Handle native target-cpu variant

and raise fatal error if the specified target cpu is not supported

Cargo.lock

@@ -306,6 +306,7 @@ dependencies = [
  "cranelift-frontend",
  "cranelift-jit",
  "cranelift-module",
+ "cranelift-native",
  "cranelift-object",
  "gimli",
  "indexmap",

Cargo.toml

@@ -12,6 +12,7 @@ crate-type = ["dylib"]
 cranelift-codegen = { git = "https://github.com/bytecodealliance/wasmtime/", branch = "main", features = ["unwind"] }
 cranelift-frontend = { git = "https://github.com/bytecodealliance/wasmtime/", branch = "main" }
 cranelift-module = { git = "https://github.com/bytecodealliance/wasmtime/", branch = "main" }
+cranelift-native = { git = "https://github.com/bytecodealliance/wasmtime/", branch = "main" }
 cranelift-jit = { git = "https://github.com/bytecodealliance/wasmtime/", branch = "main", optional = true }
 cranelift-object = { git = "https://github.com/bytecodealliance/wasmtime/", branch = "main" }
 target-lexicon = "0.12.0"
@@ -28,6 +29,7 @@ smallvec = "1.6.1"
 #cranelift-codegen = { path = "../wasmtime/cranelift/codegen" }
 #cranelift-frontend = { path = "../wasmtime/cranelift/frontend" }
 #cranelift-module = { path = "../wasmtime/cranelift/module" }
+#cranelift-native = { path = ../wasmtime/cranelift/native" }
 #cranelift-jit = { path = "../wasmtime/cranelift/jit" }
 #cranelift-object = { path = "../wasmtime/cranelift/object" }
 

src/lib.rs

@@ -272,15 +272,28 @@ fn build_isa(sess: &Session, backend_config: &BackendConfig) -> Box<dyn isa::Tar
     let flags = settings::Flags::new(flags_builder);
 
     let variant = cranelift_codegen::isa::BackendVariant::MachInst;
-    let mut isa_builder = cranelift_codegen::isa::lookup_variant(target_triple, variant).unwrap();
+
+    let isa_builder = match sess.opts.cg.target_cpu.as_deref() {
+        Some("native") => {
+            let builder = cranelift_native::builder_with_options(variant, true).unwrap();
+            builder
+        }
+        Some(value) => {
+            let mut builder = cranelift_codegen::isa::lookup_variant(target_triple, variant).unwrap();
+            if let Err(_) = builder.enable(value) {
+                sess.fatal("The target cpu isn't currently supported by Cranelift.");
+            }
+            builder
+        }
+        None => {
+            let mut builder = cranelift_codegen::isa::lookup_variant(target_triple, variant).unwrap();
+            // Don't use "haswell" as the default, as it implies `has_lzcnt`.
+            // macOS CI is still at Ivy Bridge EP, so `lzcnt` is interpreted as `bsr`.
+            builder.enable("nehalem").unwrap();
+            builder
+        }
+    };
     
-    if let Some(target_cpu) = sess.opts.cg.target_cpu.as_ref() {
-        isa_builder.enable(target_cpu).unwrap();
-    } else {
-        // Don't use "haswell" as the default, as it implies `has_lzcnt`.
-        // macOS CI is still at Ivy Bridge EP, so `lzcnt` is interpreted as `bsr`.
-        isa_builder.enable("nehalem").unwrap();
-    }
     isa_builder.finish(flags)
 }