[TargetSchedule] Expose sub-units of a ProcResGroup in MCProcResourceDesc.

[courbet]

Summary

Right now using a ProcResource automatically counts as usage of all
super ProcResGroups. All this is done during codegen, so there is no
way for schedulers to get this information at runtime.

This adds the information of which individual ProcRes units are
contained in a ProcResGroup in MCProcResourceDesc.

[gchatelet]

include/llvm/MC/MCSchedule.h

47

What if the resource has no sub-units?

utils/TableGen/SubtargetEmitter.cpp

591

Do you mind writing the negation:

// skipping non ProcResGroup.
if (!PRDef->isSubClassOf("ProcResGroup")) continue;

[courbet]

• Better comments
• Cosmetics

include/llvm/MC/MCSchedule.h

#endif
   //
   // Unbuffered resources (BufferSize == 0) always consume their resource some
   // fixed number of cycles after dispatch. If a resource is unbuffered, then
   // the scheduler will avoid scheduling instructions with conflicting resources
   // in the same cycle. This is for in-order cpus, or the in-order portion of
   // an out-of-order cpus.
   int BufferSize;
 
+  // If the resource has sub-units, a pointer to the first element of an array
+  // of `NumUnits` elements containing the ProcResourceIdx of the sub units.
+  // nullptr if the resource does not have sub-units.
+  const unsigned *SubUnitsIdxBegin;
+
   bool operator==(const MCProcResourceDesc &Other) const {
     return NumUnits == Other.NumUnits && SuperIdx == Other.SuperIdx
       && BufferSize == Other.BufferSize;
   }
 };
 
 /// Identify one of the processor resource kinds consumed by a particular
 /// scheduling class for the specified number of cycles.

include/llvm/Target/TargetSchedule.td

 // separate reservation station. This simply models the size of the
 // reservation station.
 //
 // To model both dispatch/issue groups and in-order execution units,
 // create two types of units, one with BufferSize=0 and one with
 // BufferSize=1.
 //
 // SchedModel ties these units to a processor for any stand-alone defs
-// of this class. Instances of subclass ProcResource will be automatically
-// attached to a processor, so SchedModel is not needed.
+// of this class.
 class ProcResourceUnits<ProcResourceKind kind, int num> {
   ProcResourceKind Kind = kind;
   int NumUnits = num;
   ProcResourceKind Super = ?;
   int BufferSize = -1;
   SchedMachineModel SchedModel = ?;
 }
 

utils/TableGen/SubtargetEmitter.cpp

class SubtargetEmitter {
   void EmitStageAndOperandCycleData(raw_ostream &OS,
                                     std::vector<std::vector<InstrItinerary>>
                                       &ProcItinLists);
   void EmitItineraries(raw_ostream &OS,
                        std::vector<std::vector<InstrItinerary>>
                          &ProcItinLists);
   void EmitProcessorProp(raw_ostream &OS, const Record *R, StringRef Name,
                          char Separator);
+  void EmitProcessorResourceSubUnits(const CodeGenProcModel &ProcModel,
+                                     raw_ostream &OS);
   void EmitProcessorResources(const CodeGenProcModel &ProcModel,
                               raw_ostream &OS);
   Record *FindWriteResources(const CodeGenSchedRW &SchedWrite,
                              const CodeGenProcModel &ProcModel);
   Record *FindReadAdvance(const CodeGenSchedRW &SchedRead,
                           const CodeGenProcModel &ProcModel);
   void ExpandProcResources(RecVec &PRVec, std::vector<int64_t> &Cycles,
                            const CodeGenProcModel &ProcModel);
void SubtargetEmitter::EmitProcessorProp(raw_ostream &OS, const Record *R,
   int V = R ? R->getValueAsInt(Name) : -1;
   if (V >= 0)
     OS << V << Separator << " // " << Name;
   else
     OS << "MCSchedModel::Default" << Name << Separator;
   OS << '\n';
 }
 
