fix llvm_uadd_with_overflow_i64 in the case of 0 higher bits

2 files changed, 5 insertions, 2 deletions

diff --git a/src/library.js b/src/library.js
index 957f69bd..9b63084f 100644
--- a/src/library.js
+++ b/src/library.js
@@ -7522,8 +7522,10 @@ LibraryManager.library = {
     l = (a + c)>>>0;
     h = (b + d)>>>0;
     overflow = ((h>>>0) < (b>>>0))|0; // Return whether addition overflowed even the high word.
-    h = (h + (((l>>>0) < (a>>>0))|0))>>>0; // Add carry from low word to high word on overflow.
-    overflow = overflow | (!h); // Check again for overflow.
+    if ((l>>>0) < (a>>>0)) {
+      h = (h + 1)>>>0; // Add carry from low word to high word on overflow.
+      overflow = overflow | (!h); // Check again for overflow.
+    }
     {{{ makeStructuralReturn(['l|0', 'h', 'overflow'], true) }}};
   },
 
diff --git a/tests/runner.py b/tests/runner.py
index ba0c4aa0..4107d57e 100755
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -1118,6 +1118,7 @@ m_divisor is 1091269979
         {
             a = argc;
             b = argv[1][0];
+            printf("%d,%d\n", a, b);
             if (a > a + b || a > a + b + 1) {
                 printf("one %lld, %lld", a, b);
                 return 0;