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//===- BTFDebug.cpp - BTF Generator ---------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing BTF debug info.
//
//===----------------------------------------------------------------------===//
#include "BTFDebug.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include <fstream>
#include <sstream>
using namespace llvm;
static const char *BTFKindStr[] = {
#define HANDLE_BTF_KIND(ID, NAME) "BTF_KIND_" #NAME,
#include "BTF.def"
};
/// Emit a BTF common type.
void BTFTypeBase::emitType(MCStreamer &OS) {
OS.AddComment(std::string(BTFKindStr[Kind]) + "(id = " + std::to_string(Id) +
")");
OS.EmitIntValue(BTFType.NameOff, 4);
OS.AddComment("0x" + Twine::utohexstr(BTFType.Info));
OS.EmitIntValue(BTFType.Info, 4);
OS.EmitIntValue(BTFType.Size, 4);
}
BTFTypeDerived::BTFTypeDerived(const DIDerivedType *DTy, unsigned Tag)
: DTy(DTy) {
switch (Tag) {
case dwarf::DW_TAG_pointer_type:
Kind = BTF::BTF_KIND_PTR;
break;
case dwarf::DW_TAG_const_type:
Kind = BTF::BTF_KIND_CONST;
break;
case dwarf::DW_TAG_volatile_type:
Kind = BTF::BTF_KIND_VOLATILE;
break;
case dwarf::DW_TAG_typedef:
Kind = BTF::BTF_KIND_TYPEDEF;
break;
case dwarf::DW_TAG_restrict_type:
Kind = BTF::BTF_KIND_RESTRICT;
break;
default:
llvm_unreachable("Unknown DIDerivedType Tag");
}
BTFType.Info = Kind << 24;
}
void BTFTypeDerived::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(DTy->getName());
// The base type for PTR/CONST/VOLATILE could be void.
const DIType *ResolvedType = DTy->getBaseType().resolve();
if (!ResolvedType) {
assert((Kind == BTF::BTF_KIND_PTR || Kind == BTF::BTF_KIND_CONST ||
Kind == BTF::BTF_KIND_VOLATILE) &&
"Invalid null basetype");
BTFType.Type = 0;
} else {
BTFType.Type = BDebug.getTypeId(ResolvedType);
}
}
void BTFTypeDerived::emitType(MCStreamer &OS) { BTFTypeBase::emitType(OS); }
/// Represent a struct/union forward declaration.
BTFTypeFwd::BTFTypeFwd(StringRef Name, bool IsUnion) : Name(Name) {
Kind = BTF::BTF_KIND_FWD;
BTFType.Info = IsUnion << 31 | Kind << 24;
BTFType.Type = 0;
}
void BTFTypeFwd::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(Name);
}
void BTFTypeFwd::emitType(MCStreamer &OS) { BTFTypeBase::emitType(OS); }
BTFTypeInt::BTFTypeInt(uint32_t Encoding, uint32_t SizeInBits,
uint32_t OffsetInBits, StringRef TypeName)
: Name(TypeName) {
// Translate IR int encoding to BTF int encoding.
uint8_t BTFEncoding;
switch (Encoding) {
case dwarf::DW_ATE_boolean:
BTFEncoding = BTF::INT_BOOL;
break;
case dwarf::DW_ATE_signed:
case dwarf::DW_ATE_signed_char:
BTFEncoding = BTF::INT_SIGNED;
break;
case dwarf::DW_ATE_unsigned:
case dwarf::DW_ATE_unsigned_char:
BTFEncoding = 0;
break;
default:
llvm_unreachable("Unknown BTFTypeInt Encoding");
}
Kind = BTF::BTF_KIND_INT;
BTFType.Info = Kind << 24;
BTFType.Size = roundupToBytes(SizeInBits);
IntVal = (BTFEncoding << 24) | OffsetInBits << 16 | SizeInBits;
}
void BTFTypeInt::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(Name);
}
void BTFTypeInt::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
OS.AddComment("0x" + Twine::utohexstr(IntVal));
OS.EmitIntValue(IntVal, 4);
}
BTFTypeEnum::BTFTypeEnum(const DICompositeType *ETy, uint32_t VLen) : ETy(ETy) {
Kind = BTF::BTF_KIND_ENUM;
BTFType.Info = Kind << 24 | VLen;
BTFType.Size = roundupToBytes(ETy->getSizeInBits());
}
void BTFTypeEnum::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(ETy->getName());
DINodeArray Elements = ETy->getElements();
for (const auto Element : Elements) {
const auto *Enum = cast<DIEnumerator>(Element);
struct BTF::BTFEnum BTFEnum;
BTFEnum.NameOff = BDebug.addString(Enum->getName());
// BTF enum value is 32bit, enforce it.
