Feature detection

Collaboration diagram for Feature detection:

Classes
struct	native::cpuid_t

Functions
cpuid_t	native::cpuid (std::int32_t eax, std::int32_t ecx) noexcept

Detailed Description

x86-only queries and wait helpers. Feature queries belong outside hot loops; SIMD instruction admission also requires the appropriate OS vector state.

void capabilities() {
  auto maximum_leaf = native::cpuid(0, 0).eax;
  check(maximum_leaf >= 0);
  // A real feature test must also admit the required OS vector state.
  // Waiting is independent of SIMD architecture selection.
  int ready = 1;
  native::wait_until<native::spin>(&ready, [](volatile int * p) { return *p != 0; });
}

Function Documentation

cpuid()

cpuid_t native::cpuid ( std::int32_t eax, std::int32_t ecx )

exportnoexcept

Execute CPUID with leaf eax and subleaf ecx, returning all four registers. Unsupported leaves retain the instruction's behavior; check maximum leaves before interpreting feature bits. This does not check XCR0/OS vector state. CPUID serializes execution; query capabilities outside critical paths.

Definition at line 117 of file native.x86.features.ccm.

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