Don't try to construct debug LexicalScopes hierarchy for functions that do not have top level debug information.

If a function isn't actually in a CU's subprogram list in the debug info
metadata, ignore all the DebugLocs and don't try to build scopes, track
variables, etc.

While this is possibly a minor optimization, it's also a correctness fix
for an incoming patch that will add assertions to LexicalScopes and the
debug info verifier to ensure that all scope chains lead to debug info
for the current function.

Fix up a few test cases that had broken/incomplete debug info that could
violate this constraint.

Add a test case where this occurs by design (inlining a
debug-info-having function in an attribute nodebug function - we want
this to work because /if/ the nodebug function is then inlined into a
debug-info-having function, it should be fine (and will work fine - we
just stitch the scopes up as usual), but should the inlining not happen
we need to not assert fail either).

llvm-svn: 212203

4 files changed, 26 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index f78ca2c03b4..7c7f1c6ff5e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -730,6 +730,8 @@ void DwarfDebug::beginModule() {
 
   const Module *M = MMI->getModule();
 
+  FunctionDIs = makeSubprogramMap(*M);
+
   // If module has named metadata anchors then use them, otherwise scan the
   // module using debug info finder to collect debug info.
   NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
@@ -1415,6 +1417,10 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   if (!MMI->hasDebugInfo())
     return;
 
+  auto DI = FunctionDIs.find(MF->getFunction());
+  if (DI == FunctionDIs.end())
+    return;
+
   // Grab the lexical scopes for the function, if we don't have any of those
   // then we're not going to be able to do anything.
   LScopes.initialize(*MF);
@@ -1430,6 +1436,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   // belongs to so that we add to the correct per-cu line table in the
   // non-asm case.
   LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
+  assert(FnScope->getScopeNode() == DI->second);
   DwarfCompileUnit *TheCU = SPMap.lookup(FnScope->getScopeNode());
   assert(TheCU && "Unable to find compile unit!");
   if (Asm->OutStreamer.hasRawTextSupport())
@@ -1527,7 +1534,8 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
     assert(CurFn == MF);
   assert(CurFn != nullptr);
 
-  if (!MMI->hasDebugInfo() || LScopes.empty()) {
+  if (!MMI->hasDebugInfo() || LScopes.empty() ||
+      !FunctionDIs.count(MF->getFunction())) {
     // If we don't have a lexical scope for this function then there will
     // be a hole in the range information. Keep note of this by setting the
     // previously used section to nullptr.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index f2aa80845a0..ffe4843b987 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -330,6 +330,8 @@ class DwarfDebug : public AsmPrinterHandler {
   DwarfAccelTable AccelNamespace;
   DwarfAccelTable AccelTypes;
 
+  DenseMap<const Function *, DISubprogram> FunctionDIs;
+
   MCDwarfDwoLineTable *getDwoLineTable(const DwarfCompileUnit &);
 
   void addScopeVariable(LexicalScope *LS, DbgVariable *Var);
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index 388f58fde2a..7d5646bebfa 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -329,12 +329,13 @@ class LDVImpl {
   void computeIntervals();
 
 public:
-  LDVImpl(LiveDebugVariables *ps) : pass(*ps), EmitDone(false),
-                                    ModifiedMF(false) {}
+  LDVImpl(LiveDebugVariables *ps)
+      : pass(*ps), MF(nullptr), EmitDone(false), ModifiedMF(false) {}
   bool runOnMachineFunction(MachineFunction &mf);
 
   /// clear - Release all memory.
   void clear() {
+    MF = nullptr;
     userValues.clear();
     virtRegToEqClass.clear();
     userVarMap.clear();
@@ -693,11 +694,11 @@ void LDVImpl::computeIntervals() {
 }
 
 bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
+  clear();
   MF = &mf;
   LIS = &pass.getAnalysis<LiveIntervals>();
   MDT = &pass.getAnalysis<MachineDominatorTree>();
   TRI = mf.getTarget().getRegisterInfo();
-  clear();
   LS.initialize(mf);
   DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
                << mf.getName() << " **********\n");
@@ -712,6 +713,8 @@ bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
 bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
   if (!EnableLDV)
     return false;
+  if (!FunctionDIs.count(mf.getFunction()))
+    return false;
   if (!pImpl)
     pImpl = new LDVImpl(this);
   return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
@@ -974,6 +977,8 @@ void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
 
 void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
   DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
+  if (!MF)
+    return;
   const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
   for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
     DEBUG(userValues[i]->print(dbgs(), &MF->getTarget()));
@@ -988,6 +993,10 @@ void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
     static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
 }
 
+bool LiveDebugVariables::doInitialization(Module &M) {
+  FunctionDIs = makeSubprogramMap(M);
+  return Pass::doInitialization(M);
+}
 
 #ifndef NDEBUG
 void LiveDebugVariables::dump() {
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.h b/llvm/lib/CodeGen/LiveDebugVariables.h
index bb6743547e3..7ec0d17e42d 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.h
+++ b/llvm/lib/CodeGen/LiveDebugVariables.h
@@ -22,6 +22,7 @@
 #define LLVM_CODEGEN_LIVEDEBUGVARIABLES_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 
 namespace llvm {
@@ -32,6 +33,7 @@ class VirtRegMap;
 
 class LiveDebugVariables : public MachineFunctionPass {
   void *pImpl;
+  DenseMap<const Function*, DISubprogram> FunctionDIs;
 public:
   static char ID; // Pass identification, replacement for typeid
 
@@ -64,6 +66,7 @@ private:
   bool runOnMachineFunction(MachineFunction &) override;
   void releaseMemory() override;
   void getAnalysisUsage(AnalysisUsage &) const override;
+  bool doInitialization(Module &) override;
 
 };