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Revert "[clang][deps] Only cache files with specific extension"
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This reverts commit d1e00b6.

Internally, there were issues with caching stat failures for .framework directories. We need some time for investigation to pinpoint what exactly was going wrong.
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@jansvoboda11
jansvoboda11 committed May 16, 2023
1 parent 692ae97 commit 09c5d69
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Showing 3 changed files with 52 additions and 192 deletions.
41 changes: 7 additions & 34 deletions clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
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Original file line number Diff line number Diff line change
Expand Up @@ -269,32 +269,6 @@ class EntryRef {
}
};

enum class ScanFile { Yes, No };
enum class CacheStatFailure { Yes, No };

struct PathPolicy {
/// Implies caching of all open and stat results.
unsigned Enable : 1;
/// Controls whether a file will be scanned for dependency directives.
unsigned ScanFile : 1;
/// Explicitly disables stat failure caching when false.
unsigned CacheStatFailure : 1;

static PathPolicy fallThrough() { return {false, false, false}; }

static PathPolicy cache(enum ScanFile SF,
enum CacheStatFailure CSF = CacheStatFailure::Yes) {
return {true, SF == ScanFile::Yes, CSF == CacheStatFailure::Yes};
}

private:
PathPolicy(bool E, bool SF, bool CSF)
: Enable(E), ScanFile(SF), CacheStatFailure(CSF) {}
};

/// Determine caching and scanning behavior based on file extension.
PathPolicy getPolicy(StringRef Filename);

/// A virtual file system optimized for the dependency discovery.
///
/// It is primarily designed to work with source files whose contents was
Expand All @@ -319,25 +293,24 @@ class DependencyScanningWorkerFilesystem : public llvm::vfs::ProxyFileSystem {
///
/// Attempts to use the local and shared caches first, then falls back to
/// using the underlying filesystem.
llvm::ErrorOr<EntryRef> getOrCreateFileSystemEntry(StringRef Filename) {
return getOrCreateFileSystemEntry(Filename, getPolicy(Filename));
}
llvm::ErrorOr<EntryRef>
getOrCreateFileSystemEntry(StringRef Filename,
bool DisableDirectivesScanning = false);

private:
/// Same as the public version, but with explicit PathPolicy parameter.
llvm::ErrorOr<EntryRef> getOrCreateFileSystemEntry(StringRef Filename,
PathPolicy Policy);
/// Check whether the file should be scanned for preprocessor directives.
bool shouldScanForDirectives(StringRef Filename);

/// For a filename that's not yet associated with any entry in the caches,
/// uses the underlying filesystem to either look up the entry based in the
/// shared cache indexed by unique ID, or creates new entry from scratch.
llvm::ErrorOr<const CachedFileSystemEntry &>
computeAndStoreResult(StringRef Filename, PathPolicy Policy);
computeAndStoreResult(StringRef Filename);

/// Scan for preprocessor directives for the given entry if necessary and
/// returns a wrapper object with reference semantics.
EntryRef scanForDirectivesIfNecessary(const CachedFileSystemEntry &Entry,
StringRef Filename, PathPolicy Policy);
StringRef Filename, bool Disable);

/// Represents a filesystem entry that has been stat-ed (and potentially read)
/// and that's about to be inserted into the cache as `CachedFileSystemEntry`.
Expand Down
76 changes: 45 additions & 31 deletions clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -42,8 +42,9 @@ DependencyScanningWorkerFilesystem::readFile(StringRef Filename) {
}

EntryRef DependencyScanningWorkerFilesystem::scanForDirectivesIfNecessary(
const CachedFileSystemEntry &Entry, StringRef Filename, PathPolicy Policy) {
if (Entry.isError() || Entry.isDirectory() || !Policy.ScanFile)
const CachedFileSystemEntry &Entry, StringRef Filename, bool Disable) {
if (Entry.isError() || Entry.isDirectory() || Disable ||
!shouldScanForDirectives(Filename))
return EntryRef(Filename, Entry);

CachedFileContents *Contents = Entry.getCachedContents();
Expand Down Expand Up @@ -158,22 +159,39 @@ DependencyScanningFilesystemSharedCache::CacheShard::
return *EntriesByFilename.insert({Filename, &Entry}).first->getValue();
}

