[llvm] [SystemZ, DebugInfo] Support InstrRef-based Debug Value Tracking in the SystemZ backend (PR #132415)

[Jonas Paulsson via llvm-commits]

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@@ -346,6 +346,52 @@ Register SystemZInstrInfo::isStoreToStackSlot(const MachineInstr &MI,
   return isSimpleMove(MI, FrameIndex, SystemZII::SimpleBDXStore);
 }
 
+Register SystemZInstrInfo::isLoadFromStackSlotPostFE(const MachineInstr &MI,
+                                                     int &FrameIndex) const {
+  // if this is not a simple load from memory, it's not a load from stack slot
+  // either.
+  const MCInstrDesc &MCID = MI.getDesc();
+  if (!(MCID.TSFlags & SystemZII::SimpleBDXLoad))
+    return 0;
+
+  Register Reg;
+  // If the frame index is still there, use it.
+  if ((Reg = isLoadFromStackSlot(MI, FrameIndex)))
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JonPsson1 wrote:

Given that this should be run very late (after PrologEpilogInserter), I am not sure how an FI could still be present here in a register operand: I thought they were all replaced during frameIndex elimination in PrologEpilogInserter..? Did you try to assert against finding it?

https://github.com/llvm/llvm-project/pull/132415