Detect when CPU supports AVX(2), but feature not enabled

src/main.rs

@@ -8,7 +8,6 @@ use breakwater::{
 };
 use clap::Parser;
 use env_logger::Env;
-use log::warn;
 use std::sync::Arc;
 use tokio::sync::{broadcast, mpsc};
 #[cfg(feature = "vnc")]
@@ -22,14 +21,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     env_logger::Builder::from_env(Env::default().default_filter_or("info")).init();
     let args = Args::parse();
 
-    #[cfg(target_arch = "x86_64")]
-    {
-        if !is_x86_feature_detected!("avx2") {
-            warn!("Your CPU does not support AVX2. Consider using a CPU supporting AVX2 for best performance");
-        } else if !is_x86_feature_detected!("avx") {
-            warn!("Your CPU does not support AVX. Consider using a CPU supporting AVX2 (or at least AVX) for best performance");
-        }
-    }
+    breakwater::parser::check_cpu_support();
 
     let fb = Arc::new(FrameBuffer::new(args.width, args.height));
 

src/parser.rs

@@ -1,5 +1,6 @@
 use crate::framebuffer::FrameBuffer;
 use const_format::formatcp;
+use log::{info, warn};
 use std::simd::{u32x8, Simd, SimdUint};
 use std::sync::Arc;
 use tokio::io::AsyncWriteExt;
@@ -356,6 +357,25 @@ fn simd_unhex(value: &[u8]) -> u32 {
     shifted.reduce_or()
 }
 
+pub fn check_cpu_support() {
+    #[cfg(target_arch = "x86_64")]
+    {
+        if !is_x86_feature_detected!("avx2") {
+            warn!("Your CPU does not support AVX2. Consider using a CPU supporting AVX2 for best performance");
+        } else if !is_x86_feature_detected!("avx") {
+            warn!("Your CPU does not support AVX. Consider using a CPU supporting AVX2 (or at least AVX) for best performance");
+        } else {
+            // At this point the CPU should support AVX und AVX2
+            // Warn the user when he has compiled breakwater without the needed target features
+            if cfg!(all(target_feature = "avx", target_feature = "avx2")) {
+                info!("Using AVX and AVX2 support");
+            } else {
+                warn!("Your CPU does support AVX and AVX2, but you have not enabled avx and avx2 support. Please re-compile using RUSTFLAGS='-C target-cpu=native' cargo build --release`");
+            }
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;