1 files changed, 92 insertions, 78 deletions

diff --git a/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp b/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
index 7dbc6cb..61b2c7e6 100644
--- a/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
+++ b/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
@@ -46,7 +46,9 @@ void DwarfExpression::AddRegIndirect(int DwarfReg, int Offset, bool Deref) {
 }
 
 void DwarfExpression::AddOpPiece(unsigned SizeInBits, unsigned OffsetInBits) {
-  assert(SizeInBits > 0 && "piece has size zero");
+  if (!SizeInBits)
+    return;
+
   const unsigned SizeOfByte = 8;
   if (OffsetInBits > 0 || SizeInBits % SizeOfByte) {
     EmitOp(dwarf::DW_OP_bit_piece);
@@ -57,6 +59,7 @@ void DwarfExpression::AddOpPiece(unsigned SizeInBits, unsigned OffsetInBits) {
     unsigned ByteSize = SizeInBits / SizeOfByte;
     EmitUnsigned(ByteSize);
   }
+  this->OffsetInBits += SizeInBits;
 }
 
 void DwarfExpression::AddShr(unsigned ShiftBy) {
@@ -82,10 +85,8 @@ bool DwarfExpression::AddMachineRegIndirect(const TargetRegisterInfo &TRI,
   return true;
 }
 
-bool DwarfExpression::AddMachineRegPiece(const TargetRegisterInfo &TRI,
-                                         unsigned MachineReg,
-                                         unsigned PieceSizeInBits,
-                                         unsigned PieceOffsetInBits) {
+bool DwarfExpression::AddMachineReg(const TargetRegisterInfo &TRI,
+                                    unsigned MachineReg, unsigned MaxSize) {
   if (!TRI.isPhysicalRegister(MachineReg))
     return false;
 
@@ -94,13 +95,11 @@ bool DwarfExpression::AddMachineRegPiece(const TargetRegisterInfo &TRI,
   // If this is a valid register number, emit it.
   if (Reg >= 0) {
     AddReg(Reg);
-    if (PieceSizeInBits)
-      AddOpPiece(PieceSizeInBits, PieceOffsetInBits);
     return true;
   }
 
   // Walk up the super-register chain until we find a valid number.
-  // For example, EAX on x86_64 is a 32-bit piece of RAX with offset 0.
+  // For example, EAX on x86_64 is a 32-bit fragment of RAX with offset 0.
   for (MCSuperRegIterator SR(MachineReg, &TRI); SR.isValid(); ++SR) {
     Reg = TRI.getDwarfRegNum(*SR, false);
     if (Reg >= 0) {
@@ -108,27 +107,15 @@ bool DwarfExpression::AddMachineRegPiece(const TargetRegisterInfo &TRI,
       unsigned Size = TRI.getSubRegIdxSize(Idx);
       unsigned RegOffset = TRI.getSubRegIdxOffset(Idx);
       AddReg(Reg, "super-register");
-      if (PieceOffsetInBits == RegOffset) {
-        AddOpPiece(Size, RegOffset);
-      } else {
-        // If this is part of a variable in a sub-register at a
-        // non-zero offset, we need to manually shift the value into
-        // place, since the DW_OP_piece describes the part of the
-        // variable, not the position of the subregister.
-        if (RegOffset)
-          AddShr(RegOffset);
-        AddOpPiece(Size, PieceOffsetInBits);
-      }
+      // Use a DW_OP_bit_piece to describe the sub-register.
+      setSubRegisterPiece(Size, RegOffset);
       return true;
     }
   }
 
   // Otherwise, attempt to find a covering set of sub-register numbers.
   // For example, Q0 on ARM is a composition of D0+D1.
-  //
-  // Keep track of the current position so we can emit the more
-  // efficient DW_OP_piece.
-  unsigned CurPos = PieceOffsetInBits;
+  unsigned CurPos = 0;
   // The size of the register in bits, assuming 8 bits per byte.
   unsigned RegSize = TRI.getMinimalPhysRegClass(MachineReg)->getSize() * 8;
   // Keep track of the bits in the register we already emitted, so we
@@ -150,7 +137,12 @@ bool DwarfExpression::AddMachineRegPiece(const TargetRegisterInfo &TRI,
     // its range, emit a DWARF piece for it.
     if (Reg >= 0 && Intersection.any()) {
       AddReg(Reg, "sub-register");
-      AddOpPiece(Size, Offset == CurPos ? 0 : Offset);
+      if (Offset >= MaxSize)
+	break;
+      // Emit a piece for the any gap in the coverage.
+      if (Offset > CurPos)
+        AddOpPiece(Offset - CurPos);
+      AddOpPiece(std::min<unsigned>(Size, MaxSize - Offset));
       CurPos = Offset + Size;
 
