Make lrint more correct. Closes #1265.

Author: int3

src/library.js

@@ -5732,7 +5732,8 @@ LibraryManager.library = {
   llround: 'round',
   llroundf: 'round',
   rint: function(x) {
-    return (x > 0) ? -Math.round(-x) : Math.round(x);
+    if (Math.abs(x % 1) !== 0.5) return Math.round(x);
+    return x + x % 2 + ((x < 0) ? 1 : -1);
   },
   rintf: 'rint',
   lrint: 'rint',

tests/runner.py

@@ -1957,6 +1957,39 @@ def test_frexp(self):
 1.000000=1.000000*2^0
 -1.000000=-1.000000*2^0''')
 
+    def test_rounding(self):
+        src = '''
+          #include <stdio.h>
+          #include <math.h>
+
+          int main()
+          {
+            printf("%.1f ", round(1.4));
+            printf("%.1f ", round(1.6));
+            printf("%.1f ", round(-1.4));
+            printf("%.1f ", round(-1.6));
+
+            printf("%.1f ", round(1.5));
+            printf("%.1f ", round(2.5));
+            printf("%.1f ", round(-1.5));
+            printf("%.1f ", round(-2.5));
+
+            printf("%ld ", lrint(1.4));
+            printf("%ld ", lrint(1.6));
+            printf("%ld ", lrint(-1.4));
+            printf("%ld ", lrint(-1.6));
+
+            printf("%ld ", lrint(1.5));
+            printf("%ld ", lrint(2.5));
+            printf("%ld ", lrint(-1.5));
+            printf("%ld ", lrint(-2.5));
+
+            return 0;
+          }
+          '''
+        self.do_run(src, "1.0 2.0 -1.0 -2.0 2.0 3.0 -2.0 -3.0 "
+                         "1 2 -1 -2 2 2 -2 -2")
+
     def test_getgep(self):
         # Generated code includes getelementptr (getelementptr, 0, 1), i.e., GEP as the first param to GEP
         src = '''