[Driver] Add -fdiagnostics-hotness-threshold

Summary:
Depends on https://reviews.llvm.org/D34867.

Add a Clang frontend option to enable optimization remark hotness
thresholds, which were added to LLVM in https://reviews.llvm.org/D34867.
This prevents diagnostics that do not meet a minimum hotness
threshold from being output. When generating optimization remarks for large
codebases with a ton of cold code paths, this option can be used
to limit the optimization remark output at a reasonable size.
Discussion of this change can be read here:
http://lists.llvm.org/pipermail/llvm-dev/2017-June/114377.html

Reviewers: anemet, davidxl, hfinkel

Reviewed By: anemet

Subscribers: fhahn, cfe-commits

Differential Revision: https://reviews.llvm.org/D34868

llvm-svn: 306945

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index ba033d9413c..4f03de55149 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -229,6 +229,9 @@ namespace clang {
       void *OldDiagnosticContext = Ctx.getDiagnosticContext();
       Ctx.setDiagnosticHandler(DiagnosticHandler, this);
       Ctx.setDiagnosticsHotnessRequested(CodeGenOpts.DiagnosticsWithHotness);
+      if (CodeGenOpts.DiagnosticsHotnessThreshold != 0)
+        Ctx.setDiagnosticsHotnessThreshold(
+            CodeGenOpts.DiagnosticsHotnessThreshold);
 
       std::unique_ptr<llvm::tool_output_file> OptRecordFile;
       if (!CodeGenOpts.OptRecordFile.empty()) {