+void SubtargetEmitter::EmitProcessorResourceSubUnits(
+    const CodeGenProcModel &ProcModel, raw_ostream &OS) {
+  OS << "\nstatic const unsigned " << ProcModel.ModelName
+     << "ProcResourceSubUnits[] = {\n"
+     << "  0,  // Invalid\n";
+
+  for (unsigned i = 0, e = ProcModel.ProcResourceDefs.size(); i < e; ++i) {
+    Record *PRDef = ProcModel.ProcResourceDefs[i];
+    if (!PRDef->isSubClassOf("ProcResGroup"))
+      continue;
+    RecVec ResUnits = PRDef->getValueAsListOfDefs("Resources");
+    for (Record *RUDef : ResUnits) {
+      Record *const RU =
+          SchedModels.findProcResUnits(RUDef, ProcModel, PRDef->getLoc());
+      for (unsigned J = 0; J < RU->getValueAsInt("NumUnits"); ++J) {
+        OS << "  " << ProcModel.getProcResourceIdx(RU) << ", ";
+      }
+    }
+    OS << "  // " << PRDef->getName() << "\n";
+  }
+  OS << "};\n";
+}
+
 void SubtargetEmitter::EmitProcessorResources(const CodeGenProcModel &ProcModel,
                                               raw_ostream &OS) {
-  OS << "\n// {Name, NumUnits, SuperIdx, IsBuffered}\n";
+  EmitProcessorResourceSubUnits(ProcModel, OS);
+
+  OS << "\n// {Name, NumUnits, SuperIdx, IsBuffered, SubUnitsIdxBegin}\n";
   OS << "static const llvm::MCProcResourceDesc "
      << ProcModel.ModelName << "ProcResources" << "[] = {\n"
      << "  {DBGFIELD(\"InvalidUnit\")     0, 0, 0},\n";
 
+  unsigned SubUnitsOffset = 1;
   for (unsigned i = 0, e = ProcModel.ProcResourceDefs.size(); i < e; ++i) {
     Record *PRDef = ProcModel.ProcResourceDefs[i];
 
     Record *SuperDef = nullptr;
     unsigned SuperIdx = 0;
     unsigned NumUnits = 0;
+    const unsigned SubUnitsBeginOffset = SubUnitsOffset;
     int BufferSize = PRDef->getValueAsInt("BufferSize");
     if (PRDef->isSubClassOf("ProcResGroup")) {
       RecVec ResUnits = PRDef->getValueAsListOfDefs("Resources");
       for (Record *RU : ResUnits) {
         NumUnits += RU->getValueAsInt("NumUnits");
+        SubUnitsOffset += NumUnits;
       }
     }
     else {
       // Find the SuperIdx
       if (PRDef->getValueInit("Super")->isComplete()) {
         SuperDef =
             SchedModels.findProcResUnits(PRDef->getValueAsDef("Super"),
                                          ProcModel, PRDef->getLoc());
         SuperIdx = ProcModel.getProcResourceIdx(SuperDef);
       }
       NumUnits = PRDef->getValueAsInt("NumUnits");
     }
     // Emit the ProcResourceDesc
     OS << "  {DBGFIELD(\"" << PRDef->getName() << "\") ";
     if (PRDef->getName().size() < 15)
       OS.indent(15 - PRDef->getName().size());
-    OS << NumUnits << ", " << SuperIdx << ", "
-       << BufferSize << "}, // #" << i+1;
+    OS << NumUnits << ", " << SuperIdx << ", " << BufferSize << ", ";
+    if (SubUnitsBeginOffset != SubUnitsOffset) {
+      OS << ProcModel.ModelName << "ProcResourceSubUnits + "
+         << SubUnitsBeginOffset;
+    } else {
+      OS << "nullptr";
+    }
+    OS << "}, // #" << i+1;
     if (SuperDef)
       OS << ", Super=" << SuperDef->getName();
     OS << "\n";
   }
   OS << "};\n";
 }
 
 // Find the WriteRes Record that defines processor resources for this