Add StringRef::compare_numeric and use it to sort TableGen register records.

This means that our Registers are now ordered R7, R8, R9, R10, R12, ...
Not R1, R10, R11, R12, R2, R3, ...

llvm-svn: 104745
diff --git a/llvm/utils/TableGen/CodeGenTarget.cpp b/llvm/utils/TableGen/CodeGenTarget.cpp
index 5d45489..3797992 100644
--- a/llvm/utils/TableGen/CodeGenTarget.cpp
+++ b/llvm/utils/TableGen/CodeGenTarget.cpp
@@ -159,6 +159,7 @@
   std::vector<Record*> Regs = Records.getAllDerivedDefinitions("Register");
   if (Regs.empty())
     throw std::string("No 'Register' subclasses defined!");
+  std::sort(Regs.begin(), Regs.end(), LessRecord());
 
   Registers.reserve(Regs.size());
   Registers.assign(Regs.begin(), Regs.end());
@@ -175,6 +176,7 @@
 
 void CodeGenTarget::ReadSubRegIndices() const {
   SubRegIndices = Records.getAllDerivedDefinitions("SubRegIndex");
+  std::sort(SubRegIndices.begin(), SubRegIndices.end(), LessRecord());
 }
 
 void CodeGenTarget::ReadRegisterClasses() const {