PathPolicy clang::tooling::dependencies::getPolicy(StringRef Filename) {
/// Whitelist file extensions that should be minimized, treating no extension as
/// a source file that should be minimized.
///
/// This is kinda hacky, it would be better if we knew what kind of file Clang
/// was expecting instead.
static bool shouldScanForDirectivesBasedOnExtension(StringRef Filename) {
StringRef Ext = llvm::sys::path::extension(Filename);
if (Ext.empty())
return PathPolicy::cache(ScanFile::Yes, CacheStatFailure::No);
// clang-format off
return llvm::StringSwitch<PathPolicy>(Ext)
.CasesLower(".c", ".cc", ".cpp", ".c++", ".cxx", PathPolicy::cache(ScanFile::Yes))
.CasesLower(".h", ".hh", ".hpp", ".h++", ".hxx", PathPolicy::cache(ScanFile::Yes))
.CasesLower(".m", ".mm", PathPolicy::cache(ScanFile::Yes))
.CasesLower(".i", ".ii", ".mi", ".mmi", PathPolicy::cache(ScanFile::Yes))
.CasesLower(".def", ".inc", PathPolicy::cache(ScanFile::Yes))
.CasesLower(".modulemap", ".map", PathPolicy::cache(ScanFile::No))
.CasesLower(".framework", ".apinotes", PathPolicy::cache(ScanFile::No))
.CasesLower(".yaml", ".json", ".hmap", PathPolicy::cache(ScanFile::No))
.Default(PathPolicy::fallThrough());
// clang-format on
return true; // C++ standard library
return llvm::StringSwitch<bool>(Ext)
.CasesLower(".c", ".cc", ".cpp", ".c++", ".cxx", true)
.CasesLower(".h", ".hh", ".hpp", ".h++", ".hxx", true)
.CasesLower(".m", ".mm", true)
.CasesLower(".i", ".ii", ".mi", ".mmi", true)
.CasesLower(".def", ".inc", true)
.Default(false);
}

static bool shouldCacheStatFailures(StringRef Filename) {
StringRef Ext = llvm::sys::path::extension(Filename);
if (Ext.empty())
return false; // This may be the module cache directory.
// Only cache stat failures on files that are not expected to change during
// the build.
StringRef FName = llvm::sys::path::filename(Filename);
if (FName == "module.modulemap" || FName == "module.map")
return true;
return shouldScanForDirectivesBasedOnExtension(Filename);
}

bool DependencyScanningWorkerFilesystem::shouldScanForDirectives(
StringRef Filename) {
return shouldScanForDirectivesBasedOnExtension(Filename);
}

const CachedFileSystemEntry &
Expand All @@ -197,11 +215,10 @@ DependencyScanningWorkerFilesystem::findEntryByFilenameWithWriteThrough(
}

llvm::ErrorOr<const CachedFileSystemEntry &>
DependencyScanningWorkerFilesystem::computeAndStoreResult(StringRef Filename,
PathPolicy Policy) {
DependencyScanningWorkerFilesystem::computeAndStoreResult(StringRef Filename) {
llvm::ErrorOr<llvm::vfs::Status> Stat = getUnderlyingFS().status(Filename);
if (!Stat) {
if (!Policy.CacheStatFailure)
if (!shouldCacheStatFailures(Filename))
return Stat.getError();
const auto &Entry =
getOrEmplaceSharedEntryForFilename(Filename, Stat.getError());
Expand All @@ -227,25 +244,25 @@ DependencyScanningWorkerFilesystem::computeAndStoreResult(StringRef Filename,

llvm::ErrorOr<EntryRef>
DependencyScanningWorkerFilesystem::getOrCreateFileSystemEntry(
StringRef Filename, PathPolicy Policy) {
StringRef Filename, bool DisableDirectivesScanning) {
if (const auto *Entry = findEntryByFilenameWithWriteThrough(Filename))
return scanForDirectivesIfNecessary(*Entry, Filename, Policy).unwrapError();
auto MaybeEntry = computeAndStoreResult(Filename, Policy);
return scanForDirectivesIfNecessary(*Entry, Filename,
DisableDirectivesScanning)
.unwrapError();
auto MaybeEntry = computeAndStoreResult(Filename);
if (!MaybeEntry)
return MaybeEntry.getError();
return scanForDirectivesIfNecessary(*MaybeEntry, Filename, Policy)
return scanForDirectivesIfNecessary(*MaybeEntry, Filename,
DisableDirectivesScanning)
.unwrapError();
}

llvm::ErrorOr<llvm::vfs::Status>
DependencyScanningWorkerFilesystem::status(const Twine &Path) {
SmallString<256> OwnedFilename;
StringRef Filename = Path.toStringRef(OwnedFilename);
PathPolicy Policy = getPolicy(Filename);
if (!Policy.Enable)
return getUnderlyingFS().status(Path);

llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename, Policy);
llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename);
if (!Result)
return Result.getError();
return Result->getStatus();
Expand Down Expand Up @@ -301,11 +318,8 @@ llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
DependencyScanningWorkerFilesystem::openFileForRead(const Twine &Path) {
SmallString<256> OwnedFilename;
StringRef Filename = Path.toStringRef(OwnedFilename);
PathPolicy Policy = getPolicy(Filename);
if (!Policy.Enable)
return getUnderlyingFS().openFileForRead(Path);

llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename, Policy);
llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename);
if (!Result)
return Result.getError();
return DepScanFile::create(Result.get());
Expand Down
127 changes: 0 additions & 127 deletions clang/unittests/Tooling/DependencyScannerTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -239,130 +239,3 @@ TEST(DependencyScanner, ScanDepsWithFS) {
EXPECT_EQ(convert_to_slash(DepFile),
"test.cpp.o: /root/test.cpp /root/header.h\n");
}

// Note: We want to test caching in DependencyScanningWorkerFilesystem. To do
// that, we need to be able to mutate the underlying file system. However,
// InMemoryFileSystem does not allow changing the contents of a file after it's
// been created.
// To simulate the behavior, we create two separate in-memory file systems, each
// containing different version of the same file. We pass those to two scanning
// file systems that share the same cache.

