Add a comment explaining why this code uses Append mode.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104095 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Timer.cpp b/lib/Support/Timer.cpp
index 481f6ba..784b77c 100644
--- a/lib/Support/Timer.cpp
+++ b/lib/Support/Timer.cpp
@@ -61,6 +61,10 @@
if (OutputFilename == "-")
return new raw_fd_ostream(1, false); // stdout.
+ // Append mode is used because the info output file is opened and closed
+ // each time -stats or -time-passes wants to print output to it. To
+ // compensate for this, the test-suite Makefiles have code to delete the
+ // info output file before running commands which write to it.
std::string Error;
raw_ostream *Result = new raw_fd_ostream(OutputFilename.c_str(),
Error, raw_fd_ostream::F_Append);