Sieve benchmark tweaks

src/web/benchmarks/benchmarks.js

@@ -70,7 +70,7 @@ const benchmarks = [
     name: "sieve-js",
     fn: () => {
       const r = sieveJS(LIMIT);
-      return r[r.length - 1];
+      return r;
     },
   },
   ...(sieveCModule == null

src/web/benchmarks/sieve/sieve.c

@@ -5,25 +5,23 @@ int sieve(int n) {
   if (n < 2) {
     return n;
   }
-  int m = (int)sqrt((double)n);
   char *sieve = calloc(n + 1, sizeof(char));
   sieve[0] = 1;
   sieve[1] = 1;
-  for (int i = 2; i <= m; i++) {
+  for (int i = 2; i * i <= n; i++) {
     if (!sieve[i]) {
       for (int j = i * i; j <= n; j += i) {
-        if (!sieve[j]) {
-          sieve[j] = 1;
-        }
+        sieve[j] = 1;
       }
     }
   }
-  for (int i = n; i >= 0; --i) {
-    if (sieve[i] == 0) {
-      free(sieve);
-      return i;
+  int lastPrime = 0;
+  for (int i = 2; i <= n; ++i) {
+    if (!sieve[i]) {
+      // printf("%d\n", i);
+      lastPrime = i;
     }
   }
   free(sieve);
-  return 0;
+  return lastPrime;
 }

src/web/benchmarks/sieve/sieve.js

@@ -1,27 +1,24 @@
 // Source: https://rosettacode.org/wiki/Sieve_of_Eratosthenes#JavaScript
 
-export default function sieve(limit) {
-  const primes = [];
-  if (limit >= 2) {
-    const sqrtlmt = Math.sqrt(limit) - 2;
-    const nums = [];
-    for (let i = 2; i <= limit; i++) {
-      nums.push(i);
-    }
-    for (let i = 0; i <= sqrtlmt; i++) {
-      const p = nums[i];
-      if (p) {
-        for (let j = p * p - 2; j < nums.length; j += p) {
-          nums[j] = 0;
-        }
-      }
-    }
-    for (let i = 0; i < nums.length; i++) {
-      const p = nums[i];
-      if (p) {
-        primes.push(p);
+export default function sieve(n) {
+  if (n < 2) {
+    return n;
+  }
+  const nums = new Uint8Array(n + 1);
+  for (let i = 2; i * i <= n; i++) {
+    if (!nums[i]) {
+      for (let j = i * i; j <= n; j += i) {
+        nums[j] = 1;
       }
     }
   }
-  return primes;
+  let lastPrime = 0;
+  for (let i = 2; i < n; i++) {
+    if (!nums[i]) {
+      // Print number.
+      // console.log(p);
+      lastPrime = i;
+    }
+  }
+  return lastPrime;
 }

src/web/benchmarks/sieve/sieve.wat

@@ -4,24 +4,16 @@
     (local $i i32)
     (local $j i32)
     (local $last i32)
-
-    (local.set $i (i32.const 0))
-    (block $endLoop
-      (loop $loop
-        (br_if $endLoop (i32.ge_s (local.get $i) (local.get $n)))
-        (i32.store8 (local.get $i) (i32.const 1))
-        (local.set $i (i32.add (local.get $i) (i32.const 1)))
-        (br $loop)))
-
+    (memory.fill (i32.const 0) (i32.const 0) (local.get $n))
     (local.set $i (i32.const 2))
     (block $endLoop
       (loop $loop
         (br_if $endLoop (i32.ge_s (i32.mul (local.get $i) (local.get $i)) (local.get $n)))
-        (if (i32.eq (i32.load8_s (local.get $i)) (i32.const 1))
+        (if (i32.eqz (i32.load8_s (local.get $i)))
           (then
             (local.set $j (i32.mul (local.get $i) (local.get $i)))
             (loop $innerLoop
-              (i32.store8 (local.get $j) (i32.const 0))
+              (i32.store8 (local.get $j) (i32.const 1))
               (local.set $j (i32.add (local.get $j) (local.get $i)))
               (br_if $innerLoop (i32.lt_s (local.get $j) (local.get $n))))))
         (local.set $i (i32.add (local.get $i) (i32.const 1)))
@@ -29,7 +21,7 @@
 
     (local.set $i (i32.const 2))
     (loop $loop
-      (if (i32.eq (i32.load8_s (local.get $i)) (i32.const 1))
+      (if (i32.eqz (i32.load8_s (local.get $i)))
         (then
           (local.set $last (local.get $i))))
       (local.set $i (i32.add (local.get $i) (i32.const 1)))