Gentle Ping!
Thanks & Regards
Jeevitha
On 10/03/26 11:42 pm, jeevitha wrote:
> Hi,
>
> This patch depends on the -mcpu=future and ISA 3.0 AMO implementation
> patches and will be upstreamed after those patches are upstreamed.
> These changes have been bootstrapped and regression tested on
> powerpc64le-linux.
>
> This patch adds support for compare-and-swap-equal atomic memory
> operations that may be added to a future PowerPC processor. Note that
> the names of these functions may change in the future.
>
> Add _AMO_LD_CS_EQ to the _AMO_LD enum and define four new
> compare-and-swap equal helper functions, all guarded by _ARCH_FUTURE.
> For non-Future targets, provide error-attribute stubs to emit a
> compile-time diagnostic.
>
> 2026-03-10 Jeevitha Palanisamy
>
> gcc/
> * config/rs6000/amo.h (_AMO_LD): Add _AMO_LD_CS_EQ enumerator,
> gated on _ARCH_FUTURE.
> (amo_lwat_cas_eq, amo_lwat_scas_eq, amo_ldat_cas_eq,
> amo_ldat_scas_eq): New compare-and-swap equal helper functions.
> (_AMO_ERR_CMPSWP): New macro for error-attribute stubs on
> non-Future targets.
>
> gcc/testsuite/
> * gcc.target/powerpc/amo8.c: New test.
>
> diff --git a/gcc/config/rs6000/amo.h b/gcc/config/rs6000/amo.h
> index 2b52ec755de..0b6997327ae 100644
> --- a/gcc/config/rs6000/amo.h
> +++ b/gcc/config/rs6000/amo.h
> @@ -44,6 +44,9 @@ enum _AMO_LD {
>_AMO_LD_SMIN = 0x07, /* Fetch and Signed Minimum. */
>_AMO_LD_SWAP = 0x08, /* Swap. */
>_AMO_LD_CS_NE = 0x10, /* Compare and Swap Not Equal. */
> +#ifdef _ARCH_FUTURE
> + _AMO_LD_CS_EQ = 0x11, /* Compare and Swap Equal. */
> +#endif
>_AMO_LD_INC_BOUNDED= 0x18, /* Fetch and Increment Bounded.
> */
>_AMO_LD_INC_EQUAL = 0x19, /* Fetch and Increment Equal. */
>_AMO_LD_DEC_BOUNDED= 0x1C /* Fetch and Decrement Bounded.
> */
> @@ -159,6 +162,26 @@ _AMO_LD_INCREMENT (amo_ldat_sinc_eq, int64_t,
> "ldat", _AMO_LD_INC_EQUAL)
> _AMO_LD_INCREMENT (amo_ldat_sinc_bounded, int64_t, "ldat",
> _AMO_LD_INC_BOUNDED)
> _AMO_LD_DECREMENT (amo_ldat_sdec_bounded, int64_t, "ldat",
> _AMO_LD_DEC_BOUNDED)
>
> +/* Future specific compare-and-swap equal operations. */
> +#ifdef _ARCH_FUTURE
> +_AMO_LD_CMPSWP (amo_lwat_cas_eq, uint32_t, "lwat", _AMO_LD_CS_EQ)
> +_AMO_LD_CMPSWP (amo_lwat_scas_eq, int32_t, "lwat", _AMO_LD_CS_EQ)
> +_AMO_LD_CMPSWP (amo_ldat_cas_eq, uint64_t, "ldat", _AMO_LD_CS_EQ)
> +_AMO_LD_CMPSWP (amo_ldat_scas_eq, int64_t, "ldat", _AMO_LD_CS_EQ)
> +#else /* ! _ARCH_FUTURE */
> +/* Dummy declarations with GCC error attribute: Triggers custom error on
> use. */
> +#define _AMO_ERR_CMPSWP(NAME, TYPE) \
> +extern TYPE \
> +NAME (TYPE *_ADDR, TYPE _COND, TYPE _VALUE) \
> + __attribute__ ((error (#NAME " requires -mcpu=future; not available on
> Power10 or earlier")));
> +
> +_AMO_ERR_CMPSWP (amo_lwat_cas_eq, uint32_t)
> +_AMO_ERR_CMPSWP (amo_lwat_scas_eq, int32_t)
> +_AMO_ERR_CMPSWP (amo_ldat_cas_eq, uint64_t)
> +_AMO_ERR_CMPSWP (amo_ldat_scas_eq, int64_t)
> +#undef _AMO_ERR_CMPSWP
> +#endif
> +
> /* Enumeration of the STWAT/STDAT sub-opcodes. */
> enum _AMO_ST {
>_AMO_ST_ADD= 0x00, /* Store Add. */
> diff --git a/gcc/testsuite/gcc.target/powerpc/amo8.c
> b/gcc/testsuite/gcc.target/powerpc/amo8.c
> new file mode 100644
> index 000..8c68fd290bc
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/amo8.c
> @@ -0,0 +1,34 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mdejagnu-cpu=future -O2" } */
> +
> +#include
> +#include
> +
> +/* Verify Future ISA atomic memory compare-and-swap equal operations. */
> +
> +uint32_t
> +do_lw_cs_eq (uint32_t *mem, uint32_t cond, uint32_t value)
> +{
> + return amo_lwat_cas_eq (mem, cond, value);
> +}
> +
> +int32_t
> +do_lw_scs_eq (int32_t *mem, int32_t cond, int32_t value)
> +{
> + return amo_lwat_scas_eq (mem, cond, value);
> +}
> +
> +uint64_t
> +do_ld_cs_eq (uint64_t *mem, uint64_t cond, uint64_t value)
> +{
> + return amo_ldat_cas_eq (mem, cond, value);
> +}
> +
> +int64_t
> +do_ld_scs_eq (int64_t *mem, int64_t cond, int64_t value)
> +{
> + return amo_ldat_scas_eq (mem, cond, value);
> +}
> +
> +/* { dg-final { scan-assembler-times {\mlwat\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mldat\M} 2 } } */
>
