MFC 261991:

Upgrade our copy of llvm/clang to 3.4 release.  This version supports
all of the features in the current working draft of the upcoming C++
standard, provisionally named C++1y.

The code generator's performance is greatly increased, and the loop
auto-vectorizer is now enabled at -Os and -O2 in addition to -O3.  The
PowerPC backend has made several major improvements to code generation
quality and compile time, and the X86, SPARC, ARM32, Aarch64 and SystemZ
backends have all seen major feature work.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.4/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>

MFC 262121 (by emaste):

Update lldb for clang/llvm 3.4 import

This commit largely restores the lldb source to the upstream r196259
snapshot with the addition of threaded inferior support and a few bug
fixes.

Specific upstream lldb revisions restored include:
   SVN      git
  181387  779e6ac
  181703  7bef4e2
  182099  b31044e
  182650  f2dcf35
  182683  0d91b80
  183862  15c1774
  183929  99447a6
  184177  0b2934b
  184948  4dc3761
  184954  007e7bc
  186990  eebd175

Sponsored by:	DARPA, AFRL

MFC 262186 (by emaste):

Fix mismerge in r262121

A break statement was lost in the merge.  The error had no functional
impact, but restore it to reduce the diff against upstream.

MFC 262303:

Pull in r197521 from upstream clang trunk (by rdivacky):

  Use the integrated assembler by default on FreeBSD/ppc and ppc64.

Requested by:	jhibbits

MFC 262611:

Pull in r196874 from upstream llvm trunk:

  Fix a crash that occurs when PWD is invalid.

  MCJIT needs to be able to run in hostile environments, even when PWD
  is invalid. There's no need to crash MCJIT in this case.

  The obvious fix is to simply leave MCContext's CompilationDir empty
  when PWD can't be determined. This way, MCJIT clients,
  and other clients that link with LLVM don't need a valid working directory.

  If we do want to guarantee valid CompilationDir, that should be done
  only for clients of getCompilationDir(). This is as simple as checking
  for an empty string.

  The only current use of getCompilationDir is EmitGenDwarfInfo, which
  won't conceivably run with an invalid working dir. However, in the
  purely hypothetically and untestable case that this happens, the
  AT_comp_dir will be omitted from the compilation_unit DIE.

This should help fix assertions occurring with ports-mgmt/tinderbox,
when it is using jails, and sometimes invalidates clang's current
working directory.

Reported by:	decke

MFC 262809:

Pull in r203007 from upstream clang trunk:

  Don't produce an alias between destructors with different calling conventions.

  Fixes pr19007.

(Please note that is an LLVM PR identifier, not a FreeBSD one.)

This should fix Firefox and/or libxul crashes (due to problems with
regparm/stdcall calling conventions) on i386.

Reported by:	multiple users on freebsd-current
PR:		bin/187103

MFC 263048:

Repair recognition of "CC" as an alias for the C++ compiler, since it
was silently broken by upstream for a Windows-specific use-case.

Apparently some versions of CMake still rely on this archaic feature...

Reported by:	rakuco

MFC 263049:

Garbage collect the old way of adding the libstdc++ include directories
in clang's InitHeaderSearch.cpp.  This has been superseded by David
Chisnall's commit in r255321.

Moreover, if libc++ is used, the libstdc++ include directories should
not be in the search path at all.  These directories are now only used
if you pass -stdlib=libstdc++.

1 files changed, 127 insertions, 102 deletions

diff --git a/contrib/llvm/lib/CodeGen/IfConversion.cpp b/contrib/llvm/lib/CodeGen/IfConversion.cpp
index 8264d6d..e2d0eb4 100644
--- a/contrib/llvm/lib/CodeGen/IfConversion.cpp
+++ b/contrib/llvm/lib/CodeGen/IfConversion.cpp
@@ -22,6 +22,8 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/TargetSchedule.h"
+#include "llvm/CodeGen/LiveRegUnits.h"
 #include "llvm/MC/MCInstrItineraries.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
@@ -31,6 +33,8 @@
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
 using namespace llvm;
 
 // Hidden options for help debugging.
@@ -150,14 +154,17 @@ namespace {
     /// BBAnalysis - Results of if-conversion feasibility analysis indexed by
     /// basic block number.
     std::vector<BBInfo> BBAnalysis;
+    TargetSchedModel SchedModel;
 
     const TargetLoweringBase *TLI;
     const TargetInstrInfo *TII;
     const TargetRegisterInfo *TRI;
-    const InstrItineraryData *InstrItins;
     const MachineBranchProbabilityInfo *MBPI;
     MachineRegisterInfo *MRI;
 
