[cfe-commits] r120066 - in /cfe/trunk: include/clang/Basic/FileManager.h lib/Basic/FileManager.cpp lib/Basic/FileSystemStatCache.cpp
Chris Lattner
sabre at nondot.org
Tue Nov 23 14:32:37 PST 2010
Author: lattner
Date: Tue Nov 23 16:32:37 2010
New Revision: 120066
URL: http://llvm.org/viewvc/llvm-project?rev=120066&view=rev
Log:
The final result of all this refactoring: instead of doing stat immediately
followed by an open for every source file we open, probe the file system with
'open' and then do an fstat when it succeeds. open+fstat is faster than
stat+open because the kernel only has to perform the string->inode mapping
once. Presumably it gets faster the deeper in your filesystem a lookup
happens.
For -Eonly on cocoa.h, this reduces system time from 0.042s to 0.039s on
my machine, a 7.7% speedup.
Modified:
cfe/trunk/include/clang/Basic/FileManager.h
cfe/trunk/lib/Basic/FileManager.cpp
cfe/trunk/lib/Basic/FileSystemStatCache.cpp
Modified: cfe/trunk/include/clang/Basic/FileManager.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/FileManager.h?rev=120066&r1=120065&r2=120066&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/FileManager.h (original)
+++ cfe/trunk/include/clang/Basic/FileManager.h Tue Nov 23 16:32:37 2010
@@ -61,7 +61,7 @@
/// FD - The file descriptor for the file entry if it is opened and owned
/// by the FileEntry. If not, this is set to -1.
- int FD;
+ mutable int FD;
friend class FileManager;
void operator=(const FileEntry&); // DO NOT IMPLEMENT.
Modified: cfe/trunk/lib/Basic/FileManager.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/FileManager.cpp?rev=120066&r1=120065&r2=120066&view=diff
==============================================================================
--- cfe/trunk/lib/Basic/FileManager.cpp (original)
+++ cfe/trunk/lib/Basic/FileManager.cpp Tue Nov 23 16:32:37 2010
@@ -400,11 +400,24 @@
llvm::MemoryBuffer *FileManager::
getBufferForFile(const FileEntry *Entry, std::string *ErrorStr) {
- llvm::StringRef Filename = Entry->getName();
- if (FileSystemOpts.WorkingDir.empty())
+ if (FileSystemOpts.WorkingDir.empty()) {
+ const char *Filename = Entry->getName();
+ // If the file is already open, use the open file descriptor.
+ if (Entry->FD != -1) {
+ llvm::MemoryBuffer *Buf =
+ llvm::MemoryBuffer::getOpenFile(Entry->FD, Filename, ErrorStr,
+ Entry->getSize());
+ // getOpenFile will have closed the file descriptor, don't reuse or
+ // reclose it.
+ Entry->FD = -1;
+ return Buf;
+ }
+
+ // Otherwise, open the file.
return llvm::MemoryBuffer::getFile(Filename, ErrorStr, Entry->getSize());
+ }
- llvm::sys::Path FilePath(Filename);
+ llvm::sys::Path FilePath(Entry->getName());
FixupRelativePath(FilePath, FileSystemOpts);
return llvm::MemoryBuffer::getFile(FilePath.c_str(), ErrorStr,
Entry->getSize());
Modified: cfe/trunk/lib/Basic/FileSystemStatCache.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/FileSystemStatCache.cpp?rev=120066&r1=120065&r2=120066&view=diff
==============================================================================
--- cfe/trunk/lib/Basic/FileSystemStatCache.cpp (original)
+++ cfe/trunk/lib/Basic/FileSystemStatCache.cpp Tue Nov 23 16:32:37 2010
@@ -13,6 +13,7 @@
#include "clang/Basic/FileSystemStatCache.h"
#include "llvm/System/Path.h"
+#include <fcntl.h>
// FIXME: This is terrible, we need this for ::close.
#if !defined(_MSC_VER) && !defined(__MINGW32__)
@@ -39,18 +40,52 @@
bool FileSystemStatCache::get(const char *Path, struct stat &StatBuf,
int *FileDescriptor, FileSystemStatCache *Cache) {
LookupResult R;
-
+ bool isForDir = FileDescriptor == 0;
+
+ // If we have a cache, use it to resolve the stat query.
if (Cache)
R = Cache->getStat(Path, StatBuf, FileDescriptor);
- else
+ else if (isForDir) {
+ // If this is a directory and we have no cache, just go to the file system.
R = ::stat(Path, &StatBuf) != 0 ? CacheMissing : CacheExists;
+ } else {
+ // Otherwise, we have to go to the filesystem. We can always just use
+ // 'stat' here, but (for files) the client is asking whether the file exists
+ // because it wants to turn around and *open* it. It is more efficient to
+ // do "open+fstat" on success than it is to do "stat+open".
+ //
+ // Because of this, check to see if the file exists with 'open'. If the
+ // open succeeds, use fstat to get the stat info.
+ int OpenFlags = O_RDONLY;
+#ifdef O_BINARY
+ OpenFlags |= O_BINARY; // Open input file in binary mode on win32.
+#endif
+ *FileDescriptor = ::open(Path, OpenFlags);
+
+ if (*FileDescriptor == -1) {
+ // If the open fails, our "stat" fails.
+ R = CacheMissing;
+ } else {
+ // Otherwise, the open succeeded. Do an fstat to get the information
+ // about the file. We'll end up returning the open file descriptor to the
+ // client to do what they please with it.
+ if (::fstat(*FileDescriptor, &StatBuf) == 0)
+ R = CacheExists;
+ else {
+ // fstat rarely fails. If it does, claim the initial open didn't
+ // succeed.
+ R = CacheMissing;
+ ::close(*FileDescriptor);
+ *FileDescriptor = -1;
+ }
+ }
+ }
// If the path doesn't exist, return failure.
if (R == CacheMissing) return true;
// If the path exists, make sure that its "directoryness" matches the clients
// demands.
- bool isForDir = FileDescriptor == 0;
if (S_ISDIR(StatBuf.st_mode) != isForDir) {
// If not, close the file if opened.
if (FileDescriptor && *FileDescriptor != -1) {
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