Add tail recursive fibonacci benchmark (#697)

* add tail recursive fibonacci benchmark * apply rustfmt * rename wat label
wasmi-labs · Feb 28, 2023 · 01423af · 01423af
1 parent 8b35b2b
commit 01423af
Show file tree

Hide file tree

Showing 2 changed files with 32 additions and 19 deletions.
diff --git a/crates/wasmi/benches/benches.rs b/crates/wasmi/benches/benches.rs
@@ -902,12 +902,12 @@ fn bench_execute_fibonacci(c: &mut Criterion) {
     }
 
     const FIBONACCI_REC_N: i64 = 25;
-    const FIBONACCI_REC_RESULT: i64 = fib(FIBONACCI_REC_N);
+    const FIBONACCI_TAIL_N: i64 = 50_000;
     const FIBONACCI_INC_N: i64 = 100_000;
-    const FIBONACCI_INC_RESULT: i64 = fib(FIBONACCI_INC_N);
     let (mut store, instance) = load_instance_from_wat(include_bytes!("wat/fibonacci.wat"));
-    let mut bench_fib = |bench_id: &str, func_name: &str, input: i64, expected: i64| {
+    let mut bench_fib = |bench_id: &str, func_name: &str, input: i64| {
         c.bench_function(bench_id, |b| {
+            let expected = fib(input);
             let fib = instance
                 .get_export(&store, func_name)
                 .and_then(Extern::into_func)
@@ -919,18 +919,9 @@ fn bench_execute_fibonacci(c: &mut Criterion) {
             });
         });
     };
-    bench_fib(
-        "execute/fib_recursive",
-        "fib_recursive",
-        FIBONACCI_REC_N,
-        FIBONACCI_REC_RESULT,
-    );
-    bench_fib(
-        "execute/fib_iterative",
-        "fib_iterative",
-        FIBONACCI_INC_N,
-        FIBONACCI_INC_RESULT,
-    );
+    bench_fib("execute/fibonacci_rec", "fibonacci_rec", FIBONACCI_REC_N);
+    bench_fib("execute/fibonacci_tail", "fibonacci_tail", FIBONACCI_TAIL_N);
+    bench_fib("execute/fibonacci_iter", "fibonacci_iter", FIBONACCI_INC_N);
 }
 
 fn bench_execute_memory_sum(c: &mut Criterion) {

diff --git a/crates/wasmi/benches/wat/fibonacci.wat b/crates/wasmi/benches/wat/fibonacci.wat
@@ -1,5 +1,5 @@
 (module
-    (func $fib_recursive (export "fib_recursive") (param $N i64) (result i64)
+    (func $fib_recursive (export "fibonacci_rec") (param $N i64) (result i64)
         (if
             (i64.le_s (local.get $N) (i64.const 1))
             (then (return (local.get $N)))
@@ -16,7 +16,29 @@
         )
     )
 
-    (func $fib_iterative (export "fib_iterative") (param $N i64) (result i64)
+    (func $fib_tail_recursive (param $N i64) (param $a i64) (param $b i64) (result i64)
+        (if (i64.eqz (local.get $N))
+            (then
+                (return (local.get $a))
+            )
+        )
+        (if (i64.eq (local.get $N) (i64.const 1))
+            (then
+                (return (local.get $b))
+            )
+        )
+        (call $fib_tail_recursive
+            (i64.sub (local.get $N) (i64.const 1))
+            (local.get $b)
+            (i64.add (local.get $a) (local.get $b))
+        )
+    )
+
+    (func (export "fibonacci_tail") (param $N i64) (result i64)
+        (call $fib_tail_recursive (local.get $N) (i64.const 0) (i64.const 1))
+    )
+
+    (func $fib_iterative (export "fibonacci_iter") (param $N i64) (result i64)
         (local $n1 i64)
         (local $n2 i64)
         (local $tmp i64)
@@ -30,15 +52,15 @@
         (local.set $n2 (i64.const 1))
         (local.set $i (i64.const 2))
         ;;since we normally return n2, handle n=1 case specially
-        (loop $again
+        (loop $continue
             (if
                 (i64.lt_s (local.get $i) (local.get $N))
                 (then
                     (local.set $tmp (i64.add (local.get $n1) (local.get $n2)))
                     (local.set $n1 (local.get $n2))
                     (local.set $n2 (local.get $tmp))
                     (local.set $i (i64.add (local.get $i) (i64.const 1)))
-                    (br $again)
+                    (br $continue)
                 )
             )
         )