[PATCH] D21218: [LibFuzzer] Avoid using std::random_swap() due to platform differences and implement our own version.

[Mike Aizatsky via llvm-commits]

aizatsky requested changes to this revision.
This revision now requires changes to proceed.

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Comment at: lib/Fuzzer/FuzzerInternal.h:145
@@ +144,3 @@
+  //
+  // The algorithm used here will pick a permutation at
+  // random where every permutation has equal probability
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Specify algorithm reference.

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Comment at: lib/Fuzzer/FuzzerInternal.h:152
@@ +151,3 @@
+    N = End - First;
+    for (Offset = 0; Offset < N; ++Offset) {
+      std::swap(First[Offset], First[Offset + (*this)(N - Offset)]);
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Let's see that this is literally Fisher-Yates shuffle:

https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle

Even (N-2) is important to have it produce uniform shuffles. 


http://reviews.llvm.org/D21218