Fix leak in lib/CodeGen/CGException.cpp, PR18318

[kcc]

Summary

This fixes the leak described in http://llvm.org/bugs/show_bug.cgi?id=18318

[chandlerc]

lib/CodeGen/CGException.cpp

1247–1248

This should really be a method on the EHCatchScope object. I would call it 'clearHandlerBlocks()'.

I would also add a FIXME comment to that function which suggests switching EHCatchScope to *always* clear the blocks on destruction, and to add a 'takeHandler' or some such function which removes ownership from the EHCatchScope. Not asking that you make this change because of the innards of EHCatchScope I expect this change would be somewhat invasive and awkward to do.

[kcc]

PTAL
Introduced EHCatchScope::clearHandlerBlocks

[kcc]

ping

[chandlerc]

LGTM

lib/CodeGen/CGCleanup.h

void setHandler(unsigned I, llvm::Value *Type, llvm::BasicBlock *Block) {
     getHandlers()[I].Block = Block;
   }
 
   const Handler &getHandler(unsigned I) const {
     assert(I < getNumHandlers());
     return getHandlers()[I];
   }
 
+  // Clear all handler blocks.
+  // FIXME: it's better to always call clearHandlerBlocks in DTOR and have a
+  // 'takeHandler' or some such function which removes ownership from the
+  // EHCatchScope object if the handlers should live longer than EHCatchScope.
+  void clearHandlerBlocks() {
+    for (unsigned I = 0, N = getNumHandlers(); I != N; ++I)
+      delete getHandler(I).Block;
+  }
+
   typedef const Handler *iterator;
   iterator begin() const { return getHandlers(); }
   iterator end() const { return getHandlers() + getNumHandlers(); }
 
   static bool classof(const EHScope *Scope) {
     return Scope->getKind() == Catch;
   }
 };

lib/CodeGen/CGException.cpp

 
 void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
   unsigned NumHandlers = S.getNumHandlers();
   EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
   assert(CatchScope.getNumHandlers() == NumHandlers);
 
   // If the catch was not required, bail out now.
   if (!CatchScope.hasEHBranches()) {
+    CatchScope.clearHandlerBlocks();
     EHStack.popCatch();
     return;
   }
 
   // Emit the structure of the EH dispatch for this catch.
   emitCatchDispatchBlock(*this, CatchScope);
 
   // Copy the handler blocks off before we pop the EH stack.  Emitting
   // the handlers might scribble on this memory.