Increase the macro id cache to look up several recent entries, not just the last...

This is important in insane cases like the one dannyb sent me recently:

#define F0(a) void a(){}
#define F1(a) F0(a##0) F0(a##1) F0(a##2) F0(a##3) F0(a##4) F0(a##5) F0(a##6) F0(a##7)
#define F2(a) F1(a##0) F1(a##1) F1(a##2) F1(a##3) F1(a##4) F1(a##5) F1(a##6) F1(a##7)
#define F3(a) F2(a##0) F2(a##1) F2(a##2) F2(a##3) F2(a##4) F2(a##5) F2(a##6) F2(a##7)
#define F4(a) F3(a##0) F3(a##1) F3(a##2) F3(a##3) F3(a##4) F3(a##5) F3(a##6) F3(a##7)
#define F5(a) F4(a##0) F4(a##1) F4(a##2) F4(a##3) F4(a##4) F4(a##5) F4(a##6) F4(a##7)
#define F6(a) F5(a##0) F5(a##1) F5(a##2) F5(a##3) F5(a##4) F5(a##5) F5(a##6) F5(a##7)
F6(f)

cpp is great.  :)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@40715 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/Basic/SourceManager.cpp b/Basic/SourceManager.cpp
index df13fad37c3162ddfd4f605054f6737d3d9ddfa2..05d58cf79e64a26833c82d7ab5ef052bc76f5273 100644 (file)
--- a/Basic/SourceManager.cpp
+++ b/Basic/SourceManager.cpp
@@ -178,18 +178,21 @@ SourceLocation SourceManager::getInstantiationLoc(SourceLocation PhysLoc,
   
   
   // If the last macro id is close to the currently requested location, try to
-  // reuse it.  This implements a single-entry cache.
-  if (!MacroIDs.empty()) {
-    MacroIDInfo &LastOne = MacroIDs.back();
+  // reuse it.  This implements a small cache.
+  for (int i = MacroIDs.size()-1, e = MacroIDs.size()-6; i >= 0 && i != e; --i){
+    MacroIDInfo &LastOne = MacroIDs[i];
     
-    if (LastOne.getInstantiationLoc() == InstantLoc &&
-        LastOne.getPhysicalLoc().getFileID() == PhysLoc.getFileID()) {
-      
-      int PhysDelta = PhysLoc.getRawFilePos() -
-                      LastOne.getPhysicalLoc().getRawFilePos();
-      if (SourceLocation::isValidMacroPhysOffs(PhysDelta))
-        return SourceLocation::getMacroLoc(MacroIDs.size()-1, PhysDelta, 0);
-    }
+    // The instanitation point and source physloc have to exactly match to reuse
+    // (for now).  We could allow "nearby" instantiations in the future.
+    if (LastOne.getInstantiationLoc() != InstantLoc ||
+        LastOne.getPhysicalLoc().getFileID() != PhysLoc.getFileID())
+      continue;
+  
+    // Check to see if the physloc of the token came from near enough to reuse.
+    int PhysDelta = PhysLoc.getRawFilePos() -
+                    LastOne.getPhysicalLoc().getRawFilePos();
+    if (SourceLocation::isValidMacroPhysOffs(PhysDelta))
+      return SourceLocation::getMacroLoc(MacroIDs.size()-1, PhysDelta, 0);
   }