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reclaim my precious bit in FileInfo by ensuring that ContentCache objects 

are 8-byte aligned.

llvm-svn: 63630
This commit is contained in:
Chris Lattner 2009-02-03 07:41:46 +00:00
parent ed8903e45a
commit 9be4f6d6c7
2 changed files with 14 additions and 9 deletions
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4
clang/include/clang/Basic/SourceManager.h
View File

@ -144,7 +144,7 @@ namespace SrcMgr {
FileInfo X; FileInfo X;
X.IncludeLoc = IL.getRawEncoding(); X.IncludeLoc = IL.getRawEncoding();
X.Data = (uintptr_t)Con; X.Data = (uintptr_t)Con;
assert((X.Data & 3) == 0 &&"ContentCache pointer insufficiently aligned"); assert((X.Data & 7) == 0 &&"ContentCache pointer insufficiently aligned");
assert((unsigned)FileCharacter < 4 && "invalid file character"); assert((unsigned)FileCharacter < 4 && "invalid file character");
X.Data |= (unsigned)FileCharacter; X.Data |= (unsigned)FileCharacter;
return X; return X;
@ -154,7 +154,7 @@ namespace SrcMgr {
return SourceLocation::getFromRawEncoding(IncludeLoc); return SourceLocation::getFromRawEncoding(IncludeLoc);
} }
const ContentCache* getContentCache() const { const ContentCache* getContentCache() const {
return reinterpret_cast<const ContentCache*>(Data & ~3UL); return reinterpret_cast<const ContentCache*>(Data & ~7UL);
} }
/// getCharacteristic - Return whether this is a system header or not. /// getCharacteristic - Return whether this is a system header or not.

19
clang/lib/Basic/SourceManager.cpp
View File

@ -160,8 +160,12 @@ SourceManager::getOrCreateContentCache(const FileEntry *FileEnt) {
ContentCache *&Entry = FileInfos[FileEnt]; ContentCache *&Entry = FileInfos[FileEnt];
if (Entry) return Entry; if (Entry) return Entry;
// Nope, create a new Cache entry. // Nope, create a new Cache entry. Make sure it is at least 8-byte aligned
Entry = ContentCacheAlloc.Allocate<ContentCache>(); // so that FileInfo can use the low 3 bits of the pointer for its own
// nefarious purposes.
unsigned EntryAlign = llvm::AlignOf<ContentCache>::Alignment;
EntryAlign = std::max(8U, EntryAlign);
Entry = ContentCacheAlloc.Allocate<ContentCache>(1, EntryAlign);
new (Entry) ContentCache(FileEnt); new (Entry) ContentCache(FileEnt);
return Entry; return Entry;
} }
@ -171,11 +175,12 @@ SourceManager::getOrCreateContentCache(const FileEntry *FileEnt) {
/// memory buffer. This does no caching. /// memory buffer. This does no caching.
const ContentCache* const ContentCache*
SourceManager::createMemBufferContentCache(const MemoryBuffer *Buffer) { SourceManager::createMemBufferContentCache(const MemoryBuffer *Buffer) {
// Add a new ContentCache to the MemBufferInfos list and return it. We // Add a new ContentCache to the MemBufferInfos list and return it. Make sure
// must default construct the object first that the instance actually // it is at least 8-byte aligned so that FileInfo can use the low 3 bits of
// stored within MemBufferInfos actually owns the Buffer, and not any // the pointer for its own nefarious purposes.
// temporary we would use in the call to "push_back". unsigned EntryAlign = llvm::AlignOf<ContentCache>::Alignment;
ContentCache *Entry = ContentCacheAlloc.Allocate<ContentCache>(); EntryAlign = std::max(8U, EntryAlign);
ContentCache *Entry = ContentCacheAlloc.Allocate<ContentCache>(1, EntryAlign);
new (Entry) ContentCache(); new (Entry) ContentCache();
MemBufferInfos.push_back(Entry); MemBufferInfos.push_back(Entry);
Entry->setBuffer(Buffer); Entry->setBuffer(Buffer);