3 files changed, 14 insertions, 0 deletions
diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp
index 9d7ec06..a0544d0 100644
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define DEBUG_TYPE "codegen-dce"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/Pass.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
@@ -19,8 +20,11 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/ADT/Statistic.h"
 using namespace llvm;
 
+STATISTIC(NumDeletes,          "Number of dead instructions deleted");
+
 namespace {
   class DeadMachineInstructionElim : public MachineFunctionPass {
     virtual bool runOnMachineFunction(MachineFunction &MF);
@@ -126,6 +130,7 @@ bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
         DEBUG(dbgs() << "DeadMachineInstructionElim: DELETING: " << *MI);
         AnyChanges = true;
         MI->eraseFromParent();
+        ++NumDeletes;
         MIE = MBB->rend();
         // MII is now pointing to the next instruction to process,
         // so don't increment it.
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index c03e429..40e0150 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -291,6 +291,12 @@ bool LLVMTargetMachine::addCommonCodeGenPasses(PassManagerBase &PM,
   printAndVerify(PM, "After Instruction Selection",
                  /* allowDoubleDefs= */ true);
 
+
+  // Delete dead machine instructions regardless of optimization level.
+  PM.add(createDeadMachineInstructionElimPass());
+  printAndVerify(PM, "After codegen DCE pass",
+                 /* allowDoubleDefs= */ true);
+
   if (OptLevel != CodeGenOpt::None) {
     PM.add(createOptimizeExtsPass());
     if (!DisableMachineLICM)
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 8746bf9..c52156a 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -671,6 +671,9 @@ void LiveIntervals::computeIntervals() {
   for (MachineFunction::iterator MBBI = mf_->begin(), E = mf_->end();
        MBBI != E; ++MBBI) {
     MachineBasicBlock *MBB = MBBI;
+    if (MBB->empty())
+      continue;
+
     // Track the index of the current machine instr.
     SlotIndex MIIndex = getMBBStartIdx(MBB);
     DEBUG(dbgs() << MBB->getName() << ":\n");