Slightly optimize Math.mod (#1521)

Author: MaxGraey

std/assembly/math.ts

@@ -1583,19 +1583,18 @@ export namespace NativeMath {
     }
     var ux1 = ux << 1;
     if (ux1 <= uy1) {
-      if (ux1 == uy1) return 0 * x;
-      return x;
+      return x * f64(ux1 != uy1);
     }
     if (!ex) {
       ex -= builtin_clz<i64>(ux << 12);
-      ux <<= -ex + 1;
+      ux <<= 1 - ex;
     } else {
       ux &= <u64>-1 >> 12;
       ux |= 1 << 52;
     }
     if (!ey) {
       ey -= builtin_clz<i64>(uy << 12);
-      uy <<= -ey + 1;
+      uy <<= 1 - ey;
     } else {
       uy &= <u64>-1 >> 12;
       uy |= 1 << 52;
@@ -1622,8 +1621,7 @@ export namespace NativeMath {
     } else {
       ux >>= -ex + 1;
     }
-    ux |= sx << 63;
-    return reinterpret<f64>(ux);
+    return reinterpret<f64>(ux | (sx << 63));
   }
 
   export function rem(x: f64, y: f64): f64 { // see: musl/src/math/remquo.c
@@ -1640,14 +1638,14 @@ export namespace NativeMath {
     var uxi = ux;
     if (!ex) {
       ex -= builtin_clz<i64>(uxi << 12);
-      uxi <<= -ex + 1;
+      uxi <<= 1 - ex;
     } else {
       uxi &= <u64>-1 >> 12;
       uxi |= 1 << 52;
     }
     if (!ey) {
       ey -= builtin_clz<i64>(uy << 12);
-      uy <<= -ey + 1;
+      uy <<= 1 - ey;
     } else {
       uy &= <u64>-1 >> 12;
       uy |= 1 << 52;
@@ -2884,27 +2882,26 @@ export namespace NativeMathf {
     var uy = reinterpret<u32>(y);
     var ex = <i32>(ux >> 23 & 0xFF);
     var ey = <i32>(uy >> 23 & 0xFF);
-    var sx = ux & 0x80000000;
+    var sm = ux & 0x80000000;
     var uy1 = uy << 1;
     if (uy1 == 0 || ex == 0xFF || isNaN<f32>(y)) {
       let m = x * y;
       return m / m;
     }
     var ux1 = ux << 1;
     if (ux1 <= uy1) {
-      if (ux1 == uy1) return 0 * x;
-      return x;
+      return x * f32(ux1 != uy1);
     }
     if (!ex) {
       ex -= builtin_clz<u32>(ux << 9);
-      ux <<= -ex + 1;
+      ux <<= 1 - ex;
     } else {
       ux &= <u32>-1 >> 9;
       ux |= 1 << 23;
     }
     if (!ey) {
       ey -= builtin_clz<u32>(uy << 9);
-      uy <<= -ey + 1;
+      uy <<= 1 - ey;
     } else {
       uy &= <u32>-1 >> 9;
       uy |= 1 << 23;
@@ -2931,8 +2928,7 @@ export namespace NativeMathf {
     } else {
       ux >>= -ex + 1;
     }
-    ux |= sx;
-    return reinterpret<f32>(ux);
+    return reinterpret<f32>(ux | sm);
   }
 
   export function rem(x: f32, y: f32): f32 { // see: musl/src/math/remquof.c
@@ -2946,14 +2942,14 @@ export namespace NativeMathf {
     if (ux << 1 == 0) return x;
     if (!ex) {
       ex -= builtin_clz<u32>(uxi << 9);
-      uxi <<= -ex + 1;
+      uxi <<= 1 - ex;
     } else {
       uxi &= <u32>-1 >> 9;
       uxi |= 1 << 23;
     }
     if (!ey) {
       ey -= builtin_clz<u32>(uy << 9);
-      uy <<= -ey + 1;
+      uy <<= 1 - ey;
     } else {
       uy &= <u32>-1 >> 9;
       uy |= 1 << 23;

tests/compiler/binary.untouched.wat

@@ -1288,16 +1288,12 @@
   local.get $7
   i32.le_u
   if
+   local.get $0
    local.get $9
    local.get $7
-   i32.eq
-   if
-    f32.const 0
-    local.get $0
-    f32.mul
-    return
-   end
-   local.get $0
+   i32.ne
+   f32.convert_i32_u
+   f32.mul
    return
   end
   local.get $4
@@ -1311,11 +1307,9 @@
    i32.sub
    local.set $4
    local.get $2
-   i32.const 0
+   i32.const 1
    local.get $4
    i32.sub
-   i32.const 1
-   i32.add
    i32.shl
    local.set $2
   else
@@ -1343,11 +1337,9 @@
    i32.sub
    local.set $5
    local.get $3
-   i32.const 0
+   i32.const 1
    local.get $5
    i32.sub
-   i32.const 1
-   i32.add
    i32.shl
    local.set $3
   else
@@ -1460,8 +1452,6 @@
   local.get $2
   local.get $6
   i32.or
-  local.set $2
-  local.get $2
   f32.reinterpret_i32
  )
  (func $~lib/math/NativeMathf.pow (param $0 f32) (param $1 f32) (result f32)
@@ -2163,16 +2153,12 @@
   local.get $7
   i64.le_u
   if
+   local.get $0
    local.get $9
    local.get $7
-   i64.eq
-   if
-    f64.const 0
-    local.get $0
-    f64.mul
-    return
-   end
-   local.get $0
+   i64.ne
+   f64.convert_i32_u
+   f64.mul
    return
   end
   local.get $4
@@ -2188,11 +2174,9 @@
    i64.sub
    local.set $4
    local.get $2
-   i64.const 0
+   i64.const 1
    local.get $4
    i64.sub
-   i64.const 1
-   i64.add
    i64.shl
    local.set $2
   else
@@ -2222,11 +2206,9 @@
    i64.sub
    local.set $5
    local.get $3
-   i64.const 0
+   i64.const 1
    local.get $5
    i64.sub
-   i64.const 1
-   i64.add
    i64.shl
    local.set $3
   else
@@ -2341,8 +2323,6 @@
   i64.const 63
   i64.shl
   i64.or
-  local.set $2
-  local.get $2
   f64.reinterpret_i64
  )
  (func $start:binary