Re: [PATCH v2] rs6000: Rework option -mpowerpc64 handling [PR106680]

[Iain Sandoe <iain@sandoe.co.uk>]

Hi Kewen,

> On 12 Oct 2022, at 09:12, Kewen.Lin <linkw@linux.ibm.com> wrote:

> PR106680 shows that -m32 -mpowerpc64 is different from
> -mpowerpc64 -m32, this is determined by the way how we
> handle option powerpc64 in rs6000_handle_option.
> 
> Segher pointed out this difference should be taken as
> a bug and we should ensure that option powerpc64 is
> independent of -m32/-m64.  So this patch removes the
> handlings in rs6000_handle_option and add some necessary
> supports in rs6000_option_override_internal instead.
> 
> With this patch, if users specify -m{no-,}powerpc64, the
> specified value is honoured, otherwise, for 64bit it
> always enables OPTION_MASK_POWERPC64; while for 32bit
> and TARGET_POWERPC64 and OS_MISSING_POWERPC64, it disables
> OPTION_MASK_POWERPC64.
> 
> btw, following Segher's suggestion, I did some tries to warn
> when OPTION_MASK_POWERPC64 is set for OS_MISSING_POWERPC64.
> If warn for the case that powerpc64 is specified explicitly,
> there are some TCs using -m32 -mpowerpc64 on ppc64-linux,
> they need some updates, meanwhile the artificial run
> with "--target_board=unix'{-m32/-mpowerpc64}'" will have
> noisy warnings on ppc64-linux.  If warn for the case that
> it's specified implicitly, they can just be initialized by
> TARGET_DEFAULT (like -m32 on ppc64-linux) or set from the 
> given cpu mask, we have to special case them and not to warn.
> As Segher's latest comment, I decide not to warn them and
> keep it consistent with before.
> 
> Bootstrapped and regress-tested on:
>  - powerpc64-linux-gnu P7 and P8 {-m64,-m32}
>  - powerpc64le-linux-gnu P9 and P10
>  - powerpc-ibm-aix7.2.0.0 {-maix64,-maix32}
> 
> Hi Iain, could you help to test this new patch on darwin
> again?  Thanks in advance!

I kicked off a bootstrap - and 'check-gcc-c' .. if all goes well, there will be an 
answer in ≈ 7hours.  If something fails, the answer will be sooner ;)
cheers
Iain

