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| author | Christoph Müllner <christoph.muellner@vrull.eu> | 2024-04-18 23:58:58 +0200 |
|---|---|---|
| committer | Andreas K. Hüttel <dilfridge@gentoo.org> | 2024-06-24 21:36:49 +0200 |
| commit | 81c7f6193ce66480b2a29a5b2c66a7356e743308 (patch) | |
| tree | a4337e4852e0a1042250783985cb2fe5f720fd2c | |
| parent | 9e06e4a43b58519991acbed1d7f33abc40249226 (diff) | |
| download | glibc-81c7f6193ce66480b2a29a5b2c66a7356e743308.zip glibc-81c7f6193ce66480b2a29a5b2c66a7356e743308.tar.gz glibc-81c7f6193ce66480b2a29a5b2c66a7356e743308.tar.bz2 | |
RISC-V: Execute a PAUSE hint in spin loops
The atomic_spin_nop() macro can be used to run arch-specific
code in the body of a spin loop to potentially improve efficiency.
RISC-V's Zihintpause extension includes a PAUSE instruction for
this use-case, which is encoded as a HINT, which means that it
behaves like a NOP on systems that don't implement Zihintpause.
Binutils supports Zihintpause since 2.36, so this patch uses
the ".insn" directive to keep the code compatible with older
toolchains.
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
| -rw-r--r-- | sysdeps/unix/sysv/linux/riscv/atomic-machine.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/riscv/atomic-machine.h b/sysdeps/unix/sysv/linux/riscv/atomic-machine.h index c1c9d94..90283d9 100644 --- a/sysdeps/unix/sysv/linux/riscv/atomic-machine.h +++ b/sysdeps/unix/sysv/linux/riscv/atomic-machine.h @@ -178,4 +178,7 @@ # error "ISAs that do not subsume the A extension are not supported" #endif /* !__riscv_atomic */ +/* Execute a PAUSE hint when spinning. */ +#define atomic_spin_nop() __asm(".insn i 0x0f, 0, x0, x0, 0x010") + #endif /* bits/atomic.h */ |