Update a comment and a changelog

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## **[Unreleased]**
 
 - [#1009](https://github.com/wasmerio/wasmer/pull/1009) Enable LLVM verifier for all tests, add new llvm-backend-tests crate.
+- [#1004](https://github.com/wasmerio/wasmer/pull/1004) Add Auto backend to enable change backend usage depending on wasm file executed.
 
 ## 0.11.0 - 2019-11-22
 

lib/runtime-core/src/backend.rs

@@ -59,7 +59,7 @@ impl Backend {
 
 impl Default for Backend {
     fn default() -> Self {
-        Backend::Cranelift
+        Backend::Auto
     }
 }
 

src/bin/wasmer.rs

@@ -548,9 +548,9 @@ fn execute_wasm(options: &mut Run) -> Result<(), String> {
     };
 
     // Update backend when a backend flag is `auto` or a default value.
-    // Use a singlepass if it's enable and the file provided is larger
-    // than 10MiB (10485760 bytes), or it's enable and the target architecture
-    // is aarch64. Otherwise, use a cranelift as a backend.
+    // Use the Singlepass backend if it's enabled and the file provided is larger
+    // than 10MiB (10485760 bytes), or it's enabled and the target architecture
+    // is AArch64. Otherwise, use the Cranelift backend.
     if options.backend == Backend::Auto {
         if Backend::variants().contains(&Backend::Singlepass.to_string())
             && (wasm_binary.len() > 10485760 || cfg!(target_arch = "aarch64"))