[ORE] Add diagnostics hotness threshold

Summary:
Add an option to prevent 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: qcolombet, javed.absar, fhahn, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D34867

llvm-svn: 306912

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/tools/llc/llc.cpp b/llvm/tools/llc/llc.cpp
index cd2481bcf46..f13a19213c6 100644
--- a/llvm/tools/llc/llc.cpp
+++ b/llvm/tools/llc/llc.cpp
@@ -149,6 +149,11 @@ static cl::opt<bool> PassRemarksWithHotness(
     cl::desc("With PGO, include profile count in optimization remarks"),
     cl::Hidden);
 
+static cl::opt<unsigned> PassRemarksHotnessThreshold(
+    "pass-remarks-hotness-threshold",
+    cl::desc("Minimum profile count required for an optimization remark to be output"),
+    cl::Hidden);
+
 static cl::opt<std::string>
     RemarksFilename("pass-remarks-output",
                     cl::desc("YAML output filename for pass remarks"),
@@ -325,6 +330,9 @@ int main(int argc, char **argv) {
   if (PassRemarksWithHotness)
     Context.setDiagnosticsHotnessRequested(true);
 
+  if (PassRemarksHotnessThreshold)
+    Context.setDiagnosticsHotnessThreshold(PassRemarksHotnessThreshold);
+
   std::unique_ptr<tool_output_file> YamlFile;
   if (RemarksFilename != "") {
     std::error_code EC;