[TableGen] Use emplace_back instead of resize to size() + 1. NFC.

Author: jayfoad

llvm/utils/TableGen/CodeGenRegisters.cpp

@@ -1986,15 +1986,15 @@ void CodeGenRegBank::computeRegUnitSets() {
       continue;
 
     // Speculatively grow the RegUnitSets to hold the new set.
-    RegUnitSets.resize(RegUnitSets.size() + 1);
-    RegUnitSets.back().Name = RC.getName();
+    RegUnitSet &RUSet = RegUnitSets.emplace_back();
+    RUSet.Name = RC.getName();
 
     // Compute a sorted list of units in this class.
-    RC.buildRegUnitSet(*this, RegUnitSets.back().Units);
+    RC.buildRegUnitSet(*this, RUSet.Units);
 
     // Find an existing RegUnitSet.
     std::vector<RegUnitSet>::const_iterator SetI =
-        findRegUnitSet(RegUnitSets, RegUnitSets.back());
+        findRegUnitSet(RegUnitSets, RUSet);
     if (SetI != std::prev(RegUnitSets.end()))
       RegUnitSets.pop_back();
   }
@@ -2043,27 +2043,26 @@ void CodeGenRegBank::computeRegUnitSets() {
         continue;
 
       // Speculatively grow the RegUnitSets to hold the new set.
-      RegUnitSets.resize(RegUnitSets.size() + 1);
-      RegUnitSets.back().Name =
+      RegUnitSet &RUSet = RegUnitSets.emplace_back();
+      RUSet.Name =
           RegUnitSets[Idx].Name + "_with_" + RegUnitSets[SearchIdx].Name;
 
       std::set_union(RegUnitSets[Idx].Units.begin(),
                      RegUnitSets[Idx].Units.end(),
                      RegUnitSets[SearchIdx].Units.begin(),
                      RegUnitSets[SearchIdx].Units.end(),
-                     std::inserter(RegUnitSets.back().Units,
-                                   RegUnitSets.back().Units.begin()));
+                     std::inserter(RUSet.Units, RUSet.Units.begin()));
 
       // Find an existing RegUnitSet, or add the union to the unique sets.
       std::vector<RegUnitSet>::const_iterator SetI =
-          findRegUnitSet(RegUnitSets, RegUnitSets.back());
+          findRegUnitSet(RegUnitSets, RUSet);
       if (SetI != std::prev(RegUnitSets.end()))
         RegUnitSets.pop_back();
       else {
         LLVM_DEBUG(dbgs() << "UnitSet " << RegUnitSets.size() - 1 << " "
-                          << RegUnitSets.back().Name << ":";
+                          << RUSet.Name << ":";
                    for (auto &U
-                        : RegUnitSets.back().Units) printRegUnitName(U);
+                        : RUSet.Units) printRegUnitName(U);
                    dbgs() << "\n";);
       }
     }
@@ -2138,8 +2137,7 @@ void CodeGenRegBank::computeRegUnitSets() {
     RegUnits[UnitIdx].RegClassUnitSetsIdx = RCUnitSetsIdx;
     if (RCUnitSetsIdx == RegClassUnitSets.size()) {
       // Create a new list of UnitSets as a "fake" register class.
-      RegClassUnitSets.resize(RCUnitSetsIdx + 1);
-      RegClassUnitSets[RCUnitSetsIdx] = std::move(RUSets);
+      RegClassUnitSets.push_back(std::move(RUSets));
     }
   }
 }

llvm/utils/TableGen/CodeGenRegisters.h

@@ -712,8 +712,7 @@ class CodeGenRegBank {
   // Create a native register unit that is associated with one or two root
   // registers.
   unsigned newRegUnit(CodeGenRegister *R0, CodeGenRegister *R1 = nullptr) {
-    RegUnits.resize(RegUnits.size() + 1);
-    RegUnit &RU = RegUnits.back();
+    RegUnit &RU = RegUnits.emplace_back();
     RU.Roots[0] = R0;
     RU.Roots[1] = R1;
     RU.Artificial = R0->Artificial;
@@ -725,8 +724,8 @@ class CodeGenRegBank {
   // Create a new non-native register unit that can be adopted by a register
   // to increase its pressure. Note that NumNativeRegUnits is not increased.
   unsigned newRegUnit(unsigned Weight) {
-    RegUnits.resize(RegUnits.size() + 1);
-    RegUnits.back().Weight = Weight;
+    RegUnit &RU = RegUnits.emplace_back();
+    RU.Weight = Weight;
     return RegUnits.size() - 1;
   }
 

llvm/utils/TableGen/SubtargetEmitter.cpp

@@ -486,11 +486,10 @@ void SubtargetEmitter::EmitStageAndOperandCycleData(
   std::map<std::string, unsigned> ItinStageMap, ItinOperandMap;
   for (const CodeGenProcModel &ProcModel : SchedModels.procModels()) {
     // Add process itinerary to the list.
-    ProcItinLists.resize(ProcItinLists.size() + 1);
+    std::vector<InstrItinerary> &ItinList = ProcItinLists.emplace_back();
 
     // If this processor defines no itineraries, then leave the itinerary list
     // empty.
-    std::vector<InstrItinerary> &ItinList = ProcItinLists.back();
     if (!ProcModel.hasItineraries())
       continue;
 
@@ -1029,17 +1028,16 @@ void SubtargetEmitter::ExpandProcResources(
 // tables. Must be called for each processor in order.
 void SubtargetEmitter::GenSchedClassTables(const CodeGenProcModel &ProcModel,
                                            SchedClassTables &SchedTables) {
-  SchedTables.ProcSchedClasses.resize(SchedTables.ProcSchedClasses.size() + 1);
+  std::vector<MCSchedClassDesc> &SCTab =
+      SchedTables.ProcSchedClasses.emplace_back();
   if (!ProcModel.hasInstrSchedModel())
     return;
 
-  std::vector<MCSchedClassDesc> &SCTab = SchedTables.ProcSchedClasses.back();
   LLVM_DEBUG(dbgs() << "\n+++ SCHED CLASSES (GenSchedClassTables) +++\n");
   for (const CodeGenSchedClass &SC : SchedModels.schedClasses()) {
     LLVM_DEBUG(SC.dump(&SchedModels));
 
-    SCTab.resize(SCTab.size() + 1);
-    MCSchedClassDesc &SCDesc = SCTab.back();
+    MCSchedClassDesc &SCDesc = SCTab.emplace_back();
     // SCDesc.Name is guarded by NDEBUG
     SCDesc.NumMicroOps = 0;
     SCDesc.BeginGroup = false;