Adds `-ftime-trace` option to clang that produces Chrome `chrome://tracing` compatible JSON profiling output dumps.
This change adds hierarchical "time trace" profiling blocks that can be visualized in Chrome, in a "flame chart" style. Each profiling block can have a "detail" string that for example indicates the file being processed, template name being instantiated, function being optimized etc.
This is taken from GitHub PR: https://github.com/aras-p/llvm-project-20170507/pull/2
Patch by Aras Pranckevičius.
Differential Revision: https://reviews.llvm.org/D58675
llvm-svn: 357340
diff --git a/llvm/lib/Support/TimeProfiler.cpp b/llvm/lib/Support/TimeProfiler.cpp
new file mode 100644
index 0000000..6b999ca
--- /dev/null
+++ b/llvm/lib/Support/TimeProfiler.cpp
@@ -0,0 +1,184 @@
+//===-- TimeProfiler.cpp - Hierarchical Time Profiler ---------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file Hierarchical time profiler implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/TimeProfiler.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/FileSystem.h"
+#include <cassert>
+#include <chrono>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+using namespace std::chrono;
+
+namespace llvm {
+
+TimeTraceProfiler *TimeTraceProfilerInstance = nullptr;
+
+static std::string escapeString(StringRef Src) {
+ std::string OS;
+ for (const unsigned char &C : Src) {
+ switch (C) {
+ case '"':
+ case '/':
+ case '\\':
+ case '\b':
+ case '\f':
+ case '\n':
+ case '\r':
+ case '\t':
+ OS += '\\';
+ OS += C;
+ break;
+ default:
+ if (isPrint(C)) {
+ OS += C;
+ }
+ }
+ }
+ return OS;
+}
+
+typedef duration<steady_clock::rep, steady_clock::period> DurationType;
+typedef std::pair<std::string, DurationType> NameAndDuration;
+
+struct Entry {
+ time_point<steady_clock> Start;
+ DurationType Duration;
+ std::string Name;
+ std::string Detail;
+};
+
+struct TimeTraceProfiler {
+ TimeTraceProfiler() {
+ Stack.reserve(8);
+ Entries.reserve(128);
+ StartTime = steady_clock::now();
+ }
+
+ void begin(std::string Name, llvm::function_ref<std::string()> Detail) {
+ Entry E = {steady_clock::now(), {}, Name, Detail()};
+ Stack.push_back(std::move(E));
+ }
+
+ void end() {
+ assert(!Stack.empty() && "Must call begin() first");
+ auto &E = Stack.back();
+ E.Duration = steady_clock::now() - E.Start;
+
+ // Only include sections longer than 500us.
+ if (duration_cast<microseconds>(E.Duration).count() > 500)
+ Entries.emplace_back(E);
+
+ // Track total time taken by each "name", but only the topmost levels of
+ // them; e.g. if there's a template instantiation that instantiates other
+ // templates from within, we only want to add the topmost one. "topmost"
+ // happens to be the ones that don't have any currently open entries above
+ // itself.
+ if (std::find_if(++Stack.rbegin(), Stack.rend(), [&](const Entry &Val) {
+ return Val.Name == E.Name;
+ }) == Stack.rend()) {
+ TotalPerName[E.Name] += E.Duration;
+ CountPerName[E.Name]++;
+ }
+
+ Stack.pop_back();
+ }
+
+ void Write(std::unique_ptr<raw_pwrite_stream> &OS) {
+ assert(Stack.empty() &&
+ "All profiler sections should be ended when calling Write");
+
+ *OS << "{ \"traceEvents\": [\n";
+
+ // Emit all events for the main flame graph.
+ for (const auto &E : Entries) {
+ auto StartUs = duration_cast<microseconds>(E.Start - StartTime).count();
+ auto DurUs = duration_cast<microseconds>(E.Duration).count();
+ *OS << "{ \"pid\":1, \"tid\":0, \"ph\":\"X\", \"ts\":" << StartUs
+ << ", \"dur\":" << DurUs << ", \"name\":\"" << escapeString(E.Name)
+ << "\", \"args\":{ \"detail\":\"" << escapeString(E.Detail)
+ << "\"} },\n";
+ }
+
+ // Emit totals by section name as additional "thread" events, sorted from
+ // longest one.
+ int Tid = 1;
+ std::vector<NameAndDuration> SortedTotals;
+ SortedTotals.reserve(TotalPerName.size());
+ for (const auto &E : TotalPerName) {
+ SortedTotals.push_back(E);
+ }
+ std::sort(SortedTotals.begin(), SortedTotals.end(),
+ [](const NameAndDuration &A, const NameAndDuration &B) {
+ return A.second > B.second;
+ });
+ for (const auto &E : SortedTotals) {
+ auto DurUs = duration_cast<microseconds>(E.second).count();
+ *OS << "{ \"pid\":1, \"tid\":" << Tid << ", \"ph\":\"X\", \"ts\":" << 0
+ << ", \"dur\":" << DurUs << ", \"name\":\"Total "
+ << escapeString(E.first)
+ << "\", \"args\":{ \"count\":" << CountPerName[E.first]
+ << ", \"avg ms\":" << (DurUs / CountPerName[E.first] / 1000)
+ << "} },\n";
+ ++Tid;
+ }
+
+ // Emit metadata event with process name.
+ *OS << "{ \"cat\":\"\", \"pid\":1, \"tid\":0, \"ts\":0, \"ph\":\"M\", "
+ "\"name\":\"process_name\", \"args\":{ \"name\":\"clang\" } }\n";
+ *OS << "] }\n";
+ }
+
+ std::vector<Entry> Stack;
+ std::vector<Entry> Entries;
+ std::unordered_map<std::string, DurationType> TotalPerName;
+ std::unordered_map<std::string, size_t> CountPerName;
+ time_point<steady_clock> StartTime;
+};
+
+void timeTraceProfilerInitialize() {
+ assert(TimeTraceProfilerInstance == nullptr &&
+ "Profiler should not be initialized");
+ TimeTraceProfilerInstance = new TimeTraceProfiler();
+}
+
+void timeTraceProfilerCleanup() {
+ delete TimeTraceProfilerInstance;
+ TimeTraceProfilerInstance = nullptr;
+}
+
+void timeTraceProfilerWrite(std::unique_ptr<raw_pwrite_stream> &OS) {
+ assert(TimeTraceProfilerInstance != nullptr &&
+ "Profiler object can't be null");
+ TimeTraceProfilerInstance->Write(OS);
+}
+
+void timeTraceProfilerBegin(StringRef Name, StringRef Detail) {
+ if (TimeTraceProfilerInstance != nullptr)
+ TimeTraceProfilerInstance->begin(Name, [&]() { return Detail; });
+}
+
+void timeTraceProfilerBegin(StringRef Name,
+ llvm::function_ref<std::string()> Detail) {
+ if (TimeTraceProfilerInstance != nullptr)
+ TimeTraceProfilerInstance->begin(Name, Detail);
+}
+
+void timeTraceProfilerEnd() {
+ if (TimeTraceProfilerInstance != nullptr)
+ TimeTraceProfilerInstance->end();
+}
+
+} // namespace llvm