[llvm] [NFC] Switch a number of DenseMaps to SmallDenseMaps for speedup (PR #109417)

[Nikita Popov via llvm-commits]

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@@ -770,7 +770,7 @@ void ScheduleDAGLinearize::Schedule() {
 MachineBasicBlock*
 ScheduleDAGLinearize::EmitSchedule(MachineBasicBlock::iterator &InsertPos) {
   InstrEmitter Emitter(DAG->getTarget(), BB, InsertPos);
-  DenseMap<SDValue, Register> VRBaseMap;
+  SmallDenseMap<SDValue, Register, 16> VRBaseMap;
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nikic wrote:

Base `VRBaseMapType` public and use `InstrEmitter::VRBaseMapType` here?

https://github.com/llvm/llvm-project/pull/109417