       // Mark it as emitted.
@@ -158,7 +150,7 @@ bool DwarfExpression::AddMachineRegPiece(const TargetRegisterInfo &TRI,
     }
   }
 
-  return CurPos > PieceOffsetInBits;
+  return CurPos;
 }
 
 void DwarfExpression::AddStackValue() {
@@ -194,92 +186,114 @@ void DwarfExpression::AddUnsignedConstant(const APInt &Value) {
   }
 }
 
-static unsigned getOffsetOrZero(unsigned OffsetInBits,
-                                unsigned PieceOffsetInBits) {
-  if (OffsetInBits == PieceOffsetInBits)
-    return 0;
-  assert(OffsetInBits >= PieceOffsetInBits && "overlapping pieces");
-  return OffsetInBits;
-}
-
 bool DwarfExpression::AddMachineRegExpression(const TargetRegisterInfo &TRI,
-                                              const DIExpression *Expr,
+                                              DIExpressionCursor &ExprCursor,
                                               unsigned MachineReg,
-                                              unsigned PieceOffsetInBits) {
-  auto I = Expr->expr_op_begin();
-  auto E = Expr->expr_op_end();
-  if (I == E)
-    return AddMachineRegPiece(TRI, MachineReg);
+                                              unsigned FragmentOffsetInBits) {
+  if (!ExprCursor)
+    return AddMachineReg(TRI, MachineReg);
 
   // Pattern-match combinations for which more efficient representations exist
   // first.
   bool ValidReg = false;
-  switch (I->getOp()) {
-  case dwarf::DW_OP_bit_piece: {
-    unsigned OffsetInBits = I->getArg(0);
-    unsigned SizeInBits   = I->getArg(1);
-    // Piece always comes at the end of the expression.
-    return AddMachineRegPiece(TRI, MachineReg, SizeInBits,
-               getOffsetOrZero(OffsetInBits, PieceOffsetInBits));
+  auto Op = ExprCursor.peek();
+  switch (Op->getOp()) {
+  default: {
+    auto Fragment = ExprCursor.getFragmentInfo();
+    ValidReg = AddMachineReg(TRI, MachineReg,
+			     Fragment ? Fragment->SizeInBits : ~1U);
+    break;
   }
   case dwarf::DW_OP_plus:
   case dwarf::DW_OP_minus: {
     // [DW_OP_reg,Offset,DW_OP_plus, DW_OP_deref] --> [DW_OP_breg, Offset].
     // [DW_OP_reg,Offset,DW_OP_minus,DW_OP_deref] --> [DW_OP_breg,-Offset].
-    auto N = I.getNext();
-    if (N != E && N->getOp() == dwarf::DW_OP_deref) {
-      unsigned Offset = I->getArg(0);
+    auto N = ExprCursor.peekNext();
+    if (N && N->getOp() == dwarf::DW_OP_deref) {
+      unsigned Offset = Op->getArg(0);
       ValidReg = AddMachineRegIndirect(
-          TRI, MachineReg, I->getOp() == dwarf::DW_OP_plus ? Offset : -Offset);
-      std::advance(I, 2);
-      break;
+          TRI, MachineReg, Op->getOp() == dwarf::DW_OP_plus ? Offset : -Offset);
+      ExprCursor.consume(2);
     } else
-      ValidReg = AddMachineRegPiece(TRI, MachineReg);
-  }
-  case dwarf::DW_OP_deref: {
-      // [DW_OP_reg,DW_OP_deref] --> [DW_OP_breg].
-      ValidReg = AddMachineRegIndirect(TRI, MachineReg);
-      ++I;
-      break;
+      ValidReg = AddMachineReg(TRI, MachineReg);
+    break;
   }
-  default:
-    llvm_unreachable("unsupported operand");
+  case dwarf::DW_OP_deref:
+    // [DW_OP_reg,DW_OP_deref] --> [DW_OP_breg].
+    ValidReg = AddMachineRegIndirect(TRI, MachineReg);
+    ExprCursor.take();
+    break;
   }
 
