Debug Info: Support variables that are described by more than one MMI

table entry. This happens when SROA splits up an alloca and the resulting
allocas cannot be lowered to SSA values because their address is passed
to a function.

Fixes PR22502.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228764 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 7e147e8466ae8980a0f9bfea1a7d258a3d710288..6a8c9b5e43fea8a10b68dd52f54a39a0e8426463 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -516,15 +516,21 @@ DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
   }
 
   // .. else use frame index.
-  int FI = DV.getFrameIndex();
-  if (FI != ~0) {
+  if (DV.getFrameIndex().back() == ~0)
+    return VariableDie;
+
+  auto Expr = DV.getExpression().begin();
+  DIELoc *Loc = new (DIEValueAllocator) DIELoc();
+  DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
+  for (auto FI : DV.getFrameIndex()) {
     unsigned FrameReg = 0;
     const TargetFrameLowering *TFI =
         Asm->TM.getSubtargetImpl()->getFrameLowering();
     int Offset = TFI->getFrameIndexReference(*Asm->MF, FI, FrameReg);
-    MachineLocation Location(FrameReg, Offset);
-    addVariableAddress(DV, *VariableDie, Location);
+    DwarfExpr.AddMachineRegIndirect(FrameReg, Offset);
+    DwarfExpr.AddExpression(*(Expr++));
   }
+  addBlock(*VariableDie, dwarf::DW_AT_location, Loc);
 
   return VariableDie;
 }
@@ -767,7 +773,8 @@ void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
                                          const MachineLocation &Location) {
   DIELoc *Loc = new (DIEValueAllocator) DIELoc();
   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
-  DIExpression Expr = DV.getExpression();
+  assert(DV.getExpression().size() == 1);
+  DIExpression Expr = DV.getExpression().back();
   bool ValidReg;
   if (Location.getOffset()) {
     ValidReg = DwarfExpr.AddMachineRegIndirect(Location.getReg(),

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 8cb033a175ee010d68d52612014c1e2dc2b56eeb..3b6f4614cac6433624f50798ac81c6e537adabc8 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -783,10 +783,9 @@ void DwarfDebug::collectVariableInfoFromMMITable(
     DIVariable DV(VI.Var);
     DIExpression Expr(VI.Expr);
     ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
-    ConcreteVariables.push_back(make_unique<DbgVariable>(DV, Expr, this));
-    DbgVariable *RegVar = ConcreteVariables.back().get();
-    RegVar->setFrameIndex(VI.Slot);
-    InfoHolder.addScopeVariable(Scope, RegVar);
+    auto RegVar = make_unique<DbgVariable>(DV, Expr, this, VI.Slot);
+    if (InfoHolder.addScopeVariable(Scope, RegVar.get()))
+      ConcreteVariables.push_back(std::move(RegVar));
   }
 }
 

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index a1a94264ddddde4564948b84957692429d039871..4755c9cd1b955020f7761de3d6960a3fb41e88bc 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -67,41 +67,66 @@ public:
 
 //===----------------------------------------------------------------------===//
 /// \brief This class is used to track local variable information.
+///
+/// - Variables whose location changes over time have a DotDebugLocOffset and the
+///   other fields are not used.
+///
+/// - Variables that are described by multiple MMI table entries have multiple
+///   expressions and frame indices.
 class DbgVariable {
-  DIVariable Var;             // Variable Descriptor.
-  DIExpression Expr;          // Complex address location expression.
-  DIE *TheDIE;                // Variable DIE.
-  unsigned DotDebugLocOffset; // Offset in DotDebugLocEntries.
-  const MachineInstr *MInsn;  // DBG_VALUE instruction of the variable.
-  int FrameIndex;
+  DIVariable Var;             /// Variable Descriptor.
+  SmallVector<DIExpression, 1> Expr; /// Complex address location expression.
+  DIE *TheDIE;                /// Variable DIE.
+  unsigned DotDebugLocOffset; /// Offset in DotDebugLocEntries.
+  const MachineInstr *MInsn;  /// DBG_VALUE instruction of the variable.
+  SmallVector<int, 1> FrameIndex; /// Frame index of the variable.
   DwarfDebug *DD;
 
 public:
   /// Construct a DbgVariable from a DIVariable.
-  DbgVariable(DIVariable V, DIExpression E, DwarfDebug *DD)
-      : Var(V), Expr(E), TheDIE(nullptr), DotDebugLocOffset(~0U),
-        MInsn(nullptr), FrameIndex(~0), DD(DD) {
-    assert(Var.Verify() && Expr.Verify());
+    DbgVariable(DIVariable V, DIExpression E, DwarfDebug *DD, int FI = ~0)
+    : Var(V), Expr(1, E), TheDIE(nullptr), DotDebugLocOffset(~0U),
+      MInsn(nullptr), DD(DD) {
+    FrameIndex.push_back(FI);
+    assert(Var.Verify() && E.Verify());
   }
 
