[compiler-rt] r339976 - Revert "[libFuzzer] Use std::discrete_distribution for input selection."

[Matt Morehouse via llvm-commits]

Author: morehouse
Date: Thu Aug 16 18:30:27 2018
New Revision: 339976

URL: http://llvm.org/viewvc/llvm-project?rev=339976&view=rev
Log:
Revert "[libFuzzer] Use std::discrete_distribution for input selection."

This reverts r339973 due to msan.test failing on
sanitizer-x86_64-linux-fuzzer bot.

Modified:
    compiler-rt/trunk/lib/fuzzer/FuzzerCorpus.h

Modified: compiler-rt/trunk/lib/fuzzer/FuzzerCorpus.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/fuzzer/FuzzerCorpus.h?rev=339976&r1=339975&r2=339976&view=diff
==============================================================================
--- compiler-rt/trunk/lib/fuzzer/FuzzerCorpus.h (original)
+++ compiler-rt/trunk/lib/fuzzer/FuzzerCorpus.h Thu Aug 16 18:30:27 2018
@@ -174,7 +174,7 @@ class InputCorpus {
 
   // Returns an index of random unit from the corpus to mutate.
   size_t ChooseUnitIdxToMutate(Random &Rand) {
-    size_t Idx = CorpusDistribution(Rand);
+    size_t Idx = static_cast<size_t>(CorpusDistribution(Rand));
     assert(Idx < Inputs.size());
     return Idx;
   }
@@ -276,7 +276,9 @@ private:
   void UpdateCorpusDistribution() {
     size_t N = Inputs.size();
     assert(N);
+    Intervals.resize(N + 1);
     Weights.resize(N);
+    std::iota(Intervals.begin(), Intervals.end(), 0);
     for (size_t i = 0; i < N; i++)
       Weights[i] = Inputs[i]->NumFeatures
                        ? (i + 1) * (Inputs[i]->HasFocusFunction ? 1000 : 1)
@@ -289,11 +291,12 @@ private:
         Printf("%f ", Weights[i]);
       Printf("Weights\n");
     }
-    CorpusDistribution =
-        std::discrete_distribution<size_t>(Weights.begin(), Weights.end());
+    CorpusDistribution = std::piecewise_constant_distribution<double>(
+        Intervals.begin(), Intervals.end(), Weights.begin());
   }
-  std::discrete_distribution<size_t> CorpusDistribution;
+  std::piecewise_constant_distribution<double> CorpusDistribution;
 
+  Vector<double> Intervals;
   Vector<double> Weights;
 
   std::unordered_set<std::string> Hashes;