Merge upstream r127116

1 files changed, 8 insertions, 2 deletions

diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp
index 786de1b..fdc1d91 100644
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -54,6 +54,12 @@ FunctionPass *llvm::createDeadMachineInstructionElimPass() {
 }
 
 bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const {
+  // Technically speaking inline asm without side effects and no defs can still
+  // be deleted. But there is so much bad inline asm code out there, we should
+  // let them be.
+  if (MI->isInlineAsm())
+    return false;
+
   // Don't delete instructions with side effects.
   bool SawStore = false;
   if (!MI->isSafeToMove(TII, 0, SawStore) && !MI->isPHI())
@@ -153,7 +159,7 @@ bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
         const MachineOperand &MO = MI->getOperand(i);
         if (MO.isReg() && MO.isDef()) {
           unsigned Reg = MO.getReg();
-          if (Reg != 0 && TargetRegisterInfo::isPhysicalRegister(Reg)) {
+          if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
             LivePhysRegs.reset(Reg);
             // Check the subreg set, not the alias set, because a def
             // of a super-register may still be partially live after
@@ -170,7 +176,7 @@ bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
         const MachineOperand &MO = MI->getOperand(i);
         if (MO.isReg() && MO.isUse()) {
           unsigned Reg = MO.getReg();
-          if (Reg != 0 && TargetRegisterInfo::isPhysicalRegister(Reg)) {
+          if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
             LivePhysRegs.set(Reg);
             for (const unsigned *AliasSet = TRI->getAliasSet(Reg);
                  *AliasSet; ++AliasSet)