Int64.of_string fixes

- Fix overflow check for positive integers
- Fix the failure message

Co-authored-by: Ricky Vetter <rickywvetter@gmail.com>

Author: vouillon

compiler/tests-jsoo/test_ints.ml

@@ -66,3 +66,20 @@ let%expect_test _ =
   [%expect {| -481418970354774920 |}];
   Printf.printf "%Ld\n" (Int64.of_string "0U17965325103354776696");
   [%expect {| -481418970354774920 |}]
+
+
+let%expect_test _ =
+  let check_fail x =
+    try
+      Printf.printf "%Lx\n" (Int64.of_string x)
+    with Failure _ ->
+      Format.printf "overflow\n"
+  in
+  Printf.printf "%Ld\n" (Int64.of_string "9223372036854775807");
+  [%expect {| 9223372036854775807 |}];
+  Printf.printf "%Ld\n" (Int64.of_string "-9223372036854775808");
+  [%expect {| -9223372036854775808 |}];
+  check_fail "9223372036854775808";
+  [%expect {| overflow |}];
+  check_fail "-9223372036854775809";
+  [%expect {| overflow |}]

runtime/js/int64.js

@@ -30,6 +30,10 @@ class MlInt64 {
     this.caml_custom = "_j";
   }
 
+  static UNSIGNED_MAX  = new MlInt64(0xffffff, 0xffffff, 0xffff);
+  static SIGNED_MAX    = new MlInt64(0xffffff, 0xffffff, 0x7fff);
+  static SIGNED_MIN    = new MlInt64(0x000000, 0x000000, 0x8000);
+
   slice() {
     return new MlInt64(this.lo, this.mi, this.hi);
   }
@@ -399,12 +403,10 @@ function caml_int64_of_string(s) {
     base = r[2],
     signedness = r[3];
   var base64 = caml_int64_of_int32(base);
-  var threshold = new MlInt64(0xffffff, 0xfffffff, 0xffff).udivmod(
-    base64,
-  ).quotient;
+  var threshold = MlInt64.UNSIGNED_MAX.udivmod(base64).quotient;
   var c = caml_string_unsafe_get(s, i);
   var d = caml_parse_digit(c);
-  if (d < 0 || d >= base) caml_failwith("int_of_string");
+  if (d < 0 || d >= base) caml_failwith("Int64.of_string");
   var res = caml_int64_of_int32(d);
   for (;;) {
     i++;
@@ -413,15 +415,15 @@ function caml_int64_of_string(s) {
     d = caml_parse_digit(c);
     if (d < 0 || d >= base) break;
     /* Detect overflow in multiplication base * res */
-    if (caml_int64_ult(threshold, res)) caml_failwith("int_of_string");
+    if (caml_int64_ult(threshold, res)) caml_failwith("Int64.of_string");
     d = caml_int64_of_int32(d);
     res = caml_int64_add(caml_int64_mul(base64, res), d);
     /* Detect overflow in addition (base * res) + d */
-    if (caml_int64_ult(res, d)) caml_failwith("int_of_string");
+    if (caml_int64_ult(res, d)) caml_failwith("Int64.of_string");
   }
-  if (i !== caml_ml_string_length(s)) caml_failwith("int_of_string");
-  if (signedness && caml_int64_ult(new MlInt64(0, 0, 0x8000), res))
-    caml_failwith("int_of_string");
+  if (i !== caml_ml_string_length(s)) caml_failwith("Int64.of_string");
+  if (signedness && caml_int64_ult(sign < 0 ? MlInt64.SIGNED_MIN : MlInt64.SIGNED_MAX, res))
+    caml_failwith("Int64.of_string");
   if (sign < 0) res = caml_int64_neg(res);
   return res;
 }