From fbd1463f28324737a33ed5ac7419c424d44f8a2e Mon Sep 17 00:00:00 2001
From: gnzlbg <gonzalobg88@gmail.com>
Date: Tue, 26 Jun 2018 12:05:54 +0200
Subject: [PATCH] Optimize has_cpuid for x86 Rust targets that have cpuid

Improves #497.
---
 coresimd/x86/cpuid.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/coresimd/x86/cpuid.rs b/coresimd/x86/cpuid.rs
index 3b2fed6339..6217d8824a 100644
--- 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: