From 28a1e486907104b85c5787345914917d74f0cf77 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Tue, 30 Mar 2010 05:49:07 +0000
Subject: [PATCH] Avoid being influenced by the presence of dbg_value
 instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99879 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/LiveIntervalAnalysis.cpp | 17 +++++++++++++----
 lib/CodeGen/VirtRegRewriter.cpp      | 19 +++++++++++++++----
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index b3e921689c7..e657c46c721 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -819,8 +819,9 @@ bool LiveIntervals::isReMaterializable(const LiveInterval &li,
   unsigned ImpUse = getReMatImplicitUse(li, MI);
   if (ImpUse) {
     const LiveInterval &ImpLi = getInterval(ImpUse);
-    for (MachineRegisterInfo::use_iterator ri = mri_->use_begin(li.reg),
-           re = mri_->use_end(); ri != re; ++ri) {
+    for (MachineRegisterInfo::use_nodbg_iterator
+           ri = mri_->use_nodbg_begin(li.reg), re = mri_->use_nodbg_end();
+         ri != re; ++ri) {
       MachineInstr *UseMI = &*ri;
       SlotIndex UseIdx = getInstructionIndex(UseMI);
       if (li.FindLiveRangeContaining(UseIdx)->valno != ValNo)
@@ -1052,7 +1053,7 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
       // all of its uses are rematerialized, simply delete it.
       if (MI == ReMatOrigDefMI && CanDelete) {
         DEBUG(dbgs() << "\t\t\t\tErasing re-materializable def: "
-                     << MI << '\n');
+                     << *MI << '\n');
         RemoveMachineInstrFromMaps(MI);
         vrm.RemoveMachineInstrFromMaps(MI);
         MI->eraseFromParent();
@@ -1520,6 +1521,12 @@ LiveIntervals::handleSpilledImpDefs(const LiveInterval &li, VirtRegMap &vrm,
     MachineOperand &O = ri.getOperand();
     MachineInstr *MI = &*ri;
     ++ri;
+    if (MI->isDebugValue()) {
+      // Remove debug info for now.
+      O.setReg(0U);
+      DEBUG(dbgs() << "Removing debug info due to spill:" << "\t" << *MI);
+      continue;
+    }
     if (O.isDef()) {
       assert(MI->isImplicitDef() &&
              "Register def was not rewritten?");
@@ -2012,6 +2019,8 @@ unsigned LiveIntervals::getNumConflictsWithPhysReg(const LiveInterval &li,
          E = mri_->reg_end(); I != E; ++I) {
     MachineOperand &O = I.getOperand();
     MachineInstr *MI = O.getParent();
+    if (MI->isDebugValue())
+      continue;
     SlotIndex Index = getInstructionIndex(MI);
     if (pli.liveAt(Index))
       ++NumConflicts;
@@ -2052,7 +2061,7 @@ bool LiveIntervals::spillPhysRegAroundRegDefsUses(const LiveInterval &li,
          E = mri_->reg_end(); I != E; ++I) {
     MachineOperand &O = I.getOperand();
     MachineInstr *MI = O.getParent();
-    if (SeenMIs.count(MI))
+    if (MI->isDebugValue() || SeenMIs.count(MI))
       continue;
     SeenMIs.insert(MI);
     SlotIndex Index = getInstructionIndex(MI);
diff --git a/lib/CodeGen/VirtRegRewriter.cpp b/lib/CodeGen/VirtRegRewriter.cpp
index 70f1d21f112..0b7fde7ec8f 100644
--- a/lib/CodeGen/VirtRegRewriter.cpp
+++ b/lib/CodeGen/VirtRegRewriter.cpp
@@ -990,10 +990,17 @@ static unsigned FindFreeRegister(MachineBasicBlock::iterator MII,
   SmallVector<unsigned, 4> Kills;
 
   // Take a look at 2 instructions at most.
-  for (unsigned Count = 0; Count < 2; ++Count) {
+  unsigned Count = 0;
+  while (Count < 2) {
     if (MII == MBB.begin())
       break;
     MachineInstr *PrevMI = prior(MII);
+    MII = PrevMI;
+
+    if (PrevMI->isDebugValue())
+      continue; // Skip over dbg_value instructions.
+    ++Count;
+
     for (unsigned i = 0, e = PrevMI->getNumOperands(); i != e; ++i) {
       MachineOperand &MO = PrevMI->getOperand(i);
       if (!MO.isReg() || MO.getReg() == 0)
@@ -1022,8 +1029,6 @@ static unsigned FindFreeRegister(MachineBasicBlock::iterator MII,
       for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
         Uses.set(*AS);
     }
-
-    MII = PrevMI;
   }
 
   return 0;
@@ -1213,6 +1218,9 @@ OptimizeByUnfold2(unsigned VirtReg, int SS,
                   std::vector<MachineOperand*> &KillOps) {
 
   MachineBasicBlock::iterator NextMII = llvm::next(MII);
+  // Skip over dbg_value instructions.
+  while (NextMII != MBB->end() && NextMII->isDebugValue())
+    NextMII = llvm::next(NextMII);
   if (NextMII == MBB->end())
     return false;
 
@@ -1277,6 +1285,9 @@ OptimizeByUnfold2(unsigned VirtReg, int SS,
     VRM->RemoveMachineInstrFromMaps(&NextMI);
     MBB->erase(&NextMI);
     ++NumModRefUnfold;
+    // Skip over dbg_value instructions.
+    while (NextMII != MBB->end() && NextMII->isDebugValue())
+      NextMII = llvm::next(NextMII);
     if (NextMII == MBB->end())
       break;
   } while (FoldsStackSlotModRef(*NextMII, SS, PhysReg, TII, TRI, *VRM));
@@ -1622,7 +1633,7 @@ TransferDeadness(unsigned Reg, BitVector &RegKills,
   for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(Reg),
          RE = MRI->reg_end(); RI != RE; ++RI) {
     MachineInstr *UDMI = &*RI;
-    if (UDMI->getParent() != MBB)
+    if (UDMI->isDebugValue() || UDMI->getParent() != MBB)
       continue;
     DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UDMI);
     if (DI == DistanceMap.end())