[llvm] r314870 - [FuzzerUtil] Partially revert D38481 on FuzzerUtil

[Tim Shen via llvm-commits]

Author: timshen
Date: Tue Oct  3 18:05:34 2017
New Revision: 314870

URL: http://llvm.org/viewvc/llvm-project?rev=314870&view=rev
Log:
[FuzzerUtil] Partially revert D38481 on FuzzerUtil

This is because lib/Fuzzer doesn't really depend on llvm infrastucture.
It's not easy to access the llvm hardware_concurrency here.

Differential Reivision: https://reviews.llvm.org/D38481

Modified:
    llvm/trunk/lib/Fuzzer/FuzzerUtil.cpp

Modified: llvm/trunk/lib/Fuzzer/FuzzerUtil.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/FuzzerUtil.cpp?rev=314870&r1=314869&r2=314870&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/FuzzerUtil.cpp (original)
+++ llvm/trunk/lib/Fuzzer/FuzzerUtil.cpp Tue Oct  3 18:05:34 2017
@@ -195,7 +195,15 @@ void PrintPC(const char *SymbolizedFMT,
     Printf(FallbackFMT, PC);
 }
 
-unsigned NumberOfCpuCores() { return hardware_concurrency(); }
+unsigned NumberOfCpuCores() {
+  unsigned N = std::thread::hardware_concurrency();
+  if (!N) {
+    Printf("WARNING: std::thread::hardware_concurrency not well defined for "
+           "your platform. Assuming CPU count of 1.\n");
+    N = 1;
+  }
+  return N;
+}
 
 size_t SimpleFastHash(const uint8_t *Data, size_t Size) {
   size_t Res = 0;