[MachineCopyPropagation] Refactor copy tracking into a class. NFC

This is a bit easier to follow than handling the copy and src maps
directly in the pass, and will make upcoming changes to how this is
done easier to follow.

llvm-svn: 342703

1 files changed, 133 insertions, 99 deletions

diff --git a/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
index 9f0a3ada7c1..0e06ddf06cf 100644
--- a/llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -74,9 +74,115 @@ DEBUG_COUNTER(FwdCounter, "machine-cp-fwd",
 
 namespace {
 
-using RegList = SmallVector<unsigned, 4>;
-using SourceMap = DenseMap<unsigned, RegList>;
-using Reg2MIMap = DenseMap<unsigned, MachineInstr *>;
+class CopyTracker {
+  using RegList = SmallVector<unsigned, 4>;
+  using SourceMap = DenseMap<unsigned, RegList>;
+  using Reg2MIMap = DenseMap<unsigned, MachineInstr *>;
+
+  /// Def -> available copies map.
+  Reg2MIMap AvailCopyMap;
+
+  /// Def -> copies map.
+  Reg2MIMap CopyMap;
+
+  /// Src -> Def map
+  SourceMap SrcMap;
+
+public:
+  /// Mark all of the given registers and their subregisters as unavailable for
+  /// copying.
+  void markRegsUnavailable(const RegList &Regs, const TargetRegisterInfo &TRI) {
+    for (unsigned Reg : Regs) {
+      // Source of copy is no longer available for propagation.
+      for (MCSubRegIterator SR(Reg, &TRI, true); SR.isValid(); ++SR)
+        AvailCopyMap.erase(*SR);
+    }
+  }
+
+  /// Remove any entry in the tracker's copy maps that is marked clobbered in \p
+  /// RegMask. The map will typically have a lot fewer entries than the regmask
+  /// clobbers, so this is more efficient than iterating the clobbered registers
+  /// and calling ClobberRegister() on them.
+  void removeClobberedRegs(const MachineOperand &RegMask,
+                           const TargetRegisterInfo &TRI) {
+    auto RemoveFromMap = [&RegMask](Reg2MIMap &Map) {
+      for (Reg2MIMap::iterator I = Map.begin(), E = Map.end(), Next; I != E;
+           I = Next) {
+        Next = std::next(I);
+        if (RegMask.clobbersPhysReg(I->first))
+          Map.erase(I);
+      }
+    };
+    RemoveFromMap(AvailCopyMap);
+    RemoveFromMap(CopyMap);
+
+    for (SourceMap::iterator I = SrcMap.begin(), E = SrcMap.end(), Next; I != E;
+         I = Next) {
+      Next = std::next(I);
+      if (RegMask.clobbersPhysReg(I->first)) {
+        markRegsUnavailable(I->second, TRI);
+        SrcMap.erase(I);
+      }
+    }
+  }
+
+  /// Clobber a single register, removing it from the tracker's copy maps.
+  void clobberRegister(unsigned Reg, const TargetRegisterInfo &TRI) {
+    for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI) {
+      CopyMap.erase(*AI);
+      AvailCopyMap.erase(*AI);
+
+      SourceMap::iterator SI = SrcMap.find(*AI);
+      if (SI != SrcMap.end()) {
+        markRegsUnavailable(SI->second, TRI);
+        SrcMap.erase(SI);
+      }
+    }
+  }
+
+  /// Add this copy's registers into the tracker's copy maps.
+  void trackCopy(MachineInstr *Copy, const TargetRegisterInfo &TRI) {
+    assert(Copy->isCopy() && "Tracking non-copy?");
+
+    unsigned Def = Copy->getOperand(0).getReg();
+    unsigned Src = Copy->getOperand(1).getReg();
+
+    // Remember Def is defined by the copy.
+    for (MCSubRegIterator SR(Def, &TRI, /*IncludeSelf=*/true); SR.isValid();
+         ++SR) {
+      CopyMap[*SR] = Copy;
+      AvailCopyMap[*SR] = Copy;
+    }
+
+    // Remember source that's copied to Def. Once it's clobbered, then
+    // it's no longer available for copy propagation.
+    RegList &DestList = SrcMap[Src];
+    if (!is_contained(DestList, Def))
+      DestList.push_back(Def);
+  }
+
+  bool hasAvailableCopies() { return !AvailCopyMap.empty(); }
+
+  MachineInstr *findAvailCopy(unsigned Reg) {
+    auto CI = AvailCopyMap.find(Reg);
+    if (CI != AvailCopyMap.end())
+      return CI->second;
+    return nullptr;
+  }
+
+  MachineInstr *findCopy(unsigned Reg) {
+    auto CI = CopyMap.find(Reg);
+    if (CI != CopyMap.end())
+      return CI->second;
+    return nullptr;
+  }
+
+  void clear() {
+    AvailCopyMap.clear();
+    CopyMap.clear();
+    SrcMap.clear();
+  }
+};
 
 class MachineCopyPropagation : public MachineFunctionPass {
   const TargetRegisterInfo *TRI;
@@ -115,14 +221,7 @@ private:
   /// Candidates for deletion.
   SmallSetVector<MachineInstr *, 8> MaybeDeadCopies;
 