+    LiveRegUnits Redefs;
+    LiveRegUnits DontKill;
+
     bool PreRegAlloc;
     bool MadeChange;
     int FnNum;
@@ -198,11 +205,9 @@ namespace {
     void PredicateBlock(BBInfo &BBI,
                         MachineBasicBlock::iterator E,
                         SmallVectorImpl<MachineOperand> &Cond,
-                        SmallSet<unsigned, 4> &Redefs,
                         SmallSet<unsigned, 4> *LaterRedefs = 0);
     void CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
                                SmallVectorImpl<MachineOperand> &Cond,
-                               SmallSet<unsigned, 4> &Redefs,
                                bool IgnoreBr = false);
     void MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges = true);
 
@@ -267,7 +272,11 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
   TRI = MF.getTarget().getRegisterInfo();
   MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
   MRI = &MF.getRegInfo();
-  InstrItins = MF.getTarget().getInstrItineraryData();
+
+  const TargetSubtargetInfo &ST =
+    MF.getTarget().getSubtarget<TargetSubtargetInfo>();
+  SchedModel.init(*ST.getSchedModel(), &ST, TII);
+
   if (!TII) return false;
 
   PreRegAlloc = MRI->isSSA();
@@ -666,32 +675,28 @@ void IfConverter::ScanInstructions(BBInfo &BBI) {
     bool isPredicated = TII->isPredicated(I);
     bool isCondBr = BBI.IsBrAnalyzable && I->isConditionalBranch();
 
-    if (!isCondBr) {
-      if (!isPredicated) {
-        BBI.NonPredSize++;
-        unsigned ExtraPredCost = 0;
-        unsigned NumCycles = TII->getInstrLatency(InstrItins, &*I,
-                                                  &ExtraPredCost);
-        if (NumCycles > 1)
-          BBI.ExtraCost += NumCycles-1;
-        BBI.ExtraCost2 += ExtraPredCost;
-      } else if (!AlreadyPredicated) {
-        // FIXME: This instruction is already predicated before the
-        // if-conversion pass. It's probably something like a conditional move.
-        // Mark this block unpredicable for now.
-        BBI.IsUnpredicable = true;
-        return;
-      }
+    // A conditional branch is not predicable, but it may be eliminated.
+    if (isCondBr)
+      continue;
+
+    if (!isPredicated) {
+      BBI.NonPredSize++;
+      unsigned ExtraPredCost = TII->getPredicationCost(&*I);
+      unsigned NumCycles = SchedModel.computeInstrLatency(&*I, false);
+      if (NumCycles > 1)
+        BBI.ExtraCost += NumCycles-1;
+      BBI.ExtraCost2 += ExtraPredCost;
+    } else if (!AlreadyPredicated) {
+      // FIXME: This instruction is already predicated before the
+      // if-conversion pass. It's probably something like a conditional move.
+      // Mark this block unpredicable for now.
+      BBI.IsUnpredicable = true;
+      return;
     }
 
     if (BBI.ClobbersPred && !isPredicated) {
       // Predicate modification instruction should end the block (except for
       // already predicated instructions and end of block branches).
-      if (isCondBr) {
-        // A conditional branch is not predicable, but it may be eliminated.
-        continue;
-      }
-
       // Predicate may have been modified, the subsequent (currently)
       // unpredicated instructions cannot be correctly predicated.
       BBI.IsUnpredicable = true;
@@ -720,9 +725,9 @@ bool IfConverter::FeasibilityAnalysis(BBInfo &BBI,
   if (BBI.IsDone || BBI.IsUnpredicable)
     return false;
 
-  // If it is already predicated, check if its predicate subsumes the new
-  // predicate.
-  if (BBI.Predicate.size() && !TII->SubsumesPredicate(BBI.Predicate, Pred))
+  // If it is already predicated, check if the new predicate subsumes
+  // its predicate.
+  if (BBI.Predicate.size() && !TII->SubsumesPredicate(Pred, BBI.Predicate))
     return false;
 
   if (BBI.BrCond.size()) {
@@ -961,64 +966,58 @@ void IfConverter::RemoveExtraEdges(BBInfo &BBI) {
     BBI.BB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty());
 }
 
