Merge ends, store locals in registers where possible

src/tests.rs

@@ -698,6 +698,18 @@ fn wrong_index() {
     );
 }
 
+    fn iterative_fib_baseline(n: u32) -> u32 {
+        let (mut a, mut b) = (1, 1);
+
+        for _ in 0..n {
+            let old_a = a;
+            a = b;
+            b += old_a;
+        }
+
+        a
+    }
+
 const FIBONACCI: &str = r#"
 (module
   (func $fib (param $n i32) (result i32)
@@ -745,25 +757,59 @@ const FIBONACCI: &str = r#"
 
 #[test]
 fn fib() {
-    fn fib(n: u32) -> u32 {
-        let (mut a, mut b) = (1, 1);
-
-        for _ in 0..n {
-            let old_a = a;
-            a = b;
-            b += old_a;
-        }
-
-        a
-    }
-
     let translated = translate_wat(FIBONACCI);
     translated.disassemble();
 
     for x in 0..30 {
         assert_eq!(
             translated.execute_func::<_, u32>(0, (x,)),
-            Ok(fib(x)),
+            Ok(iterative_fib_baseline(x)),
+            "Failed for x={}",
+            x
+        );
+    }
+}
+
+// Generated by Rust for the `fib` function in `bench_fibonacci_baseline`
+const FIBONACCI_OPT: &str = r"
+(module
+  (func $fib (param $p0 i32) (result i32)
+    (local $l1 i32)
+    (set_local $l1
+      (i32.const 1))
+    (block $B0
+      (br_if $B0
+        (i32.lt_u
+          (get_local $p0)
+          (i32.const 2)))
+      (set_local $l1
+        (i32.const 1))
+      (loop $L1
+        (set_local $l1
+          (i32.add
+            (call $fib
+              (i32.add
+                (get_local $p0)
+                (i32.const -1)))
+            (get_local $l1)))
+        (br_if $L1
+          (i32.gt_u
+            (tee_local $p0
+              (i32.add
+                (get_local $p0)
+                (i32.const -2)))
+            (i32.const 1)))))
+    (get_local $l1)))";
+
+#[test]
+fn fib_opt() {
+    let translated = translate_wat(FIBONACCI_OPT);
+    translated.disassemble();
+
+    for x in 0..30 {
+        assert_eq!(
+            translated.execute_func::<_, u32>(0, (x,)),
+            Ok(iterative_fib_baseline(x)),
             "Failed for x={}",
             x
         );
@@ -940,7 +986,7 @@ fn bench_fibonacci_compile(b: &mut test::Bencher) {
 
 #[bench]
 fn bench_fibonacci_run(b: &mut test::Bencher) {
-    let wasm = wabt::wat2wasm(FIBONACCI).unwrap();
+    let wasm = wabt::wat2wasm(FIBONACCI_OPT).unwrap();
     let module = translate(&wasm).unwrap();
 
     b.iter(|| module.execute_func::<_, u32>(0, (20,)));