[Driver] Allow to collect `-save-stats` data to a file specified in the environment variable.

Using two environment variables `CC_PRINT_INTERNAL_STAT` and
`CC_PRINT_INTERNAL_STAT_FILE` to work like `CC_PRINT_PROC_STAT`.

The purpose of the change is to allow collecting the internal stats
without modifying the build scripts. Write all stats to a single file
to simplify aggregating the data.

Differential Revision: https://reviews.llvm.org/D144981

1 files changed, 5 insertions, 2 deletions

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index f3510b0..ecf9394 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1087,9 +1087,12 @@ bool CompilerInstance::ExecuteAction(FrontendAction &Act) {
   }
   StringRef StatsFile = getFrontendOpts().StatsFile;
   if (!StatsFile.empty()) {
+    llvm::sys::fs::OpenFlags FileFlags = llvm::sys::fs::OF_TextWithCRLF;
+    if (getFrontendOpts().AppendStats)
+      FileFlags |= llvm::sys::fs::OF_Append;
     std::error_code EC;
-    auto StatS = std::make_unique<llvm::raw_fd_ostream>(
-        StatsFile, EC, llvm::sys::fs::OF_TextWithCRLF);
+    auto StatS =
+        std::make_unique<llvm::raw_fd_ostream>(StatsFile, EC, FileFlags);
     if (EC) {
       getDiagnostics().Report(diag::warn_fe_unable_to_open_stats_file)
           << StatsFile << EC.message();