BTFEnum.Val = static_cast<uint32_t>(Enum->getValue());
EnumValues.push_back(BTFEnum);
}
}
void BTFTypeEnum::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &Enum : EnumValues) {
OS.EmitIntValue(Enum.NameOff, 4);
OS.EmitIntValue(Enum.Val, 4);
}
}
BTFTypeArray::BTFTypeArray(const DICompositeType *ATy) : ATy(ATy) {
Kind = BTF::BTF_KIND_ARRAY;
BTFType.Info = Kind << 24;
}
/// Represent a BTF array. BTF does not record array dimensions,
/// so conceptually a BTF array is a one-dimensional array.
void BTFTypeArray::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(ATy->getName());
BTFType.Size = 0;
auto *BaseType = ATy->getBaseType().resolve();
ArrayInfo.ElemType = BDebug.getTypeId(BaseType);
// The IR does not really have a type for the index.
// A special type for array index should have been
// created during initial type traversal. Just
// retrieve that type id.
ArrayInfo.IndexType = BDebug.getArrayIndexTypeId();
// Get the number of array elements.
// If the array size is 0, set the number of elements as 0.
// Otherwise, recursively traverse the base types to
// find the element size. The number of elements is
// the totoal array size in bits divided by
// element size in bits.
uint64_t ArraySizeInBits = ATy->getSizeInBits();
if (!ArraySizeInBits) {
ArrayInfo.Nelems = 0;
} else {
uint32_t BaseTypeSize = BaseType->getSizeInBits();
while (!BaseTypeSize) {
const auto *DDTy = cast<DIDerivedType>(BaseType);
BaseType = DDTy->getBaseType().resolve();
assert(BaseType);
BaseTypeSize = BaseType->getSizeInBits();
}
ArrayInfo.Nelems = ATy->getSizeInBits() / BaseTypeSize;
}
}
void BTFTypeArray::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
OS.EmitIntValue(ArrayInfo.ElemType, 4);
OS.EmitIntValue(ArrayInfo.IndexType, 4);
OS.EmitIntValue(ArrayInfo.Nelems, 4);
}
/// Represent either a struct or a union.
BTFTypeStruct::BTFTypeStruct(const DICompositeType *STy, bool IsStruct,
bool HasBitField, uint32_t Vlen)
: STy(STy), HasBitField(HasBitField) {
Kind = IsStruct ? BTF::BTF_KIND_STRUCT : BTF::BTF_KIND_UNION;
BTFType.Size = roundupToBytes(STy->getSizeInBits());
BTFType.Info = (HasBitField << 31) | (Kind << 24) | Vlen;
}
void BTFTypeStruct::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(STy->getName());
// Add struct/union members.
