RV64 guarantees that naturally aligned XLEN-wide loads and stores are atomic. Define PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY for RV64 so the generic 64-bit atomic implementation can use plain loads and stores instead of compare/exchange loops. Keep RV32 on the existing generic fallback.
Co-authored-by: Ni Jincheng <[email protected]> Co-authored-by: Yuansheng <[email protected]> --- src/include/port/atomics.h | 2 ++ src/include/port/atomics/arch-riscv.h | 26 ++++++++++++++++++++++++++ 2 files changed, 28 insertions(+) create mode 100644 src/include/port/atomics/arch-riscv.h diff --git a/src/include/port/atomics.h b/src/include/port/atomics.h index a605ea81d07..985f4e2416f 100644 --- a/src/include/port/atomics.h +++ b/src/include/port/atomics.h @@ -69,6 +69,8 @@ #include "port/atomics/arch-x86.h" #elif defined(__powerpc__) || defined(__powerpc64__) #include "port/atomics/arch-ppc.h" +#elif defined(__riscv) +#include "port/atomics/arch-riscv.h" #endif /* diff --git a/src/include/port/atomics/arch-riscv.h b/src/include/port/atomics/arch-riscv.h new file mode 100644 index 00000000000..761a9811cff --- /dev/null +++ b/src/include/port/atomics/arch-riscv.h @@ -0,0 +1,26 @@ +/*------------------------------------------------------------------------- + * + * arch-riscv.h + * Atomic operations considerations specific to RISC-V + * + * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group + * + * src/include/port/atomics/arch-riscv.h + * + *------------------------------------------------------------------------- + */ + +/* intentionally no include guards, should only be included by atomics.h */ +#ifndef INSIDE_ATOMICS_H +#error "should be included via atomics.h" +#endif + +/* + * The RV64 base ISA guarantees naturally aligned XLEN-bit loads and stores + * are atomic. PostgreSQL's pg_atomic_uint64 objects are naturally aligned, + * so the generic implementation may use a single plain load/store rather + * than a compare/exchange loop. RV32 retains the generic fallback. + */ +#if __riscv_xlen == 64 +#define PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY +#endif -- 2.43.0
