[LLVM][TableGen] Speed up sorting of intrinsics

Speed up sorting of intrinsics by using the TargetPrefix to only
discriminate beteween target dependent vs target independent intrinsics
where target independent ones need to be sorted before target dependent
ones. When comaring two target dependent intrinsics, the Name already
includes llvm.<TargetPrefix> as a suffix, so no need to needlessly
compare it separately.

Author: jurahul

llvm/utils/TableGen/Basic/CodeGenIntrinsics.cpp

@@ -49,11 +49,14 @@ CodeGenIntrinsicTable::CodeGenIntrinsicTable(const RecordKeeper &RC) {
   for (const Record *Def : Defs)
     Intrinsics.push_back(CodeGenIntrinsic(Def, Ctx));
 
-  llvm::sort(Intrinsics,
-             [](const CodeGenIntrinsic &LHS, const CodeGenIntrinsic &RHS) {
-               return std::tie(LHS.TargetPrefix, LHS.Name) <
-                      std::tie(RHS.TargetPrefix, RHS.Name);
-             });
+  llvm::sort(Intrinsics, [](const CodeGenIntrinsic &LHS,
+                            const CodeGenIntrinsic &RHS) {
+    // Order target independent intrinsics before target dependent ones.
+    bool LHSHasTarget = !LHS.TargetPrefix.empty();
+    bool RHSHasTarget = !RHS.TargetPrefix.empty();
+    return std::tie(LHSHasTarget, LHS.Name) < std::tie(RHSHasTarget, RHS.Name);
+  });
+
   Targets.push_back({"", 0, 0});
   for (size_t I = 0, E = Intrinsics.size(); I < E; ++I)
     if (Intrinsics[I].TargetPrefix != Targets.back().Name) {