TableGen/AsmMatcherEmitter: Trust that stable_sort works

A debug build of AsmMatcherEmitter would use a quadratic algorithm to
check whether std::stable_sort() actually sorted. Let's hope the authors
of our C++ standard library did that testing for us. Removing the check
gives a 3x speedup in the X86 case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288655 91177308-0d34-0410-b5e6-96231b3b80d8

Author: MatzeB

utils/TableGen/AsmMatcherEmitter.cpp

@@ -2719,16 +2719,6 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
                       const std::unique_ptr<MatchableInfo> &b){
                      return *a < *b;});
 
-#ifndef NDEBUG
-  // Verify that the table is now sorted
-  for (auto I = Info.Matchables.begin(), E = Info.Matchables.end(); I != E;
-       ++I) {
-    for (auto J = I; J != E; ++J) {
-      assert(!(**J < **I));
-    }
-  }
-#endif // NDEBUG
-
   DEBUG_WITH_TYPE("instruction_info", {
       for (const auto &MI : Info.Matchables)
         MI->dump();