#include "llvm/CodeGen/AsmPrinter.h"
#include "DwarfDebug.h"
#include "DwarfException.h"
+#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/ConstantFolding.h"
/// 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 emitDwarfRegOpPiece(const AsmPrinter &AP,
- int Reg, unsigned Size, unsigned Offset) {
- assert(Reg >= 0);
+static void emitDwarfOpPiece(const AsmPrinter &AP,
+ unsigned Size, unsigned Offset) {
assert(Size > 0);
-
- emitDwarfRegOp(AP, Reg);
- // Emit Mask
if (Offset > 0) {
AP.OutStreamer.AddComment("DW_OP_bit_piece");
AP.EmitInt8(dwarf::DW_OP_bit_piece);
}
}
+/// 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(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(AP, Reg);
+ emitDwarfOpPiece(AP, 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(AP, Reg);
+ emitDwarfOpPiece(AP, 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.
+ AP.OutStreamer.AddComment("nop (could not find a dwarf register number)");
+ AP.EmitInt8(dwarf::DW_OP_nop);
+ }
+}
+
/// EmitDwarfRegOp - Emit dwarf register operation.
void AsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc,
bool Indirect) const {
const TargetRegisterInfo *TRI = TM.getRegisterInfo();
int Reg = TRI->getDwarfRegNum(MLoc.getReg(), false);
-
if (Reg < 0) {
- // Walk up the super-register chain until we find a valid number.
- 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);
- emitDwarfRegOpPiece(*this, Reg, Size, Offset);
-
- if (MLoc.isIndirect())
- EmitInt8(dwarf::DW_OP_deref);
-
- if (Indirect)
- EmitInt8(dwarf::DW_OP_deref);
-
- return;
- }
-
- // FIXME: Handle cases like a super register being encoded as
- // DW_OP_reg 32 DW_OP_piece 4 DW_OP_reg 33
-
+ // We assume that pointers are always in an addressable register.
+ if (Indirect || 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 mature.
+ OutStreamer.AddComment("nop (invalid dwarf register number for indirect loc)");
+ EmitInt8(dwarf::DW_OP_nop);
+ return;
}
- // FIXME: We have no reasonable way of handling errors in here. The
- // caller might be in the middle of an dwarf expression. We should
- // probably assert that Reg >= 0 once debug info generation is more mature.
- OutStreamer.AddComment("nop (invalid dwarf register number)");
- EmitInt8(dwarf::DW_OP_nop);
- return;
+
+ // Attempt to find a valid super- or sub-register.
+ if (!Indirect && !MLoc.isIndirect())
+ return EmitDwarfRegOpPiece(*this, MLoc);
}
if (MLoc.isIndirect())
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