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

[via llvm-commits]

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

Tablegen would generate code to access TargetResourceIndices with processor ID.
The TargetProcResourceIndexStart[] array is generated for each processor which
has itineraries. The processor which doesn't has itineraries is excluded from
the array. When a target has mixed processors, the processor ID may exceed the
array size and cause the error.
This patch is to generate a table mapping processor with itineraries to resource
index, so that scheduler can get the correct resource index with processor ID.


>From 5aa048c1adfa9d12a384e2cdf2754e919814ecc3 Mon Sep 17 00:00:00 2001
From: Yuanke Luo <ykluo at birentech.com>
Date: Thu, 11 Sep 2025 19:57:20 +0800
Subject: [PATCH] [TableGen] Add mapping from processor ID to resource index
 for packetizer

Tablegen would generate code to access TargetResourceIndices with processor ID.
The TargetProcResourceIndexStart[] array is generated for each processor which
has itineraries. The processor which doesn't has itineraries is excluded from
the array. When a target has mixed processors, the processor ID may exceed the
array size and cause the error.
This patch is to generate a table mapping processor with itineraries to resource
index, so that scheduler can get the correct resource index with processor ID.
---
 llvm/test/TableGen/DFAPacketizer.td          | 31 ++++++++++++++++++++
 llvm/utils/TableGen/DFAPacketizerEmitter.cpp | 19 +++++++++---
 2 files changed, 46 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/TableGen/DFAPacketizer.td

diff --git a/llvm/test/TableGen/DFAPacketizer.td b/llvm/test/TableGen/DFAPacketizer.td
new file mode 100644
index 0000000000000..b4c05c63811b5
--- /dev/null
+++ b/llvm/test/TableGen/DFAPacketizer.td
@@ -0,0 +1,31 @@
+// RUN: llvm-tblgen -gen-dfa-packetizer -I %p/../../include %s | FileCheck %s
+
+include "llvm/Target/Target.td"
+
+def TestTarget : Target;
+
+def TestSchedModel : SchedMachineModel {
+  let CompleteModel = 0;
+}
+
+def TestProcessor1 : ProcessorModel<"testprocessor1", TestSchedModel, []>;
+
+def FU0 : FuncUnit;
+def FU1 : FuncUnit;
+
+def OP0 : InstrItinClass;
+def OP1 : InstrItinClass;
+
+def Itin {
+  list<InstrItinData> ItinList = [
+    InstrItinData<OP0, [InstrStage<1, [FU0]>]>,
+    InstrItinData<OP1, [InstrStage<1, [FU1]>]>,
+  ];
+}
+
+// CHECK: std::map<unsigned, unsigned> TestTargetProcIdToResourceIndexStartMapping = {
+// CHECK-NEXT:   { 2,  1 }, // TestItinerariesModel
+// CHECK-NEXT: };
+
+def TestItineraries: ProcessorItineraries<[], [], Itin.ItinList>;
+def TestProcessor2 : Processor<"testprocessor2", TestItineraries, []>;
diff --git a/llvm/utils/TableGen/DFAPacketizerEmitter.cpp b/llvm/utils/TableGen/DFAPacketizerEmitter.cpp
index 8cb2c22736f8a..0fd30411451a2 100644
--- a/llvm/utils/TableGen/DFAPacketizerEmitter.cpp
+++ b/llvm/utils/TableGen/DFAPacketizerEmitter.cpp
@@ -256,6 +256,16 @@ void DFAPacketizerEmitter::emitForItineraries(
   }
   OS << "\n};\n\n";
 
+  // Output the mapping from proc ID to ResourceIndexStart
+  Idx = 1;
+  OS << "std::map<unsigned, unsigned> " << TargetName << DFAName
+     << "ProcIdToResourceIndexStartMapping = {\n";
+  for (const CodeGenProcModel *Model : ProcModels) {
+    OS << "  { " << Model->Index << ",  " << Idx++ << " }, // "
+       << Model->ModelName << "\n";
+  }
+  OS << "};\n\n";
+
   // And the mapping from Itinerary index into the previous table.
   OS << "constexpr unsigned " << TargetName << DFAName
      << "ProcResourceIndexStart[] = {\n";
@@ -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
+     << "ProcIdToResourceIndexStartMapping[IID->SchedModel.ProcID];\n"
      << "  unsigned ProcResIdxStart = " << TargetAndDFAName
-     << "ProcResourceIndexStart[IID->SchedModel.ProcID];\n"
+     << "ProcResourceIndexStart[Index];\n"
      << "  unsigned ProcResIdxNum = " << TargetAndDFAName
-     << "ProcResourceIndexStart[IID->SchedModel.ProcID + 1] - "
+     << "ProcResourceIndexStart[Index + 1] - "
         "ProcResIdxStart;\n"
      << "  return new DFAPacketizer(IID, A, {&" << TargetAndDFAName
      << "ResourceIndices[ProcResIdxStart], ProcResIdxNum});\n"