Re: [PATCH] RISC-V: Add Zawrs ISA extension support

[Palmer Dabbelt <palmer@dabbelt.com>]

On Thu, 27 Oct 2022 11:23:17 PDT (-0700), christoph.muellner@vrull.eu wrote:
> On Thu, Oct 27, 2022 at 8:11 PM Christoph Muellner <
> christoph.muellner@vrull.eu> wrote:
>
>> From: Christoph Muellner <cmuellner@gcc.gnu.org>
>>
>> This patch adds support for the Zawrs ISA extension.
>> The patch depends on the corresponding Binutils patch
>> to be usable (see [1])
>>
>> The specification can be found here:
>> https://github.com/riscv/riscv-zawrs/blob/main/zawrs.adoc
>>
>> Note, that the Zawrs extension is not frozen or ratified yet.
>> Therefore this patch is an RFC and not intended to get merged.
>>
>
> Sorry, forgot to update this part:
> The Zawrs extension is frozen but not ratified.
> Let me know if I should send a v2 for this change of the commit msg.

IMO it's fine to just fix it up at commit time.  This LGTM, we just need 
the NEWS entry too.  I also don't see any build/test results.

Thanks!

> Binuitls support has been merged recently:
>
> https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=eb668e50036e979fb0a74821df4eee0307b44e66
>
>
>>
>> [1] https://sourceware.org/pipermail/binutils/2022-April/120559.html
>>
>> gcc/ChangeLog:
>>
>>         * common/config/riscv/riscv-common.cc: Add zawrs extension.
>>         * config/riscv/riscv-opts.h (MASK_ZAWRS): New.
>>         (TARGET_ZAWRS): New.
>>         * config/riscv/riscv.opt: New.
>>
>> gcc/testsuite/ChangeLog:
>>
>>         * gcc.target/riscv/zawrs.c: New test.
>>
>> Signed-off-by: Christoph Muellner <cmuellner@gcc.gnu.org>
>> ---
>>  gcc/common/config/riscv/riscv-common.cc |  4 ++++
>>  gcc/config/riscv/riscv-opts.h           |  3 +++
>>  gcc/config/riscv/riscv.opt              |  3 +++
>>  gcc/testsuite/gcc.target/riscv/zawrs.c  | 13 +++++++++++++
>>  4 files changed, 23 insertions(+)
>>  create mode 100644 gcc/testsuite/gcc.target/riscv/zawrs.c
>>
>> diff --git a/gcc/common/config/riscv/riscv-common.cc
>> b/gcc/common/config/riscv/riscv-common.cc
>> index d6404a01205..4b7f777c103 100644
>> --- a/gcc/common/config/riscv/riscv-common.cc
>> +++ b/gcc/common/config/riscv/riscv-common.cc
>> @@ -163,6 +163,8 @@ static const struct riscv_ext_version
>> riscv_ext_version_table[] =
>>    {"zifencei", ISA_SPEC_CLASS_20191213, 2, 0},
>>    {"zifencei", ISA_SPEC_CLASS_20190608, 2, 0},
>>
>> +  {"zawrs", ISA_SPEC_CLASS_NONE, 1, 0},
>> +
>>    {"zba", ISA_SPEC_CLASS_NONE, 1, 0},
>>    {"zbb", ISA_SPEC_CLASS_NONE, 1, 0},
>>    {"zbc", ISA_SPEC_CLASS_NONE, 1, 0},
>> @@ -1180,6 +1182,8 @@ static const riscv_ext_flag_table_t
>> riscv_ext_flag_table[] =
>>    {"zicsr",    &gcc_options::x_riscv_zi_subext, MASK_ZICSR},
>>    {"zifencei", &gcc_options::x_riscv_zi_subext, MASK_ZIFENCEI},
>>
>> +  {"zawrs", &gcc_options::x_riscv_za_subext, MASK_ZAWRS},
>> +
>>    {"zba",    &gcc_options::x_riscv_zb_subext, MASK_ZBA},
>>    {"zbb",    &gcc_options::x_riscv_zb_subext, MASK_ZBB},
>>    {"zbc",    &gcc_options::x_riscv_zb_subext, MASK_ZBC},
>> diff --git a/gcc/config/riscv/riscv-opts.h b/gcc/config/riscv/riscv-opts.h
>> index 1dfe8c89209..25fd85b09b1 100644
>> --- a/gcc/config/riscv/riscv-opts.h
>> +++ b/gcc/config/riscv/riscv-opts.h
>> @@ -73,6 +73,9 @@ enum stack_protector_guard {
>>  #define TARGET_ZICSR    ((riscv_zi_subext & MASK_ZICSR) != 0)
>>  #define TARGET_ZIFENCEI ((riscv_zi_subext & MASK_ZIFENCEI) != 0)
>>
>> +#define MASK_ZAWRS   (1 << 0)
>> +#define TARGET_ZAWRS ((riscv_za_subext & MASK_ZAWRS) != 0)
>> +
>>  #define MASK_ZBA      (1 << 0)
>>  #define MASK_ZBB      (1 << 1)
>>  #define MASK_ZBC      (1 << 2)
>> diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
>> index 426ea95cd14..7c3ca48d1cc 100644
>> --- a/gcc/config/riscv/riscv.opt
>> +++ b/gcc/config/riscv/riscv.opt
>> @@ -203,6 +203,9 @@ long riscv_stack_protector_guard_offset = 0
>>  TargetVariable
>>  int riscv_zi_subext
>>
>> +TargetVariable
>> +int riscv_za_subext
>> +
>>  TargetVariable
>>  int riscv_zb_subext
>>
>> diff --git a/gcc/testsuite/gcc.target/riscv/zawrs.c
>> b/gcc/testsuite/gcc.target/riscv/zawrs.c
>> new file mode 100644
>> index 00000000000..0b7e2662343
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.target/riscv/zawrs.c
>> @@ -0,0 +1,13 @@
>> +/* { dg-do compile } */
>> +/* { dg-options "-march=rv64gc_zawrs" { target { rv64 } } } */
>> +/* { dg-options "-march=rv32gc_zawrs" { target { rv32 } } } */
>> +
>> +#ifndef __riscv_zawrs
>> +#error Feature macro not defined
>> +#endif
>> +
>> +int
>> +foo (int a)
>> +{
>> +  return a;
>> +}
>> --
>> 2.37.3
>>
>>