On Wed, Sep 28, 2022 at 01:30:46PM +0800, Kewen.Lin 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.
Thanks!
> 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
> it disables OPTION_MASK_POWERPC64 if OS_MISSING_POWERPC64.
If the user says -m64 -mno-powerpc64 it should error, and perhaps -m32
-mpowerpc64 should warn if OS_MISSING_POWERPC64?
> - /* 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_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. */
>
> set_masks = POWERPC_MASKS;
> -#ifdef OS_MISSING_POWERPC64
> - if (OS_MISSING_POWERPC64)
> - set_masks &= ~OPTION_MASK_POWERPC64;
> -#endif
As I said elsewhere, it probably is helpful if we still warn here for
-m32 -mpowerpc64 with OS_MISSING_POWERPC64 (or without the -m32 even,
same thing).
> + /* With option powerpc64 specified explicitly (either on or off), even if
> + being compiled for 64 bit we don't need to check if it's disabled here,
> + since subtargets will check and raise an error message if necessary
> + later. But without option powerpc64 specified explicitly, we need to
> + ensure powerpc64 enabled for 64 bit and disabled on those OSes with
> + OS_MISSING_POWERPC64, since they don't support saving the high part of
> + 64-bit registers on context switch. */
> + if (!(rs6000_isa_flags_explicit & OPTION_MASK_POWERPC64))
> + {
> + if (TARGET_64BIT)
> + /* Make sure we always enable it by default for 64 bit. */
> + rs6000_isa_flags |= OPTION_MASK_POWERPC64;
> +#ifdef OS_MISSING_POWERPC64
> + else if (OS_MISSING_POWERPC64)
> + /* It's unexpected to have OPTION_MASK_POWERPC64 on for OSes which
> + miss powerpc64 support, so disable it. */
> + rs6000_isa_flags &= ~OPTION_MASK_POWERPC64;
> +#endif
> + }
Aha. Please don't, just warn instead? Silently disabling such stuff is
the worst option :-(
> +/* { dg-error "'-m64' requires a PowerPC64 cpu" "PR106680" { target
> powerpc*-*-linux* powerpc-*-rtems* } 0 } */
Everything except AIX even? So it will include Darwin as well (and the
BSDs, and powerpc*-elf, etc.)
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr106680-4.c
> @@ -0,0 +1,16 @@
> +/* 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" } */
If you have -m32 you don't need ilp32, and the other way around.
> +/* 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 "addc" } } */
> +/* { dg-final { scan-assembler-not "adde" } } */
Lol, nice :-)
"adde" is a frequent substring, use \m \M please? You will always get
these exact insns anyway. And you could add a -times {\madd\M} 1 ?
- - -
The Darwin problem might be something in darwin*.h, but I don't see it.
Maybe it is a more generic problem?
Segher
