[TableGen][SubtargetEmitter] Refactor hasReadOfWrite to CodeGenProcModel (#92032)

SubtargetEmitter::GenSchedClassTables takes a CodeGenProcModel, but
calls hasReadOfWrite which loops over all ProcModels. We move
hasReadOfWrite to CodeGenProcModel and remove the loop over all
ProcModels. This leads to a 144% speedup on the RISC-V backend of our
downstream.

Author: michaelmaitland

llvm/utils/TableGen/Common/CodeGenSchedule.cpp

@@ -746,18 +746,6 @@ unsigned CodeGenSchedModels::getSchedRWIdx(const Record *Def,
   return I == RWVec.end() ? 0 : std::distance(RWVec.begin(), I);
 }
 
-bool CodeGenSchedModels::hasReadOfWrite(Record *WriteDef) const {
-  for (auto &ProcModel : ProcModels) {
-    const RecVec &RADefs = ProcModel.ReadAdvanceDefs;
-    for (auto &RADef : RADefs) {
-      RecVec ValidWrites = RADef->getValueAsListOfDefs("ValidWrites");
-      if (is_contained(ValidWrites, WriteDef))
-        return true;
-    }
-  }
-  return false;
-}
-
 static void splitSchedReadWrites(const RecVec &RWDefs, RecVec &WriteDefs,
                                  RecVec &ReadDefs) {
   for (Record *RWDef : RWDefs) {
@@ -2226,6 +2214,15 @@ bool CodeGenProcModel::isUnsupported(const CodeGenInstruction &Inst) const {
   return false;
 }
 
+bool CodeGenProcModel::hasReadOfWrite(Record *WriteDef) const {
+  for (auto &RADef : ReadAdvanceDefs) {
+    RecVec ValidWrites = RADef->getValueAsListOfDefs("ValidWrites");
+    if (is_contained(ValidWrites, WriteDef))
+      return true;
+  }
+  return false;
+}
+
 #ifndef NDEBUG
 void CodeGenProcModel::dump() const {
   dbgs() << Index << ": " << ModelName << " "

llvm/utils/TableGen/Common/CodeGenSchedule.h

@@ -277,6 +277,9 @@ struct CodeGenProcModel {
 
   bool isUnsupported(const CodeGenInstruction &Inst) const;
 
+  // Return true if the given write record is referenced by a ReadAdvance.
+  bool hasReadOfWrite(Record *WriteDef) const;
+
 #ifndef NDEBUG
   void dump() const;
 #endif
@@ -536,9 +539,6 @@ class CodeGenSchedModels {
 
   unsigned getSchedRWIdx(const Record *Def, bool IsRead) const;
 
-  // Return true if the given write record is referenced by a ReadAdvance.
-  bool hasReadOfWrite(Record *WriteDef) const;
-
   // Get a SchedClass from its index.
   CodeGenSchedClass &getSchedClass(unsigned Idx) {
     assert(Idx < SchedClasses.size() && "bad SchedClass index");

llvm/utils/TableGen/SubtargetEmitter.cpp

@@ -1122,10 +1122,8 @@ void SubtargetEmitter::GenSchedClassTables(const CodeGenProcModel &ProcModel,
       WriterNames.push_back(SchedModels.getSchedWrite(WriteID).Name);
       // If this Write is not referenced by a ReadAdvance, don't distinguish it
       // from other WriteLatency entries.
-      if (!SchedModels.hasReadOfWrite(
-              SchedModels.getSchedWrite(WriteID).TheDef)) {
+      if (!ProcModel.hasReadOfWrite(SchedModels.getSchedWrite(WriteID).TheDef))
         WriteID = 0;
-      }
       WLEntry.WriteResourceID = WriteID;
 
       for (unsigned WS : WriteSeq) {