[llvm] r329496 - [llvm-exegesis] Fix unused return value warning and add a useful error message for event counter reads.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Sat Apr  7 04:37:21 2018
New Revision: 329496

URL: http://llvm.org/viewvc/llvm-project?rev=329496&view=rev
Log:
[llvm-exegesis] Fix unused return value warning and add a useful error message for event counter reads.

Modified:
    llvm/trunk/tools/llvm-exegesis/lib/PerfHelper.cpp

Modified: llvm/trunk/tools/llvm-exegesis/lib/PerfHelper.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-exegesis/lib/PerfHelper.cpp?rev=329496&r1=329495&r2=329496&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-exegesis/lib/PerfHelper.cpp (original)
+++ llvm/trunk/tools/llvm-exegesis/lib/PerfHelper.cpp Sat Apr  7 04:37:21 2018
@@ -107,7 +107,9 @@ void Counter::stop() { ioctl(FileDescrip
 
 int64_t Counter::read() const {
   int64_t Count = 0;
-  ::read(FileDescriptor, &Count, sizeof(Count));
+  ssize_t ReadSize = ::read(FileDescriptor, &Count, sizeof(Count));
+  if (ReadSize != sizeof(Count))
+    llvm::errs() << "Failed to read event counter";
   return Count;
 }