[ReachingDefAnalysis] Extend the analysis to stack objects.

We track definitions of stack objects, the implementation is identical
to tracking of registers.

Also, added printing of all found reaching definitions for testing
purposes.

Author: mgudim

llvm/include/llvm/CodeGen/ReachingDefAnalysis.h

@@ -114,8 +114,11 @@ class ReachingDefAnalysis : public MachineFunctionPass {
 private:
   MachineFunction *MF = nullptr;
   const TargetRegisterInfo *TRI = nullptr;
+  const TargetInstrInfo *TII = nullptr;
   LoopTraversal::TraversalOrder TraversedMBBOrder;
   unsigned NumRegUnits = 0;
+  unsigned NumStackObjects = 0;
+  int ObjectIndexBegin = 0;
   /// Instruction that defined each register, relative to the beginning of the
   /// current basic block.  When a LiveRegsDefInfo is used to represent a
   /// live-out register, this value is relative to the end of the basic block,
@@ -138,6 +141,13 @@ class ReachingDefAnalysis : public MachineFunctionPass {
   DenseMap<MachineInstr *, int> InstIds;
 
   MBBReachingDefsInfo MBBReachingDefs;
+  using MBBFrameObjsReachingDefsInfo =
+      std::vector<std::vector<SmallVector<int>>>;
+  // MBBFrameObjsReachingDefs[i][j] is a list of instruction indices (relative
+  // to begining of MBB) that define frame index (j +
+  // MF->getFrameInfo().getObjectIndexBegin()) in MBB i. This is used in
+  // answering reaching definition queries.
+  MBBFrameObjsReachingDefsInfo MBBFrameObjsReachingDefs;
 
   /// Default values are 'nothing happened a long time ago'.
   const int ReachingDefDefaultVal = -(1 << 21);
@@ -158,6 +168,7 @@ class ReachingDefAnalysis : public MachineFunctionPass {
     MachineFunctionPass::getAnalysisUsage(AU);
   }
 
+  void printAllReachingDefs(MachineFunction &MF);
   bool runOnMachineFunction(MachineFunction &MF) override;
 
   MachineFunctionProperties getRequiredProperties() const override {
@@ -176,12 +187,13 @@ class ReachingDefAnalysis : public MachineFunctionPass {
   void traverse();
 
   /// Provides the instruction id of the closest reaching def instruction of
-  /// PhysReg that reaches MI, relative to the begining of MI's basic block.
-  int getReachingDef(MachineInstr *MI, MCRegister PhysReg) const;
+  /// Reg that reaches MI, relative to the begining of MI's basic block.
+  // Note that Reg may represent a stack slot.
+  int getReachingDef(MachineInstr *MI, MCRegister Reg) const;
 
-  /// Return whether A and B use the same def of PhysReg.
+  /// Return whether A and B use the same def of Reg.
   bool hasSameReachingDef(MachineInstr *A, MachineInstr *B,
-                          MCRegister PhysReg) const;
+                          MCRegister Reg) const;
 
   /// Return whether the reaching def for MI also is live out of its parent
   /// block.
@@ -309,9 +321,9 @@ class ReachingDefAnalysis : public MachineFunctionPass {
   MachineInstr *getInstFromId(MachineBasicBlock *MBB, int InstId) const;
 
   /// Provides the instruction of the closest reaching def instruction of
-  /// PhysReg that reaches MI, relative to the begining of MI's basic block.
-  MachineInstr *getReachingLocalMIDef(MachineInstr *MI,
-                                      MCRegister PhysReg) const;
+  /// Reg that reaches MI, relative to the begining of MI's basic block.
+  // Note that Reg may represent a stack slot.
+  MachineInstr *getReachingLocalMIDef(MachineInstr *MI, MCRegister Reg) const;
 };
 
 } // namespace llvm