Remove support for DIVariable's FlagIndirectVariable and expect

frontends to use a DIExpression with a DW_OP_deref instead.

This is not only a much more natural place for this informationl; there
is also a technical reason: The FlagIndirectVariable is used to mark a
variable that is turned into a reference by virtue of the calling
convention; this happens for example to aggregate return values.
The inliner, for example, may actually need to undo this indirection to
correctly represent the value in its new context. This is impossible to
implement because the DIVariable can't be safely modified. We can however
safely construct a new DIExpression on the fly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226476 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

@@ -228,14 +228,13 @@ void AsmPrinter::EmitDwarfOpPiece(ByteStreamer &Streamer,
 
 /// EmitDwarfRegOp - Emit dwarf register operation.
 void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
-                                const MachineLocation &MLoc,
-                                bool Indirect) const {
+                                const MachineLocation &MLoc) const {
   DebugLocDwarfExpression Expr(*this, Streamer);
   const TargetRegisterInfo *TRI = TM.getSubtargetImpl()->getRegisterInfo();
   int Reg = TRI->getDwarfRegNum(MLoc.getReg(), false);
   if (Reg < 0) {
     // We assume that pointers are always in an addressable register.
-    if (Indirect || MLoc.isIndirect())
+    if (MLoc.isIndirect())
       // FIXME: We have no reasonable way of handling errors in here. The
       // caller might be in the middle of a dwarf expression. We should
       // probably assert that Reg >= 0 once debug info generation is more
@@ -251,9 +250,7 @@ void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
   }
 
   if (MLoc.isIndirect())
-    Expr.AddRegIndirect(Reg, MLoc.getOffset(), Indirect);
-  else if (Indirect)
-    Expr.AddRegIndirect(Reg, 0, false);
+    Expr.AddRegIndirect(Reg, MLoc.getOffset());
   else
     Expr.AddReg(Reg);
 }

lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -737,18 +737,16 @@ void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
   else if (DV.isBlockByrefVariable())
     addBlockByrefAddress(DV, Die, dwarf::DW_AT_location, Location);
   else
-    addAddress(Die, dwarf::DW_AT_location, Location,
-               DV.getVariable().isIndirect());
+    addAddress(Die, dwarf::DW_AT_location, Location);
 }
 
 /// Add an address attribute to a die based on the location provided.
 void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
-                                  const MachineLocation &Location,
-                                  bool Indirect) {
+                                  const MachineLocation &Location) {
   DIELoc *Loc = new (DIEValueAllocator) DIELoc();
 
   bool validReg;
-  if (Location.isReg() && !Indirect)
+  if (Location.isReg())
     validReg = addRegisterOpPiece(*Loc, Location.getReg());
   else
     validReg = addRegisterOffset(*Loc, Location.getReg(), Location.getOffset());
@@ -756,9 +754,6 @@ void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
   if (!validReg)
     return;
 
-  if (!Location.isReg() && Indirect)
-    addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
-
   // Now attach the location information to the DIE.
   addBlock(Die, Attribute, Loc);
 }
@@ -775,16 +770,10 @@ void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
   DIExpression Expr = DV.getExpression();
   if (Location.getOffset()) {
     if (DwarfExpr.AddMachineRegIndirect(Location.getReg(),
-                                        Location.getOffset())) {
+                                        Location.getOffset()))
       DwarfExpr.AddExpression(Expr);
-      assert(!DV.getVariable().isIndirect()
-             && "double indirection not handled");
-    }
-  } else {
-    if (DwarfExpr.AddMachineRegExpression(Expr, Location.getReg()))
-      if (DV.getVariable().isIndirect())
-        DwarfExpr.EmitOp(dwarf::DW_OP_deref);
-  }
+  } else
+    DwarfExpr.AddMachineRegExpression(Expr, Location.getReg());
 
   // Now attach the location information to the DIE.
   addBlock(Die, Attribute, Loc);

lib/CodeGen/AsmPrinter/DwarfCompileUnit.h

@@ -213,7 +213,7 @@ public:
                           MachineLocation Location);
   /// Add an address attribute to a die based on the location provided.
   void addAddress(DIE &Die, dwarf::Attribute Attribute,
-                  const MachineLocation &Location, bool Indirect = false);
+                  const MachineLocation &Location);
 
   /// Start with the address based on the location provided, and generate the
   /// DWARF information necessary to find the actual variable (navigating the

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1683,14 +1683,12 @@ void DwarfDebug::emitLocPieces(ByteStreamer &Streamer,
 
 #ifndef NDEBUG
     DIVariable Var = Piece.getVariable();
-    assert(!Var.isIndirect() && "indirect address for piece");
     unsigned VarSize = Var.getSizeInBits(Map);
     assert(PieceSize+PieceOffset <= VarSize/SizeOfByte
            && "piece is larger than or outside of variable");
     assert(PieceSize*SizeOfByte != VarSize
            && "piece covers entire variable");
 #endif
-
     emitDebugLocValue(Streamer, Piece, PieceOffset*SizeOfByte);
   }
 }
@@ -1726,7 +1724,7 @@ void DwarfDebug::emitDebugLocValue(ByteStreamer &Streamer,
     DIExpression Expr = Value.getExpression();
     if (!Expr || (Expr.getNumElements() == 0))
       // Regular entry.
-      Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
+      Asm->EmitDwarfRegOp(Streamer, Loc);
     else {
       // Complex address entry.
       if (Loc.getOffset()) {
@@ -1735,8 +1733,6 @@ void DwarfDebug::emitDebugLocValue(ByteStreamer &Streamer,
       } else
         DwarfExpr.AddMachineRegExpression(Expr, Loc.getReg(),
                                           PieceOffsetInBits);
-      if (DV.isIndirect())
-        DwarfExpr.EmitOp(dwarf::DW_OP_deref);
     }
   }
   // else ... ignore constant fp. There is not any good way to