On Fri, 15 Mar 2024 at 12:15, Victor Do Nascimento
<victor.donascime...@arm.com> wrote:
>
> Given how, at present, the choice of using LSE128 atomic instructions
> by the toolchain is delegated to run-time selection in the form of
> Libatomic ifuncs, responsible for querying target support, the
> `+lse128' target architecture compile-time flag is absent from GCC.
>
> This, however, contrasts with the Binutils implementation, which gates
> LSE128 instructions behind the `+lse128' flag. This can lead to
> problems in GCC for certain use-cases. One such example is in the use
> of inline assembly, whereby the inability of enabling the feature in
> the command-line prevents the compiler from automatically issuing the
> necessary LSE128 `.arch' directive.
>
> This patch therefore brings GCC into alignment with LLVM and Binutils
> in adding support for the `+lse128' architectural extension flag.
>
> gcc/ChangeLog:
>
> * config/aarch64/aarch64-option-extensions.def: Add LSE128
> AARCH64_OPT_EXTENSION, adding it as a dependency for the D128
> feature.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/aarch64/lse128-flag.c: New.
> * gcc.target/aarch64/cpunative/info_23: Likewise.
> * gcc.target/aarch64/cpunative/native_cpu_23.c: Likewise.
> ---
> gcc/config/aarch64/aarch64-option-extensions.def | 4 +++-
> gcc/testsuite/gcc.target/aarch64/cpunative/info_23 | 8 ++++++++
> .../gcc.target/aarch64/cpunative/native_cpu_23.c | 11 +++++++++++
> gcc/testsuite/gcc.target/aarch64/lse128-flag.c | 10 ++++++++++
> 4 files changed, 32 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/aarch64/cpunative/info_23
> create mode 100644 gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_23.c
> create mode 100644 gcc/testsuite/gcc.target/aarch64/lse128-flag.c
>
> diff --git a/gcc/config/aarch64/aarch64-option-extensions.def
> b/gcc/config/aarch64/aarch64-option-extensions.def
> index 1a3b91c68cf..ac54b899a06 100644
> --- a/gcc/config/aarch64/aarch64-option-extensions.def
> +++ b/gcc/config/aarch64/aarch64-option-extensions.def
> @@ -275,7 +275,9 @@ AARCH64_OPT_EXTENSION("mops", MOPS, (), (), (), "")
>
> AARCH64_OPT_EXTENSION("cssc", CSSC, (), (), (), "cssc")
>
> -AARCH64_OPT_EXTENSION("d128", D128, (), (), (), "d128")
> +AARCH64_OPT_EXTENSION("lse128", LSE128, (LSE), (), (), "lse128")
> +
> +AARCH64_OPT_EXTENSION("d128", D128, (LSE128), (), (), "d128")
>
FWIW, looks good to me, I noticed that now we'll also have the
dependency of d128 on lse128, although d128 didn't have the (implicit)
dependency on lse before.
Christophe
> AARCH64_OPT_EXTENSION("the", THE, (), (), (), "the")
>
> diff --git a/gcc/testsuite/gcc.target/aarch64/cpunative/info_23
> b/gcc/testsuite/gcc.target/aarch64/cpunative/info_23
> new file mode 100644
> index 00000000000..d77c25d2f61
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/cpunative/info_23
> @@ -0,0 +1,8 @@
> +processor : 0
> +BogoMIPS : 100.00
> +Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 asimddp atomics
> lse128
> +CPU implementer : 0xfe
> +CPU architecture: 8
> +CPU variant : 0x0
> +CPU part : 0xd08
> +CPU revision : 2
> \ No newline at end of file
> diff --git a/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_23.c
> b/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_23.c
> new file mode 100644
> index 00000000000..8a1e235d8ab
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_23.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { { aarch64*-*-linux*} && native } } } */
> +/* { dg-set-compiler-env-var GCC_CPUINFO
> "$srcdir/gcc.target/aarch64/cpunative/info_23" } */
> +/* { dg-additional-options "-mcpu=native" } */
> +
> +int main()
> +{
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler {\.arch
> armv8-a\+dotprod\+crc\+crypto\+lse128} } } */
> +/* Test one where lse128 is available and so should be emitted. */
> diff --git a/gcc/testsuite/gcc.target/aarch64/lse128-flag.c
> b/gcc/testsuite/gcc.target/aarch64/lse128-flag.c
> new file mode 100644
> index 00000000000..71339c3af6d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/lse128-flag.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile { target { aarch64*-*-*} } } */
> +/* { dg-additional-options "-march=armv9.4-a+lse128" } */
> +
> +int main()
> +{
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler {\.arch armv9\.4-a\+crc\+lse128} } } */
> +/* Test a normal looking procinfo. */
> --
> 2.34.1
>