const DINodeArray Elements = STy->getElements();
for (const auto *Element : Elements) {
struct BTF::BTFMember BTFMember;
const auto *DDTy = cast<DIDerivedType>(Element);
BTFMember.NameOff = BDebug.addString(DDTy->getName());
if (HasBitField) {
uint8_t BitFieldSize = DDTy->isBitField() ? DDTy->getSizeInBits() : 0;
BTFMember.Offset = BitFieldSize << 24 | DDTy->getOffsetInBits();
} else {
BTFMember.Offset = DDTy->getOffsetInBits();
}
BTFMember.Type = BDebug.getTypeId(DDTy->getBaseType().resolve());
Members.push_back(BTFMember);
}
}
void BTFTypeStruct::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &Member : Members) {
OS.EmitIntValue(Member.NameOff, 4);
OS.EmitIntValue(Member.Type, 4);
OS.AddComment("0x" + Twine::utohexstr(Member.Offset));
OS.EmitIntValue(Member.Offset, 4);
}
}
/// The Func kind represents both subprogram and pointee of function
/// pointers. If the FuncName is empty, it represents a pointee of function
/// pointer. Otherwise, it represents a subprogram. The func arg names
/// are empty for pointee of function pointer case, and are valid names
/// for subprogram.
BTFTypeFuncProto::BTFTypeFuncProto(
const DISubroutineType *STy, uint32_t VLen,
const std::unordered_map<uint32_t, StringRef> &FuncArgNames)
: STy(STy), FuncArgNames(FuncArgNames) {
Kind = BTF::BTF_KIND_FUNC_PROTO;
BTFType.Info = (Kind << 24) | VLen;
}
void BTFTypeFuncProto::completeType(BTFDebug &BDebug) {
DITypeRefArray Elements = STy->getTypeArray();
auto RetType = Elements[0].resolve();
BTFType.Type = RetType ? BDebug.getTypeId(RetType) : 0;
BTFType.NameOff = 0;
// For null parameter which is typically the last one
// to represent the vararg, encode the NameOff/Type to be 0.
for (unsigned I = 1, N = Elements.size(); I < N; ++I) {
struct BTF::BTFParam Param;
auto Element = Elements[I].resolve();
if (Element) {
Param.NameOff = BDebug.addString(FuncArgNames[I]);
Param.Type = BDebug.getTypeId(Element);
} else {
Param.NameOff = 0;
Param.Type = 0;
}
Parameters.push_back(Param);
}
}
void BTFTypeFuncProto::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &Param : Parameters) {
OS.EmitIntValue(Param.NameOff, 4);
OS.EmitIntValue(Param.Type, 4);
}
}
BTFTypeFunc::BTFTypeFunc(StringRef FuncName, uint32_t ProtoTypeId)
: Name(FuncName) {
Kind = BTF::BTF_KIND_FUNC;
BTFType.Info = Kind << 24;
BTFType.Type = ProtoTypeId;
}
void BTFTypeFunc::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(Name);
}
void BTFTypeFunc::emitType(MCStreamer &OS) { BTFTypeBase::emitType(OS); }
uint32_t BTFStringTable::addString(StringRef S) {
// Check whether the string already exists.
for (auto &OffsetM : OffsetToIdMap) {
if (Table[OffsetM.second] == S)
return OffsetM.first;
}
// Not find, add to the string table.
uint32_t Offset = Size;
OffsetToIdMap[Offset] = Table.size();
Table.push_back(S);
Size += S.size() + 1;
return Offset;
}
BTFDebug::BTFDebug(AsmPrinter *AP)
: DebugHandlerBase(AP), OS(*Asm->OutStreamer), SkipInstruction(false),
LineInfoGenerated(false), SecNameOff(0), ArrayIndexTypeId(0) {
addString("\0");
}
void BTFDebug::addType(std::unique_ptr<BTFTypeBase> TypeEntry,
const DIType *Ty) {
TypeEntry->setId(TypeEntries.size() + 1);
DIToIdMap[Ty] = TypeEntry->getId();
TypeEntries.push_back(std::move(TypeEntry));
}
uint32_t BTFDebug::addType(std::unique_ptr<BTFTypeBase> TypeEntry) {
TypeEntry->setId(TypeEntries.size() + 1);
uint32_t Id = TypeEntry->getId();
TypeEntries.push_back(std::move(TypeEntry));
return Id;
}
void BTFDebug::visitBasicType(const DIBasicType *BTy) {
// Only int types are supported in BTF.
