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

[Richard Biener]

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

> defined to something returning true instead.
>
> Richard.
>
> > Ok for trunk and backporting to 13 and 12 branches?
> >
> > Regards
> > Senthil
> >
> >         PR target/105523
> >
> >         gcc/ChangeLog:
> >
> >                         * config/avr/avr.cc (avr_option_override): Set
> >                         param_min_pagesize to 0.
> >
> >         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..3b862f4e4ac 100644
> > --- a/gcc/config/avr/avr.cc
> > +++ b/gcc/config/avr/avr.cc
> > @@ -56,6 +56,7 @@
> >  #include "tree-pass.h"
> >  #include "print-rtl.h"
> >  #include "rtl-iter.h"
> > +#include "opts.h"
> >
> >  /* This file should be included last.  */
> >  #include "target-def.h"
> > @@ -769,6 +770,9 @@ avr_option_override (void)
> >    avr_gasisr_prologues = 0;
> >  #endif
> >
> > +  SET_OPTION_IF_UNSET (&global_options, &global_options_set,
> > +                       param_min_pagesize, 0);
> > +
> >    if (!avr_set_core_architecture())
> >      return;
> >
> > 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;
> > +}
> >