[PATCH] D142127: [llvm][codegen] Fix non-determinism in StackFrameLayoutAnalysisPass output

[Paul Kirth via Phabricator via llvm-commits]

paulkirth created this revision.
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We were iterating over a SmallPtrSet when outputting slot variables.
This is still correct but made the test fail under reverse iteration.
This patch replaces the SmallPtrSet with a SmallVector.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D142127

Files:
  llvm/lib/CodeGen/StackFrameLayoutAnalysisPass.cpp


Index: llvm/lib/CodeGen/StackFrameLayoutAnalysisPass.cpp
===================================================================
--- llvm/lib/CodeGen/StackFrameLayoutAnalysisPass.cpp
+++ llvm/lib/CodeGen/StackFrameLayoutAnalysisPass.cpp
@@ -46,7 +46,7 @@
 ///
 struct StackFrameLayoutAnalysisPass : public MachineFunctionPass {
   using SlotDbgMap =
-      SmallDenseMap<int, SmallPtrSet<const DILocalVariable *, 4>>;
+      SmallDenseMap<int, SmallVector<const DILocalVariable *, 4>>;
   static char ID;
 
   enum SlotType {
@@ -180,18 +180,15 @@
                       << MFI.getStackProtectorIndex() << "\n");
 
     std::vector<SlotData> SlotInfo;
-    SmallDenseMap<int, int> SlotOffsetMap;
 
     const unsigned int NumObj = MFI.getNumObjects();
     SlotInfo.reserve(NumObj);
-    SlotOffsetMap.reserve(NumObj);
     // initialize slot info
     for (int Idx = MFI.getObjectIndexBegin(), EndIdx = MFI.getObjectIndexEnd();
          Idx != EndIdx; ++Idx) {
       if (MFI.isDeadObjectIndex(Idx))
         continue;
-      auto &Inserted = SlotInfo.emplace_back(MFI, ValOffset, Idx);
-      SlotOffsetMap[Inserted.Slot] = Inserted.Offset;
+      SlotInfo.emplace_back(MFI, ValOffset, Idx);
     }
 
     // sort the ordering, to match the actual layout in memory
@@ -214,7 +211,7 @@
 
     // add variables to the map
     for (MachineFunction::VariableDbgInfo &DI : MF.getVariableDbgInfo())
-      SlotDebugMap[DI.Slot].insert(DI.Var);
+      SlotDebugMap[DI.Slot].push_back(DI.Var);
 
     // Then add all the spills that have debug data
     for (MachineBasicBlock &MBB : MF) {
@@ -231,7 +228,7 @@
           MI.collectDebugValues(Dbg);
 
           for (MachineInstr *MI : Dbg)
-            SlotDebugMap[FrameIdx].insert(MI->getDebugVariable());
+            SlotDebugMap[FrameIdx].push_back(MI->getDebugVariable());
         }
       }
     }


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