[PATCH] D54648: [TableGen] Emit more variant transitions

[Evandro Menezes via Phabricator via llvm-commits]

evandro created this revision.
evandro added a reviewer: andreadb.
Herald added a subscriber: llvm-commits.

`llvm-mca` relies on the predicates to be based on `MCSchedPredicate` in order to resolve the scheduling for variant instructions. Otherwise, it aborts the building of the instruction model early. However, the scheduling model emitter gives up unless all processors use only such predicates.

In order to allow more processors to be used with `llvm-mca`, this patch emits scheduling transitions if any processors uses these predicates. The transition emitted for the processors using legacy predicates is the one specified with `NoSchedPred`, which is based on `MCSchedPredicate`.


Repository:
  rL LLVM

https://reviews.llvm.org/D54648

Files:
  llvm/utils/TableGen/SubtargetEmitter.cpp


Index: llvm/utils/TableGen/SubtargetEmitter.cpp
===================================================================
--- llvm/utils/TableGen/SubtargetEmitter.cpp
+++ llvm/utils/TableGen/SubtargetEmitter.cpp
@@ -1504,9 +1504,9 @@
       continue;
 
     if (OnlyExpandMCInstPredicates) {
-      // Ignore this variant scheduling class if transitions don't uses any
+      // Ignore this variant scheduling class if no transitions use any
       // MCSchedPredicate definitions.
-      if (!all_of(SC.Transitions, [](const CodeGenSchedTransition &T) {
+      if (!any_of(SC.Transitions, [](const CodeGenSchedTransition &T) {
             return hasMCSchedPredicates(T);
           }))
         continue;
@@ -1560,6 +1560,7 @@
     PE.setExpandForMC(OnlyExpandMCInstPredicates);
     for (unsigned PI : ProcIndices) {
       OS << "    ";
+
       // Emit a guard on the processor ID.
       if (PI != 0) {
         OS << (OnlyExpandMCInstPredicates
@@ -1573,11 +1574,19 @@
       for (const CodeGenSchedTransition &T : SC.Transitions) {
         if (PI != 0 && !count(T.ProcIndices, PI))
           continue;
+
+        // Emit only transitions based on MCSchedPredicate, if it's the case.
+        // At least, the transition specified by NoSchedPred is emitted, since
+        // this class is based on MCSchedPredicate.
+        if (OnlyExpandMCInstPredicates && !hasMCSchedPredicates(T))
+          continue;
+
         PE.setIndentLevel(3);
         emitPredicates(T, SchedModels.getSchedClass(T.ToClassIdx), PE, OS);
       }
 
       OS << "    }\n";
+
       if (PI == 0)
         break;
     }


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