uint32_t Encoding = BTy->getEncoding();
if (Encoding != dwarf::DW_ATE_boolean && Encoding != dwarf::DW_ATE_signed &&
Encoding != dwarf::DW_ATE_signed_char &&
Encoding != dwarf::DW_ATE_unsigned &&
Encoding != dwarf::DW_ATE_unsigned_char)
return;
// Create a BTF type instance for this DIBasicType and put it into
// DIToIdMap for cross-type reference check.
auto TypeEntry = llvm::make_unique<BTFTypeInt>(
Encoding, BTy->getSizeInBits(), BTy->getOffsetInBits(), BTy->getName());
addType(std::move(TypeEntry), BTy);
}
/// Handle subprogram or subroutine types.
void BTFDebug::visitSubroutineType(
const DISubroutineType *STy, bool ForSubprog,
const std::unordered_map<uint32_t, StringRef> &FuncArgNames,
uint32_t &TypeId) {
DITypeRefArray Elements = STy->getTypeArray();
uint32_t VLen = Elements.size() - 1;
if (VLen > BTF::MAX_VLEN)
return;
// Subprogram has a valid non-zero-length name, and the pointee of
// a function pointer has an empty name. The subprogram type will
// not be added to DIToIdMap as it should not be referenced by
// any other types.
auto TypeEntry = llvm::make_unique<BTFTypeFuncProto>(STy, VLen, FuncArgNames);
if (ForSubprog)
TypeId = addType(std::move(TypeEntry)); // For subprogram
else
addType(std::move(TypeEntry), STy); // For func ptr
// Visit return type and func arg types.
for (const auto Element : Elements) {
visitTypeEntry(Element.resolve());
}
}
/// Handle structure/union types.
void BTFDebug::visitStructType(const DICompositeType *CTy, bool IsStruct) {
const DINodeArray Elements = CTy->getElements();
uint32_t VLen = Elements.size();
if (VLen > BTF::MAX_VLEN)
return;
// Check whether we have any bitfield members or not
bool HasBitField = false;
for (const auto *Element : Elements) {
auto E = cast<DIDerivedType>(Element);
if (E->isBitField()) {
HasBitField = true;
break;
}
}
auto TypeEntry =
llvm::make_unique<BTFTypeStruct>(CTy, IsStruct, HasBitField, VLen);
addType(std::move(TypeEntry), CTy);
// Visit all struct members.
for (const auto *Element : Elements)
visitTypeEntry(cast<DIDerivedType>(Element));
}
void BTFDebug::visitArrayType(const DICompositeType *CTy) {
auto TypeEntry = llvm::make_unique<BTFTypeArray>(CTy);
addType(std::move(TypeEntry), CTy);
// The IR does not have a type for array index while BTF wants one.
// So create an array index type if there is none.
if (!ArrayIndexTypeId) {
auto TypeEntry = llvm::make_unique<BTFTypeInt>(dwarf::DW_ATE_unsigned, 32,
0, "__ARRAY_SIZE_TYPE__");
ArrayIndexTypeId = addType(std::move(TypeEntry));
}
// Visit array element type.
visitTypeEntry(CTy->getBaseType().resolve());
}
void BTFDebug::visitEnumType(const DICompositeType *CTy) {
DINodeArray Elements = CTy->getElements();
uint32_t VLen = Elements.size();
if (VLen > BTF::MAX_VLEN)
return;
auto TypeEntry = llvm::make_unique<BTFTypeEnum>(CTy, VLen);
addType(std::move(TypeEntry), CTy);
// No need to visit base type as BTF does not encode it.
