--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/Analysis/ProfileSummaryInfo.cpp	Fri Nov 25 19:14:25 2016 +0900
@@ -0,0 +1,184 @@
+//===- ProfileSummaryInfo.cpp - Global profile summary information --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains a pass that provides access to the global profile summary
+// information.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/BlockFrequencyInfo.h"
+#include "llvm/Analysis/ProfileSummaryInfo.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/ProfileSummary.h"
+using namespace llvm;
+
+// The following two parameters determine the threshold for a count to be
+// considered hot/cold. These two parameters are percentile values (multiplied
+// by 10000). If the counts are sorted in descending order, the minimum count to
+// reach ProfileSummaryCutoffHot gives the threshold to determine a hot count.
+// Similarly, the minimum count to reach ProfileSummaryCutoffCold gives the
+// threshold for determining cold count (everything <= this threshold is
+// considered cold).
+
+static cl::opt<int> ProfileSummaryCutoffHot(
+    "profile-summary-cutoff-hot", cl::Hidden, cl::init(999000), cl::ZeroOrMore,
+    cl::desc("A count is hot if it exceeds the minimum count to"
+             " reach this percentile of total counts."));
+
+static cl::opt<int> ProfileSummaryCutoffCold(
+    "profile-summary-cutoff-cold", cl::Hidden, cl::init(999999), cl::ZeroOrMore,
+    cl::desc("A count is cold if it is below the minimum count"
+             " to reach this percentile of total counts."));
+
+// Find the minimum count to reach a desired percentile of counts.
+static uint64_t getMinCountForPercentile(SummaryEntryVector &DS,
+                                         uint64_t Percentile) {
+  auto Compare = [](const ProfileSummaryEntry &Entry, uint64_t Percentile) {
+    return Entry.Cutoff < Percentile;
+  };
+  auto It = std::lower_bound(DS.begin(), DS.end(), Percentile, Compare);
+  // The required percentile has to be <= one of the percentiles in the
+  // detailed summary.
+  if (It == DS.end())
+    report_fatal_error("Desired percentile exceeds the maximum cutoff");
+  return It->MinCount;
+}
+
+// The profile summary metadata may be attached either by the frontend or by
+// any backend passes (IR level instrumentation, for example). This method
+// checks if the Summary is null and if so checks if the summary metadata is now
+// available in the module and parses it to get the Summary object.
+void ProfileSummaryInfo::computeSummary() {
+  if (Summary)
+    return;
+  auto *SummaryMD = M.getProfileSummary();
+  if (!SummaryMD)
+    return;
+  Summary.reset(ProfileSummary::getFromMD(SummaryMD));
+}
+
+/// Returns true if the function's entry is hot. If it returns false, it
+/// either means it is not hot or it is unknown whether it is hot or not (for
+/// example, no profile data is available).
+bool ProfileSummaryInfo::isFunctionEntryHot(const Function *F) {
+  computeSummary();
+  if (!F || !Summary)
+    return false;
+  auto FunctionCount = F->getEntryCount();
+  // FIXME: The heuristic used below for determining hotness is based on
+  // preliminary SPEC tuning for inliner. This will eventually be a
+  // convenience method that calls isHotCount.
+  return FunctionCount && isHotCount(FunctionCount.getValue());
+}
+
+/// Returns true if the function's entry is a cold. If it returns false, it
+/// either means it is not cold or it is unknown whether it is cold or not (for
+/// example, no profile data is available).
+bool ProfileSummaryInfo::isFunctionEntryCold(const Function *F) {
+  computeSummary();
+  if (!F)
+    return false;
+  if (F->hasFnAttribute(Attribute::Cold)) {
+    return true;
+  }
+  if (!Summary)
+    return false;
+  auto FunctionCount = F->getEntryCount();
+  // FIXME: The heuristic used below for determining coldness is based on
+  // preliminary SPEC tuning for inliner. This will eventually be a
+  // convenience method that calls isHotCount.
+  return FunctionCount && isColdCount(FunctionCount.getValue());
+}
+
+/// Compute the hot and cold thresholds.
+void ProfileSummaryInfo::computeThresholds() {
+  if (!Summary)
+    computeSummary();
+  if (!Summary)
+    return;
+  auto &DetailedSummary = Summary->getDetailedSummary();
+  HotCountThreshold =
+      getMinCountForPercentile(DetailedSummary, ProfileSummaryCutoffHot);
+  ColdCountThreshold =
+      getMinCountForPercentile(DetailedSummary, ProfileSummaryCutoffCold);
+}
+
+bool ProfileSummaryInfo::isHotCount(uint64_t C) {
+  if (!HotCountThreshold)
+    computeThresholds();
+  return HotCountThreshold && C >= HotCountThreshold.getValue();
+}
+
+bool ProfileSummaryInfo::isColdCount(uint64_t C) {
+  if (!ColdCountThreshold)
+    computeThresholds();
+  return ColdCountThreshold && C <= ColdCountThreshold.getValue();
+}
+
+bool ProfileSummaryInfo::isHotBB(const BasicBlock *B, BlockFrequencyInfo *BFI) {
+  auto Count = BFI->getBlockProfileCount(B);
+  if (Count && isHotCount(*Count))
+    return true;
+  // Use extractProfTotalWeight to get BB count.
+  // For Sample PGO, BFI may not provide accurate BB count due to errors
+  // magnified during sample count propagation. This serves as a backup plan
+  // to ensure all hot BB will not be missed.
+  // The query currently has false positives as branch instruction cloning does
+  // not update/scale branch weights. Unlike false negatives, this will not cause
+  // performance problem.
+  uint64_t TotalCount;
+  if (B->getTerminator()->extractProfTotalWeight(TotalCount) &&
+      isHotCount(TotalCount))
+    return true;
+  return false;
+}
+
+INITIALIZE_PASS(ProfileSummaryInfoWrapperPass, "profile-summary-info",
+                "Profile summary info", false, true)
+
+ProfileSummaryInfoWrapperPass::ProfileSummaryInfoWrapperPass()
+    : ImmutablePass(ID) {
+  initializeProfileSummaryInfoWrapperPassPass(*PassRegistry::getPassRegistry());
+}
+
+bool ProfileSummaryInfoWrapperPass::doInitialization(Module &M) {
+  PSI.reset(new ProfileSummaryInfo(M));
+  return false;
+}
+
+bool ProfileSummaryInfoWrapperPass::doFinalization(Module &M) {
+  PSI.reset();
+  return false;
+}
+
+AnalysisKey ProfileSummaryAnalysis::Key;
+ProfileSummaryInfo ProfileSummaryAnalysis::run(Module &M,
+                                               ModuleAnalysisManager &) {
+  return ProfileSummaryInfo(M);
+}
+
+PreservedAnalyses ProfileSummaryPrinterPass::run(Module &M,
+                                                 ModuleAnalysisManager &AM) {
+  ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
+
+  OS << "Functions in " << M.getName() << " with hot/cold annotations: \n";
+  for (auto &F : M) {
+    OS << F.getName();
+    if (PSI.isFunctionEntryHot(&F))
+      OS << " :hot entry ";
+    else if (PSI.isFunctionEntryCold(&F))
+      OS << " :cold entry ";
+    OS << "\n";
+  }
+  return PreservedAnalyses::all();
+}
+
+char ProfileSummaryInfoWrapperPass::ID = 0;