[PATCH] D101064: [WIP] improve debug-info in stack-slot-coloring

[Markus Lavin via Phabricator via llvm-commits]

markus created this revision.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D101064

Files:
  llvm/lib/CodeGen/StackSlotColoring.cpp


Index: llvm/lib/CodeGen/StackSlotColoring.cpp
===================================================================
--- llvm/lib/CodeGen/StackSlotColoring.cpp
+++ llvm/lib/CodeGen/StackSlotColoring.cpp
@@ -72,6 +72,7 @@
     // to be careful that renames like [FI0, FI1] -> [FI1, FI2] do not
     // become FI0 -> FI1 -> FI2.
     SmallVector<SmallVector<MachineMemOperand *, 8>, 16> SSRefs;
+    DenseMap<unsigned, MachineOperand *> BBDbgRefs;
 
     // OrigAlignments - Alignments of stack objects before coloring.
     SmallVector<Align, 16> OrigAlignments;
@@ -370,8 +371,14 @@
 
   // Rewrite all MO_FrameIndex operands.  Look for dead stores.
   for (MachineBasicBlock &MBB : MF) {
-    for (MachineInstr &MI : MBB)
+    BBDbgRefs.clear();
+    for (MachineInstr &MI : MBB) {
+      if (MI.isDebugValue() && MI.getOperand(0).isFI()) {
+        auto FI = MI.getOperand(0).getIndex();
+        BBDbgRefs[FI] = &MI.getOperand(0);
+      }
       RewriteInstruction(MI, SlotMapping, MF);
+    }
     RemoveDeadStores(&MBB);
   }
 
@@ -405,6 +412,20 @@
     if (NewFI == -1 || NewFI == OldFI)
       continue;
 
+    // If NewFI (!= OldFI) has active DBG_VALUE we need to kill that variable.
+    if (MI.isDebugValue() && BBDbgRefs[NewFI]) {
+      auto MO = BBDbgRefs[NewFI];
+      auto DbgValue = MO->getParent();
+      BuildMI(*DbgValue->getParent(), MI, DbgValue->getDebugLoc(),
+              TII->get(TargetOpcode::DBG_VALUE))
+          .addReg(0) // $noreg
+          .add(DbgValue->getOperand(1))
+          .add(DbgValue->getOperand(2))
+          .add(DbgValue->getOperand(3));
+
+      BBDbgRefs.erase(NewFI);
+    }
+
     assert(MFI->getStackID(OldFI) == MFI->getStackID(NewFI));
     MO.setIndex(NewFI);
   }


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