-  if (!ValidReg)
-    return false;
-
-  // Emit remaining elements of the expression.
-  AddExpression(I, E, PieceOffsetInBits);
-  return true;
+  return ValidReg;
 }
 
-void DwarfExpression::AddExpression(DIExpression::expr_op_iterator I,
-                                    DIExpression::expr_op_iterator E,
-                                    unsigned PieceOffsetInBits) {
-  for (; I != E; ++I) {
-    switch (I->getOp()) {
-    case dwarf::DW_OP_bit_piece: {
-      unsigned OffsetInBits = I->getArg(0);
-      unsigned SizeInBits   = I->getArg(1);
-      AddOpPiece(SizeInBits, getOffsetOrZero(OffsetInBits, PieceOffsetInBits));
+void DwarfExpression::AddExpression(DIExpressionCursor &&ExprCursor,
+                                    unsigned FragmentOffsetInBits) {
+  while (ExprCursor) {
+    auto Op = ExprCursor.take();
+    switch (Op->getOp()) {
+    case dwarf::DW_OP_LLVM_fragment: {
+      unsigned SizeInBits = Op->getArg(1);
+      unsigned FragmentOffset = Op->getArg(0);
+      // The fragment offset must have already been adjusted by emitting an
+      // empty DW_OP_piece / DW_OP_bit_piece before we emitted the base
+      // location.
+      assert(OffsetInBits >= FragmentOffset && "fragment offset not added?");
+
+      // If \a AddMachineReg already emitted DW_OP_piece operations to represent
+      // a super-register by splicing together sub-registers, subtract the size
+      // of the pieces that was already emitted.
+      SizeInBits -= OffsetInBits - FragmentOffset;
+
+      // If \a AddMachineReg requested a DW_OP_bit_piece to stencil out a
+      // sub-register that is smaller than the current fragment's size, use it.
+      if (SubRegisterSizeInBits)
+        SizeInBits = std::min<unsigned>(SizeInBits, SubRegisterSizeInBits);
+      
+      AddOpPiece(SizeInBits, SubRegisterOffsetInBits);
+      setSubRegisterPiece(0, 0);
       break;
     }
     case dwarf::DW_OP_plus:
       EmitOp(dwarf::DW_OP_plus_uconst);
-      EmitUnsigned(I->getArg(0));
+      EmitUnsigned(Op->getArg(0));
       break;
     case dwarf::DW_OP_minus:
       // There is no OP_minus_uconst.
       EmitOp(dwarf::DW_OP_constu);
-      EmitUnsigned(I->getArg(0));
+      EmitUnsigned(Op->getArg(0));
       EmitOp(dwarf::DW_OP_minus);
       break;
     case dwarf::DW_OP_deref:
       EmitOp(dwarf::DW_OP_deref);
       break;
+    case dwarf::DW_OP_constu:
+      EmitOp(dwarf::DW_OP_constu);
+      EmitUnsigned(Op->getArg(0));
+      break;
+    case dwarf::DW_OP_stack_value:
+      AddStackValue();
+      break;
     default:
       llvm_unreachable("unhandled opcode found in expression");
     }
   }
 }
+
+void DwarfExpression::finalize() {
+  if (SubRegisterSizeInBits)
+    AddOpPiece(SubRegisterSizeInBits, SubRegisterOffsetInBits);
+}
+
+void DwarfExpression::addFragmentOffset(const DIExpression *Expr) {
+  if (!Expr || !Expr->isFragment())
+    return;
+
+  uint64_t FragmentOffset = Expr->getFragmentInfo()->OffsetInBits;
+  assert(FragmentOffset >= OffsetInBits &&
+         "overlapping or duplicate fragments");
+  if (FragmentOffset > OffsetInBits)
+    AddOpPiece(FragmentOffset - OffsetInBits);
+  OffsetInBits = FragmentOffset;
+}