Clear kill flags before propagating a copy.

The live range of the source register may be extended when a redundant
copy is eliminated. Make sure any kill flags between the two copies are
cleared.

This fixes PR11765.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149069 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 1 deletions

diff --git a/lib/CodeGen/MachineCopyPropagation.cpp b/lib/CodeGen/MachineCopyPropagation.cpp
index c82f81b..f96c869 100644
--- a/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/lib/CodeGen/MachineCopyPropagation.cpp
@@ -142,7 +142,12 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
           // %RSP<def> = COPY %RAX
           // CALL
           // %RAX<def> = COPY %RSP
-          CopyMI->getOperand(1).setIsKill(false);
+
+          // Clear any kills of Def between CopyMI and MI. This extends the
+          // live range.
+          for (MachineBasicBlock::iterator I = CopyMI, E = MI; I != E; ++I)
+            I->clearRegisterKills(Def, TRI);
+
           MI->eraseFromParent();
           Changed = true;
           ++NumDeletes;
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index 18e9f1a..c281cd1 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1707,6 +1707,20 @@ bool MachineInstr::addRegisterKilled(unsigned IncomingReg,
   return Found;
 }
 
+void MachineInstr::clearRegisterKills(unsigned Reg,
+                                      const TargetRegisterInfo *RegInfo) {
+  if (!TargetRegisterInfo::isPhysicalRegister(Reg))
+    RegInfo = 0;
+  for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
+    MachineOperand &MO = getOperand(i);
+    if (!MO.isReg() || !MO.isUse() || !MO.isKill())
+      continue;
+    unsigned OpReg = MO.getReg();
+    if (OpReg == Reg || (RegInfo && RegInfo->isSuperRegister(Reg, OpReg)))
+      MO.setIsKill(false);
+  }
+}
+
 bool MachineInstr::addRegisterDead(unsigned IncomingReg,
                                    const TargetRegisterInfo *RegInfo,
                                    bool AddIfNotFound) {