}
/// Handle structure/union forward declarations.
void BTFDebug::visitFwdDeclType(const DICompositeType *CTy, bool IsUnion) {
auto TypeEntry = llvm::make_unique<BTFTypeFwd>(CTy->getName(), IsUnion);
addType(std::move(TypeEntry), CTy);
}
/// Handle structure, union, array and enumeration types.
void BTFDebug::visitCompositeType(const DICompositeType *CTy) {
auto Tag = CTy->getTag();
if (Tag == dwarf::DW_TAG_structure_type || Tag == dwarf::DW_TAG_union_type) {
// Handle forward declaration differently as it does not have members.
if (CTy->isForwardDecl())
visitFwdDeclType(CTy, Tag == dwarf::DW_TAG_union_type);
else
visitStructType(CTy, Tag == dwarf::DW_TAG_structure_type);
} else if (Tag == dwarf::DW_TAG_array_type)
visitArrayType(CTy);
else if (Tag == dwarf::DW_TAG_enumeration_type)
visitEnumType(CTy);
}
/// Handle pointer, typedef, const, volatile, restrict and member types.
void BTFDebug::visitDerivedType(const DIDerivedType *DTy) {
unsigned Tag = DTy->getTag();
if (Tag == dwarf::DW_TAG_pointer_type || Tag == dwarf::DW_TAG_typedef ||
Tag == dwarf::DW_TAG_const_type || Tag == dwarf::DW_TAG_volatile_type ||
Tag == dwarf::DW_TAG_restrict_type) {
auto TypeEntry = llvm::make_unique<BTFTypeDerived>(DTy, Tag);
addType(std::move(TypeEntry), DTy);
} else if (Tag != dwarf::DW_TAG_member) {
return;
}
// Visit base type of pointer, typedef, const, volatile, restrict or
// struct/union member.
visitTypeEntry(DTy->getBaseType().resolve());
}
void BTFDebug::visitTypeEntry(const DIType *Ty) {
if (!Ty || DIToIdMap.find(Ty) != DIToIdMap.end())
return;
uint32_t TypeId;
if (const auto *BTy = dyn_cast<DIBasicType>(Ty))
visitBasicType(BTy);
else if (const auto *STy = dyn_cast<DISubroutineType>(Ty))
visitSubroutineType(STy, false, std::unordered_map<uint32_t, StringRef>(),
TypeId);
else if (const auto *CTy = dyn_cast<DICompositeType>(Ty))
visitCompositeType(CTy);
else if (const auto *DTy = dyn_cast<DIDerivedType>(Ty))
visitDerivedType(DTy);
else
llvm_unreachable("Unknown DIType");
}
/// Read file contents from the actual file or from the source
std::string BTFDebug::populateFileContent(const DISubprogram *SP) {
auto File = SP->getFile();
std::string FileName;
if (!File->getFilename().startswith("/") && File->getDirectory().size())
FileName = File->getDirectory().str() + "/" + File->getFilename().str();
else
FileName = File->getFilename();
// No need to populate the contends if it has been populated!
if (FileContent.find(FileName) != FileContent.end())
return FileName;
std::vector<std::string> Content;
std::string Line;
Content.push_back(Line); // Line 0 for empty string
auto Source = File->getSource();
if (Source) {
std::istringstream InputString(Source.getValue());
while (std::getline(InputString, Line))
Content.push_back(Line);
} else {
std::ifstream InputFile(FileName);
while (std::getline(InputFile, Line))
Content.push_back(Line);
}
FileContent[FileName] = Content;
return FileName;
}
void BTFDebug::constructLineInfo(const DISubprogram *SP, MCSymbol *Label,
uint32_t Line, uint32_t Column) {
std::string FileName = populateFileContent(SP);
BTFLineInfo LineInfo;
LineInfo.Label = Label;
LineInfo.FileNameOff = addString(FileName);
// If file content is not available, let LineOff = 0.
if (Line < FileContent[FileName].size())
LineInfo.LineOff = addString(FileContent[FileName][Line]);
else
LineInfo.LineOff = 0;
LineInfo.LineNum = Line;
LineInfo.ColumnNum = Column;
LineInfoTable[SecNameOff].push_back(LineInfo);
}
void BTFDebug::emitCommonHeader() {
OS.AddComment("0x" + Twine::utohexstr(BTF::MAGIC));
OS.EmitIntValue(BTF::MAGIC, 2);
OS.EmitIntValue(BTF::VERSION, 1);
OS.EmitIntValue(0, 1);
}
void BTFDebug::emitBTFSection() {
// Do not emit section if no types and only "" string.