TEST(DependencyScanningFileSystemTest, CacheFileContentsEnabled) {
DependencyScanningFilesystemSharedCache SharedCache;

StringRef Path = "/root/source.c";
auto Contents1 = llvm::MemoryBuffer::getMemBuffer("contents1");
auto Contents2 = llvm::MemoryBuffer::getMemBuffer("contents2");

{
auto InMemoryFS =
llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
ASSERT_TRUE(InMemoryFS->addFile(Path, 0, std::move(Contents1)));
DependencyScanningWorkerFilesystem ScanningFS(SharedCache, InMemoryFS);
auto File = ScanningFS.openFileForRead(Path);
ASSERT_TRUE(File);
auto Buffer = (*File)->getBuffer("Buffer for /root/source.c.");
ASSERT_TRUE(Buffer);
auto Contents = (*Buffer)->getBuffer();
EXPECT_EQ(Contents, "contents1");
}

{
auto InMemoryFS =
llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
ASSERT_TRUE(InMemoryFS->addFile(Path, 0, std::move(Contents2)));
DependencyScanningWorkerFilesystem ScanningFS(SharedCache, InMemoryFS);
auto File = ScanningFS.openFileForRead(Path);
ASSERT_TRUE(File);
auto Buffer = (*File)->getBuffer("Buffer for /root/source.c.");
ASSERT_TRUE(Buffer);
auto Contents = (*Buffer)->getBuffer();
EXPECT_EQ(Contents, "contents1");
}
}

TEST(DependencyScanningFileSystemTest, CacheFileContentsDisabled) {
DependencyScanningFilesystemSharedCache SharedCache;

StringRef Path = "/root/module.pcm";
auto Contents1 = llvm::MemoryBuffer::getMemBuffer("contents1");
auto Contents2 = llvm::MemoryBuffer::getMemBuffer("contents2");

{
auto InMemoryFS =
llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
ASSERT_TRUE(InMemoryFS->addFile(Path, 0, std::move(Contents1)));
DependencyScanningWorkerFilesystem ScanningFS(SharedCache, InMemoryFS);
auto File = ScanningFS.openFileForRead(Path);
ASSERT_TRUE(File);
auto Buffer = (*File)->getBuffer("Buffer for /root/module.pcm.");
ASSERT_TRUE(Buffer);
auto Contents = (*Buffer)->getBuffer();
EXPECT_EQ(Contents, "contents1");
}

{
auto InMemoryFS =
llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
ASSERT_TRUE(InMemoryFS->addFile(Path, 0, std::move(Contents2)));
DependencyScanningWorkerFilesystem ScanningFS(SharedCache, InMemoryFS);
auto File = ScanningFS.openFileForRead(Path);
ASSERT_TRUE(File);
auto Buffer = (*File)->getBuffer("Buffer for /root/module.pcm.");
ASSERT_TRUE(Buffer);
auto Contents = (*Buffer)->getBuffer();
EXPECT_EQ(Contents, "contents2");
}
}

TEST(DependencyScanningFileSystemTest, CacheStatFailureEnabled) {
DependencyScanningFilesystemSharedCache SharedCache;
auto InMemoryFS = llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
DependencyScanningWorkerFilesystem ScanningFS(SharedCache, InMemoryFS);

StringRef Path = "/root/source.c";

auto Stat1 = ScanningFS.status(Path);
EXPECT_FALSE(Stat1);

auto Contents = llvm::MemoryBuffer::getMemBuffer("contents");
InMemoryFS->addFile(Path, 0, std::move(Contents));

auto Stat2 = ScanningFS.status(Path);
EXPECT_FALSE(Stat2);
}

TEST(DependencyScanningFileSystemTest, CacheStatFailureDisabledFile) {
DependencyScanningFilesystemSharedCache SharedCache;
auto InMemoryFS = llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
DependencyScanningWorkerFilesystem ScanningFS(SharedCache, InMemoryFS);

StringRef Path = "/root/vector";

auto Stat1 = ScanningFS.status(Path);
EXPECT_FALSE(Stat1);

auto Contents = llvm::MemoryBuffer::getMemBuffer("contents");
InMemoryFS->addFile(Path, 0, std::move(Contents));

auto Stat2 = ScanningFS.status(Path);
EXPECT_TRUE(Stat2);
}

TEST(DependencyScanningFileSystemTest, CacheStatFailureDisabledDirectory) {
DependencyScanningFilesystemSharedCache SharedCache;
auto InMemoryFS = llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
DependencyScanningWorkerFilesystem ScanningFS(SharedCache, InMemoryFS);

StringRef Path = "/root/dir";

auto Stat1 = ScanningFS.status(Path);
EXPECT_FALSE(Stat1);

auto Contents = llvm::MemoryBuffer::getMemBuffer("contents");
InMemoryFS->addFile("/root/dir/file", 0, std::move(Contents));

auto Stat2 = ScanningFS.status(Path);
EXPECT_TRUE(Stat2);
}

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