DebugInfo: Remove special iterators from DIExpression

Remove special iterators from `DIExpression` in favour of same in
`MDExpression`.  There should be no functionality change here.

Note that the APIs are slightly different: `getArg(unsigned)` counts
from 0, not 1, in the `MDExpression` version of the iterator.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234285 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/DebugInfo.h

@@ -872,66 +872,6 @@ public:
   uint64_t getBitPieceOffset() const;
   /// \brief Return the size of this piece in bits.
   uint64_t getBitPieceSize() const;
-
-  class iterator;
-  /// \brief A lightweight wrapper around an element of a DIExpression.
-  class Operand {
-    friend class iterator;
-    MDExpression::element_iterator I;
-    Operand() {}
-    Operand(MDExpression::element_iterator I) : I(I) {}
-  public:
-    /// \brief Operands such as DW_OP_piece have explicit (non-stack) arguments.
-    /// Argument 0 is the operand itself.
-    uint64_t getArg(unsigned N) const {
-      MDExpression::element_iterator In = I;
-      std::advance(In, N);
-      return *In;
-    }
-    operator uint64_t () const { return *I; }
-    /// \brief Returns underlying MDExpression::element_iterator.
-    const MDExpression::element_iterator &getBase() const { return I; }
-    /// \brief Returns the next operand.
-    iterator getNext() const;
-  };
-
-  /// \brief An iterator for DIExpression elements.
-  class iterator : public std::iterator<std::input_iterator_tag, StringRef,
-                                        unsigned, const Operand*, Operand> {
-    friend class Operand;
-    MDExpression::element_iterator I;
-    Operand Tmp;
-
-  public:
-    iterator(MDExpression::element_iterator I) : I(I) {}
-    const Operand &operator*() { return Tmp = Operand(I); }
-    const Operand *operator->() { return &(Tmp = Operand(I)); }
-    iterator &operator++() {
-      increment();
-      return *this;
-    }
-    iterator operator++(int) {
-      iterator X(*this);
-      increment();
-      return X;
-    }
-    bool operator==(const iterator &X) const { return I == X.I; }
-    bool operator!=(const iterator &X) const { return !(*this == X); }
-
-  private:
-    void increment() {
-      switch (**this) {
-      case dwarf::DW_OP_bit_piece: std::advance(I, 3); break;
-      case dwarf::DW_OP_plus:      std::advance(I, 2); break;
-      case dwarf::DW_OP_deref:     std::advance(I, 1); break;
-      default:
-        llvm_unreachable("unsupported operand");
-      }
-    }
-  };
-
-  iterator begin() const { return get()->elements_begin(); }
-  iterator end() const { return get()->elements_end(); }
 };
 
 /// \brief This object holds location information.

include/llvm/IR/DebugInfoMetadata.h

@@ -1885,6 +1885,13 @@ public:
       return T;
     }
 
+    /// \brief Get the next iterator.
+    ///
+    /// \a std::next() doesn't work because this is technically an
+    /// input_iterator, but it's a perfectly valid operation.  This is an
+    /// accessor to provide the same functionality.
+    expr_op_iterator getNext() const { return ++expr_op_iterator(*this); }
+
     bool operator==(const expr_op_iterator &X) const {
       return getBase() == X.getBase();
     }

lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -523,7 +523,7 @@ DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
     assert(Expr != DV.getExpression().end() &&
            "Wrong number of expressions");
     DwarfExpr.AddMachineRegIndirect(FrameReg, Offset);
-    DwarfExpr.AddExpression(Expr->begin(), Expr->end());
+    DwarfExpr.AddExpression((*Expr)->expr_op_begin(), (*Expr)->expr_op_end());
     ++Expr;
   }
   addBlock(*VariableDie, dwarf::DW_AT_location, Loc);
@@ -773,7 +773,7 @@ void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
     ValidReg = DwarfExpr.AddMachineRegIndirect(Location.getReg(),
                                                Location.getOffset());
     if (ValidReg)
-      DwarfExpr.AddExpression(Expr.begin(), Expr.end());
+      DwarfExpr.AddExpression(Expr->expr_op_begin(), Expr->expr_op_end());
   } else
     ValidReg = DwarfExpr.AddMachineRegExpression(Expr, Location.getReg());
 