-  /// Def -> available copies map.
-  Reg2MIMap AvailCopyMap;
-
-  /// Def -> copies map.
-  Reg2MIMap CopyMap;
-
-  /// Src -> Def map
-  SourceMap SrcMap;
+  CopyTracker Tracker;
 
   bool Changed;
 };
@@ -136,54 +235,13 @@ char &llvm::MachineCopyPropagationID = MachineCopyPropagation::ID;
 INITIALIZE_PASS(MachineCopyPropagation, DEBUG_TYPE,
                 "Machine Copy Propagation Pass", false, false)
 
-/// Remove any entry in \p Map where the register is a subregister or equal to
-/// a register contained in \p Regs.
-static void removeRegsFromMap(Reg2MIMap &Map, const RegList &Regs,
-                              const TargetRegisterInfo &TRI) {
-  for (unsigned Reg : Regs) {
-    // Source of copy is no longer available for propagation.
-    for (MCSubRegIterator SR(Reg, &TRI, true); SR.isValid(); ++SR)
-      Map.erase(*SR);
-  }
-}
-
-/// Remove any entry in \p Map that is marked clobbered in \p RegMask.
-/// The map will typically have a lot fewer entries than the regmask clobbers,
-/// so this is more efficient than iterating the clobbered registers and calling
-/// ClobberRegister() on them.
-static void removeClobberedRegsFromMap(Reg2MIMap &Map,
-                                       const MachineOperand &RegMask) {
-  for (Reg2MIMap::iterator I = Map.begin(), E = Map.end(), Next; I != E;
-       I = Next) {
-    Next = std::next(I);
-    unsigned Reg = I->first;
-    if (RegMask.clobbersPhysReg(Reg))
-      Map.erase(I);
-  }
-}
-
-void MachineCopyPropagation::ClobberRegister(unsigned Reg) {
-  for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
-    CopyMap.erase(*AI);
-    AvailCopyMap.erase(*AI);
-
-    SourceMap::iterator SI = SrcMap.find(*AI);
-    if (SI != SrcMap.end()) {
-      removeRegsFromMap(AvailCopyMap, SI->second, *TRI);
-      SrcMap.erase(SI);
-    }
-  }
-}
-
 void MachineCopyPropagation::ReadRegister(unsigned Reg) {
   // If 'Reg' is defined by a copy, the copy is no longer a candidate
   // for elimination.
   for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
-    Reg2MIMap::iterator CI = CopyMap.find(*AI);
-    if (CI != CopyMap.end()) {
-      LLVM_DEBUG(dbgs() << "MCP: Copy is used - not dead: ";
-                 CI->second->dump());
-      MaybeDeadCopies.remove(CI->second);
+    if (MachineInstr *Copy = Tracker.findCopy(*AI)) {
+      LLVM_DEBUG(dbgs() << "MCP: Copy is used - not dead: "; Copy->dump());
+      MaybeDeadCopies.remove(Copy);
     }
   }
 }
@@ -219,15 +277,14 @@ bool MachineCopyPropagation::eraseIfRedundant(MachineInstr &Copy, unsigned Src,
     return false;
 
   // Search for an existing copy.
-  Reg2MIMap::iterator CI = AvailCopyMap.find(Def);
-  if (CI == AvailCopyMap.end())
+  MachineInstr *PrevCopy = Tracker.findAvailCopy(Def);
+  if (!PrevCopy)
     return false;
 
   // Check that the existing copy uses the correct sub registers.
-  MachineInstr &PrevCopy = *CI->second;
-  if (PrevCopy.getOperand(0).isDead())
+  if (PrevCopy->getOperand(0).isDead())
     return false;
-  if (!isNopCopy(PrevCopy, Src, Def, TRI))
+  if (!isNopCopy(*PrevCopy, Src, Def, TRI))
     return false;
 
   LLVM_DEBUG(dbgs() << "MCP: copy is a NOP, removing: "; Copy.dump());
@@ -238,7 +295,7 @@ bool MachineCopyPropagation::eraseIfRedundant(MachineInstr &Copy, unsigned Src,
   unsigned CopyDef = Copy.getOperand(0).getReg();
   assert(CopyDef == Src || CopyDef == Def);
   for (MachineInstr &MI :
-       make_range(PrevCopy.getIterator(), Copy.getIterator()))
+       make_range(PrevCopy->getIterator(), Copy.getIterator()))
     MI.clearRegisterKills(CopyDef, TRI);
 
   Copy.eraseFromParent();
@@ -314,7 +371,7 @@ bool MachineCopyPropagation::hasImplicitOverlap(const MachineInstr &MI,
 /// Look for available copies whose destination register is used by \p MI and
 /// replace the use in \p MI with the copy's source register.
 void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
-  if (AvailCopyMap.empty())
+  if (!Tracker.hasAvailableCopies())
     return;
 
   // Look for non-tied explicit vreg uses that have an active COPY
@@ -341,13 +398,12 @@ void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
     if (!MOUse.isRenamable())
       continue;
 
-    auto CI = AvailCopyMap.find(MOUse.getReg());
-    if (CI == AvailCopyMap.end())
+    MachineInstr *Copy = Tracker.findAvailCopy(MOUse.getReg());
+    if (!Copy)
       continue;
 
-    MachineInstr &Copy = *CI->second;
-    unsigned CopyDstReg = Copy.getOperand(0).getReg();
-    const MachineOperand &CopySrc = Copy.getOperand(1);
+    unsigned CopyDstReg = Copy->getOperand(0).getReg();
+    const MachineOperand &CopySrc = Copy->getOperand(1);
     unsigned CopySrcReg = CopySrc.getReg();
 
     // FIXME: Don't handle partial uses of wider COPYs yet.
@@ -362,7 +418,7 @@ void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
     if (MRI->isReserved(CopySrcReg) && !MRI->isConstantPhysReg(CopySrcReg))
       continue;
 
-    if (!isForwardableRegClassCopy(Copy, MI, OpIdx))
+    if (!isForwardableRegClassCopy(*Copy, MI, OpIdx))
       continue;
 
     if (hasImplicitOverlap(MI, MOUse))
@@ -376,7 +432,7 @@ void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
 
     LLVM_DEBUG(dbgs() << "MCP: Replacing " << printReg(MOUse.getReg(), TRI)
                       << "\n     with " << printReg(CopySrcReg, TRI)
-                      << "\n     in " << MI << "     from " << Copy);
+                      << "\n     in " << MI << "     from " << *Copy);
 
     MOUse.setReg(CopySrcReg);
     if (!CopySrc.isRenamable())
@@ -386,7 +442,7 @@ void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
 
     // Clear kill markers that may have been invalidated.
     for (MachineInstr &KMI :
-         make_range(Copy.getIterator(), std::next(MI.getIterator())))
+         make_range(Copy->getIterator(), std::next(MI.getIterator())))
       KMI.clearRegisterKills(CopySrcReg, TRI);
 
     ++NumCopyForwards;
@@ -459,28 +515,17 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
       // %xmm2 = copy %xmm0
       // ...
       // %xmm2 = copy %xmm9
-      ClobberRegister(Def);
+      Tracker.clobberRegister(Def, *TRI);
       for (const MachineOperand &MO : MI->implicit_operands()) {
         if (!MO.isReg() || !MO.isDef())
           continue;
         unsigned Reg = MO.getReg();
         if (!Reg)
           continue;
-        ClobberRegister(Reg);
-      }
-
-      // Remember Def is defined by the copy.
-      for (MCSubRegIterator SR(Def, TRI, /*IncludeSelf=*/true); SR.isValid();
-           ++SR) {
-        CopyMap[*SR] = MI;
-        AvailCopyMap[*SR] = MI;
+        Tracker.clobberRegister(Reg, *TRI);
       }
 
-      // Remember source that's copied to Def. Once it's clobbered, then
-      // it's no longer available for copy propagation.
-      RegList &DestList = SrcMap[Src];
-      if (!is_contained(DestList, Def))
-          DestList.push_back(Def);
+      Tracker.trackCopy(MI, *TRI);
 
       continue;
     }
@@ -494,7 +539,7 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
         // later.
         if (MO.isTied())
           ReadRegister(Reg);
-        ClobberRegister(Reg);
+        Tracker.clobberRegister(Reg, *TRI);
       }
 
     forwardUses(*MI);
@@ -549,21 +594,12 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
         ++NumDeletes;
       }
 
-      removeClobberedRegsFromMap(AvailCopyMap, *RegMask);
-      removeClobberedRegsFromMap(CopyMap, *RegMask);
-      for (SourceMap::iterator I = SrcMap.begin(), E = SrcMap.end(), Next;
-           I != E; I = Next) {
-        Next = std::next(I);
-        if (RegMask->clobbersPhysReg(I->first)) {
-          removeRegsFromMap(AvailCopyMap, I->second, *TRI);
-          SrcMap.erase(I);
-        }
-      }
+      Tracker.removeClobberedRegs(*RegMask, *TRI);
     }
 
     // Any previous copy definition or reading the Defs is no longer available.
     for (unsigned Reg : Defs)
-      ClobberRegister(Reg);
+      Tracker.clobberRegister(Reg, *TRI);
   }
 
   // If MBB doesn't have successors, delete the copies whose defs are not used.
@@ -581,9 +617,7 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
   }
 
   MaybeDeadCopies.clear();
-  AvailCopyMap.clear();
-  CopyMap.clear();
-  SrcMap.clear();
+  Tracker.clear();
 }
 
 bool MachineCopyPropagation::runOnMachineFunction(MachineFunction &MF) {