- EmitLabelDifference(Label, SectionLabel, 4);
-}
-
-/// Emit a dwarf register operation.
-static void emitDwarfRegOp(ByteStreamer &Streamer, int Reg) {
- assert(Reg >= 0);
- if (Reg < 32) {
- Streamer.EmitInt8(dwarf::DW_OP_reg0 + Reg,
- dwarf::OperationEncodingString(dwarf::DW_OP_reg0 + Reg));
- } else {
- Streamer.EmitInt8(dwarf::DW_OP_regx, "DW_OP_regx");
- Streamer.EmitULEB128(Reg, Twine(Reg));
- }
-}
-
-/// Emit an (double-)indirect dwarf register operation.
-static void emitDwarfRegOpIndirect(ByteStreamer &Streamer, int Reg, int Offset,
- bool Deref) {
- assert(Reg >= 0);
- if (Reg < 32) {
- Streamer.EmitInt8(dwarf::DW_OP_breg0 + Reg,
- dwarf::OperationEncodingString(dwarf::DW_OP_breg0 + Reg));
- } else {
- Streamer.EmitInt8(dwarf::DW_OP_bregx, "DW_OP_bregx");
- Streamer.EmitULEB128(Reg, Twine(Reg));
- }
- Streamer.EmitSLEB128(Offset);
- if (Deref)
- Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
-}
-
-/// Emit a dwarf register operation for describing
-/// - a small value occupying only part of a register or
-/// - a small register representing only part of a value.
-static void emitDwarfOpPiece(ByteStreamer &Streamer, unsigned Size,
- unsigned Offset) {
- assert(Size > 0);
- if (Offset > 0) {
- Streamer.EmitInt8(dwarf::DW_OP_bit_piece, "DW_OP_bit_piece");
- Streamer.EmitULEB128(Size, Twine(Size));
- Streamer.EmitULEB128(Offset, Twine(Offset));
- } else {
- Streamer.EmitInt8(dwarf::DW_OP_piece, "DW_OP_piece");
- unsigned ByteSize = Size / 8; // Assuming 8 bits per byte.
- Streamer.EmitULEB128(ByteSize, Twine(ByteSize));
- }
-}
-
-/// Some targets do not provide a DWARF register number for every
-/// register. This function attempts to emit a dwarf register by
-/// emitting a piece of a super-register or by piecing together
-/// multiple subregisters that alias the register.
-static void EmitDwarfRegOpPiece(ByteStreamer &Streamer, const AsmPrinter &AP,
- const MachineLocation &MLoc) {
- assert(!MLoc.isIndirect());
- const TargetRegisterInfo *TRI = AP.TM.getRegisterInfo();
- int Reg = TRI->getDwarfRegNum(MLoc.getReg(), false);
-
- // 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 (MCSuperRegIterator SR(MLoc.getReg(), TRI); SR.isValid(); ++SR) {
- Reg = TRI->getDwarfRegNum(*SR, false);
- if (Reg >= 0) {
- unsigned Idx = TRI->getSubRegIndex(*SR, MLoc.getReg());
- unsigned Size = TRI->getSubRegIdxSize(Idx);
- unsigned Offset = TRI->getSubRegIdxOffset(Idx);
- AP.OutStreamer.AddComment("super-register");
- emitDwarfRegOp(Streamer, Reg);
- emitDwarfOpPiece(Streamer, Size, Offset);
- return;
- }
- }
-
- // 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 = 0;
- // The size of the register in bits, assuming 8 bits per byte.
- unsigned RegSize = TRI->getMinimalPhysRegClass(MLoc.getReg())->getSize() * 8;
- // Keep track of the bits in the register we already emitted, so we
- // can avoid emitting redundant aliasing subregs.
- SmallBitVector Coverage(RegSize, false);
- for (MCSubRegIterator SR(MLoc.getReg(), TRI); SR.isValid(); ++SR) {
- unsigned Idx = TRI->getSubRegIndex(MLoc.getReg(), *SR);
- unsigned Size = TRI->getSubRegIdxSize(Idx);
- unsigned Offset = TRI->getSubRegIdxOffset(Idx);
- Reg = TRI->getDwarfRegNum(*SR, false);
-
- // Intersection between the bits we already emitted and the bits
- // covered by this subregister.
- SmallBitVector Intersection(RegSize, false);
- Intersection.set(Offset, Offset + Size);
- Intersection ^= Coverage;
-
- // If this sub-register has a DWARF number and we haven't covered
- // its range, emit a DWARF piece for it.
- if (Reg >= 0 && Intersection.any()) {
- AP.OutStreamer.AddComment("sub-register");
- emitDwarfRegOp(Streamer, Reg);
- emitDwarfOpPiece(Streamer, Size, Offset == CurPos ? 0 : Offset);
- CurPos = Offset + Size;
-
- // Mark it as emitted.
- Coverage.set(Offset, Offset + Size);
- }
- }
-
- if (CurPos == 0) {
- // FIXME: We have no reasonable way of handling errors in here.
- Streamer.EmitInt8(dwarf::DW_OP_nop,
- "nop (could not find a dwarf register number)");
- }