Load most of the source manager's information lazily from the PCH

file. In particular, only eagerly load source location entries for
files and for the predefines buffer. Other buffers and
macro-instantiation source location entries are loaded lazily.

With the Cocoa-prefixed "Hello, World", we only load 815/26555 source
location entities. This halves the amount of user time we spend in
this "Hello, World" program with -fsyntax-only (down to .007s).

This optimization is part 1 of 2 for the source manager. This
eliminates most of the user time in loading a PCH file. We still spend
too much time initialize File structures (especially in the calls to
stat), so we need to either make the loading of source location
entries for files lazy or import the stat cache from the PTH
implementation.

llvm-svn: 70196

1 files changed, 52 insertions, 4 deletions

diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 9ed21635259..50576636db3 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -308,6 +308,17 @@ SourceManager::createMemBufferContentCache(const MemoryBuffer *Buffer) {
   return Entry;
 }
 
+void SourceManager::PreallocateSLocEntries(ExternalSLocEntrySource *Source,
+                                           unsigned NumSLocEntries,
+                                           unsigned NextOffset) {
+  ExternalSLocEntries = Source;
+  this->NextOffset = NextOffset;
+  SLocEntryLoaded.resize(NumSLocEntries + 1);
+  SLocEntryLoaded[0] = true;
+  SLocEntryTable.resize(SLocEntryTable.size() + NumSLocEntries);
+}
+
+
 //===----------------------------------------------------------------------===//
 // Methods to create new FileID's and instantiations.
 //===----------------------------------------------------------------------===//
@@ -317,7 +328,26 @@ SourceManager::createMemBufferContentCache(const MemoryBuffer *Buffer) {
 /// corresponds to a file or some other input source.
 FileID SourceManager::createFileID(const ContentCache *File,
                                    SourceLocation IncludePos,
-                                   SrcMgr::CharacteristicKind FileCharacter) {
+                                   SrcMgr::CharacteristicKind FileCharacter,
+                                   unsigned PreallocatedID,
+                                   unsigned Offset) {
+  SLocEntry NewEntry = SLocEntry::get(NextOffset, 
+                                      FileInfo::get(IncludePos, File,
+                                                    FileCharacter));
+  if (PreallocatedID) {
+    // If we're filling in a preallocated ID, just load in the file
+    // entry and return.
+    assert(PreallocatedID < SLocEntryLoaded.size() && 
+           "Preallocate ID out-of-range");
+    assert(!SLocEntryLoaded[PreallocatedID] && 
+           "Source location entry already loaded");
+    assert(Offset && "Preallocate source location cannot have zero offset");
+    SLocEntryTable[PreallocatedID] 
+      = SLocEntry::get(Offset, FileInfo::get(IncludePos, File, FileCharacter));
+    SLocEntryLoaded[PreallocatedID] = true;
+    return LastFileIDLookup = FileID::get(PreallocatedID);
+  }
+
   SLocEntryTable.push_back(SLocEntry::get(NextOffset, 
                                           FileInfo::get(IncludePos, File,
                                                         FileCharacter)));
@@ -336,8 +366,22 @@ FileID SourceManager::createFileID(const ContentCache *File,
 SourceLocation SourceManager::createInstantiationLoc(SourceLocation SpellingLoc,
                                                      SourceLocation ILocStart,
                                                      SourceLocation ILocEnd,
-                                                     unsigned TokLength) {
+                                                     unsigned TokLength,
+                                                     unsigned PreallocatedID,
+                                                     unsigned Offset) {
   InstantiationInfo II = InstantiationInfo::get(ILocStart,ILocEnd, SpellingLoc);
+  if (PreallocatedID) {
+    // If we're filling in a preallocated ID, just load in the
+    // instantiation entry and return.
+    assert(PreallocatedID < SLocEntryLoaded.size() && 
+           "Preallocate ID out-of-range");
+    assert(!SLocEntryLoaded[PreallocatedID] && 
+           "Source location entry already loaded");
+    assert(Offset && "Preallocate source location cannot have zero offset");
+    SLocEntryTable[PreallocatedID] = SLocEntry::get(Offset, II);
+    SLocEntryLoaded[PreallocatedID] = true;
+    return SourceLocation::getMacroLoc(Offset);
+  }
   SLocEntryTable.push_back(SLocEntry::get(NextOffset, II));
   assert(NextOffset+TokLength+1 > NextOffset && "Ran out of source locations!");
   NextOffset += TokLength+1;
@@ -391,6 +435,8 @@ FileID SourceManager::getFileIDSlow(unsigned SLocOffset) const {
   unsigned NumProbes = 0;
   while (1) {
     --I;
+    if (ExternalSLocEntries)
+      getSLocEntry(FileID::get(I - SLocEntryTable.begin()));
     if (I->getOffset() <= SLocOffset) {
 #if 0
       printf("lin %d -> %d [%s] %d %d\n", SLocOffset,
@@ -399,7 +445,7 @@ FileID SourceManager::getFileIDSlow(unsigned SLocOffset) const {
              LastFileIDLookup.ID,  int(SLocEntryTable.end()-I));
 #endif
       FileID Res = FileID::get(I-SLocEntryTable.begin());
-      
+
       // If this isn't an instantiation, remember it.  We have good locality
       // across FileID lookups.
       if (!I->isInstantiation())
@@ -421,7 +467,7 @@ FileID SourceManager::getFileIDSlow(unsigned SLocOffset) const {
   NumProbes = 0;
   while (1) {
     unsigned MiddleIndex = (GreaterIndex-LessIndex)/2+LessIndex;
-    unsigned MidOffset = SLocEntryTable[MiddleIndex].getOffset();
+    unsigned MidOffset = getSLocEntry(FileID::get(MiddleIndex)).getOffset();
     
     ++NumProbes;
     
@@ -865,3 +911,5 @@ void SourceManager::PrintStats() const {
   llvm::cerr << "FileID scans: " << NumLinearScans << " linear, "
              << NumBinaryProbes << " binary.\n";
 }
+
+ExternalSLocEntrySource::~ExternalSLocEntrySource() { }