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Differential D3373 Diff 12002 lib/CodeGen/AsmPrinter/DwarfDebug.cpp

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lib/CodeGen/AsmPrinter/DwarfDebug.cpp

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llvm_unreachable("Unexpected 3 operand DBG_VALUE instruction!"); llvm_unreachable("Unexpected 3 operand DBG_VALUE instruction!");
} }
/// Determine whether two variable pieces overlap.
static bool piecesOverlap(DIVariable P1, DIVariable P2) {
if (!P1.isVariablePiece() || !P2.isVariablePiece())
return true;
unsigned l1 = P1.getPieceOffset();
unsigned l2 = P2.getPieceOffset();
unsigned r1 = l1 + P1.getPieceSize();
unsigned r2 = l2 + P2.getPieceSize();
// True where [l1,r1[ and [r1,r2[ overlap.
return (l1 < r2) && (l2 < r1);
}
/// Build the location list for all DBG_VALUEs in the function that
/// describe the same variable. If the ranges of several independent
/// pieces of the same variable overlap partially, split them up and
/// combine the ranges. The resulting DebugLocEntries are will have
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Is it possible to break this function up a bit? Realize it's an unrelated refactor, but it would help a lot.

echristo: Is it possible to break this function up a bit? Realize it's an unrelated refactor, but it…
/// strict monotonically increasing begin addresses and will never
/// overlap.
//
// Input:
//
// Ranges History [var, loc, piece ofs size]
// 0 | [x, (reg0, piece 0, 32)]
// 1 | | [x, (reg1, piece 32, 32)] <- IsPieceOfPrevEntry
// 2 | | ...
// 3 | [clobber reg0]
// 4 [x, (mem, piece 0, 64)] <- overlapping with both previous pieces of x.
//
// Output:
//
// [0-1] [x, (reg0, piece 0, 32)]
// [1-3] [x, (reg0, piece 0, 32), (reg1, piece 32, 32)]
// [3-4] [x, (reg1, piece 32, 32)]
// [4- ] [x, (mem, piece 0, 64)]
void DwarfDebug::
buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
const DbgValueHistoryMap::InstrRanges &Ranges,
DwarfCompileUnit *TheCU) {
typedef std::pair<DIVariable, DebugLocEntry::Value> Range;
SmallVector<Range, 4> OpenRanges;
for (auto I = Ranges.begin(), E = Ranges.end(); I != E; ++I) {
const MachineInstr *Begin = I->first;
const MachineInstr *End = I->second;
assert(Begin->isDebugValue() && "Invalid History entry");
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Extra white space.

echristo: Extra white space.
// Check if a variable is unaccessible in this range.
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"inaccessible"

echristo: "inaccessible"
if (!Begin->isDebugValue() ||
(Begin->getNumOperands() > 1 && Begin->getOperand(0).isReg() &&
!Begin->getOperand(0).getReg())) {
OpenRanges.clear();
continue;
}
// If this piece overlaps with any open ranges, truncate them.
DIVariable DIVar = Begin->getDebugVariable();
auto Last = std::remove_if(OpenRanges.begin(), OpenRanges.end(), [&](Range R){
return piecesOverlap(DIVar, R.first);
});
OpenRanges.erase(Last, OpenRanges.end());
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Extra whitespace.

echristo: Extra whitespace.
const MCSymbol *StartLabel = getLabelBeforeInsn(Begin);
assert(StartLabel && "Forgot label before DBG_VALUE starting a range!");
const MCSymbol *EndLabel;
if (End != nullptr)
EndLabel = getLabelAfterInsn(End);
else if (std::next(I) == Ranges.end())
EndLabel = FunctionEndSym;
else
EndLabel = getLabelBeforeInsn(std::next(I)->first);
assert(EndLabel && "Forgot label after instruction ending a range!");
DEBUG(dbgs() << "DotDebugLoc: " << *Begin << "\n");
auto Value = getDebugLocValue(Begin);
DebugLocEntry Loc(StartLabel, EndLabel, Value, TheCU);
if (DebugLoc.empty() || !DebugLoc.back().Merge(Loc)) {
// Add all values from still valid non-overlapping pieces.
for (auto Range : OpenRanges)
Loc.addValue(Range.second);
DebugLoc.push_back(std::move(Loc));
}
// Add this value to the list of open ranges.
if (DIVar.isVariablePiece())
OpenRanges.push_back({DIVar, Value});
DEBUG(dbgs() << "Values:\n";
for (auto Value : DebugLoc.back().getValues())
Value.getVariable()->dump();
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Removed a nullptr initialization?

