Simplify lifetime management of MacroInfo objects in Preprocessor by having the Preprocessor maintain them in a linked

list of allocated MacroInfos.  This requires only 1 extra pointer per MacroInfo object, and allows us to blow them
away in one place.  This fixes an elusive memory leak with MacroInfos (whose exact location I couldn't still figure
out despite substantial digging).

Fixes <rdar://problem/8361834>.

llvm-svn: 116842

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 5e3b16e60de..ffdc6ae5894 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -33,8 +33,12 @@ MacroInfo *Preprocessor::AllocateMacroInfo() {
   if (!MICache.empty()) {
     MI = MICache.back();
     MICache.pop_back();
-  } else
-    MI = (MacroInfo*) BP.Allocate<MacroInfo>();
+  } else {
+    MacroInfoChain *MIChain = BP.Allocate<MacroInfoChain>();
+    MIChain->Next = MIChainHead;
+    MIChainHead = MIChain;
+    MI = &(MIChainHead->MI);
+  }
   return MI;
 }