Minor performance tweaks to llvm-tblgen (and a few that might be a good idea)

[rnk]

Summary

This patch adds a reserve call to an expensive function (llvm::LoadIntrinsics), and may fix a few other low hanging performance fruit (I've put them in comments for now, so we can discuss).

Motivation:

As I'm sure other developers do, when I build LLVM, I build the entire project with the same config (Debug, MinSizeRel, Release, or RelWithDebInfo). However, the Debug config also builds llvm-tblgen in Debug mode. Later build steps that run llvm-tblgen then can actually be the slowest steps in the entire build. Nobody likes slow builds.

[ariccio]

(posted elaborative comments)

C:/LLVM/llvm/include/llvm/TableGen/Record.h

1312

This is more of a long term suggestion, as I'm not immediately sure how to modify this to eliminate the copy.

C:/LLVM/llvm/utils/TableGen/CodeGenTarget.cpp

451

rnk added this code ~8 days ago... any reason why you wrote it as a by-value lambda?

[ariccio]

Responded to comments.

[ariccio]

Changes discussed on llvm-commits, changes implemented, comments marked as Done.

[rnk]

lgtm, do you need someone to commit this?

C:/LLVM/llvm/include/llvm/TableGen/Record.h

1312

This should do the trick:

if (SCPair.first->getNameInit()->getValue() == Name)

[ariccio]

In D16832#343220, @rnk wrote:

lgtm, do you need someone to commit this?

Yup, no privs.

Although, if SCPair.first->getNameInit()->getValue() returns the same string, maybe I should update the diff first?

C:/LLVM/llvm/include/llvm/TableGen/Record.h

1312

Does that return the equivalent string vs getAsUnquotedString?

[ariccio]

Bump?

(I kinda wanna get this out of the way, I hope that's not too pushy!)

C:/LLVM/llvm/include/llvm/TableGen/Record.h

1312

Bump?

[rnk]

This landed as r259683, but didn't autoclose because "Differential revision" wasn't the last line in the commit.

[rnk]

marking accepted

[rnk]

closing

C:/LLVM/llvm/include/llvm/TableGen/Record.h

public:
   bool isSubClassOf(const Record *R) const {
     for (const auto &SCPair : SuperClasses)
       if (SCPair.first == R)
         return true;
     return false;
   }
 
   bool isSubClassOf(StringRef Name) const {
-    for (const auto &SCPair : SuperClasses)
+    for (const auto &SCPair : SuperClasses) {
       if (SCPair.first->getNameInitAsString() == Name)
         return true;
+    }
     return false;
   }
 
   void addSuperClass(Record *R, SMRange Range) {
     assert(!isSubClassOf(R) && "Already subclassing record!");
     SuperClasses.push_back(std::make_pair(R, Range));
   }
 

C:/LLVM/llvm/utils/TableGen/CodeGenInstruction.cpp

CGIOperandList::CGIOperandList(Record *R) : TheDef(R) {
   if (DefInit *Init = dyn_cast<DefInit>(InDI->getOperator())) {
     if (Init->getDef()->getName() != "ins")
       PrintFatalError(R->getName() + ": invalid def name for input list: use 'ins'");
   } else
     PrintFatalError(R->getName() + ": invalid input list: use 'ins'");
 
   unsigned MIOperandNo = 0;
   std::set<std::string> OperandNames;
-  for (unsigned i = 0, e = InDI->getNumArgs()+OutDI->getNumArgs(); i != e; ++i){
+  unsigned e = InDI->getNumArgs()+OutDI->getNumArgs();
+  OperandList.reserve(e);
+  for (unsigned i = 0; i != e; ++i){
     Init *ArgInit;
     std::string ArgName;
     if (i < NumDefs) {
       ArgInit = OutDI->getArg(i);
       ArgName = OutDI->getArgName(i);
     } else {
       ArgInit = InDI->getArg(i-NumDefs);
       ArgName = InDI->getArgName(i-NumDefs);

C:/LLVM/llvm/utils/TableGen/CodeGenTarget.cpp

 // CodeGenIntrinsic Implementation
 //===----------------------------------------------------------------------===//
 
 std::vector<CodeGenIntrinsic> llvm::LoadIntrinsics(const RecordKeeper &RC,
                                                    bool TargetOnly) {
   std::vector<Record*> I = RC.getAllDerivedDefinitions("Intrinsic");
 
   std::vector<CodeGenIntrinsic> Result;
+  Result.reserve(I.size());
 
   for (unsigned i = 0, e = I.size(); i != e; ++i) {
     bool isTarget = I[i]->getValueAsBit("isTarget");
     if (isTarget == TargetOnly)
       Result.push_back(CodeGenIntrinsic(I[i]));
   }
   std::sort(Result.begin(), Result.end(),
-            [](CodeGenIntrinsic LHS, CodeGenIntrinsic RHS) {
+            [](const CodeGenIntrinsic& LHS, const CodeGenIntrinsic& RHS) {
               return LHS.Name < RHS.Name;
             });
   return Result;
 }
 
 CodeGenIntrinsic::CodeGenIntrinsic(Record *R) {
   TheDef = R;
   std::string DefName = R->getName();