[llvm-cov] Use a thread pool to speed up report generation (NFC)
It's safe to print out source coverage views using multiple threads when
using the -output-dir mode of the `llvm-cov show` sub-command.
While testing this on my development machine, I observed that the speed
up is roughly linear with the number of available cores. Avg. time for
`llvm-cov show ./llvm-as -show-line-counts-or-regions`:
1 thread: 7.79s user 0.33s system 98% cpu 8.228 total
4 threads: 7.82s user 0.34s system 283% cpu 2.880 total
llvm-svn: 275321
diff --git a/llvm/tools/llvm-cov/CodeCoverage.cpp b/llvm/tools/llvm-cov/CodeCoverage.cpp
index 7b9edc0..693c802 100644
--- a/llvm/tools/llvm-cov/CodeCoverage.cpp
+++ b/llvm/tools/llvm-cov/CodeCoverage.cpp
@@ -28,6 +28,7 @@
#include "llvm/Support/Format.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
+#include "llvm/Support/ThreadPool.h"
#include <functional>
#include <system_error>
@@ -48,6 +49,15 @@
/// \brief Print the error message to the error output stream.
void error(const Twine &Message, StringRef Whence = "");
+ /// \brief Record (but do not print) an error message in a thread-safe way.
+ void deferError(const Twine &Message, StringRef Whence = "");
+
+ /// \brief Record (but do not print) a warning message in a thread-safe way.
+ void deferWarning(const Twine &Message, StringRef Whence = "");
+
+ /// \brief Print (and then clear) all deferred error and warning messages.
+ void consumeDeferredMessages();
+
/// \brief Append a reference to a private copy of \p Path into SourceFiles.
void addCollectedPath(const std::string &Path);
@@ -85,22 +95,51 @@
std::string PGOFilename;
CoverageFiltersMatchAll Filters;
std::vector<StringRef> SourceFiles;
- std::vector<std::pair<std::string, std::unique_ptr<MemoryBuffer>>>
- LoadedSourceFiles;
bool CompareFilenamesOnly;
StringMap<std::string> RemappedFilenames;
std::string CoverageArch;
private:
std::vector<std::string> CollectedPaths;
+
+ std::mutex DeferredMessagesLock;
+ std::vector<std::string> DeferredMessages;
+
+ std::mutex LoadedSourceFilesLock;
+ std::vector<std::pair<std::string, std::unique_ptr<MemoryBuffer>>>
+ LoadedSourceFiles;
};
}
-void CodeCoverageTool::error(const Twine &Message, StringRef Whence) {
- errs() << "error: ";
+static std::string getErrorString(const Twine &Message, StringRef Whence,
+ bool Warning) {
+ std::string Str = (Warning ? "warning" : "error");
+ Str += ": ";
if (!Whence.empty())
- errs() << Whence << ": ";
- errs() << Message << "\n";
+ Str += Whence;
+ Str += Message.str() + "\n";
+ return Str;
+}
+
+void CodeCoverageTool::error(const Twine &Message, StringRef Whence) {
+ errs() << getErrorString(Message, Whence, false);
+}
+
+void CodeCoverageTool::deferError(const Twine &Message, StringRef Whence) {
+ std::unique_lock<std::mutex> Guard{DeferredMessagesLock};
+ DeferredMessages.emplace_back(getErrorString(Message, Whence, false));
+}
+
+void CodeCoverageTool::deferWarning(const Twine &Message, StringRef Whence) {
+ std::unique_lock<std::mutex> Guard{DeferredMessagesLock};
+ DeferredMessages.emplace_back(getErrorString(Message, Whence, true));
+}
+
+void CodeCoverageTool::consumeDeferredMessages() {
+ std::unique_lock<std::mutex> Guard{DeferredMessagesLock};
+ for (const std::string &Message : DeferredMessages)
+ ViewOpts.colored_ostream(errs(), raw_ostream::RED) << Message;
+ DeferredMessages.clear();
}
void CodeCoverageTool::addCollectedPath(const std::string &Path) {
@@ -121,9 +160,10 @@
return *Files.second;
auto Buffer = MemoryBuffer::getFile(SourceFile);
if (auto EC = Buffer.getError()) {
- error(EC.message(), SourceFile);
+ deferError(EC.message(), SourceFile);
return EC;
}
+ std::unique_lock<std::mutex> Guard{LoadedSourceFilesLock};
LoadedSourceFiles.emplace_back(SourceFile, std::move(Buffer.get()));
return *LoadedSourceFiles.back().second;
}
@@ -505,26 +545,37 @@
}
}
- for (const auto &SourceFile : SourceFiles) {
- auto mainView = createSourceFileView(SourceFile, *Coverage);
- if (!mainView) {
- ViewOpts.colored_ostream(errs(), raw_ostream::RED)
- << "warning: The file '" << SourceFile << "' isn't covered.";
- errs() << "\n";
- continue;
- }
+ // In -output-dir mode, it's safe to use multiple threads to print files.
+ unsigned ThreadCount = 1;
+ if (ViewOpts.hasOutputDirectory())
+ ThreadCount = std::thread::hardware_concurrency();
+ ThreadPool Pool(ThreadCount);
- auto OSOrErr = Printer->createViewFile(SourceFile, /*InToplevel=*/false);
- if (Error E = OSOrErr.takeError()) {
- error(toString(std::move(E)));
- return 1;
- }
- auto OS = std::move(OSOrErr.get());
- mainView->print(*OS.get(), /*Wholefile=*/true,
- /*ShowSourceName=*/ShowFilenames);
- Printer->closeViewFile(std::move(OS));
+ for (StringRef &SourceFile : SourceFiles) {
+ Pool.async([this, &SourceFile, &Coverage, &Printer, ShowFilenames] {
+ auto View = createSourceFileView(SourceFile, *Coverage);
+ if (!View) {
+ deferWarning("The file '" + SourceFile.str() + "' isn't covered.");
+ return;
+ }
+
+ auto OSOrErr = Printer->createViewFile(SourceFile, /*InToplevel=*/false);
+ if (Error E = OSOrErr.takeError()) {
+ deferError(toString(std::move(E)));
+ return;
+ }
+ auto OS = std::move(OSOrErr.get());
+
+ View->print(*OS.get(), /*Wholefile=*/true,
+ /*ShowSourceName=*/ShowFilenames);
+ Printer->closeViewFile(std::move(OS));
+ });
}
+ Pool.wait();
+
+ consumeDeferredMessages();
+
return 0;
}