LGTM, but I would like to make sure either Jeff or Patrick is OK too :)
On Wed, Jun 11, 2025 at 4:48 PM Umesh Kalappa <ukalappa.m...@gmail.com> wrote:
>
> gcc/ChangeLog:
>
> * config/riscv/sync.md (lrsc_atomic_exchange<mode>):
> Use the scratch reg for rd.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/zalrsc.c: New test.
> ---
> gcc/config/riscv/sync.md | 11 +++++------
> gcc/testsuite/gcc.target/riscv/zalrsc.c | 13 +++++++++++++
> 2 files changed, 18 insertions(+), 6 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/riscv/zalrsc.c
>
> diff --git a/gcc/config/riscv/sync.md b/gcc/config/riscv/sync.md
> index 726800a9662..a75ea6834e4 100644
> --- a/gcc/config/riscv/sync.md
> +++ b/gcc/config/riscv/sync.md
> @@ -405,18 +405,17 @@
> (match_operand:SI 3 "const_int_operand")] ;; model
> UNSPEC_SYNC_EXCHANGE))
> (set (match_dup 1)
> - (match_operand:GPR 2 "register_operand" "0"))
> + (match_operand:GPR 2 "reg_or_0_operand" "rJ"))
> (clobber (match_scratch:GPR 4 "=&r"))] ;; tmp_1
> "!TARGET_ZAAMO && TARGET_ZALRSC"
> {
> return "1:\;"
> - "lr.<amo>%I3\t%4, %1\;"
> - "sc.<amo>%J3\t%0, %0, %1\;"
> - "bnez\t%0, 1b\;"
> - "mv\t%0, %4";
> + "lr.<amo>%I3\t%0, %1\;"
> + "sc.<amo>%J3\t%4, %z2, %1\;"
> + "bnez\t%4, 1b\";
> }
> [(set_attr "type" "atomic")
> - (set (attr "length") (const_int 16))])
> + (set (attr "length") (const_int 12))])
>
> (define_expand "atomic_exchange<mode>"
> [(match_operand:SHORT 0 "register_operand") ;; old value at mem
> diff --git a/gcc/testsuite/gcc.target/riscv/zalrsc.c
> b/gcc/testsuite/gcc.target/riscv/zalrsc.c
> new file mode 100644
> index 00000000000..b8991f13da8
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/zalrsc.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64imfd_zalrsc -mabi=lp64" } */
> +/* { dg-skip-if "" { *-*-* } {"-O0"} } */
> +
> +/* lr.w/sc.w */
> +int *i;
> +int lr_sc(int v)
> +{
> + return __atomic_exchange_4(i, v, __ATOMIC_RELAXED);
> +}
> +
> +/* { dg-final { scan-assembler-times {\mlr.w} 1 } } */
> +/* { dg-final { scan-assembler-times {\msc.w} 1 } } */
>
> base-commit: e477e7cd104af96c55379f69125db3f1c350c9ed
> --
> 2.43.0
>
