Debug info: Use DW_OP_bit_piece instead of DW_OP_piece in the

intermediate representation. This
- increases consistency by using the same granularity everywhere
- allows for pieces < 1 byte
- DW_OP_piece didn't actually allow storing an offset.

Part of PR22495.

llvm-svn: 228631

4 files changed, 30 insertions, 33 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 57d6fae0fbd..7fb84605071 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -656,9 +656,9 @@ static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
   OS << V.getName();
 
   DIExpression Expr = MI->getDebugExpression();
-  if (Expr.isVariablePiece())
-    OS << " [piece offset=" << Expr.getPieceOffset()
-       << " size=" << Expr.getPieceSize() << "]";
+  if (Expr.isBitPiece())
+    OS << " [bit_piece offset=" << Expr.getBitPieceOffset()
+       << " size=" << Expr.getBitPieceSize() << "]";
   OS << " <- ";
 
   // The second operand is only an offset if it's an immediate.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h b/llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h
index b4fcada59ec..6d55c038541 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h
@@ -74,7 +74,7 @@ public:
     MachineLocation getLoc() const { return Loc; }
     const MDNode *getVariableNode() const { return Variable; }
     DIVariable getVariable() const { return DIVariable(Variable); }
-    bool isVariablePiece() const { return getExpression().isVariablePiece(); }
+    bool isBitPiece() const { return getExpression().isBitPiece(); }
     DIExpression getExpression() const { return DIExpression(Expression); }
     friend bool operator==(const Value &, const Value &);
     friend bool operator<(const Value &, const Value &);
@@ -101,8 +101,8 @@ public:
       DIVariable Var(Values[0].Variable);
       DIExpression NextExpr(Next.Values[0].Expression);
       DIVariable NextVar(Next.Values[0].Variable);
-      if (Var == NextVar && Expr.isVariablePiece() &&
-          NextExpr.isVariablePiece()) {
+      if (Var == NextVar && Expr.isBitPiece() &&
+          NextExpr.isBitPiece()) {
         addValues(Next.Values);
         End = Next.End;
         return true;
@@ -131,7 +131,7 @@ public:
     Values.append(Vals.begin(), Vals.end());
     sortUniqueValues();
     assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value V){
-          return V.isVariablePiece();
+          return V.isBitPiece();
         }) && "value must be a piece");
   }
 
@@ -176,8 +176,8 @@ inline bool operator==(const DebugLocEntry::Value &A,
 /// Compare two pieces based on their offset.
 inline bool operator<(const DebugLocEntry::Value &A,
                       const DebugLocEntry::Value &B) {
-  return A.getExpression().getPieceOffset() <
-         B.getExpression().getPieceOffset();
+  return A.getExpression().getBitPieceOffset() <
+         B.getExpression().getBitPieceOffset();
 }
 
 }
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index e8bcf0b856b..8cb033a175e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -818,12 +818,12 @@ static DebugLocEntry::Value getDebugLocValue(const MachineInstr *MI) {
 
 /// Determine whether two variable pieces overlap.
 static bool piecesOverlap(DIExpression P1, DIExpression P2) {
-  if (!P1.isVariablePiece() || !P2.isVariablePiece())
+  if (!P1.isBitPiece() || !P2.isBitPiece())
     return true;
-  unsigned l1 = P1.getPieceOffset();
-  unsigned l2 = P2.getPieceOffset();
-  unsigned r1 = l1 + P1.getPieceSize();
-  unsigned r2 = l2 + P2.getPieceSize();
+  unsigned l1 = P1.getBitPieceOffset();
+  unsigned l2 = P2.getBitPieceOffset();
+  unsigned r1 = l1 + P1.getBitPieceSize();
+  unsigned r2 = l2 + P2.getBitPieceSize();
   // True where [l1,r1[ and [r1,r2[ overlap.
   return (l1 < r2) && (l2 < r1);
 }
@@ -894,7 +894,7 @@ DwarfDebug::buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
     bool couldMerge = false;
 
     // If this is a piece, it may belong to the current DebugLocEntry.
-    if (DIExpr.isVariablePiece()) {
+    if (DIExpr.isBitPiece()) {
       // Add this value to the list of open ranges.
       OpenRanges.push_back(Value);
 
