[llvm-cov] Don't spawn a thread unless ThreadCount > 1
Initializing a ThreadPool with ThreadCount = 1 spawns a thread even
though we don't need to. This is at least slower than it needs to be,
and at worst may somehow be exacerbating PR30735 (llvm-cov times out
on ARM bots).
As a follow-up, I'll try to add logic to llvm::ThreadPool to avoid
spawning a thread when ThreadCount = 1.
llvm-svn: 284621
diff --git a/llvm/tools/llvm-cov/CodeCoverage.cpp b/llvm/tools/llvm-cov/CodeCoverage.cpp
index b3457a9..b48c594 100644
--- a/llvm/tools/llvm-cov/CodeCoverage.cpp
+++ b/llvm/tools/llvm-cov/CodeCoverage.cpp
@@ -101,6 +101,10 @@
/// \brief Demangle \p Sym if possible. Otherwise, just return \p Sym.
StringRef getSymbolForHumans(StringRef Sym) const;
+ /// \brief Write out a source file view to the filesystem.
+ void writeSourceFileView(StringRef SourceFile, CoverageMapping *Coverage,
+ CoveragePrinter *Printer, bool ShowFilenames);
+
typedef llvm::function_ref<int(int, const char **)> CommandLineParserType;
int show(int argc, const char **argv,
@@ -457,6 +461,28 @@
return DemangledName->getValue();
}
+void CodeCoverageTool::writeSourceFileView(StringRef SourceFile,
+ CoverageMapping *Coverage,
+ CoveragePrinter *Printer,
+ bool ShowFilenames) {
+ auto View = createSourceFileView(SourceFile, *Coverage);
+ if (!View) {
+ warning("The file '" + SourceFile + "' isn't covered.");
+ return;
+ }
+
+ auto OSOrErr = Printer->createViewFile(SourceFile, /*InToplevel=*/false);
+ if (Error E = OSOrErr.takeError()) {
+ error("Could not create view file!", toString(std::move(E)));
+ return;
+ }
+ auto OS = std::move(OSOrErr.get());
+
+ View->print(*OS.get(), /*Wholefile=*/true,
+ /*ShowSourceName=*/ShowFilenames);
+ Printer->closeViewFile(std::move(OS));
+}
+
int CodeCoverageTool::run(Command Cmd, int argc, const char **argv) {
cl::opt<std::string, true> ObjectFilename(
cl::Positional, cl::Required, cl::location(this->ObjectFilename),
@@ -764,35 +790,21 @@
}
}
- // 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);
-
- for (const std::string &SourceFile : SourceFiles) {
- Pool.async([this, &SourceFile, &Coverage, &Printer, ShowFilenames] {
- auto View = createSourceFileView(SourceFile, *Coverage);
- if (!View) {
- warning("The file '" + SourceFile + "' isn't covered.");
- return;
- }
-
- auto OSOrErr = Printer->createViewFile(SourceFile, /*InToplevel=*/false);
- if (Error E = OSOrErr.takeError()) {
- error("Could not create view file!", toString(std::move(E)));
- return;
- }
- auto OS = std::move(OSOrErr.get());
-
- View->print(*OS.get(), /*Wholefile=*/true,
- /*ShowSourceName=*/ShowFilenames);
- Printer->closeViewFile(std::move(OS));
- });
+ // FIXME: Sink the hardware_concurrency() == 1 check into ThreadPool.
+ if (!ViewOpts.hasOutputDirectory() ||
+ std::thread::hardware_concurrency() == 1) {
+ for (const std::string &SourceFile : SourceFiles)
+ writeSourceFileView(SourceFile, Coverage.get(), Printer.get(),
+ ShowFilenames);
+ } else {
+ // In -output-dir mode, it's safe to use multiple threads to print files.
+ ThreadPool Pool;
+ for (const std::string &SourceFile : SourceFiles)
+ Pool.async(&CodeCoverageTool::writeSourceFileView, this, SourceFile,
+ Coverage.get(), Printer.get(), ShowFilenames);
+ Pool.wait();
}
- Pool.wait();
-
return 0;
}