Re: [PATCH V3] rs6000: cannot_force_const_mem for HIGH code rtx[PR106460]

[Jiufu Guo <guojiufu@linux.ibm.com>]

Hi,

Gentle ping:
https://gcc.gnu.org/pipermail/gcc-patches/2022-September/601190.html

BR,
Jeff (Jiufu)

Jiufu Guo <guojiufu@linux.ibm.com> writes:

> Hi,
>
> As the issue in PR106460, a rtx 'high:DI (symbol_ref:DI ("var_48")' is tried
> to store into constant pool and ICE occur.  But actually, this rtx represents
> partial address and can not be put into a .rodata section.
>
> This patch updates rs6000_cannot_force_const_mem to return true for rtx(s) with
> HIGH code, because these rtx(s) indicate part of address and are not ok for
> constant pool.
>
> Below are some examples:
> (high:DI (const:DI (plus:DI (symbol_ref:DI ("xx") (const_int 12 [0xc])))))
> (high:DI (symbol_ref:DI ("var_1")..)))
>
> This patch updated the previous patch, and drafted an test case which ICE
> without the patch, and assoicated with one PR.
> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/597712.html
> This patch also updated the message for previous patch V2.
>
> I would ask help to review this patch one more time.
>
> Bootstrap and regtest pass on ppc64 and ppc64le.
> Is this ok for trunk.
>
> BR,
> Jeff(Jiufu)
>
> 	PR target/106460
>
> gcc/ChangeLog:
>
> 	* config/rs6000/rs6000.cc (rs6000_cannot_force_const_mem): Return true
> 	for HIGH code rtx.
>
> gcc/testsuite/ChangeLog:
>
> 	* gcc.target/powerpc/pr106460.c: New test.
> ---
>  gcc/config/rs6000/rs6000.cc                 |  7 +++++--
>  gcc/testsuite/gcc.target/powerpc/pr106460.c | 11 +++++++++++
>  2 files changed, 16 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/pr106460.c
>
> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
> index 2f3146e56f8..04e3a393147 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -9643,8 +9643,11 @@ rs6000_init_stack_protect_guard (void)
>  static bool
>  rs6000_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x)
>  {
> -  if (GET_CODE (x) == HIGH
> -      && GET_CODE (XEXP (x, 0)) == UNSPEC)
> +  /* If GET_CODE (x) is HIGH, the 'X' represets the high part of a symbol_ref.
> +     It indicates partial address,  which can not be put into a constant pool.
> +     e.g.  (high:DI (unspec:DI [(symbol_ref/u:DI ("*.LC0")..)
> +     (high:DI (symbol_ref:DI ("var")..)).  */
> +  if (GET_CODE (x) == HIGH)
>      return true;
>  
>    /* A TLS symbol in the TOC cannot contain a sum.  */
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106460.c b/gcc/testsuite/gcc.target/powerpc/pr106460.c
> new file mode 100644
> index 00000000000..dfaffcb6e28
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr106460.c
> @@ -0,0 +1,11 @@
> +/* { dg-options "-O1 -mdejagnu-cpu=power10" } */
> +
> +/* (high:DI (symbol_ref:DI ("var_48")..))) should not cause ICE. */
> +extern short var_48;
> +void
> +foo (double *r)
> +{
> +  if (var_48)
> +    *r = 1234.5678;
> +}
> +