Incorporate review comments from r221742

This change implements the comment and style changes Sean requested during post commit review with r221742.  Sorry for the delay.

llvm-svn: 222707

1 files changed, 11 insertions, 2 deletions

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 7ed9099..fbf94b3 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -456,7 +456,15 @@ unsigned Function::lookupIntrinsicID() const {
 }
 
 /// Returns a stable mangling for the type specified for use in the name
-/// mangling scheme used by 'any' types in intrinsic signatures.
+/// mangling scheme used by 'any' types in intrinsic signatures.  The mangling
+/// of named types is simply their name.  Manglings for unnamed types consist
+/// of a prefix ('p' for pointers, 'a' for arrays, 'f_' for functions)
+/// combined with the mangling of their component types.  A vararg function
+/// type will have a suffix of 'vararg'.  Since function types can contain
+/// other function types, we close a function type mangling with suffix 'f'
+/// which can't be confused with it's prefix.  This ensures we don't have
+/// collisions between two unrelated function types. Otherwise, you might
+/// parse ffXX as f(fXX) or f(fX)X.  (X is a placeholder for any other type.)
 static std::string getMangledTypeStr(Type* Ty) {
   std::string Result;
   if (PointerType* PTyp = dyn_cast<PointerType>(Ty)) {
@@ -476,7 +484,8 @@ static std::string getMangledTypeStr(Type* Ty) {
       Result += getMangledTypeStr(FT->getParamType(i));
     if (FT->isVarArg())
       Result += "vararg";
-    Result += "f"; //ensure distinguishable
+    // Ensure nested function types are distinguishable.
+    Result += "f"; 
   } else if (Ty)
     Result += EVT::getEVT(Ty).getEVTString();
   return Result;