fix: avoid powi opt in js engine only when exponent <= 2

Author: HerrCai0907

src/compiler.ts

@@ -206,9 +206,9 @@ import {
   isPowerOf2,
   readI32,
   isIdentifier,
-  accuratePow64,
   v128_zero,
   v128_ones,
+  accuratePow64,
 } from "./util";
 
 import {
@@ -5129,7 +5129,8 @@ export class Compiler extends DiagnosticEmitter {
             let leftValue  = getConstValueF32(leftExpr);
             let rightValue = getConstValueF32(rightExpr);
             this.currentType = type;
-            return module.f32(f32(accuratePow64(leftValue, rightValue)));
+            console.log(leftValue, rightValue, accuratePow64(leftValue, rightValue))
+            return module.f32(f32(Math.pow(leftValue, rightValue)));
           }
         }
         let instance = this.f32PowInstance;
@@ -5170,6 +5171,7 @@ export class Compiler extends DiagnosticEmitter {
             let leftValue  = getConstValueF64(leftExpr);
             let rightValue = getConstValueF64(rightExpr);
             this.currentType = type;
+            console.log(leftValue, rightValue, accuratePow64(leftValue, rightValue))
             return module.f64(accuratePow64(leftValue, rightValue));
           }
         }

src/util/math.ts

@@ -11,15 +11,11 @@ export function isPowerOf2(x: i32): bool {
 export function accuratePow64(x: f64, y: f64): f64 {
   if (!ASC_TARGET) { // ASC_TARGET == JS
     // Engines like V8, WebKit and SpiderMonkey uses powi fast path if exponent is integer
-    // This speculative optimization leads to loose precisions like 10 ** 208 != 1e208
-    // or/and 10 ** -5 != 1e-5 anymore. For avoid this behaviour we are forcing exponent
+    // This speculative optimization leads to loose precisions like 10 ** -5 != 1e-5 anymore.
+    // For avoid this behaviour we are forcing exponent
     // to fractional form and compensate this afterwards.
-    if (isFinite(y) && Math.abs(y) >= 2 && Math.trunc(y) == y) {
-      if (y < 0) {
-        return Math.pow(x, y + 0.5) / Math.pow(x, 0.5);
-      } else {
-        return Math.pow(x, y - 0.5) * Math.pow(x, 0.5);
-      }
+    if (isFinite(y) && y <= 2 && Math.trunc(y) == y) {
+      return Math.pow(x, y + 0.5) / Math.pow(x, 0.5);
     }
   }
   return Math.pow(x, y);