[libc] add more APIs of cmgxchg variants by SchrodingerZhu · Pull Request #91208 · llvm/llvm-project (original) (raw)

@llvm/pr-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

Changes

Such APIs are useful in lock implementations

Full diff: https://github.com/llvm/llvm-project/pull/91208.diff

1 Files Affected:

• (modified) libc/src/__support/CPP/atomic.h (+30)

diff --git a/libc/src/__support/CPP/atomic.h b/libc/src/__support/CPP/atomic.h index 5e428940565b99..e273d998c07029 100644 --- a/libc/src/__support/CPP/atomic.h +++ b/libc/src/__support/CPP/atomic.h @@ -101,6 +101,36 @@ template struct Atomic { int(mem_ord), int(mem_ord)); }

• // Atomic compare exchange (separate success and failure memory orders)
• bool compare_exchange_strong(

•  T &expected, T desired, MemoryOrder success_order,

•  MemoryOrder failure_order,

•  [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {

• return __atomic_compare_exchange_n(&val, &expected, desired, false,

•                                   static_cast<int>(success_order),

•                                   static_cast<int>(failure_order));

• }
• // Atomic compare exchange (weak version)
• bool compare_exchange_weak(

•  T &expected, T desired, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,

•  [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {

• return __atomic_compare_exchange_n(&val, &expected, desired, true,

•                                   static_cast<int>(mem_ord),

•                                   static_cast<int>(mem_ord));

• }
• // Atomic compare exchange (weak version with separate success and failure
• // memory orders)
• bool compare_exchange_weak(

•  T &expected, T desired, MemoryOrder success_order,

•  MemoryOrder failure_order,

•  [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {

• return __atomic_compare_exchange_n(&val, &expected, desired, true,

•                                   static_cast<int>(success_order),

•                                   static_cast<int>(failure_order));

• }
• T exchange(T desired, MemoryOrder mem_ord = MemoryOrder::SEQ_CST, [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) { #if __has_builtin(__scoped_atomic_exchange_n)