Optimize has_cpuid for x86 Rust targets that have cpuid

Improves rust-lang#497.
gnzlbg · Jun 26, 2018 · fbd1463 · fbd1463
1 parent fd3a3f2
commit fbd1463
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/coresimd/x86/cpuid.rs b/coresimd/x86/cpuid.rs
@@ -86,6 +86,14 @@ pub fn has_cpuid() -> bool {
  }
  #[cfg(target_arch = "x86")]
  {
+ // Optimization for i586 and i686 Rust targets which SSE enabled
+ // and support cpuid:
+ #[cfg(target_feature = "sse")] {
+ true
+ }
+
+ // If SSE is not enabled, detect whether cpuid is available:
+ #[cfg(not(target_feature = "sse"))]
  unsafe {
  // On `x86` the `cpuid` instruction is not always available.
  // This follows the approach indicated in: