Revert 85799 for now. It might be breaking llvm-gcc driver.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85827 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 46 deletions

diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp
index 1306aa6..7b64047 100644
--- a/lib/CodeGen/MachineLICM.cpp
+++ b/lib/CodeGen/MachineLICM.cpp
@@ -56,12 +56,12 @@ namespace {
 
     // State that is updated as we process loops
     bool         Changed;          // True if a loop is changed.
-    bool         FirstInLoop;      // True if it's the first LICM in the loop.
     MachineLoop *CurLoop;          // The current loop we are working on.
     MachineBasicBlock *CurPreheader; // The preheader for CurLoop.
 
-    // For each opcode, keep a list of potentail CSE instructions.
-    DenseMap<unsigned, std::vector<const MachineInstr*> > CSEMap;
+    // For each BB and opcode pair, keep a list of hoisted instructions.
+    DenseMap<std::pair<unsigned, unsigned>,
+      std::vector<const MachineInstr*> > CSEMap;
   public:
     static char ID; // Pass identification, replacement for typeid
     MachineLICM() : MachineFunctionPass(&ID) {}
@@ -115,11 +115,6 @@ namespace {
     /// that is safe to hoist, this instruction is called to do the dirty work.
     ///
     void Hoist(MachineInstr *MI);
-
-    /// InitCSEMap - Initialize the CSE map with instructions that are in the
-    /// current loop preheader that may become duplicates of instructions that
-    /// are hoisted out of the loop.
-    void InitCSEMap(MachineBasicBlock *BB);
   };
 } // end anonymous namespace
 
@@ -145,7 +140,7 @@ static bool LoopIsOuterMostWithPreheader(MachineLoop *CurLoop) {
 bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
   DEBUG(errs() << "******** Machine LICM ********\n");
 
-  Changed = FirstInLoop = false;
+  Changed = false;
   TM = &MF.getTarget();
   TII = TM->getInstrInfo();
   TRI = TM->getRegisterInfo();
@@ -157,7 +152,8 @@ bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
   DT = &getAnalysis<MachineDominatorTree>();
   AA = &getAnalysis<AliasAnalysis>();
 
-  for (MachineLoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
+  for (MachineLoopInfo::iterator
+         I = LI->begin(), E = LI->end(); I != E; ++I) {
     CurLoop = *I;
 
     // Only visit outer-most preheader-sporting loops.
@@ -174,11 +170,7 @@ bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
     if (!CurPreheader)
       continue;
 
-    // CSEMap is initialized for loop header when the first instruction is
-    // being hoisted.
-    FirstInLoop = true;
     HoistRegion(DT->getNode(CurLoop->getHeader()));
-    CSEMap.clear();
   }
 
   return Changed;
@@ -199,7 +191,10 @@ void MachineLICM::HoistRegion(MachineDomTreeNode *N) {
   for (MachineBasicBlock::iterator
          MII = BB->begin(), E = BB->end(); MII != E; ) {
     MachineBasicBlock::iterator NextMII = MII; ++NextMII;
-    Hoist(&*MII);
+    MachineInstr &MI = *MII;
+
+    Hoist(&MI);
+
     MII = NextMII;
   }
 
@@ -435,27 +430,6 @@ MachineInstr *MachineLICM::ExtractHoistableLoad(MachineInstr *MI) {
   return NewMIs[0];
 }
 
-void MachineLICM::InitCSEMap(MachineBasicBlock *BB) {
-  for (MachineBasicBlock::iterator I = BB->begin(),E = BB->end(); I != E; ++I) {
-    const MachineInstr *MI = &*I;
-    // FIXME: For now, only hoist re-materilizable instructions. LICM will
-    // increase register pressure. We want to make sure it doesn't increase
-    // spilling.
-    if (TII->isTriviallyReMaterializable(MI, AA)) {
-      unsigned Opcode = MI->getOpcode();
-      DenseMap<unsigned, std::vector<const MachineInstr*> >::iterator
-        CI = CSEMap.find(Opcode);
-      if (CI != CSEMap.end())
-        CI->second.push_back(MI);
-      else {
-        std::vector<const MachineInstr*> CSEMIs;
-        CSEMIs.push_back(MI);
-        CSEMap.insert(std::make_pair(Opcode, CSEMIs));
-      }
-    }
-  }
-}
-
 /// Hoist - When an instruction is found to use only loop invariant operands
 /// that are safe to hoist, this instruction is called to do the dirty work.
 ///
@@ -480,14 +454,11 @@ void MachineLICM::Hoist(MachineInstr *MI) {
       errs() << "\n";
     });
 
-  // If this is the first instruction being hoisted to the preheader,
-  // initialize the CSE map with potential common expressions.
-  InitCSEMap(CurPreheader);
-
   // Look for opportunity to CSE the hoisted instruction.
-  unsigned Opcode = MI->getOpcode();
-  DenseMap<unsigned, std::vector<const MachineInstr*> >::iterator
-    CI = CSEMap.find(Opcode);
+  std::pair<unsigned, unsigned> BBOpcPair =
+    std::make_pair(CurPreheader->getNumber(), MI->getOpcode());
+  DenseMap<std::pair<unsigned, unsigned>,
+    std::vector<const MachineInstr*> >::iterator CI = CSEMap.find(BBOpcPair);
   bool DoneCSE = false;
   if (CI != CSEMap.end()) {
     const MachineInstr *Dup = LookForDuplicate(MI, CI->second, RegInfo);
@@ -506,15 +477,15 @@ void MachineLICM::Hoist(MachineInstr *MI) {
 
   // Otherwise, splice the instruction to the preheader.
   if (!DoneCSE) {
-    CurPreheader->splice(CurPreheader->getFirstTerminator(),MI->getParent(),MI);
-
+    CurPreheader->splice(CurPreheader->getFirstTerminator(),
+                         MI->getParent(), MI);
     // Add to the CSE map.
     if (CI != CSEMap.end())
       CI->second.push_back(MI);
     else {
       std::vector<const MachineInstr*> CSEMIs;
       CSEMIs.push_back(MI);
-      CSEMap.insert(std::make_pair(Opcode, CSEMIs));
+      CSEMap.insert(std::make_pair(BBOpcPair, CSEMIs));
     }
   }