Verifier: Check for incompatible bit piece expressions

Convert an assertion into a `Verifier` check.  Bit piece expressions
must fit inside the variable, and mustn't be the entire variable.
Catching this in the verifier will help us find bugs sooner, and makes
`DIVariable::getSizeInBits()` dead code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234698 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/DebugInfo.h

@@ -740,9 +740,6 @@ public:
   /// \brief Check if this is an inlined function argument.
   bool isInlinedFnArgument(const Function *CurFn);
 
-  /// \brief Return the size reported by the variable's type.
-  unsigned getSizeInBits(const DITypeIdentifierMap &Map);
-
   void printExtendedName(raw_ostream &OS) const;
 };
 

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1535,15 +1535,7 @@ void DebugLocEntry::finalize(const AsmPrinter &AP,
         Offset += PieceOffset-Offset;
       }
       Offset += PieceSize;
-   
-#ifndef NDEBUG
-      DIVariable Var = Piece.getVariable();
-      unsigned VarSize = Var.getSizeInBits(TypeIdentifierMap);
-      assert(PieceSize+PieceOffset <= VarSize
-             && "piece is larger than or outside of variable");
-      assert(PieceSize != VarSize
-             && "piece covers entire variable");
-#endif
+
       emitDebugLocValue(AP, TypeIdentifierMap, Streamer, Piece, PieceOffset);
     }
   } else {

lib/IR/DebugInfo.cpp

@@ -33,19 +33,6 @@
 using namespace llvm;
 using namespace llvm::dwarf;
 
-/// \brief Return the size reported by the variable's type.
-unsigned DIVariable::getSizeInBits(const DITypeIdentifierMap &Map) {
-  DIType Ty = getType().resolve(Map);
-  // Follow derived types until we reach a type that
-  // reports back a size.
-  while (isa<MDDerivedType>(Ty) && !Ty.getSizeInBits()) {
-    DIDerivedType DT = cast<MDDerivedType>(Ty);
-    Ty = DT.getTypeDerivedFrom().resolve(Map);
-  }
-  assert(Ty.getSizeInBits() && "type with size 0");
-  return Ty.getSizeInBits();
-}
-
 //===----------------------------------------------------------------------===//
 // Simple Descriptor Constructors and other Methods
 //===----------------------------------------------------------------------===//

lib/IR/Verifier.cpp

@@ -178,8 +178,11 @@ class Verifier : public InstVisitor<Verifier>, VerifierSupport {
   /// \brief Keep track of the metadata nodes that have been checked already.
   SmallPtrSet<const Metadata *, 32> MDNodes;
 
-  /// \brief Track string-based type references.
-  SmallDenseMap<const MDString *, const MDNode *, 32> TypeRefs;
+  /// \brief Track unresolved string-based type references.
+  SmallDenseMap<const MDString *, const MDNode *, 32> UnresolvedTypeRefs;
+
+  /// \brief Track queue of bit piece expressions to verify.
+  SmallVector<const DbgInfoIntrinsic *, 32> QueuedBitPieceExpressions;
 
   /// \brief The personality function referenced by the LandingPadInsts.
   /// All LandingPadInsts within the same function must use the same
@@ -407,6 +410,9 @@ private:
 
   // Module-level debug info verification...
   void verifyTypeRefs();
+  template <class MapTy>
+  void verifyBitPieceExpression(const DbgInfoIntrinsic &I,
+                                const MapTy &TypeRefs);
   void visitUnresolvedTypeRef(const MDString *S, const MDNode *N);
 };
 } // End anonymous namespace
@@ -702,7 +708,7 @@ bool Verifier::isValidUUID(const MDNode &N, const Metadata *MD) {
 
   // Keep track of names of types referenced via UUID so we can check that they
   // actually exist.
-  TypeRefs.insert(std::make_pair(S, &N));
+  UnresolvedTypeRefs.insert(std::make_pair(S, &N));
   return true;
 }
 
@@ -3375,6 +3381,11 @@ void Verifier::visitDbgIntrinsic(StringRef Kind, DbgIntrinsicTy &DII) {
          "invalid llvm.dbg." + Kind + " intrinsic expression", &DII,
          DII.getRawExpression());
 
