[flang-commits] [PATCH] D83428: [flang] Fix negative unit number hashing

[Peter Klausler via Phabricator via flang-commits]

klausler created this revision.
klausler added reviewers: tskeith, sscalpone.
klausler added a project: Flang.
Herald added a reviewer: jdoerfert.
Herald added a reviewer: DavidTruby.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Ensure that external unit number hashing produces a valid
index for a negative unit number, viz. a NEWUNIT=.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D83428

Files:
  flang/runtime/unit-map.h


Index: flang/runtime/unit-map.h
===================================================================
--- flang/runtime/unit-map.h
+++ flang/runtime/unit-map.h
@@ -15,6 +15,7 @@
 #include "lock.h"
 #include "memory.h"
 #include "unit.h"
+#include <cstdlib>
 
 namespace Fortran::runtime::io {
 
@@ -59,7 +60,7 @@
   };
 
   static constexpr int buckets_{1031}; // must be prime
-  int Hash(int n) { return n % buckets_; }
+  int Hash(int n) { return std::abs(n) % buckets_; }
 
   ExternalFileUnit *Find(int n) {
     Chain *previous{nullptr};


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D83428.276561.patch
Type: text/x-patch
Size: 542 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/flang-commits/attachments/20200708/856a2aa2/attachment.bin>