> 
> Is it ok for trunk if darwin testing goes well?
> 
> BR,
> Kewen
> -----
> 	PR target/106680
> 
> gcc/ChangeLog:
> 
> 	* common/config/rs6000/rs6000-common.cc (rs6000_handle_option): Remove
> 	the adjustment for option powerpc64 in -m64 handling, and remove the
> 	whole -m32 handling.
> 	* config/rs6000/rs6000.cc (rs6000_option_override_internal): When no
> 	explicit powerpc64 option is provided, enable it for -m64.  For 32 bit
> 	and OS_MISSING_POWERPC64, disable powerpc64 if it's enabled but not
> 	specified explicitly.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.target/powerpc/pr106680-1.c: New test.
> 	* gcc.target/powerpc/pr106680-2.c: New test.
> 	* gcc.target/powerpc/pr106680-3.c: New test.
> 	* gcc.target/powerpc/pr106680-4.c: New test.
> 
> 2022-10-12  Kewen Lin  <linkw@linux.ibm.com>
> 	    Iain Sandoe  <iain@sandoe.co.uk>
> ---
> gcc/common/config/rs6000/rs6000-common.cc     | 11 ------
> gcc/config/rs6000/rs6000.cc                   | 37 ++++++++++++++-----
> gcc/testsuite/gcc.target/powerpc/pr106680-1.c | 13 +++++++
> gcc/testsuite/gcc.target/powerpc/pr106680-2.c | 14 +++++++
> gcc/testsuite/gcc.target/powerpc/pr106680-3.c | 13 +++++++
> gcc/testsuite/gcc.target/powerpc/pr106680-4.c | 17 +++++++++
> 6 files changed, 85 insertions(+), 20 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr106680-1.c
> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr106680-2.c
> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr106680-3.c
> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr106680-4.c
> 
> diff --git a/gcc/common/config/rs6000/rs6000-common.cc b/gcc/common/config/rs6000/rs6000-common.cc
> index 8e393d08a23..c76b5c27bb6 100644
> --- a/gcc/common/config/rs6000/rs6000-common.cc
> +++ b/gcc/common/config/rs6000/rs6000-common.cc
> @@ -119,19 +119,8 @@ rs6000_handle_option (struct gcc_options *opts, struct gcc_options *opts_set,
> #else
>     case OPT_m64:
> #endif
> -      opts->x_rs6000_isa_flags |= OPTION_MASK_POWERPC64;
>       opts->x_rs6000_isa_flags |= (~opts_set->x_rs6000_isa_flags
> 				   & OPTION_MASK_PPC_GFXOPT);
> -      opts_set->x_rs6000_isa_flags |= OPTION_MASK_POWERPC64;
> -      break;
> -
> -#ifdef TARGET_USES_AIX64_OPT
> -    case OPT_maix32:
> -#else
> -    case OPT_m32:
> -#endif
> -      opts->x_rs6000_isa_flags &= ~OPTION_MASK_POWERPC64;
> -      opts_set->x_rs6000_isa_flags |= OPTION_MASK_POWERPC64;
>       break;
> 
>     case OPT_mminimal_toc:
> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
> index e6fa3ad0eb7..e37d99deb61 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -3648,17 +3648,12 @@ rs6000_option_override_internal (bool global_init_p)
>       rs6000_pointer_size = 32;
>     }
> 
> -  /* Some OSs don't support saving the high part of 64-bit registers on context
> -     switch.  Other OSs don't support saving Altivec registers.  On those OSs,
> -     we don't touch the OPTION_MASK_POWERPC64 or OPTION_MASK_ALTIVEC settings;
> -     if the user wants either, the user must explicitly specify them and we
> -     won't interfere with the user's specification.  */
> +  /* Some OSs don't support saving Altivec registers.  On those OSs, we don't
> +     touch the OPTION_MASK_ALTIVEC settings; if the user wants it, the user
> +     must explicitly specify it and we won't interfere with the user's
> +     specification.  */
> 
>   set_masks = POWERPC_MASKS;
> -#ifdef OS_MISSING_POWERPC64
> -  if (OS_MISSING_POWERPC64)
> -    set_masks &= ~OPTION_MASK_POWERPC64;
> -#endif
> #ifdef OS_MISSING_ALTIVEC
>   if (OS_MISSING_ALTIVEC)
>     set_masks &= ~(OPTION_MASK_ALTIVEC | OPTION_MASK_VSX
> @@ -3668,6 +3663,18 @@ rs6000_option_override_internal (bool global_init_p)
>   /* Don't override by the processor default if given explicitly.  */
>   set_masks &= ~rs6000_isa_flags_explicit;
> 
> +  /* Without option powerpc64 specified explicitly, we need to ensure
> +     powerpc64 always enabled for 64 bit here, otherwise some following
> +     checks can use unexpected TARGET_POWERPC64 value.  Meanwhile, we
> +     need to ensure set_masks doesn't have OPTION_MASK_POWERPC64 on,
> +     otherwise later processing can clear it.  */
> +  if (!(rs6000_isa_flags_explicit & OPTION_MASK_POWERPC64)
> +      && TARGET_64BIT)
> +    {
> +      rs6000_isa_flags |= OPTION_MASK_POWERPC64;
> +      set_masks &= ~OPTION_MASK_POWERPC64;
> +    }
> +
>   /* Process the -mcpu=<xxx> and -mtune=<xxx> argument.  If the user changed
