[llvm] [TableGen] Emit better error message for duplicate Subtarget features. (PR #102090)

[Rahul Joshi via llvm-commits]

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@@ -494,7 +497,7 @@ void SubtargetEmitter::EmitStageAndOperandCycleData(
   // operand cycles, and pipeline bypass tables. Then add the new Itinerary
   // object with computed offsets to the ProcItinLists result.
   unsigned StageCount = 1, OperandCycleCount = 1;
-  std::map<std::string, unsigned> ItinStageMap, ItinOperandMap;
+  std::unordered_map<std::string, unsigned> ItinStageMap, ItinOperandMap;
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jurahul wrote:

Done.

https://github.com/llvm/llvm-project/pull/102090