   /// Construct a DbgVariable from a DEBUG_VALUE.
   /// AbstractVar may be NULL.
   DbgVariable(const MachineInstr *DbgValue, DwarfDebug *DD)
-      : Var(DbgValue->getDebugVariable()), Expr(DbgValue->getDebugExpression()),
-        TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(DbgValue),
-        FrameIndex(~0), DD(DD) {}
+    : Var(DbgValue->getDebugVariable()), Expr(1, DbgValue->getDebugExpression()),
+        TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(DbgValue), DD(DD) {
+    FrameIndex.push_back(~0);
+  }
 
   // Accessors.
   DIVariable getVariable() const { return Var; }
-  DIExpression getExpression() const { return Expr; }
+  const ArrayRef<DIExpression> getExpression() const { return Expr; }
   void setDIE(DIE &D) { TheDIE = &D; }
   DIE *getDIE() const { return TheDIE; }
   void setDotDebugLocOffset(unsigned O) { DotDebugLocOffset = O; }
   unsigned getDotDebugLocOffset() const { return DotDebugLocOffset; }
   StringRef getName() const { return Var.getName(); }
   const MachineInstr *getMInsn() const { return MInsn; }
-  int getFrameIndex() const { return FrameIndex; }
-  void setFrameIndex(int FI) { FrameIndex = FI; }
+  const ArrayRef<int> getFrameIndex() const { return FrameIndex; }
+
+  void addMMIEntry(const DbgVariable &V) {
+    assert(  DotDebugLocOffset == ~0U &&   !MInsn && "not an MMI entry");
+    assert(V.DotDebugLocOffset == ~0U && !V.MInsn && "not an MMI entry");
+    assert(V.Var == Var && "conflicting DIVariable");
+
+    if (V.getFrameIndex().back() != ~0) {
+      auto E = V.getExpression();
+      auto FI = V.getFrameIndex();
+      Expr.append(E.begin(), E.end());
+      FrameIndex.append(FI.begin(), FI.end());
+    }
+    assert(Expr.size() > 1
+           ? std::all_of(Expr.begin(), Expr.end(),
+                         [](DIExpression &E) { return E.isBitPiece(); })
+           : (true && "conflicting locations for variable"));
+  }
+
   // Translate tag to proper Dwarf tag.
   dwarf::Tag getTag() const {
     if (Var.getTag() == dwarf::DW_TAG_arg_variable)
@@ -128,14 +153,11 @@ public:
 
   bool variableHasComplexAddress() const {
     assert(Var.isVariable() && "Invalid complex DbgVariable!");
-    return Expr.getNumElements() > 0;
+    assert(Expr.size() == 1 &&
+           "variableHasComplexAddress() invoked on multi-FI variable");
+    return Expr.back().getNumElements() > 0;
   }
   bool isBlockByrefVariable() const;
-  unsigned getNumAddrElements() const {
-    assert(Var.isVariable() && "Invalid complex DbgVariable!");
-    return Expr.getNumElements();
-  }
-  uint64_t getAddrElement(unsigned i) const { return Expr.getElement(i); }
   DIType getType() const;
 
 private:

diff --git a/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 408f683301d0b03b53106cadd804793258d24154..3988f0def3176c3ce40b9685d8604f1d9aa184c8 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -146,7 +146,7 @@ void DwarfFile::emitStrings(const MCSection *StrSection,
   StrPool.emit(*Asm, StrSection, OffsetSection);
 }
 
-void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
+bool DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
   SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS];
   DIVariable DV = Var->getVariable();
   // Variables with positive arg numbers are parameters.
@@ -168,13 +168,17 @@ void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
       // A later indexed parameter has been found, insert immediately before it.
       if (CurNum > ArgNum)
         break;
-      assert(CurNum != ArgNum && "Duplicate argument");
+      if (CurNum == ArgNum) {
+        (*I)->addMMIEntry(*Var);
+        return false;
+      }
       ++I;
     }
     Vars.insert(I, Var);
-    return;
+    return true;
   }
 
   Vars.push_back(Var);
+  return true;
 }
 }

diff --git a/lib/CodeGen/AsmPrinter/DwarfFile.h b/lib/CodeGen/AsmPrinter/DwarfFile.h
index f14d673bf6ac02f4ef850588e599ffbfa020dba9..35bf33ab95815c91034be425b947e5367588027a 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfFile.h
+++ b/lib/CodeGen/AsmPrinter/DwarfFile.h
@@ -95,7 +95,8 @@ public:
   /// \brief Returns the string pool.
   DwarfStringPool &getStringPool() { return StrPool; }
 
-  void addScopeVariable(LexicalScope *LS, DbgVariable *Var);
+  /// \returns false if the variable was merged with a previous one.
+  bool addScopeVariable(LexicalScope *LS, DbgVariable *Var);
 
   DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8>> &getScopeVariables() {
     return ScopeVariables;