:
> > >
> > > On Wed, Apr 26, 2023 at 11:01 AM SenthilKumar.Selvaraj--- via
> > > Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> > > >
> > > > Hi,
> > > >
> > > > This patch fixes PR 105523 by setting param_min_pagesize to 0 for the
> > > > avr target. For this target, zero and offsets from zero are perfectly
> > > > valid addresses, and the default value of param_min_pagesize ends up
> > > > triggering warnings on valid memory accesses.
> > >
> > > I think the proper configuration is to have
> > > DEFAULT_ADDR_SPACE_ZERO_ADDRESS_VALID
> >
> > Err, TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID
>
> That worked. Ok for trunk and backporting to 13 and 12 branches
> (pending regression testing)?

OK, but please let Denis time to comment.

Richard.

> Regards,
> Senthil
>
>         PR 105523
>
> gcc/ChangeLog:
>
>         * config/avr/avr.cc (avr_addr_space_zero_address_valid):
>         (TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID): Return true.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/avr/pr105523.c: New test.
>
>
>
> diff --git a/gcc/config/avr/avr.cc b/gcc/config/avr/avr.cc
> index c193430cf07..5439eb8e55c 100644
> --- a/gcc/config/avr/avr.cc
> +++ b/gcc/config/avr/avr.cc
> @@ -9788,6 +9788,16 @@ avr_addr_space_diagnose_usage (addr_space_t as, location_t loc)
>    (void) avr_addr_space_supported_p (as, loc);
>  }
>
> +/* Implement `TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID. Zero is a valid
> +   address in all address spaces. Even in ADDR_SPACE_FLASH1 etc.,
> +   a zero address is valid and means 0x<RAMPZ>0000, where RAMPZ is
> +   set to the appropriate segment value. */
> +
> +static bool
> +avr_addr_space_zero_address_valid (addr_space_t as)
> +{
> +  return true;
> +}
>
>  /* Look if DECL shall be placed in program memory space by
>     means of attribute `progmem' or some address-space qualifier.
> @@ -14688,6 +14698,9 @@ avr_float_lib_compare_returns_bool (machine_mode mode, enum rtx_code)
>  #undef  TARGET_ADDR_SPACE_DIAGNOSE_USAGE
>  #define TARGET_ADDR_SPACE_DIAGNOSE_USAGE avr_addr_space_diagnose_usage
>
> +#undef  TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID
> +#define TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID avr_addr_space_zero_address_valid
> +
>  #undef  TARGET_MODE_DEPENDENT_ADDRESS_P
>  #define TARGET_MODE_DEPENDENT_ADDRESS_P avr_mode_dependent_address_p
>
> diff --git a/gcc/testsuite/gcc.target/avr/pr105523.c b/gcc/testsuite/gcc.target/avr/pr105523.c
> new file mode 100644
> index 00000000000..fbbf7bf4422
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/avr/pr105523.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Os -Wall" } */
> +
> +/* Verify no "array subscript 0 is outside array bounds of" is generated
> +   for accessing memory addresses in the 0-4096 range. */
> +
> +typedef __UINT8_TYPE__ uint8_t;
> +
> +#define SREG (*(volatile uint8_t*) (0x3F + __AVR_SFR_OFFSET__ ))
> +
> +void bar (void)
> +{
> +    SREG = 0;
> +}
>
>