Index: llvm/trunk/lib/Target/AMDGPU/AMDGPU.h
===================================================================
--- llvm/trunk/lib/Target/AMDGPU/AMDGPU.h
+++ llvm/trunk/lib/Target/AMDGPU/AMDGPU.h
@@ -49,6 +49,7 @@
 FunctionPass *createSIFixSGPRCopiesPass();
 FunctionPass *createSIFixSGPRLiveRangesPass();
 FunctionPass *createSICodeEmitterPass(formatted_raw_ostream &OS);
+FunctionPass *createSIInsertNopsPass();
 FunctionPass *createSIInsertWaitsPass();
 
 ScheduleDAGInstrs *createSIMachineScheduler(MachineSchedContext *C);
@@ -97,6 +98,9 @@
 void initializeSIAnnotateControlFlowPass(PassRegistry&);
 extern char &SIAnnotateControlFlowPassID;
 
+void initializeSIInsertNopsPass(PassRegistry&);
+extern char &SIInsertNopsID;
+
 void initializeSIInsertWaitsPass(PassRegistry&);
 extern char &SIInsertWaitsID;
 
Index: llvm/trunk/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
===================================================================
--- llvm/trunk/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
+++ llvm/trunk/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
@@ -30,6 +30,7 @@
 #include "llvm/IR/Verifier.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/IR/LegacyPassManager.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/raw_os_ostream.h"
 #include "llvm/Transforms/IPO.h"
@@ -54,6 +55,7 @@
   initializeAMDGPUAnnotateUniformValuesPass(*PR);
   initializeAMDGPUPromoteAllocaPass(*PR);
   initializeSIAnnotateControlFlowPass(*PR);
+  initializeSIInsertNopsPass(*PR);
   initializeSIInsertWaitsPass(*PR);
   initializeSILowerControlFlowPass(*PR);
 }
@@ -145,6 +147,12 @@
 //===----------------------------------------------------------------------===//
 
 namespace {
+
+cl::opt<bool> InsertNops(
+  "amdgpu-insert-nops",
+  cl::desc("Insert two nop instructions for each high level source statement"),
+  cl::init(false));
+
 class AMDGPUPassConfig : public TargetPassConfig {
 public:
   AMDGPUPassConfig(TargetMachine *TM, PassManagerBase &PM)
@@ -364,6 +372,9 @@
 void GCNPassConfig::addPreEmitPass() {
   addPass(createSIInsertWaitsPass(), false);
   addPass(createSILowerControlFlowPass(), false);
+  if (InsertNops) {
+    addPass(createSIInsertNopsPass(), false);
+  }
 }
 
 TargetPassConfig *GCNTargetMachine::createPassConfig(PassManagerBase &PM) {
Index: llvm/trunk/lib/Target/AMDGPU/CMakeLists.txt
===================================================================
--- llvm/trunk/lib/Target/AMDGPU/CMakeLists.txt
+++ llvm/trunk/lib/Target/AMDGPU/CMakeLists.txt
@@ -51,6 +51,7 @@
   SIFixSGPRLiveRanges.cpp
   SIFoldOperands.cpp
   SIFrameLowering.cpp
+  SIInsertNopsPass.cpp
   SIInsertWaits.cpp
   SIInstrInfo.cpp
   SIISelLowering.cpp
Index: llvm/trunk/lib/Target/AMDGPU/SIInsertNopsPass.cpp
===================================================================
--- llvm/trunk/lib/Target/AMDGPU/SIInsertNopsPass.cpp
+++ llvm/trunk/lib/Target/AMDGPU/SIInsertNopsPass.cpp
@@ -0,0 +1,94 @@
+//===--- SIInsertNopsPass.cpp - Use predicates for control flow -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// \brief Insert two S_NOP instructions for every high level source statement.
+///
+/// Tools, such as debugger, need to pause execution based on user input (i.e.
+/// breakpoint). In order to do this, two S_NOP instructions are inserted for
+/// each high level source statement: one before first isa instruction of high
+/// level source statement, and one after last isa instruction of high level
+/// source statement. Further, debugger may replace S_NOP instructions with
+/// S_TRAP instructions based on user input.
+//
+//===----------------------------------------------------------------------===//
+
+#include "SIInstrInfo.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "si-insert-nops"
+#define PASS_NAME "SI Insert Nops"
+
+namespace {
+
+class SIInsertNops : public MachineFunctionPass {
+public:
+  static char ID;
+
+  SIInsertNops() : MachineFunctionPass(ID) { }
+  const char *getPassName() const override { return PASS_NAME; }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+};
+
+} // anonymous namespace
+
+INITIALIZE_PASS(SIInsertNops, DEBUG_TYPE, PASS_NAME, false, false)
+
+char SIInsertNops::ID = 0;
+char &llvm::SIInsertNopsID = SIInsertNops::ID;
+
+FunctionPass *llvm::createSIInsertNopsPass() {
+  return new SIInsertNops();
+}
+
+bool SIInsertNops::runOnMachineFunction(MachineFunction &MF) {
+  const SIInstrInfo *TII =
+    static_cast<const SIInstrInfo*>(MF.getSubtarget().getInstrInfo());
+
+  DenseMap<unsigned, MachineBasicBlock::iterator> LineToInst;
+  for (auto MBB = MF.begin(); MBB != MF.end(); ++MBB) {
+    for (auto MI = MBB->begin(); MI != MBB->end(); ++MI) {
+      if (MI->isDebugValue() || !MI->getDebugLoc()) {
+        continue;
+      }
+      auto DL = MI->getDebugLoc();
+      auto CL = DL.getLine();
+      auto LineToInstEntry = LineToInst.find(CL);
+      if (LineToInstEntry == LineToInst.end()) {
+        BuildMI(*MBB, *MI, DL, TII->get(AMDGPU::S_NOP))
+          .addImm(0);
+        LineToInst.insert(std::make_pair(CL, MI));
+      } else {
+        LineToInstEntry->second = MI;
+      }
+    }
+  }
+  for (auto LineToInstEntry = LineToInst.begin();
+         LineToInstEntry != LineToInst.end(); ++LineToInstEntry) {
+    auto MBB = LineToInstEntry->second->getParent();
+    auto DL = LineToInstEntry->second->getDebugLoc();
+    MachineBasicBlock::iterator MI = LineToInstEntry->second;
+    ++MI;
+    if (MI != MBB->end()) {
+      BuildMI(*MBB, *MI, DL, TII->get(AMDGPU::S_NOP))
+        .addImm(0);
+    }
+  }
+  MachineBasicBlock &MBB = MF.front();
+  MachineInstr &MI = MBB.front();
+  BuildMI(MBB, MI, DebugLoc(), TII->get(AMDGPU::S_NOP))
+    .addImm(0);
+
+  return true;
+}