echristo: Removed a nullptr initialization?
dbgs() << "-----\n");
}
}
// Find variables for each lexical scope. // Find variables for each lexical scope.
void void
DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) { DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
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nullptr?

echristo: nullptr?
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weird formatting?

echristo: weird formatting?
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if (!Scope) if (!Scope)
continue; continue;
Processed.insert(DV); Processed.insert(getEntireVariable(DV));
const MachineInstr *MInsn = Ranges.front().first; const MachineInstr *MInsn = Ranges.front().first;
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Comment please :)

echristo: Comment please :)
assert(MInsn->isDebugValue() && "History must begin with debug value"); assert(MInsn->isDebugValue() && "History must begin with debug value");
ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode()); ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
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DebugLocList &LocList = DotDebugLocEntries.back(); DebugLocList &LocList = DotDebugLocEntries.back();
LocList.Label = LocList.Label =
Asm->GetTempSymbol("debug_loc", DotDebugLocEntries.size() - 1); Asm->GetTempSymbol("debug_loc", DotDebugLocEntries.size() - 1);
SmallVector<DebugLocEntry, 4> &DebugLoc = LocList.List;
for (auto I = Ranges.begin(), E = Ranges.end(); I != E; ++I) { // Build the location list for this variable.
const MachineInstr *Begin = I->first; buildLocationList(LocList.List, Ranges, TheCU);
const MachineInstr *End = I->second;
assert(Begin->isDebugValue() && "Invalid History entry");
// Check if a variable is unaccessible in this range.
if (Begin->getNumOperands() > 1 && Begin->getOperand(0).isReg() &&
!Begin->getOperand(0).getReg())
continue;
DEBUG(dbgs() << "DotDebugLoc Pair:\n" << "\t" << *Begin);
if (End != nullptr)
DEBUG(dbgs() << "\t" << *End);
else
DEBUG(dbgs() << "\tNULL\n");
const MCSymbol *StartLabel = getLabelBeforeInsn(Begin);
assert(StartLabel && "Forgot label before DBG_VALUE starting a range!");
const MCSymbol *EndLabel;
if (End != nullptr)
EndLabel = getLabelAfterInsn(End);
else if (std::next(I) == Ranges.end())
EndLabel = FunctionEndSym;
else
EndLabel = getLabelBeforeInsn(std::next(I)->first);
assert(EndLabel && "Forgot label after instruction ending a range!");
DebugLocEntry Loc(StartLabel, EndLabel, getDebugLocValue(Begin), TheCU);
if (DebugLoc.empty() || !DebugLoc.back().Merge(Loc))
DebugLoc.push_back(std::move(Loc));
}
} }
// Collect info for variables that were optimized out. // Collect info for variables that were optimized out.
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Formatting.

echristo: Formatting.
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I'm not sure I understand the AtFnBegin stuff, could you explain it a bit more?

echristo: I'm not sure I understand the AtFnBegin stuff, could you explain it a bit more?
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// The first mention of a function argument gets the FunctionBeginSym // The first mention of a function argument gets the FunctionBeginSym
// label, so arguments are visible when breaking at function entry. // label, so arguments are visible when breaking at function entry.
DIVariable DV(I.first); DIVariable DV(Ranges.front().first->getDebugVariable());
if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable && if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
getDISubprogram(DV.getContext()).describes(MF->getFunction())) getDISubprogram(DV.getContext()).describes(MF->getFunction())) {
LabelsBeforeInsn[Ranges.front().first] = FunctionBeginSym; if (!DV.isVariablePiece())
LabelsBeforeInsn[Ranges.front().first] = FunctionBeginSym;
else {
// Mark all non-overlapping initial pieces.
for (auto I = Ranges.begin(); I != Ranges.end(); ++I) {
DIVariable Piece = I->first->getDebugVariable();
if (std::all_of(Ranges.begin(), I,
[&](DbgValueHistoryMap::InstrRange Pred){
return !piecesOverlap(Piece, Pred.first->getDebugVariable());
}))
LabelsBeforeInsn[I->first] = FunctionBeginSym;
else
break;
}
}
}
for (const auto &Range : Ranges) { for (const auto &Range : Ranges) {
requestLabelBeforeInsn(Range.first); requestLabelBeforeInsn(Range.first);
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Comment update.

