UBSan now uses prologue data instead of prefix data

[bgamari]

Summary

As the semantics of prefix data has changed. See D6454.

[pcc]

Closed by commit rL223190 (authored by @pcc).

cfe/trunk/lib/CodeGen/CodeGenFunction.cpp

void CodeGenFunction::StartFunction(GlobalDecl GD,
 
   if (getLangOpts().OpenCL) {
     // Add metadata for a kernel function.
     if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
       EmitOpenCLKernelMetadata(FD, Fn);
   }
 
   // If we are checking function types, emit a function type signature as
-  // prefix data.
+  // prologue data.
   if (getLangOpts().CPlusPlus && SanOpts.has(SanitizerKind::Function)) {
     if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
-      if (llvm::Constant *PrefixSig =
+      if (llvm::Constant *PrologueSig =
               CGM.getTargetCodeGenInfo().getUBSanFunctionSignature(CGM)) {
         llvm::Constant *FTRTTIConst =
             CGM.GetAddrOfRTTIDescriptor(FD->getType(), /*ForEH=*/true);
-        llvm::Constant *PrefixStructElems[] = { PrefixSig, FTRTTIConst };
-        llvm::Constant *PrefixStructConst =
-            llvm::ConstantStruct::getAnon(PrefixStructElems, /*Packed=*/true);
-        Fn->setPrefixData(PrefixStructConst);
+        llvm::Constant *PrologueStructElems[] = { PrologueSig, FTRTTIConst };
+        llvm::Constant *PrologueStructConst =
+            llvm::ConstantStruct::getAnon(PrologueStructElems, /*Packed=*/true);
+        Fn->setPrologueData(PrologueStructConst);
       }
     }
   }
 
   llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
 
   // Create a marker to make it easy to insert allocas into the entryblock
   // later.  Don't create this with the builder, because we don't want it