[llvm] [TableGen] Add mapping from processor ID to resource index for packetizer (PR #158182)

[Haohai Wen via llvm-commits]

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@@ -339,16 +349,17 @@ void DFAPacketizerEmitter::emitForItineraries(
 
   std::string SubTargetClassName = TargetName + "GenSubtargetInfo";
   OS << "namespace llvm {\n";
-  OS << "DFAPacketizer *" << SubTargetClassName << "::"
-     << "create" << DFAName
+  OS << "DFAPacketizer *" << SubTargetClassName << "::" << "create" << DFAName
      << "DFAPacketizer(const InstrItineraryData *IID) const {\n"
      << "  static Automaton<uint64_t> A(ArrayRef<" << TargetAndDFAName
      << "Transition>(" << TargetAndDFAName << "Transitions), "
      << TargetAndDFAName << "TransitionInfo);\n"
+     << "  unsigned Index = " << TargetName << DFAName
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HaohaiWen wrote:

```The TargetProcResourceIndexStart[] array is generated for each processor which
has itineraries. The processor which doesn't has itineraries is excluded from
the array. ```

Is it possible that createDFAPacketizer accesses an IID that has no itinerary. (i.e. No such key exists in ProcIdToResourceIndexStartMapping?

https://github.com/llvm/llvm-project/pull/158182