@@ -1193,7 +1193,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
     if (DIVar.isVariable() && DIVar.getTag() == dwarf::DW_TAG_arg_variable &&
         getDISubprogram(DIVar.getContext()).describes(MF->getFunction())) {
       LabelsBeforeInsn[Ranges.front().first] = FunctionBeginSym;
-      if (Ranges.front().first->getDebugExpression().isVariablePiece()) {
+      if (Ranges.front().first->getDebugExpression().isBitPiece()) {
         // Mark all non-overlapping initial pieces.
         for (auto I = Ranges.begin(); I != Ranges.end(); ++I) {
           DIExpression Piece = I->first->getDebugExpression();
@@ -1661,21 +1661,20 @@ void DwarfDebug::emitLocPieces(ByteStreamer &Streamer,
                                const DITypeIdentifierMap &Map,
                                ArrayRef<DebugLocEntry::Value> Values) {
   assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value P) {
-        return P.isVariablePiece();
+        return P.isBitPiece();
       }) && "all values are expected to be pieces");
   assert(std::is_sorted(Values.begin(), Values.end()) &&
          "pieces are expected to be sorted");
 
   unsigned Offset = 0;
   for (auto Piece : Values) {
-    const unsigned SizeOfByte = 8;
     DIExpression Expr = Piece.getExpression();
-    unsigned PieceOffset = Expr.getPieceOffset();
-    unsigned PieceSize = Expr.getPieceSize();
+    unsigned PieceOffset = Expr.getBitPieceOffset();
+    unsigned PieceSize = Expr.getBitPieceSize();
     assert(Offset <= PieceOffset && "overlapping or duplicate pieces");
     if (Offset < PieceOffset) {
       // The DWARF spec seriously mandates pieces with no locations for gaps.
-      Asm->EmitDwarfOpPiece(Streamer, (PieceOffset-Offset)*SizeOfByte);
+      Asm->EmitDwarfOpPiece(Streamer, PieceOffset-Offset);
       Offset += PieceOffset-Offset;
     }
     Offset += PieceSize;
@@ -1683,12 +1682,12 @@ void DwarfDebug::emitLocPieces(ByteStreamer &Streamer,
 #ifndef NDEBUG
     DIVariable Var = Piece.getVariable();
     unsigned VarSize = Var.getSizeInBits(Map);
-    assert(PieceSize+PieceOffset <= VarSize/SizeOfByte
+    assert(PieceSize+PieceOffset <= VarSize
            && "piece is larger than or outside of variable");
-    assert(PieceSize*SizeOfByte != VarSize
+    assert(PieceSize != VarSize
            && "piece covers entire variable");
 #endif
-    emitDebugLocValue(Streamer, Piece, PieceOffset*SizeOfByte);
+    emitDebugLocValue(Streamer, Piece, PieceOffset);
   }
 }
 
@@ -1696,7 +1695,7 @@ void DwarfDebug::emitLocPieces(ByteStreamer &Streamer,
 void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer,
                                    const DebugLocEntry &Entry) {
   const DebugLocEntry::Value Value = Entry.getValues()[0];
-  if (Value.isVariablePiece())
+  if (Value.isBitPiece())
     // Emit all pieces that belong to the same variable and range.
     return emitLocPieces(Streamer, TypeIdentifierMap, Entry.getValues());
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
index 7c5c879289b..3d1e3822c51 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
@@ -211,10 +211,9 @@ bool DwarfExpression::AddMachineRegExpression(DIExpression Expr,
 
   bool ValidReg = false;
   switch (*I) {
-  case dwarf::DW_OP_piece: {
-    unsigned SizeOfByte = 8;
-    unsigned OffsetInBits = I->getArg(1) * SizeOfByte;
-    unsigned SizeInBits   = I->getArg(2) * SizeOfByte;
+  case dwarf::DW_OP_bit_piece: {
+    unsigned OffsetInBits = I->getArg(1);
+    unsigned SizeInBits   = I->getArg(2);
     // Piece always comes at the end of the expression.
     return AddMachineRegPiece(MachineReg, SizeInBits,
                getOffsetOrZero(OffsetInBits, PieceOffsetInBits));
@@ -249,10 +248,9 @@ void DwarfExpression::AddExpression(DIExpression::iterator I,
                                     unsigned PieceOffsetInBits) {
  for (; I != DIExpression::iterator(); ++I) {
     switch (*I) {
-    case dwarf::DW_OP_piece: {
-      unsigned SizeOfByte = 8;
-      unsigned OffsetInBits = I->getArg(1) * SizeOfByte;
-      unsigned SizeInBits   = I->getArg(2) * SizeOfByte;
+    case dwarf::DW_OP_bit_piece: {
+      unsigned OffsetInBits = I->getArg(1);
+      unsigned SizeInBits   = I->getArg(2);
       AddOpPiece(SizeInBits, getOffsetOrZero(OffsetInBits, PieceOffsetInBits));
       break;
     }