+  // Queue up bit piece expressions to be verified once we can resolve
+  // typerefs.
+  if (DII.getExpression()->isValid() && DII.getExpression()->isBitPiece())
+    QueuedBitPieceExpressions.push_back(&DII);
+
   // Ignore broken !dbg attachments; they're checked elsewhere.
   if (MDNode *N = DII.getDebugLoc().getAsMDNode())
     if (!isa<MDLocation>(N))
@@ -3390,6 +3401,66 @@ void Verifier::visitDbgIntrinsic(StringRef Kind, DbgIntrinsicTy &DII) {
          BB ? BB->getParent() : nullptr, Var, VarIA, Loc, LocIA);
 }
 
+template <class MapTy>
+static uint64_t getVariableSize(const MDLocalVariable &V, const MapTy &Map) {
+  // Be careful of broken types (checked elsewhere).
+  const Metadata *RawType = V.getRawType();
+  while (RawType) {
+    // Try to get the size directly.
+    if (auto *T = dyn_cast<MDType>(RawType))
+      if (uint64_t Size = T->getSizeInBits())
+        return Size;
+
+    if (auto *DT = dyn_cast<MDDerivedType>(RawType)) {
+      // Look at the base type.
+      RawType = DT->getRawBaseType();
+      continue;
+    }
+
+    if (auto *S = dyn_cast<MDString>(RawType)) {
+      // Don't error on missing types (checked elsewhere).
+      RawType = Map.lookup(S);
+      continue;
+    }
+
+    // Missing type or size.
+    break;
+  }
+
+  // Fail gracefully.
+  return 0;
+}
+
+template <class MapTy>
+void Verifier::verifyBitPieceExpression(const DbgInfoIntrinsic &I,
+                                        const MapTy &TypeRefs) {
+  MDLocalVariable *V;
+  MDExpression *E;
+  if (auto *DVI = dyn_cast<DbgValueInst>(&I)) {
+    V = DVI->getVariable();
+    E = DVI->getExpression();
+  } else {
+    auto *DDI = cast<DbgDeclareInst>(&I);
+    V = DDI->getVariable();
+    E = DDI->getExpression();
+  }
+
+  assert(V && E->isValid() && E->isBitPiece() &&
+         "Expected valid bitpieces here");
+
+  // If there's no size, the type is broken, but that should be checked
+  // elsewhere.
+  uint64_t VarSize = getVariableSize(*V, TypeRefs);
+  if (!VarSize)
+    return;
+
+  unsigned PieceSize = E->getBitPieceSize();
+  unsigned PieceOffset = E->getBitPieceOffset();
+  Assert(PieceSize + PieceOffset <= VarSize,
+         "piece is larger than or outside of variable", &I, V, E);
+  Assert(PieceSize != VarSize, "piece covers entire variable", &I, V, E);
+}
+
 void Verifier::visitUnresolvedTypeRef(const MDString *S, const MDNode *N) {
   // This is in its own function so we get an error for each bad type ref (not
   // just the first).
@@ -3401,18 +3472,29 @@ void Verifier::verifyTypeRefs() {
   if (!CUs)
     return;
 
-  // Visit all the compile units again to check the type references.
+  // Visit all the compile units again to map the type references.
+  SmallDenseMap<const MDString *, const MDType *, 32> TypeRefs;
   for (auto *CU : CUs->operands())
     if (auto Ts = cast<MDCompileUnit>(CU)->getRetainedTypes())
       for (MDType *Op : Ts)
         if (auto *T = dyn_cast<MDCompositeType>(Op))
-          TypeRefs.erase(T->getRawIdentifier());
-  if (TypeRefs.empty())
+          if (auto *S = T->getRawIdentifier()) {
+            UnresolvedTypeRefs.erase(S);
+            TypeRefs.insert(std::make_pair(S, T));
+          }
+
+  // Verify debug intrinsic bit piece expressions.
+  for (auto *DII : QueuedBitPieceExpressions)
+    verifyBitPieceExpression(*DII, TypeRefs);
+
+  // Return early if all typerefs were resolved.
+  if (UnresolvedTypeRefs.empty())
     return;
 
   // Sort the unresolved references by name so the output is deterministic.
   typedef std::pair<const MDString *, const MDNode *> TypeRef;
-  SmallVector<TypeRef, 32> Unresolved(TypeRefs.begin(), TypeRefs.end());
+  SmallVector<TypeRef, 32> Unresolved(UnresolvedTypeRefs.begin(),
+                                      UnresolvedTypeRefs.end());
   std::sort(Unresolved.begin(), Unresolved.end(),
             [](const TypeRef &LHS, const TypeRef &RHS) {
     return LHS.first->getString() < RHS.first->getString();