cranelift: Add wasm tests for duplicate loads (#5514)

* cranelift-filetests: Add the ability to test optimized CLIF in Wasm tests

* cranelift: Add Wasm tests for identical loads, back to back

cranelift/filetests/src/test_wasm.rs

@@ -61,6 +61,11 @@ pub fn run(path: &Path, wat: &str) -> Result<()> {
                 .map_err(|e| crate::pretty_anyhow_error(&e.func, e.inner))?;
             writeln!(&mut actual, "function {}:", func.name).unwrap();
             writeln!(&mut actual, "{}", code.disasm.as_ref().unwrap()).unwrap();
+        } else if config.optimize {
+            let mut ctx = cranelift_codegen::Context::for_function(func.clone());
+            ctx.optimize(isa)
+                .map_err(|e| crate::pretty_anyhow_error(&ctx.func, e))?;
+            writeln!(&mut actual, "{}", ctx.func.display()).unwrap();
         } else {
             writeln!(&mut actual, "{}", func.display()).unwrap();
         }

cranelift/filetests/src/test_wasm/config.rs

@@ -18,6 +18,9 @@ pub struct TestConfig {
     #[serde(default)]
     pub compile: bool,
 
+    #[serde(default)]
+    pub optimize: bool,
+
     #[serde(default)]
     pub settings: Vec<String>,
 
@@ -30,6 +33,13 @@ pub struct TestConfig {
 
 impl TestConfig {
     pub fn validate(&self) -> Result<()> {
+        if self.compile || self.optimize {
+            ensure!(
+                !(self.compile && self.optimize),
+                "The `compile` and `optimize` options are mutually exclusive."
+            );
+        }
+
         for global in self.globals.values() {
             ensure!(
                 global.vmctx || global.load.is_some(),