[clang] d1e00b6 - [clang][deps] Only cache files with specific extension
Jan Svoboda via cfe-commits
cfe-commits at lists.llvm.org
Mon Mar 20 11:12:51 PDT 2023
Author: Jan Svoboda
Date: 2023-03-20T11:12:00-07:00
New Revision: d1e00b6f136ec71a4c95a7eb4fd81ec0ab547962
URL: https://github.com/llvm/llvm-project/commit/d1e00b6f136ec71a4c95a7eb4fd81ec0ab547962
DIFF: https://github.com/llvm/llvm-project/commit/d1e00b6f136ec71a4c95a7eb4fd81ec0ab547962.diff
LOG: [clang][deps] Only cache files with specific extension
In the scanner's VFS, we cache all files by default and only avoid caching stat failures for certain files. This tanks the performance of scanning with pre-populated module cache. When there is a stale PCM file, it gets cached by the scanner at the start and the rebuilt version never makes it through the VFS again. The TU invocation that rebuilds the PCM only sees the copy in its InMemoryModuleCache, which is invisible to other invocations. This means the PCM gets rebuilt for every TU given to the scanner.
This patch fixes the situation by flipping the default, only caching files that are known to be important, and letting everything else fall through to the underlying VFS.
rdar://106376153
Reviewed By: Bigcheese
Differential Revision: https://reviews.llvm.org/D146328
Added:
Modified:
clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
clang/unittests/Tooling/DependencyScannerTest.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
index 4b4e3c7eb2ecd..357a5b9423005 100644
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
@@ -269,6 +269,32 @@ 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
@@ -293,24 +319,25 @@ 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,
- bool DisableDirectivesScanning = false);
+ llvm::ErrorOr<EntryRef> getOrCreateFileSystemEntry(StringRef Filename) {
+ return getOrCreateFileSystemEntry(Filename, getPolicy(Filename));
+ }
private:
- /// Check whether the file should be scanned for preprocessor directives.
- bool shouldScanForDirectives(StringRef Filename);
+ /// Same as the public version, but with explicit PathPolicy parameter.
+ llvm::ErrorOr<EntryRef> getOrCreateFileSystemEntry(StringRef Filename,
+ PathPolicy Policy);
/// 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);
+ computeAndStoreResult(StringRef Filename, PathPolicy Policy);
/// 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, bool Disable);
+ StringRef Filename, PathPolicy Policy);
/// Represents a filesystem entry that has been stat-ed (and potentially read)
/// and that's about to be inserted into the cache as `CachedFileSystemEntry`.
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
index 0ddb5c24c5e6c..eb15fc532995c 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -42,9 +42,8 @@ DependencyScanningWorkerFilesystem::readFile(StringRef Filename) {
}
EntryRef DependencyScanningWorkerFilesystem::scanForDirectivesIfNecessary(
- const CachedFileSystemEntry &Entry, StringRef Filename, bool Disable) {
- if (Entry.isError() || Entry.isDirectory() || Disable ||
- !shouldScanForDirectives(Filename))
+ const CachedFileSystemEntry &Entry, StringRef Filename, PathPolicy Policy) {
+ if (Entry.isError() || Entry.isDirectory() || !Policy.ScanFile)
return EntryRef(Filename, Entry);
CachedFileContents *Contents = Entry.getCachedContents();
@@ -159,39 +158,22 @@ DependencyScanningFilesystemSharedCache::CacheShard::
return *EntriesByFilename.insert({Filename, &Entry}).first->getValue();
}
-/// 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) {
+PathPolicy clang::tooling::dependencies::getPolicy(StringRef Filename) {
StringRef Ext = llvm::sys::path::extension(Filename);
if (Ext.empty())
- 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);
+ 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
}
const CachedFileSystemEntry &
@@ -215,10 +197,11 @@ DependencyScanningWorkerFilesystem::findEntryByFilenameWithWriteThrough(
}
llvm::ErrorOr<const CachedFileSystemEntry &>
-DependencyScanningWorkerFilesystem::computeAndStoreResult(StringRef Filename) {
+DependencyScanningWorkerFilesystem::computeAndStoreResult(StringRef Filename,
+ PathPolicy Policy) {
llvm::ErrorOr<llvm::vfs::Status> Stat = getUnderlyingFS().status(Filename);
if (!Stat) {
- if (!shouldCacheStatFailures(Filename))
+ if (!Policy.CacheStatFailure)
return Stat.getError();
const auto &Entry =
getOrEmplaceSharedEntryForFilename(Filename, Stat.getError());
@@ -244,16 +227,13 @@ DependencyScanningWorkerFilesystem::computeAndStoreResult(StringRef Filename) {
llvm::ErrorOr<EntryRef>
DependencyScanningWorkerFilesystem::getOrCreateFileSystemEntry(
- StringRef Filename, bool DisableDirectivesScanning) {
+ StringRef Filename, PathPolicy Policy) {
if (const auto *Entry = findEntryByFilenameWithWriteThrough(Filename))
- return scanForDirectivesIfNecessary(*Entry, Filename,
- DisableDirectivesScanning)
- .unwrapError();
- auto MaybeEntry = computeAndStoreResult(Filename);
+ return scanForDirectivesIfNecessary(*Entry, Filename, Policy).unwrapError();
+ auto MaybeEntry = computeAndStoreResult(Filename, Policy);
if (!MaybeEntry)
return MaybeEntry.getError();
- return scanForDirectivesIfNecessary(*MaybeEntry, Filename,
- DisableDirectivesScanning)
+ return scanForDirectivesIfNecessary(*MaybeEntry, Filename, Policy)
.unwrapError();
}
@@ -261,8 +241,11 @@ 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);
+ llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename, Policy);
if (!Result)
return Result.getError();
return Result->getStatus();
@@ -318,8 +301,11 @@ 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);
+ llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename, Policy);
if (!Result)
return Result.getError();
return DepScanFile::create(Result.get());
diff --git a/clang/unittests/Tooling/DependencyScannerTest.cpp b/clang/unittests/Tooling/DependencyScannerTest.cpp
index abcc2c787b0d0..a7bd1ddbbdb5c 100644
--- a/clang/unittests/Tooling/DependencyScannerTest.cpp
+++ b/clang/unittests/Tooling/DependencyScannerTest.cpp
@@ -239,3 +239,130 @@ 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
diff erent 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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