Re: [PATCH] regcprop: Determine subreg offset depending on endianness [PR101260]

[Stefan Schulze Frielinghaus <stefansf@linux.ibm.com>]

ping

On Mon, Oct 11, 2021 at 02:14:53PM +0200, Stefan Schulze Frielinghaus wrote:
> On Mon, Oct 11, 2021 at 09:38:36AM +0200, Richard Biener wrote:
> > On Fri, Oct 8, 2021 at 1:31 PM Stefan Schulze Frielinghaus via
> > Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> > >
> > > gcc/ChangeLog:
> > >
> > >         * regcprop.c (maybe_mode_change): Determine offset relative to
> > >         high or low part depending on endianness.
> > >
> > > Bootstrapped and regtested on IBM Z. Ok for mainline and gcc-{11,10,9}?
> > 
> > Is there a testcase to add?
> 
> I've updated the patch and added the testcase from the PR.
> 
> > 
> > > ---
> > >  gcc/regcprop.c | 11 ++++++++---
> > >  1 file changed, 8 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/gcc/regcprop.c b/gcc/regcprop.c
> > > index d2a01130fe1..0e1ac12458a 100644
> > > --- a/gcc/regcprop.c
> > > +++ b/gcc/regcprop.c
> > > @@ -414,9 +414,14 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
> > >                             copy_nregs, &bytes_per_reg))
> > >         return NULL_RTX;
> > >        poly_uint64 copy_offset = bytes_per_reg * (copy_nregs - use_nregs);
> > > -      poly_uint64 offset
> > > -       = subreg_size_lowpart_offset (GET_MODE_SIZE (new_mode) + copy_offset,
> > > -                                     GET_MODE_SIZE (orig_mode));
> > > +      poly_uint64 offset =
> > > +#if WORDS_BIG_ENDIAN
> > > +       subreg_size_highpart_offset
> > > +#else
> > > +       subreg_size_lowpart_offset
> > > +#endif
> > > +                                   (GET_MODE_SIZE (new_mode) + copy_offset,
> > > +                                    GET_MODE_SIZE (orig_mode));
> > >        regno += subreg_regno_offset (regno, orig_mode, offset, new_mode);
> > >        if (targetm.hard_regno_mode_ok (regno, new_mode))
> > >         return gen_raw_REG (new_mode, regno);
> > > --
> > > 2.31.1
> > >

> From 299959788321e21c27f0d4a6d437a586c5f6c92e Mon Sep 17 00:00:00 2001
> From: Stefan Schulze Frielinghaus <stefansf@linux.ibm.com>
> Date: Mon, 4 Oct 2021 09:36:21 +0200
> Subject: [PATCH] regcprop: Determine subreg offset depending on endianness
>  [PR101260]
> 
> gcc/ChangeLog:
> 
> 	* regcprop.c (maybe_mode_change): Determine offset relative to
> 	high or low part depending on endianness.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/pr101260.c: New test.
> ---
>  gcc/regcprop.c                  | 11 ++++++--
>  gcc/testsuite/gcc.dg/pr101260.c | 49 +++++++++++++++++++++++++++++++++
>  2 files changed, 57 insertions(+), 3 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/pr101260.c
> 
> diff --git a/gcc/regcprop.c b/gcc/regcprop.c
> index d2a01130fe1..0e1ac12458a 100644
> --- a/gcc/regcprop.c
> +++ b/gcc/regcprop.c
> @@ -414,9 +414,14 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
>  			    copy_nregs, &bytes_per_reg))
>  	return NULL_RTX;
>        poly_uint64 copy_offset = bytes_per_reg * (copy_nregs - use_nregs);
> -      poly_uint64 offset
> -	= subreg_size_lowpart_offset (GET_MODE_SIZE (new_mode) + copy_offset,
> -				      GET_MODE_SIZE (orig_mode));
> +      poly_uint64 offset =
> +#if WORDS_BIG_ENDIAN
> +	subreg_size_highpart_offset
> +#else
> +	subreg_size_lowpart_offset
> +#endif
> +				    (GET_MODE_SIZE (new_mode) + copy_offset,
> +				     GET_MODE_SIZE (orig_mode));
>        regno += subreg_regno_offset (regno, orig_mode, offset, new_mode);
>        if (targetm.hard_regno_mode_ok (regno, new_mode))
>  	return gen_raw_REG (new_mode, regno);
> diff --git a/gcc/testsuite/gcc.dg/pr101260.c b/gcc/testsuite/gcc.dg/pr101260.c
> new file mode 100644
> index 00000000000..0e9ec4e203a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr101260.c
> @@ -0,0 +1,49 @@
> +/* PR rtl-optimization/101260 */
> +/* { dg-do run } */
> +/* { dg-options -O1 } */
> +struct a {
> +  unsigned b : 7;
> +  int c;
> +  int d;
> +  short e;
> +} p, *q = &p;
> +int f, g, h, i, r, s;
> +static short j[8][1][6] = {0};
> +char k[7];
> +short l, m;
> +int *n;
> +int **o = &n;
> +void t() {
> +  for (; f;)
> +    ;
> +}
> +static struct a u(int x) {
> +  struct a a = {4, 8, 5, 4};
> +  for (; i <= 6; i++) {
> +    struct a v = {0};
> +    for (; l; l++)
> +      h = 0;
> +    for (; h >= 0; h--) {
> +      struct a *w;
> +      j[i];
> +      w = &p;
> +      s = 0;
> +      for (; s < 3; s++) {
> +        r ^= x;
> +        m = j[i][g][h] == (k[g] = g);
> +        *w = v;
> +      }
> +      r = 2;
> +      for (; r; r--)
> +        *o = &r;
> +    }
> +  }
> +  t();
> +  return a;
> +}
> +int main() {
> +  *q = u(636);
> +  if (p.b != 4)
> +    __builtin_abort ();
> +  return 0;
> +}
> -- 
> 2.31.1
>