diff options
Diffstat (limited to 'library/stdarch/crates/core_arch/src/x86/rdtsc.rs')
-rw-r--r-- | library/stdarch/crates/core_arch/src/x86/rdtsc.rs | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/library/stdarch/crates/core_arch/src/x86/rdtsc.rs b/library/stdarch/crates/core_arch/src/x86/rdtsc.rs new file mode 100644 index 000000000..67f6e48fa --- /dev/null +++ b/library/stdarch/crates/core_arch/src/x86/rdtsc.rs @@ -0,0 +1,77 @@ +//! RDTSC instructions. + +#[cfg(test)] +use stdarch_test::assert_instr; + +/// Reads the current value of the processor’s time-stamp counter. +/// +/// The processor monotonically increments the time-stamp counter MSR +/// every clock cycle and resets it to 0 whenever the processor is +/// reset. +/// +/// The RDTSC instruction is not a serializing instruction. It does +/// not necessarily wait until all previous instructions have been +/// executed before reading the counter. Similarly, subsequent +/// instructions may begin execution before the read operation is +/// performed. +/// +/// On processors that support the Intel 64 architecture, the +/// high-order 32 bits of each of RAX and RDX are cleared. +/// +/// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_rdtsc) +#[inline] +#[cfg_attr(test, assert_instr(rdtsc))] +#[stable(feature = "simd_x86", since = "1.27.0")] +pub unsafe fn _rdtsc() -> u64 { + rdtsc() +} + +/// Reads the current value of the processor’s time-stamp counter and +/// the `IA32_TSC_AUX MSR`. +/// +/// The processor monotonically increments the time-stamp counter MSR +/// every clock cycle and resets it to 0 whenever the processor is +/// reset. +/// +/// The RDTSCP instruction waits until all previous instructions have +/// been executed before reading the counter. However, subsequent +/// instructions may begin execution before the read operation is +/// performed. +/// +/// On processors that support the Intel 64 architecture, the +/// high-order 32 bits of each of RAX, RDX, and RCX are cleared. +/// +/// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=__rdtscp) +#[inline] +#[cfg_attr(test, assert_instr(rdtscp))] +#[stable(feature = "simd_x86", since = "1.27.0")] +pub unsafe fn __rdtscp(aux: *mut u32) -> u64 { + rdtscp(aux as *mut _) +} + +#[allow(improper_ctypes)] +extern "C" { + #[link_name = "llvm.x86.rdtsc"] + fn rdtsc() -> u64; + #[link_name = "llvm.x86.rdtscp"] + fn rdtscp(aux: *mut u8) -> u64; +} + +#[cfg(test)] +mod tests { + use crate::core_arch::x86::*; + use stdarch_test::simd_test; + + #[simd_test(enable = "sse2")] + unsafe fn _rdtsc() { + let r = rdtsc::_rdtsc(); + assert_ne!(r, 0); // The chances of this being 0 are infinitesimal + } + + #[simd_test(enable = "sse2")] + unsafe fn _rdtscp() { + let mut aux = 0; + let r = rdtsc::__rdtscp(&mut aux); + assert_ne!(r, 0); // The chances of this being 0 are infinitesimal + } +} |