Implement new min/max semantics

Following the proposal in
tc39#67

These min and max functions follow the Math.min and Math.max semantics,
and are arguably the more intuitive and semantics.

This patch also introduces minNum and maxNum functions, which follow the
IEEE-754 minNum and maxNum semantics.

src/ecmascript_simd.js

@@ -46,6 +46,18 @@ _PRIVATE.truncatei32 = function(x) {
   return _PRIVATE._i32[0];
 }
 
+_PRIVATE.minNum = function(x, y) {
+    return x != x ? y :
+           y != y ? x :
+           Math.min(x, y);
+}
+
+_PRIVATE.maxNum = function(x, y) {
+    return x != x ? y :
+           y != y ? x :
+           Math.max(x, y);
+}
+
 function checkFloat32x4(t) {
   if (!(t instanceof SIMD.float32x4)) {
     throw new TypeError("argument is not a float32x4.");
@@ -437,10 +449,10 @@ SIMD.float32x4.clamp = function(t, lowerLimit, upperLimit) {
 SIMD.float32x4.min = function(t, other) {
   checkFloat32x4(t);
   checkFloat32x4(other);
-  var cx = t.x > other.x ? other.x : t.x;
-  var cy = t.y > other.y ? other.y : t.y;
-  var cz = t.z > other.z ? other.z : t.z;
-  var cw = t.w > other.w ? other.w : t.w;
+  var cx = Math.min(t.x, other.x);
+  var cy = Math.min(t.y, other.y);
+  var cz = Math.min(t.z, other.z);
+  var cw = Math.min(t.w, other.w);
   return SIMD.float32x4(cx, cy, cz, cw);
 }
 
@@ -451,10 +463,38 @@ SIMD.float32x4.min = function(t, other) {
 SIMD.float32x4.max = function(t, other) {
   checkFloat32x4(t);
   checkFloat32x4(other);
-  var cx = t.x < other.x ? other.x : t.x;
-  var cy = t.y < other.y ? other.y : t.y;
-  var cz = t.z < other.z ? other.z : t.z;
-  var cw = t.w < other.w ? other.w : t.w;
+  var cx = Math.max(t.x, other.x);
+  var cy = Math.max(t.y, other.y);
+  var cz = Math.max(t.z, other.z);
+  var cw = Math.max(t.w, other.w);
+  return SIMD.float32x4(cx, cy, cz, cw);
+}
+
+/**
+  * @return {float32x4} New instance of float32x4 with the minimum value of
+  * t and other, preferring numbers over NaNs.
+  */
+SIMD.float32x4.minNum = function(t, other) {
+  checkFloat32x4(t);
+  checkFloat32x4(other);
+  var cx = _PRIVATE.minNum(t.x, other.x);
+  var cy = _PRIVATE.minNum(t.y, other.y);
+  var cz = _PRIVATE.minNum(t.z, other.z);
+  var cw = _PRIVATE.minNum(t.w, other.w);
+  return SIMD.float32x4(cx, cy, cz, cw);
+}
+
+/**
+  * @return {float32x4} New instance of float32x4 with the maximum value of
+  * t and other, preferring numbers over NaNs.
+  */
+SIMD.float32x4.maxNum = function(t, other) {
+  checkFloat32x4(t);
+  checkFloat32x4(other);
+  var cx = _PRIVATE.maxNum(t.x, other.x);
+  var cy = _PRIVATE.maxNum(t.y, other.y);
+  var cz = _PRIVATE.maxNum(t.z, other.z);
+  var cw = _PRIVATE.maxNum(t.w, other.w);
   return SIMD.float32x4(cx, cy, cz, cw);
 }
 
@@ -965,8 +1005,8 @@ SIMD.float64x2.clamp = function(t, lowerLimit, upperLimit) {
 SIMD.float64x2.min = function(t, other) {
   checkFloat64x2(t);
   checkFloat64x2(other);
-  var cx = t.x > other.x ? other.x : t.x;
-  var cy = t.y > other.y ? other.y : t.y;
+  var cx = Math.min(t.x, other.x);
+  var cy = Math.min(t.y, other.y);
   return SIMD.float64x2(cx, cy);
 }
 
