Debug Info: LiveDebugVarible can remove DBG_VALUEs, make sure we emit them back.

RegisterCoalescer used to depend on LiveDebugVariable. LDV removes DBG_VALUEs
without emitting them at the end.

We fix this by removing LDV from RegisterCoalescer. Also add an assertion to
make sure we call emitDebugValues if DBG_VALUEs are removed at
runOnMachineFunction.

rdar://problem/13183203
Reviewed by Andy & Jakob


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175023 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 16 insertions, 14 deletions

diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp
index 786f3534a1..3e31051dbc 100644
--- a/lib/CodeGen/LiveDebugVariables.cpp
+++ b/lib/CodeGen/LiveDebugVariables.cpp
@@ -64,7 +64,8 @@ void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const {
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
-LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(0) {
+LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(0),
+                                           EmitDone(false), ModifiedMF(false) {
   initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
 }
 
@@ -701,12 +702,17 @@ bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
     return false;
   if (!pImpl)
     pImpl = new LDVImpl(this);
-  return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
+  ModifiedMF = static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
+  return ModifiedMF;
 }
 
 void LiveDebugVariables::releaseMemory() {
-  if (pImpl)
+  if (pImpl) {
     static_cast<LDVImpl*>(pImpl)->clear();
+    // Make sure we call emitDebugValues if the machine function was modified.
+    assert((!ModifiedMF || EmitDone) &&
+           "Dbg values are not emitted in LDV");
+  }
 }
 
 LiveDebugVariables::~LiveDebugVariables() {
@@ -1014,8 +1020,10 @@ void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
 }
 
 void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
-  if (pImpl)
+  if (pImpl) {
     static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
+    EmitDone = true;
+  }
 }
 
 
diff --git a/lib/CodeGen/LiveDebugVariables.h b/lib/CodeGen/LiveDebugVariables.h
index 3ce3c398bd..bb4c160b30 100644
--- a/lib/CodeGen/LiveDebugVariables.h
+++ b/lib/CodeGen/LiveDebugVariables.h
@@ -31,6 +31,10 @@ class VirtRegMap;
 
 class LiveDebugVariables : public MachineFunctionPass {
   void *pImpl;
+  /// Whether emitDebugValues is called.
+  bool EmitDone;
+  /// Whether the machine function is modified during the pass.
+  bool ModifiedMF;
 public:
   static char ID; // Pass identification, replacement for typeid
 
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 36d8101422..e682d63c8f 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -15,7 +15,6 @@
 
 #define DEBUG_TYPE "regalloc"
 #include "RegisterCoalescer.h"
-#include "LiveDebugVariables.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallSet.h"
@@ -84,7 +83,6 @@ namespace {
     const TargetRegisterInfo* TRI;
     const TargetInstrInfo* TII;
     LiveIntervals *LIS;
-    LiveDebugVariables *LDV;
     const MachineLoopInfo* Loops;
     AliasAnalysis *AA;
     RegisterClassInfo RegClassInfo;
@@ -208,7 +206,6 @@ char &llvm::RegisterCoalescerID = RegisterCoalescer::ID;
 INITIALIZE_PASS_BEGIN(RegisterCoalescer, "simple-register-coalescing",
                       "Simple Register Coalescing", false, false)
 INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
-INITIALIZE_PASS_DEPENDENCY(LiveDebugVariables)
 INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
@@ -394,8 +391,6 @@ void RegisterCoalescer::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<AliasAnalysis>();
   AU.addRequired<LiveIntervals>();
   AU.addPreserved<LiveIntervals>();
-  AU.addRequired<LiveDebugVariables>();
-  AU.addPreserved<LiveDebugVariables>();
   AU.addPreserved<SlotIndexes>();
   AU.addRequired<MachineLoopInfo>();
   AU.addPreserved<MachineLoopInfo>();
@@ -883,9 +878,6 @@ void RegisterCoalescer::updateRegDefsUses(unsigned SrcReg,
   bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
   LiveInterval *DstInt = DstIsPhys ? 0 : &LIS->getInterval(DstReg);
 
-  // Update LiveDebugVariables.
-  LDV->renameRegister(SrcReg, DstReg, SubIdx);
-
   SmallPtrSet<MachineInstr*, 8> Visited;
   for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(SrcReg);
        MachineInstr *UseMI = I.skipInstruction();) {
@@ -2136,7 +2128,6 @@ bool RegisterCoalescer::runOnMachineFunction(MachineFunction &fn) {
   TRI = TM->getRegisterInfo();
   TII = TM->getInstrInfo();
   LIS = &getAnalysis<LiveIntervals>();
-  LDV = &getAnalysis<LiveDebugVariables>();
   AA = &getAnalysis<AliasAnalysis>();
   Loops = &getAnalysis<MachineLoopInfo>();
 
@@ -2182,7 +2173,6 @@ bool RegisterCoalescer::runOnMachineFunction(MachineFunction &fn) {
   }
 
   DEBUG(dump());
-  DEBUG(LDV->dump());
   if (VerifyCoalescing)
     MF->verify(this, "After register coalescing");
   return true;