Re: [PATCH V2]HIGH part of symbol ref is invalid for constant pool[PR106460]

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

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

New patch V6 is updated as:
https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600475.html.

BR,
Jeff(Jiufu)

> Hi,
>
> As the issue in PR106460, a rtx 'high:DI (symbol_ref:DI ("var_48")' is tried
> to store into constant pool.  But actually, it indicates partial address,
> which to be forced to constant memory.
>
> In function rs6000_cannot_force_const_mem, we already return true for
> "HIGH with UNSPEC" rtx.  For this function if GET_CODE (X) is HIGH, the "X"
> represents the high part of a symbol ref, this function would also return
> true.  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 updates rs6000_cannot_force_const_mem to return true for
> rtx with HIGH code.
>
> 	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 0af2085adc0..d56832ebbfc 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -9704,8 +9704,11 @@ 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..ed7a994827b
> --- /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;
> +}
> +