@@ -977,8 +1017,32 @@ SIMD.float64x2.min = function(t, other) {
 SIMD.float64x2.max = function(t, other) {
   checkFloat64x2(t);
   checkFloat64x2(other);
-  var cx = t.x < other.x ? other.x : t.x;
-  var cy = t.y < other.y ? other.y : t.y;
+  var cx = Math.max(t.x, other.x);
+  var cy = Math.max(t.y, other.y);
+  return SIMD.float64x2(cx, cy);
+}
+
+/**
+  * @return {float64x2} New instance of float64x2 with the minimum value of
+  * t and other, preferring numbers over NaNs.
+  */
+SIMD.float64x2.minNum = function(t, other) {
+  checkFloat64x2(t);
+  checkFloat64x2(other);
+  var cx = _PRIVATE.minNum(t.x > other.x);
+  var cy = _PRIVATE.minNum(t.y > other.y);
+  return SIMD.float64x2(cx, cy);
+}
+
+/**
+  * @return {float64x2} New instance of float64x2 with the maximum value of
+  * t and other, preferring numbers over NaNs.
+  */
+SIMD.float64x2.maxNum = function(t, other) {
+  checkFloat64x2(t);
+  checkFloat64x2(other);
+  var cx = _PRIVATE.maxNum(t.x, other.x);
+  var cy = _PRIVATE.maxNum(t.y, other.y);
   return SIMD.float64x2(cx, cy);
 }
 

src/ecmascript_simd_tests.js

@@ -222,6 +222,16 @@ test('float32x4 min', function() {
   equal(1.0, c.y);
   equal(30.0, c.z);
   equal(0.0, c.w);
+
+  var x = SIMD.float32x4(-0, 0, NaN, 0);
+  var y = SIMD.float32x4(0, -0, 0, NaN);
+  var z = SIMD.float32x4.min(x, y);
+  equal(0, z.x);
+  equal(1 / z.x, -Infinity);
+  equal(0, z.y);
+  equal(1 / z.y, -Infinity);
+  notEqual(z.z, z.z);
+  notEqual(z.w, z.w);
 });
 
 test('float32x4 min exceptions', function() {
@@ -243,6 +253,16 @@ test('float32x4 max', function() {
   equal(10.0, c.y);
   equal(55.0, c.z);
   equal(1.0, c.w);
+
+  var x = SIMD.float32x4(-0, 0, NaN, 0);
+  var y = SIMD.float32x4(0, -0, 0, NaN);
+  var z = SIMD.float32x4.max(x, y);
+  equal(0, z.x);
+  equal(1 / z.x, Infinity);
+  equal(0, z.y);
+  equal(1 / z.y, Infinity);
+  notEqual(z.z, z.z);
+  notEqual(z.w, z.w);
 });
 
 test('float32x4 max exceptions', function() {
@@ -843,6 +863,19 @@ test('float64x2 min', function() {
   var c = SIMD.float64x2.min(a, lower);
   equal(-20.0, c.x);
   equal(1.0, c.y);
+
+  var x = SIMD.float64x2(-0, 0);
+  var y = SIMD.float64x2(0, -0);
+  var z = SIMD.float64x2.min(x, y);
+  equal(0, z.x);
+  equal(1 / z.x, -Infinity);
+  equal(0, z.y);
+  equal(1 / z.y, -Infinity);
+  x = SIMD.float64x2(NaN, 0);
+  y = SIMD.float64x2(0, NaN);
+  z = SIMD.float64x2.min(x, y);
+  notEqual(z.x, z.x);
+  notEqual(z.y, z.y);
 });
 
 test('float64x2 min exceptions', function() {
@@ -862,6 +895,19 @@ test('float64x2 max', function() {
   var c = SIMD.float64x2.max(a, upper);
   equal(2.5, c.x);
   equal(10.0, c.y);
+
+  var x = SIMD.float64x2(-0, 0);
+  var y = SIMD.float64x2(0, -0);
+  var z = SIMD.float64x2.max(x, y);
+  equal(0, z.x);
+  equal(1 / z.x, Infinity);
+  equal(0, z.y);
+  equal(1 / z.y, Infinity);
+  x = SIMD.float64x2(NaN, 0);
+  y = SIMD.float64x2(0, NaN);
+  z = SIMD.float64x2.max(x, y);
+  notEqual(z.x, z.x);
+  notEqual(z.y, z.y);
 });
 
 test('float64x2 max exceptions', function() {