Carry the ClickHouse patches onto v4.5.0

src/h3lib/include/coordijk.h

@@ -362,9 +362,11 @@ static inline Direction _unitIjkToDigit(const CoordIJK *ijk) {
     _ijkNormalize(&c);
 
     Direction digit = INVALID_DIGIT;
-    for (Direction i = CENTER_DIGIT; i < NUM_DIGITS; i++) {
+    // Iterate with an int rather than a Direction: incrementing an enum is
+    // valid C but not C++, and this header is included by C++ code.
+    for (int i = CENTER_DIGIT; i < NUM_DIGITS; i++) {
         if (_ijkMatches(&c, &UNIT_VECS[i])) {
-            digit = i;
+            digit = (Direction)i;
             break;
         }
     }

src/h3lib/include/mathExtensions.h

@@ -20,6 +20,7 @@
 #ifndef MATHEXTENSIONS_H
 #define MATHEXTENSIONS_H
 
+#include <math.h>
 #include <stdbool.h>
 #include <stdint.h>
 
@@ -28,6 +29,25 @@
  */
 #define MAX(a, b) (((a) > (b)) ? (a) : (b))
 
+/**
+ * Simultaneously compute the sine and cosine of an angle.
+ *
+ * Many H3 coordinate transforms need both sin(x) and cos(x) of the same angle.
+ * Computing them together lets the math library share the argument reduction
+ * and polynomial evaluation, which is roughly twice as fast as two independent
+ * sin()/cos() calls, while returning identical values. The compiler builtin
+ * lowers to a single libm `sincos` call where one exists and falls back to
+ * separate sin()/cos() otherwise, so this stays portable.
+ */
+static inline void _sincos(double x, double *s, double *c) {
+#if defined(__GNUC__) || defined(__clang__)
+    __builtin_sincos(x, s, c);
+#else
+    *s = sin(x);
+    *c = cos(x);
+#endif
+}
+
 /** Evaluates to true if a + b would overflow for int32 */
 static inline bool ADD_INT32S_OVERFLOWS(int32_t a, int32_t b) {
     if (a > 0) {

src/h3lib/include/vec3d.h

@@ -27,6 +27,7 @@
 
 #include "h3api.h"
 #include "latLng.h"
+#include "mathExtensions.h"
 
 /** @struct Vec3d
  *  @brief 3D floating point structure
@@ -42,11 +43,17 @@ typedef struct {
 
 /** Convert latitude and longitude to a unit Vec3d on the sphere. */
 static inline Vec3d latLngToVec3(LatLng geo) {
-    double r = cos(geo.lat);
+    // sin and cos of the latitude and of the longitude are each needed as a
+    // pair, so compute them together instead of with four separate calls.
+    double sinLat, cosLat, sinLng, cosLng;
+    _sincos(geo.lat, &sinLat, &cosLat);
+    _sincos(geo.lng, &sinLng, &cosLng);
+
+    double r = cosLat;
     Vec3d out = {
-        .x = cos(geo.lng) * r,
-        .y = sin(geo.lng) * r,
-        .z = sin(geo.lat),
+        .x = cosLng * r,
+        .y = sinLng * r,
+        .z = sinLat,
     };
     return out;
 }

src/h3lib/lib/faceijk.c

@@ -30,6 +30,7 @@
 #include "coordijk.h"
 #include "h3Index.h"
 #include "latLng.h"
+#include "mathExtensions.h"
 #include "vec3d.h"
 
 /** square root of 7 and inverse square root of 7 */
@@ -438,9 +439,11 @@ static void _vec3ToHex2d(const Vec3d *p, int res, int *face, Vec2d *v) {
 
     // we now have (r, theta) in hex2d with theta ccw from x-axes
 
-    // convert to local x,y
-    v->x = r * cos(theta);
-    v->y = r * sin(theta);
+    // convert to local x,y (both the sine and cosine of theta are needed)
+    double sinTheta, cosTheta;
+    _sincos(theta, &sinTheta, &cosTheta);
+    v->x = r * cosTheta;
+    v->y = r * sinTheta;
 }
 
 /**
@@ -493,9 +496,15 @@ static void _hex2dToVec3(const Vec2d *v, int face, int res, int substrate,
     Vec3d northDir, eastDir;
     _vec3TangentBasis(faceCenterPoint[face], &northDir, &eastDir);
 
-    Vec3d dir = vec3LinComb(cos(theta), northDir, sin(theta), eastDir);
+    // Both the sine and cosine of theta and of r are needed, so compute each
+    // pair together instead of with four separate calls.
+    double sinTheta, cosTheta, sinR, cosR;
+    _sincos(theta, &sinTheta, &cosTheta);
+    _sincos(r, &sinR, &cosR);
 
-    *v3 = vec3LinComb(cos(r), faceCenterPoint[face], sin(r), dir);
+    Vec3d dir = vec3LinComb(cosTheta, northDir, sinTheta, eastDir);
+
+    *v3 = vec3LinComb(cosR, faceCenterPoint[face], sinR, dir);
     vec3Normalize(v3);
 }