-/// InitPredRedefs / UpdatePredRedefs - Defs by predicated instructions are
-/// modeled as read + write (sort like two-address instructions). These
-/// routines track register liveness and add implicit uses to if-converted
-/// instructions to conform to the model.
-static void InitPredRedefs(MachineBasicBlock *BB, SmallSet<unsigned,4> &Redefs,
-                           const TargetRegisterInfo *TRI) {
-  for (MachineBasicBlock::livein_iterator I = BB->livein_begin(),
-         E = BB->livein_end(); I != E; ++I) {
-    unsigned Reg = *I;
-    Redefs.insert(Reg);
-    for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
-      Redefs.insert(*SubRegs);
-  }
-}
-
-static void UpdatePredRedefs(MachineInstr *MI, SmallSet<unsigned,4> &Redefs,
-                             const TargetRegisterInfo *TRI,
-                             bool AddImpUse = false) {
-  SmallVector<unsigned, 4> Defs;
-  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-    const MachineOperand &MO = MI->getOperand(i);
-    if (!MO.isReg())
+/// Behaves like LiveRegUnits::StepForward() but also adds implicit uses to all
+/// values defined in MI which are not live/used by MI.
+static void UpdatePredRedefs(MachineInstr *MI, LiveRegUnits &Redefs,
+                             const TargetRegisterInfo *TRI) {
+  for (ConstMIBundleOperands Ops(MI); Ops.isValid(); ++Ops) {
+    if (!Ops->isReg() || !Ops->isKill())
       continue;
-    unsigned Reg = MO.getReg();
-    if (!Reg)
+    unsigned Reg = Ops->getReg();
+    if (Reg == 0)
       continue;
-    if (MO.isDef())
-      Defs.push_back(Reg);
-    else if (MO.isKill()) {
-      Redefs.erase(Reg);
-      for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
-        Redefs.erase(*SubRegs);
-    }
+    Redefs.removeReg(Reg, *TRI);
   }
-  MachineInstrBuilder MIB(*MI->getParent()->getParent(), MI);
-  for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
-    unsigned Reg = Defs[i];
-    if (!Redefs.insert(Reg)) {
-      if (AddImpUse)
-        // Treat predicated update as read + write.
-        MIB.addReg(Reg, RegState::Implicit | RegState::Undef);
-    } else {
-      for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
-        Redefs.insert(*SubRegs);
-    }
+  for (MIBundleOperands Ops(MI); Ops.isValid(); ++Ops) {
+    if (!Ops->isReg() || !Ops->isDef())
+      continue;
+    unsigned Reg = Ops->getReg();
+    if (Reg == 0 || Redefs.contains(Reg, *TRI))
+      continue;
+    Redefs.addReg(Reg, *TRI);
+
+    MachineOperand &Op = *Ops;
+    MachineInstr *MI = Op.getParent();
+    MachineInstrBuilder MIB(*MI->getParent()->getParent(), MI);
+    MIB.addReg(Reg, RegState::Implicit | RegState::Undef);
   }
 }
 
-static void UpdatePredRedefs(MachineBasicBlock::iterator I,
-                             MachineBasicBlock::iterator E,
-                             SmallSet<unsigned,4> &Redefs,
-                             const TargetRegisterInfo *TRI) {
-  while (I != E) {
-    UpdatePredRedefs(I, Redefs, TRI);
-    ++I;
+/**
+ * Remove kill flags from operands with a registers in the @p DontKill set.
+ */
+static void RemoveKills(MachineInstr &MI, const LiveRegUnits &DontKill,
+                        const MCRegisterInfo &MCRI) {
+  for (MIBundleOperands O(&MI); O.isValid(); ++O) {
+    if (!O->isReg() || !O->isKill())
+      continue;
+    if (DontKill.contains(O->getReg(), MCRI))
+      O->setIsKill(false);
   }
 }
 
+/**
+ * Walks a range of machine instructions and removes kill flags for registers
+ * in the @p DontKill set.
+ */
+static void RemoveKills(MachineBasicBlock::iterator I,
+                        MachineBasicBlock::iterator E,
+                        const LiveRegUnits &DontKill,
+                        const MCRegisterInfo &MCRI) {
+  for ( ; I != E; ++I)
+    RemoveKills(*I, DontKill, MCRI);
+}
+
 /// IfConvertSimple - If convert a simple (split, no rejoin) sub-CFG.
 ///
 bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) {
@@ -1049,21 +1048,27 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) {
 