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1511,7 +1511,8 @@ static void emitDebugLocValue(const AsmPrinter &AP,
       // Complex address entry.
       if (Loc.getOffset()) {
         DwarfExpr.AddMachineRegIndirect(Loc.getReg(), Loc.getOffset());
-        DwarfExpr.AddExpression(Expr.begin(), Expr.end(), PieceOffsetInBits);
+        DwarfExpr.AddExpression(Expr->expr_op_begin(), Expr->expr_op_end(),
+                                PieceOffsetInBits);
       } else
         DwarfExpr.AddMachineRegExpression(Expr, Loc.getReg(),
                                           PieceOffsetInBits);

lib/CodeGen/AsmPrinter/DwarfExpression.cpp

@@ -195,27 +195,27 @@ static unsigned getOffsetOrZero(unsigned OffsetInBits,
 bool DwarfExpression::AddMachineRegExpression(DIExpression Expr,
                                               unsigned MachineReg,
                                               unsigned PieceOffsetInBits) {
-  auto I = Expr.begin();
+  auto I = Expr->expr_op_begin();
-  auto E = Expr.end();
+  auto E = Expr->expr_op_end();
   if (I == E)
     return AddMachineRegPiece(MachineReg);
 
   // Pattern-match combinations for which more efficient representations exist
   // first.
   bool ValidReg = false;
-  switch (*I) {
+  switch (I->getOp()) {
   case dwarf::DW_OP_bit_piece: {
-    unsigned OffsetInBits = I->getArg(1);
+    unsigned OffsetInBits = I->getArg(0);
-    unsigned SizeInBits   = I->getArg(2);
+    unsigned SizeInBits   = I->getArg(1);
     // Piece always comes at the end of the expression.
     return AddMachineRegPiece(MachineReg, SizeInBits,
                getOffsetOrZero(OffsetInBits, PieceOffsetInBits));
   }
   case dwarf::DW_OP_plus: {
     // [DW_OP_reg,Offset,DW_OP_plus,DW_OP_deref] --> [DW_OP_breg,Offset].
-    auto N = I->getNext();
+    auto N = I.getNext();
-    if ((N != E) && (*N == dwarf::DW_OP_deref)) {
+    if (N != E && N->getOp() == dwarf::DW_OP_deref) {
-      unsigned Offset = I->getArg(1);
+      unsigned Offset = I->getArg(0);
       ValidReg = AddMachineRegIndirect(MachineReg, Offset);
       std::advance(I, 2);
       break;
@@ -240,20 +240,20 @@ bool DwarfExpression::AddMachineRegExpression(DIExpression Expr,
   return true;
 }
 
-void DwarfExpression::AddExpression(DIExpression::iterator I,
+void DwarfExpression::AddExpression(MDExpression::expr_op_iterator I,
-                                    DIExpression::iterator E,
+                                    MDExpression::expr_op_iterator E,
                                     unsigned PieceOffsetInBits) {
   for (; I != E; ++I) {
-    switch (*I) {
+    switch (I->getOp()) {
     case dwarf::DW_OP_bit_piece: {
-      unsigned OffsetInBits = I->getArg(1);
+      unsigned OffsetInBits = I->getArg(0);
-      unsigned SizeInBits   = I->getArg(2);
+      unsigned SizeInBits   = I->getArg(1);
       AddOpPiece(SizeInBits, getOffsetOrZero(OffsetInBits, PieceOffsetInBits));
       break;
     }
     case dwarf::DW_OP_plus:
       EmitOp(dwarf::DW_OP_plus_uconst);
-      EmitUnsigned(I->getArg(1));
+      EmitUnsigned(I->getArg(0));
       break;
     case dwarf::DW_OP_deref:
       EmitOp(dwarf::DW_OP_deref);

lib/CodeGen/AsmPrinter/DwarfExpression.h

@@ -97,7 +97,8 @@ public:
   /// Emit a the operations remaining the DIExpressionIterator I.
   /// \param PieceOffsetInBits If this is one piece out of a fragmented
   /// location, this is the offset of the piece inside the entire variable.
-  void AddExpression(DIExpression::iterator I, DIExpression::iterator E,
+  void AddExpression(MDExpression::expr_op_iterator I,
+                     MDExpression::expr_op_iterator E,
                      unsigned PieceOffsetInBits = 0);
 };
 

lib/IR/DebugInfo.cpp

@@ -80,11 +80,6 @@ uint64_t DIExpression::getBitPieceSize() const {
   return getElement(getNumElements()-1);
 }
 
-DIExpression::iterator DIExpression::Operand::getNext() const {
-  iterator it(I);
-  return ++it;
-}
-
 //===----------------------------------------------------------------------===//
 // Simple Descriptor Constructors and other Methods
 //===----------------------------------------------------------------------===//