Re: [PATCH V4 2/3] Using pli for constant splitting

[Kewen.Lin]

Hi,

on 2023/12/11 11:26, Jiufu Guo wrote:
> Hi,
> 
> For constant building e.g. r120=0x66666666, which does not fit 'li or lis',
> 'pli' is used to build this constant via 'emit_move_insn'.
> 
> While for a complicated constant, e.g. 0x6666666666666666ULL, when using
> 'rs6000_emit_set_long_const' to split the constant recursively, it fails to
> use 'pli' to build the half part constant: 0x66666666.
> 
> 'rs6000_emit_set_long_const' could be updated to use 'pli' to build half
> part of the constant when necessary.  For example: 0x6666666666666666ULL,
> "pli 3,1717986918; rldimi 3,3,32,0" can be used.
> 
> Compare with previous:
> https://gcc.gnu.org/pipermail/gcc-patches/2023-December/639492.html
> This verion is refreshed and updated testcase name.
> 
> Bootstrap&regtest pass on ppc64{,le}.
> Is this ok for trunk?

OK for trunk, thanks!

BR,
Kewen

> 
> BR,
> Jeff (Jiufu Guo)
> 
> gcc/ChangeLog:
> 
>       * config/rs6000/rs6000.cc (rs6000_emit_set_long_const): Add code to use
>       pli for 34bit constant.
> 
> gcc/testsuite/ChangeLog:
> 
>       * gcc.target/powerpc/const-build-1.c: New test.
> 
> ---
>  gcc/config/rs6000/rs6000.cc                      | 9 ++++++++-
>  gcc/testsuite/gcc.target/powerpc/const-build-1.c | 9 +++++++++
>  2 files changed, 17 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/const-build-1.c
> 
> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
> index 017000a4e02..531c40488b4 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -10511,7 +10511,14 @@ rs6000_emit_set_long_const (rtx dest, HOST_WIDE_INT 
> c, int *num_insns)
>        emit_insn (dest_or_insn);
>    };
> 
> -  if ((ud4 == 0xffff && ud3 == 0xffff && ud2 == 0xffff && (ud1 & 0x8000))
> +  if (TARGET_PREFIXED && SIGNED_INTEGER_34BIT_P (c))
> +    {
> +      /* li/lis/pli */
> +      count_or_emit_insn (dest, GEN_INT (c));
> +      return;
> +    }
> +
> + if ((ud4 == 0xffff && ud3 == 0xffff && ud2 == 0xffff && (ud1 & 0x8000))
>        || (ud4 == 0 && ud3 == 0 && ud2 == 0 && !(ud1 & 0x8000)))
>      {
>        /* li */
> diff --git a/gcc/testsuite/gcc.target/powerpc/const-build-1.c 
> b/gcc/testsuite/gcc.target/powerpc/const-build-1.c
> new file mode 100644
> index 00000000000..7e35f8c507f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/const-build-1.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile { target lp64 } } */
> +/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
> +/* { dg-require-effective-target power10_ok } */
> +
> +unsigned long long msk66() { return 0x6666666666666666ULL; }
> +
> +/* { dg-final { scan-assembler-times {\mpli\M} 1 } } */
> +/* { dg-final { scan-assembler-not {\mli\M} } } */
> +/* { dg-final { scan-assembler-not {\mlis\M} } } */