   // Initialize liveins to the first BB. These are potentiall redefined by
   // predicated instructions.
-  SmallSet<unsigned, 4> Redefs;
-  InitPredRedefs(CvtBBI->BB, Redefs, TRI);
-  InitPredRedefs(NextBBI->BB, Redefs, TRI);
+  Redefs.init(TRI);
+  Redefs.addLiveIns(CvtBBI->BB, *TRI);
+  Redefs.addLiveIns(NextBBI->BB, *TRI);
+
+  // Compute a set of registers which must not be killed by instructions in
+  // BB1: This is everything live-in to BB2.
+  DontKill.init(TRI);
+  DontKill.addLiveIns(NextBBI->BB, *TRI);
 
   if (CvtBBI->BB->pred_size() > 1) {
     BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
     // Copy instructions in the true block, predicate them, and add them to
     // the entry block.
-    CopyAndPredicateBlock(BBI, *CvtBBI, Cond, Redefs);
+    CopyAndPredicateBlock(BBI, *CvtBBI, Cond);
 
     // RemoveExtraEdges won't work if the block has an unanalyzable branch, so
     // explicitly remove CvtBBI as a successor.
     BBI.BB->removeSuccessor(CvtBBI->BB);
   } else {
-    PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond, Redefs);
+    RemoveKills(CvtBBI->BB->begin(), CvtBBI->BB->end(), DontKill, *TRI);
+    PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond);
 
     // Merge converted block into entry block.
     BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
@@ -1148,16 +1153,18 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
 
   // Initialize liveins to the first BB. These are potentially redefined by
   // predicated instructions.
-  SmallSet<unsigned, 4> Redefs;
-  InitPredRedefs(CvtBBI->BB, Redefs, TRI);
-  InitPredRedefs(NextBBI->BB, Redefs, TRI);
+  Redefs.init(TRI);
+  Redefs.addLiveIns(CvtBBI->BB, *TRI);
+  Redefs.addLiveIns(NextBBI->BB, *TRI);
+
+  DontKill.clear();
 
   bool HasEarlyExit = CvtBBI->FalseBB != NULL;
   if (CvtBBI->BB->pred_size() > 1) {
     BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
     // Copy instructions in the true block, predicate them, and add them to
     // the entry block.
-    CopyAndPredicateBlock(BBI, *CvtBBI, Cond, Redefs, true);
+    CopyAndPredicateBlock(BBI, *CvtBBI, Cond, true);
 
     // RemoveExtraEdges won't work if the block has an unanalyzable branch, so
     // explicitly remove CvtBBI as a successor.
@@ -1165,7 +1172,7 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
   } else {
     // Predicate the 'true' block after removing its branch.
     CvtBBI->NonPredSize -= TII->RemoveBranch(*CvtBBI->BB);
-    PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond, Redefs);
+    PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond);
 
     // Now merge the entry of the triangle with the true block.
     BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
@@ -1276,8 +1283,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
 
   // Initialize liveins to the first BB. These are potentially redefined by
   // predicated instructions.
-  SmallSet<unsigned, 4> Redefs;
-  InitPredRedefs(BBI1->BB, Redefs, TRI);
+  Redefs.init(TRI);
+  Redefs.addLiveIns(BBI1->BB, *TRI);
 
   // Remove the duplicated instructions at the beginnings of both paths.
   MachineBasicBlock::iterator DI1 = BBI1->BB->begin();
@@ -1304,7 +1311,19 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
       --NumDups1;
   }
 
-  UpdatePredRedefs(BBI1->BB->begin(), DI1, Redefs, TRI);
+  // Compute a set of registers which must not be killed by instructions in BB1:
+  // This is everything used+live in BB2 after the duplicated instructions. We
+  // can compute this set by simulating liveness backwards from the end of BB2.
+  DontKill.init(TRI);
+  for (MachineBasicBlock::reverse_iterator I = BBI2->BB->rbegin(),
+       E = MachineBasicBlock::reverse_iterator(DI2); I != E; ++I) {
+    DontKill.stepBackward(*I, *TRI);
+  }
+
+  for (MachineBasicBlock::const_iterator I = BBI1->BB->begin(), E = DI1; I != E;
+       ++I) {
+    Redefs.stepForward(*I, *TRI);
+  }
   BBI.BB->splice(BBI.BB->end(), BBI1->BB, BBI1->BB->begin(), DI1);
   BBI2->BB->erase(BBI2->BB->begin(), DI2);
 
