"Andre Vieira (lists)" <andre.simoesdiasvie...@arm.com> writes:
> Hi,
>
> This addresses the compile-time increase seen in the PR target/105157.
> This was being caused by selecting the wrong core tuning, as when we
> added the latest AArch64 the TARGET_CPU_generic tuning was pushed beyond
> the 0x3f mask we used to encode both target cpu and attributes into
> TARGET_CPU_DEFAULT.
>
> This is a quick fix to increase the number of allowed cores for now late
> in stage 4, but for next GCC we plan to fix this in a more suitable and
> maintainable manner.
>
> gcc/ChangeLog:
>
> PR target/105157
> * config.gcc: Shift ext_mask by TARGET_CPU_NBITS.
> * config/aarch64/aarch64.h (TARGET_CPU_NBITS): New macro.
> (TARGET_CPU_MASK): Likewise.
> (TARGET_CPU_DEFAULT): Use TARGET_CPU_NBITS.
> * config/aarch64/aarch64.cc (aarch64_get_tune_cpu): Use
> TARGET_CPU_MASK.
> (aarch64_get_arch): Likewise.
> (aarch64_override_options): Use TARGET_CPU_NBITS.
> (aarch64_run_selftests): Add test to guarantee TARGET_CPU_NBITS
> is big enough.
Looks good, just a minor nit:
>
> diff --git a/gcc/config.gcc b/gcc/config.gcc
> index
> 2cc5aeec9e46aacc46e4e509d01f57f9f6585169..8946984f5e93cd6fe5364b44e74c64e714ba1d6a
> 100644
> --- a/gcc/config.gcc
> +++ b/gcc/config.gcc
> @@ -4239,7 +4239,7 @@ case "${target}" in
> ext_val=`echo $ext_val | sed -e
> 's/[a-z0-9]\+//'`
> done
>
> - ext_mask="(("$ext_mask") << 6)"
> + ext_mask="(("$ext_mask") << TARGET_CPU_NBITS)"
> if [ x"$base_id" != x ]; then
> target_cpu_cname="TARGET_CPU_$base_id |
> $ext_mask"
> fi
> diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
> index
> efa46ac0b8799b5849b609d591186e26e5cb37ff..97b2d38dac9f13717e90f4f6996ab94814922950
> 100644
> --- a/gcc/config/aarch64/aarch64.h
> +++ b/gcc/config/aarch64/aarch64.h
> @@ -813,10 +813,17 @@ enum target_cpus
> TARGET_CPU_generic
> };
>
> +
Nit: excess extra line.
> +/* Define how many bits are used to represent the CPU in TARGET_CPU_DEFAULT.
> + This needs to be big enough to fit the value of TARGET_CPU_generic.
> + All bits after this are used to represent the AARCH64_CPU_DEFAULT_FLAGS.
> */
> +#define TARGET_CPU_NBITS 8
> +#define TARGET_CPU_MASK ((1 << TARGET_CPU_NBITS) - 1)
> +
> /* If there is no CPU defined at configure, use generic as default. */
> #ifndef TARGET_CPU_DEFAULT
> #define TARGET_CPU_DEFAULT \
> - (TARGET_CPU_generic | (AARCH64_CPU_DEFAULT_FLAGS << 6))
> + (TARGET_CPU_generic | (AARCH64_CPU_DEFAULT_FLAGS << TARGET_CPU_NBITS))
> #endif
>
> /* If inserting NOP before a mult-accumulate insn remember to adjust the
> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> index
> d66626748e5edc46e46edf10e243114a9f74be97..9d83e007d7a31455c167bf21124cf9fbc0d31788
> 100644
> --- a/gcc/config/aarch64/aarch64.cc
> +++ b/gcc/config/aarch64/aarch64.cc
> @@ -18062,12 +18062,12 @@ aarch64_get_tune_cpu (enum aarch64_processor cpu)
> if (cpu != aarch64_none)
> return &all_cores[cpu];
>
> - /* The & 0x3f is to extract the bottom 6 bits that encode the
> - default cpu as selected by the --with-cpu GCC configure option
> + /* The & TARGET_CPU_MASK is to extract the bottom TARGET_CPU_NBITS bits
> that
> + encode the default cpu as selected by the --with-cpu GCC configure
> option
> in config.gcc.
> ???: The whole TARGET_CPU_DEFAULT and AARCH64_CPU_DEFAULT_FLAGS
> flags mechanism should be reworked to make it more sane. */
> - return &all_cores[TARGET_CPU_DEFAULT & 0x3f];
> + return &all_cores[TARGET_CPU_DEFAULT & TARGET_CPU_MASK];
> }
>
> /* Return the architecture corresponding to the enum ARCH.
> @@ -18079,7 +18079,8 @@ aarch64_get_arch (enum aarch64_arch arch)
> if (arch != aarch64_no_arch)
> return &all_architectures[arch];
>
> - const struct processor *cpu = &all_cores[TARGET_CPU_DEFAULT & 0x3f];
> + const struct processor *cpu
> + = &all_cores[TARGET_CPU_DEFAULT & TARGET_CPU_MASK];
>
> return &all_architectures[cpu->arch];
> }
> @@ -18166,7 +18167,7 @@ aarch64_override_options (void)
> {
> /* Get default configure-time CPU. */
> selected_cpu = aarch64_get_tune_cpu (aarch64_none);
> - aarch64_isa_flags = TARGET_CPU_DEFAULT >> 6;
> + aarch64_isa_flags = TARGET_CPU_DEFAULT >> TARGET_CPU_NBITS;
> }
>
> if (selected_tune)
> @@ -27260,6 +27261,9 @@ aarch64_run_selftests (void)
> {
> aarch64_test_loading_full_dump ();
> aarch64_test_fractional_cost ();
> + /* Check whether the TARGET_CPU_MASK is big enough to fit all of the
> definded
> + CPUs. */
> + ASSERT_TRUE (TARGET_CPU_generic < TARGET_CPU_MASK);
I think this would be better as a static assert at the top level:
static_assert (TARGET_CPU_generic < TARGET_CPU_MASK,
"TARGET_CPU_NBITS is big enough");
OK with that change, thanks.
Richard
> }
>
> } // namespace selftest
