Automerge: [ARM] Use RegisterClassInfo::getRegPressureSetLimit (#120377)

`RegisterClassInfo::getRegPressureSetLimit` is a wrapper of
`TargetRegisterInfo::getRegPressureSetLimit` with some logics to
adjust the limit by removing reserved registers.

It seems that we shouldn't use
`TargetRegisterInfo::getRegPressureSetLimit`
directly, just like the comment "This limit must be adjusted
dynamically for reserved registers" said.

Separate from llvm/llvm-project#118787

Author: wangpc-pp

Diff for: llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

@@ -6938,7 +6938,6 @@ bool ARMPipelinerLoopInfo::tooMuchRegisterPressure(SwingSchedulerDAG &SSD,
   RegClassInfo.runOnMachineFunction(*MF);
   RPTracker.init(MF, &RegClassInfo, nullptr, EndLoop->getParent(),
                  EndLoop->getParent()->end(), false, false);
-  const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
 
   bumpCrossIterationPressure(RPTracker, CrossIterationNeeds);
 
@@ -6980,10 +6979,16 @@ bool ARMPipelinerLoopInfo::tooMuchRegisterPressure(SwingSchedulerDAG &SSD,
   }
 
   auto &P = RPTracker.getPressure().MaxSetPressure;
-  for (unsigned I = 0, E = P.size(); I < E; ++I)
-    if (P[I] > TRI->getRegPressureSetLimit(*MF, I)) {
+  for (unsigned I = 0, E = P.size(); I < E; ++I) {
+    // Exclude some Neon register classes.
+    if (I == ARM::DQuad_with_ssub_0 || I == ARM::DTripleSpc_with_ssub_0 ||
+        I == ARM::DTriple_with_qsub_0_in_QPR)
+      continue;
+
+    if (P[I] > RegClassInfo.getRegPressureSetLimit(I)) {
       return true;
     }
+  }
   return false;
 }