Use wabt, and make the wasm subcommand optional. (#347)

* Use wabt for wasm testing.

* Use wabt in cton-util.

* Make the wasm subcommand optional.

cranelift/src/wasm.rs

@@ -9,14 +9,11 @@ use cretonne_codegen::print_errors::{pretty_error, pretty_verifier_error};
 use cretonne_codegen::settings::FlagsOrIsa;
 use cretonne_wasm::{translate_module, DummyEnvironment, ModuleEnvironment};
 use std::error::Error;
-use std::fs::File;
-use std::io;
 use std::path::Path;
 use std::path::PathBuf;
-use std::process::Command;
-use tempdir::TempDir;
 use term;
 use utils::{parse_sets_and_isa, read_to_end};
+use wabt::wat2wasm;
 
 macro_rules! vprintln {
     ($x: expr, $($tts:tt)*) => {
@@ -85,23 +82,12 @@ fn handle_module(
     let mut data = read_to_end(path.clone()).map_err(|err| {
         String::from(err.description())
     })?;
+
     if !data.starts_with(&[b'\0', b'a', b's', b'm']) {
-        let tmp_dir = TempDir::new("cretonne-wasm").unwrap();
-        let file_path = tmp_dir.path().join("module.wasm");
-        File::create(file_path.clone()).unwrap();
-        Command::new("wat2wasm")
-            .arg(path.clone())
-            .arg("-o")
-            .arg(file_path.to_str().unwrap())
-            .output()
-            .or_else(|e| if let io::ErrorKind::NotFound = e.kind() {
-                return Err(String::from("wat2wasm not found"));
-            } else {
-                return Err(String::from(e.description()));
-            })?;
-        data = read_to_end(file_path).map_err(
-            |err| String::from(err.description()),
-        )?;
+        data = match wat2wasm(&data) {
+            Ok(data) => data,
+            Err(e) => return Err(String::from(e.description())),
+        };
     }
 
     let mut dummy_environ = DummyEnvironment::with_flags(fisa.flags.clone());