@@ -1322,6 +1341,10 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
   }
   BBI1->BB->erase(DI1, BBI1->BB->end());
 
+  // Kill flags in the true block for registers living into the false block
+  // must be removed.
+  RemoveKills(BBI1->BB->begin(), BBI1->BB->end(), DontKill, *TRI);
+
   // Remove 'false' block branch and find the last instruction to predicate.
   BBI2->NonPredSize -= TII->RemoveBranch(*BBI2->BB);
   DI2 = BBI2->BB->end();
@@ -1362,8 +1385,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
         } else if (!RedefsByFalse.count(Reg)) {
           // These are defined before ctrl flow reach the 'false' instructions.
           // They cannot be modified by the 'true' instructions.
-          ExtUses.insert(Reg);
-          for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
+          for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true);
+               SubRegs.isValid(); ++SubRegs)
             ExtUses.insert(*SubRegs);
         }
       }
@@ -1371,8 +1394,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
       for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
         unsigned Reg = Defs[i];
         if (!ExtUses.count(Reg)) {
-          RedefsByFalse.insert(Reg);
-          for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
+          for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true);
+               SubRegs.isValid(); ++SubRegs)
             RedefsByFalse.insert(*SubRegs);
         }
       }
@@ -1380,10 +1403,10 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
   }
 
   // Predicate the 'true' block.
-  PredicateBlock(*BBI1, BBI1->BB->end(), *Cond1, Redefs, &RedefsByFalse);
+  PredicateBlock(*BBI1, BBI1->BB->end(), *Cond1, &RedefsByFalse);
 
   // Predicate the 'false' block.
-  PredicateBlock(*BBI2, DI2, *Cond2, Redefs);
+  PredicateBlock(*BBI2, DI2, *Cond2);
 
   // Merge the true block into the entry of the diamond.
   MergeBlocks(BBI, *BBI1, TailBB == 0);
@@ -1458,7 +1481,6 @@ static bool MaySpeculate(const MachineInstr *MI,
 void IfConverter::PredicateBlock(BBInfo &BBI,
                                  MachineBasicBlock::iterator E,
                                  SmallVectorImpl<MachineOperand> &Cond,
-                                 SmallSet<unsigned, 4> &Redefs,
                                  SmallSet<unsigned, 4> *LaterRedefs) {
   bool AnyUnpred = false;
   bool MaySpec = LaterRedefs != 0;
@@ -1484,7 +1506,7 @@ void IfConverter::PredicateBlock(BBInfo &BBI,
 
     // If the predicated instruction now redefines a register as the result of
     // if-conversion, add an implicit kill.
-    UpdatePredRedefs(I, Redefs, TRI, true);
+    UpdatePredRedefs(I, Redefs, TRI);
   }
 
   std::copy(Cond.begin(), Cond.end(), std::back_inserter(BBI.Predicate));
@@ -1501,7 +1523,6 @@ void IfConverter::PredicateBlock(BBInfo &BBI,
 /// the destination block. Skip end of block branches if IgnoreBr is true.
 void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
                                         SmallVectorImpl<MachineOperand> &Cond,
-                                        SmallSet<unsigned, 4> &Redefs,
                                         bool IgnoreBr) {
   MachineFunction &MF = *ToBBI.BB->getParent();
 
@@ -1514,8 +1535,8 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
     MachineInstr *MI = MF.CloneMachineInstr(I);
     ToBBI.BB->insert(ToBBI.BB->end(), MI);
     ToBBI.NonPredSize++;
-    unsigned ExtraPredCost = 0;
-    unsigned NumCycles = TII->getInstrLatency(InstrItins, &*I, &ExtraPredCost);
+    unsigned ExtraPredCost = TII->getPredicationCost(&*I);
+    unsigned NumCycles = SchedModel.computeInstrLatency(&*I, false);
     if (NumCycles > 1)
       ToBBI.ExtraCost += NumCycles-1;
     ToBBI.ExtraCost2 += ExtraPredCost;
@@ -1531,7 +1552,11 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
 
     // If the predicated instruction now redefines a register as the result of
     // if-conversion, add an implicit kill.
-    UpdatePredRedefs(MI, Redefs, TRI, true);
+    UpdatePredRedefs(MI, Redefs, TRI);
+
+    // Some kill flags may not be correct anymore.
+    if (!DontKill.empty())
+      RemoveKills(*MI, DontKill, *TRI);
   }
 
   if (!IgnoreBr) {