echristo: Comment update.
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Holder.emitStrings(Asm->getObjFileLowering().getDwarfStrSection()); Holder.emitStrings(Asm->getObjFileLowering().getDwarfStrSection());
} }
/// Emits an optimal (=sorted) sequence of DW_OP_pieces.
void DwarfDebug::emitLocPieces(ByteStreamer &Streamer,
const DITypeIdentifierMap &Map,
ArrayRef<DebugLocEntry::Value> Values) {
typedef DebugLocEntry::Value Piece;
SmallVector<Piece, 4> Pieces(Values.begin(), Values.end());
assert(std::all_of(Pieces.begin(), Pieces.end(), [](Piece &P) {
return DIVariable(P.getVariable()).isVariablePiece();
}) && "all values are expected to be pieces");
// Sort the pieces so they can be emitted using DW_OP_piece.
std::sort(Pieces.begin(), Pieces.end(), [](const Piece &A, const Piece &B) {
DIVariable VarA(A.getVariable());
DIVariable VarB(B.getVariable());
return VarA.getPieceOffset() < VarB.getPieceOffset();
});
// Remove any duplicate entries by dropping all but the first.
Pieces.erase(std::unique(Pieces.begin(), Pieces.end(),
[] (const Piece &A,const Piece &B){
return A.getVariable() == B.getVariable();
}), Pieces.end());
unsigned Offset = 0;
for (auto Piece : Pieces) {
DIVariable Var(Piece.getVariable());
unsigned PieceOffset = Var.getPieceOffset();
unsigned PieceSize = Var.getPieceSize();
assert(Offset <= PieceOffset && "overlapping pieces in DebugLocEntry");
if (Offset < PieceOffset) {
// The DWARF spec seriously mandates pieces with no locations for gaps.
Asm->EmitDwarfOpPiece(Streamer, (PieceOffset-Offset)*8);
Offset += PieceOffset-Offset;
}
Offset += PieceSize;
// Assuming 8 bits per byte.
assert(!Var.isIndirect() && "indirect address for piece");
#ifndef NDEBUG
unsigned VarSize = Var.getSizeInBits(Map);
assert(PieceSize+PieceOffset <= VarSize/8
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Weird formatting?

echristo: Weird formatting?
&& "piece is larger than or outside of variable");
assert(PieceSize*8 != VarSize
&& "piece covers entire variable");
#endif
if (Piece.isLocation() && Piece.getLoc().isReg())
Asm->EmitDwarfRegOpPiece(Streamer,
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Weird formatting?

echristo: Weird formatting?
Piece.getLoc(),
PieceSize*8);
else {
emitDebugLocValue(Streamer, Piece);
Asm->EmitDwarfOpPiece(Streamer, PieceSize*8);
}
}
}
void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer, void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer,
const DebugLocEntry &Entry) { const DebugLocEntry &Entry) {
assert(Entry.getValues().size() == 1 &&
"multi-value entries are not supported yet.");
const DebugLocEntry::Value Value = Entry.getValues()[0]; const DebugLocEntry::Value Value = Entry.getValues()[0];
DIVariable DV(Value.getVariable()); DIVariable DV(Value.getVariable());
if (DV.isVariablePiece())
// Emit all pieces that belong to the same variable and range.
return emitLocPieces(Streamer, TypeIdentifierMap, Entry.getValues());
assert(Entry.getValues().size() == 1 && "only pieces may have >1 value");
emitDebugLocValue(Streamer, Value);
}
void DwarfDebug::emitDebugLocValue(ByteStreamer &Streamer,
const DebugLocEntry::Value &Value) {
DIVariable DV(Value.getVariable());
// Regular entry.
if (Value.isInt()) { if (Value.isInt()) {
DIBasicType BTy(resolve(DV.getType())); DIBasicType BTy(resolve(DV.getType()));
if (BTy.Verify() && (BTy.getEncoding() == dwarf::DW_ATE_signed || if (BTy.Verify() && (BTy.getEncoding() == dwarf::DW_ATE_signed ||
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Probably just emitLocPieces.

echristo: Probably just emitLocPieces.
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Clever. How about some text? :)

echristo: Clever. How about some text? :)
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} else if (Element == DIBuilder::OpDeref) { } else if (Element == DIBuilder::OpDeref) {
if (!Loc.isReg()) if (!Loc.isReg())
Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref"); Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
} else if (Element == DIBuilder::OpPiece) {
i += 3;
// handled in emitDebugLocEntry.
} else } else
llvm_unreachable("unknown Opcode found in complex address"); llvm_unreachable("unknown Opcode found in complex address");
} }
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