MIR Serialization: Report an error when machine functions have the same name.

[arphaman]

Summary

This patch is based on the patch that connects MIRParser to the machine function analysis pass (http://reviews.llvm.org/D9928).

This patch reports an error when the mir parser encounters a machine function with the name that is the same as the name of a different machine function.

[arphaman]

I just saw that I can remove the check for the empty function's name - it should go into another patch.

The updated patch doesn't check if the function's name is empty.

llvm/trunk/lib/CodeGen/MIRParser/MIRParser.cpp

 }
 
 bool MIRParserImpl::parseMachineFunction(yaml::Input &In) {
   auto MF = llvm::make_unique<yaml::MachineFunction>();
   yaml::yamlize(In, *MF, false);
   if (In.error())
     return true;
   auto FunctionName = MF->Name;
+  if (Functions.find(FunctionName) != Functions.end())
+    return error(Twine("redefinition of machine function '") + FunctionName +
+                 "'");
   Functions.insert(std::make_pair(FunctionName, std::move(MF)));
   return false;
 }
 
 bool MIRParserImpl::initializeMachineFunction(MachineFunction &MF) {
   auto It = Functions.find(MF.getName());
   if (It == Functions.end())
     return error(Twine("no machine function information for function '") +

llvm/trunk/test/CodeGen/MIR/machine-function-redefinition-error.mir

+# RUN: not llc -start-after branch-folder -stop-after branch-folder -o /dev/null %s 2>&1 | FileCheck %s
+# This test ensures that the machine function errors are reported correctly.
+
+---
+name:            foo
+...
+---
+# CHECK: redefinition of machine function 'foo'
+name:            foo
+...