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

llvm-svn: 175023

1 files changed, 12 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index 786f353..3e31051 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/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;
+  }
 }