[llvm] [ADT] Add and use (for AArch64) `ValueWithSentinel<T, Sentinel>` (PR #158120)

[Jakub Kuderski via llvm-commits]

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@@ -3488,16 +3488,16 @@ bool AArch64FrameLowering::assignCalleeSavedSpillSlots(
     if (AFI->hasStackHazardSlotIndex() &&
         (!LastReg || !AArch64InstrInfo::isFpOrNEON(LastReg)) &&
         AArch64InstrInfo::isFpOrNEON(Reg)) {
-      assert(HazardSlotIndex == std::numeric_limits<int>::max() &&
+      assert(!HazardSlotIndex.has_value() &&
              "Unexpected register order for hazard slot");
       HazardSlotIndex = MFI.CreateStackObject(StackHazardSize, Align(8), true);
-      LLVM_DEBUG(dbgs() << "Created CSR Hazard at slot " << HazardSlotIndex
+      LLVM_DEBUG(dbgs() << "Created CSR Hazard at slot " << *HazardSlotIndex
                         << "\n");
-      AFI->setStackHazardCSRSlotIndex(HazardSlotIndex);
-      if ((unsigned)HazardSlotIndex < MinCSFrameIndex)
-        MinCSFrameIndex = HazardSlotIndex;
-      if ((unsigned)HazardSlotIndex > MaxCSFrameIndex)
-        MaxCSFrameIndex = HazardSlotIndex;
+      AFI->setStackHazardCSRSlotIndex(*HazardSlotIndex);
+      if ((unsigned)*HazardSlotIndex < MinCSFrameIndex)
+        MinCSFrameIndex = *HazardSlotIndex;
+      if ((unsigned)*HazardSlotIndex > MaxCSFrameIndex)
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kuhar wrote:

These should be static casts

https://github.com/llvm/llvm-project/pull/158120