>      the cpu in a target attribute or pragma, but did not specify a tuning
>      option, use the cpu for the tuning option rather than the option specified
> @@ -3718,6 +3725,18 @@ rs6000_option_override_internal (bool global_init_p)
>       rs6000_isa_flags |= (flags & ~rs6000_isa_flags_explicit);
>     }
> 
> +  /* Don't expect powerpc64 enabled on those OSes with OS_MISSING_POWERPC64,
> +     since they don't support saving the high part of 64-bit registers on
> +     context switch.  If the user explicitly specifies it, we won't interfere
> +     with the user's specification.  */
> +#ifdef OS_MISSING_POWERPC64
> +  if (OS_MISSING_POWERPC64
> +      && TARGET_32BIT
> +      && TARGET_POWERPC64
> +      && !(rs6000_isa_flags_explicit & OPTION_MASK_POWERPC64))
> +    rs6000_isa_flags &= ~OPTION_MASK_POWERPC64;
> +#endif
> +
>   if (rs6000_tune_index >= 0)
>     tune_index = rs6000_tune_index;
>   else if (cpu_index >= 0)
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106680-1.c b/gcc/testsuite/gcc.target/powerpc/pr106680-1.c
> new file mode 100644
> index 00000000000..d624d43230a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr106680-1.c
> @@ -0,0 +1,13 @@
> +/* { dg-require-effective-target lp64 } */
> +/* { dg-options "-mno-powerpc64" } */
> +
> +/* Verify there is an error message about PowerPC64 requirement.  */
> +
> +int foo ()
> +{
> +  return 1;
> +}
> +
> +/* { dg-error "'-m64' requires a PowerPC64 cpu" "PR106680" { target powerpc*-*-linux* powerpc*-*-freebsd* powerpc-*-rtems* } 0 } */
> +/* { dg-warning "'-m64' requires PowerPC64 architecture, enabling" "PR106680" { target powerpc*-*-darwin* } 0 } */
> +/* { dg-warning "'-maix64' requires PowerPC64 architecture remain enabled" "PR106680" { target powerpc*-*-aix* } 0 } */
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106680-2.c b/gcc/testsuite/gcc.target/powerpc/pr106680-2.c
> new file mode 100644
> index 00000000000..a9ed73726ef
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr106680-2.c
> @@ -0,0 +1,14 @@
> +/* { dg-require-effective-target lp64 } */
> +/* { dg-options "-mno-powerpc64 -m64" } */
> +
> +/* Verify option -m64 doesn't override option -mno-powerpc64,
> +   and there is an error message about PowerPC64 requirement.  */
> +
> +int foo ()
> +{
> +  return 1;
> +}
> +
> +/* { dg-error "'-m64' requires a PowerPC64 cpu" "PR106680" { target powerpc*-*-linux* powerpc*-*-freebsd* powerpc-*-rtems* } 0 } */
> +/* { dg-warning "'-m64' requires PowerPC64 architecture, enabling" "PR106680" { target powerpc*-*-darwin* } 0 } */
> +/* { dg-warning "'-maix64' requires PowerPC64 architecture remain enabled" "PR106680" { target powerpc*-*-aix* } 0 } */
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106680-3.c b/gcc/testsuite/gcc.target/powerpc/pr106680-3.c
> new file mode 100644
> index 00000000000..b642d5c7a00
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr106680-3.c
> @@ -0,0 +1,13 @@
> +/* { dg-require-effective-target lp64 } */
> +/* { dg-options "-m64 -mno-powerpc64" } */
> +
> +/* Verify there is an error message about PowerPC64 requirement.  */
> +
> +int foo ()
> +{
> +  return 1;
> +}
> +
> +/* { dg-error "'-m64' requires a PowerPC64 cpu" "PR106680" { target powerpc*-*-linux* powerpc*-*-freebsd* powerpc-*-rtems* } 0 } */
> +/* { dg-warning "'-m64' requires PowerPC64 architecture, enabling" "PR106680" { target powerpc*-*-darwin* } 0 } */
> +/* { dg-warning "'-maix64' requires PowerPC64 architecture remain enabled" "PR106680" { target powerpc*-*-aix* } 0 } */
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106680-4.c b/gcc/testsuite/gcc.target/powerpc/pr106680-4.c
> new file mode 100644
> index 00000000000..7fee48d39f3
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr106680-4.c
> @@ -0,0 +1,17 @@
> +/* Skip this on aix, otherwise it emits the error message like "64-bit
> +   computation with 32-bit addressing not yet supported" on aix.  */
> +/* { dg-skip-if "" { powerpc*-*-aix* } } */
> +/* { dg-require-effective-target ilp32 } */
> +/* { dg-options "-mpowerpc64 -m32 -O2" } */
> +
> +/* Verify option -m32 doesn't override option -mpowerpc64.
> +   If option -mpowerpc64 gets overridden, the assembly would
> +   end up with addc and adde.  */
> +/* { dg-final { scan-assembler-not {\maddc\M} } } */
> +/* { dg-final { scan-assembler-not {\madde\M} } } */
> +/* { dg-final { scan-assembler-times {\madd\M} 1 } } */
> +
> +long long foo (long long a, long long b)
> +{
> +  return a+b;
> +}
> --
> 2.27.0