[libcxx-commits] [PATCH] D74997: [libc++] Bugfix to std::binomial_distribution<int>

[Atmn Patel via Phabricator via libcxx-commits]

atmnpatel created this revision.
atmnpatel added reviewers: ldionne, mclow.lists.
Herald added a reviewer: EricWF.
Herald added subscribers: libcxx-commits, dexonsmith.
Herald added a project: libc++.

The current implementation is not guaranteed to converge. This
adds a break condition where 0 is returned if it is impossible for
the method to converge. This should only affect extreme edge cases.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=44847


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74997

Files:
  libcxx/include/random


Index: libcxx/include/random
===================================================================
--- libcxx/include/random
+++ libcxx/include/random
@@ -4048,10 +4048,12 @@
     result_type __rd = __ru;
     while (true)
     {
+        bool __break = true;
         if (__rd >= 1)
         {
             __pd *= __rd / (__pr.__odds_ratio_ * (__pr.__t_ - __rd + 1));
             __u -= __pd;
+            __break = false;
             if (__u < 0)
                 return __rd - 1;
         }
@@ -4062,9 +4064,12 @@
         {
             __pu *= (__pr.__t_ - __ru + 1) * __pr.__odds_ratio_ / __ru;
             __u -= __pu;
+            __break = false;
             if (__u < 0)
                 return __ru;
         }
+        if (__break)
+            return 0;
     }
 }
 


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