if (!TypeEntries.size() && StringTable.getSize() == 1)
return;
MCContext &Ctx = OS.getContext();
OS.SwitchSection(Ctx.getELFSection(".BTF", ELF::SHT_PROGBITS, 0));
// Emit header.
emitCommonHeader();
OS.EmitIntValue(BTF::HeaderSize, 4);
uint32_t TypeLen = 0, StrLen;
for (const auto &TypeEntry : TypeEntries)
TypeLen += TypeEntry->getSize();
StrLen = StringTable.getSize();
OS.EmitIntValue(0, 4);
OS.EmitIntValue(TypeLen, 4);
OS.EmitIntValue(TypeLen, 4);
OS.EmitIntValue(StrLen, 4);
// Emit type table.
for (const auto &TypeEntry : TypeEntries)
TypeEntry->emitType(OS);
// Emit string table.
uint32_t StringOffset = 0;
for (const auto &S : StringTable.getTable()) {
OS.AddComment("string offset=" + std::to_string(StringOffset));
OS.EmitBytes(S);
OS.EmitBytes(StringRef("\0", 1));
StringOffset += S.size() + 1;
}
}
void BTFDebug::emitBTFExtSection() {
// Do not emit section if empty FuncInfoTable and LineInfoTable.
if (!FuncInfoTable.size() && !LineInfoTable.size())
return;
MCContext &Ctx = OS.getContext();
OS.SwitchSection(Ctx.getELFSection(".BTF.ext", ELF::SHT_PROGBITS, 0));
// Emit header.
emitCommonHeader();
OS.EmitIntValue(BTF::ExtHeaderSize, 4);
// Account for FuncInfo/LineInfo record size as well.
uint32_t FuncLen = 4, LineLen = 4;
for (const auto &FuncSec : FuncInfoTable) {
FuncLen += BTF::SecFuncInfoSize;
FuncLen += FuncSec.second.size() * BTF::BPFFuncInfoSize;
}
for (const auto &LineSec : LineInfoTable) {
LineLen += BTF::SecLineInfoSize;
LineLen += LineSec.second.size() * BTF::BPFLineInfoSize;
}
OS.EmitIntValue(0, 4);
OS.EmitIntValue(FuncLen, 4);
OS.EmitIntValue(FuncLen, 4);
OS.EmitIntValue(LineLen, 4);
// Emit func_info table.
OS.AddComment("FuncInfo");
OS.EmitIntValue(BTF::BPFFuncInfoSize, 4);
for (const auto &FuncSec : FuncInfoTable) {
OS.AddComment("FuncInfo section string offset=" +
std::to_string(FuncSec.first));
OS.EmitIntValue(FuncSec.first, 4);
OS.EmitIntValue(FuncSec.second.size(), 4);
for (const auto &FuncInfo : FuncSec.second) {
Asm->EmitLabelReference(FuncInfo.Label, 4);
OS.EmitIntValue(FuncInfo.TypeId, 4);
}
}
// Emit line_info table.
OS.AddComment("LineInfo");
OS.EmitIntValue(BTF::BPFLineInfoSize, 4);
for (const auto &LineSec : LineInfoTable) {
OS.AddComment("LineInfo section string offset=" +
std::to_string(LineSec.first));
OS.EmitIntValue(LineSec.first, 4);
OS.EmitIntValue(LineSec.second.size(), 4);
for (const auto &LineInfo : LineSec.second) {
Asm->EmitLabelReference(LineInfo.Label, 4);
OS.EmitIntValue(LineInfo.FileNameOff, 4);
OS.EmitIntValue(LineInfo.LineOff, 4);
OS.AddComment("Line " + std::to_string(LineInfo.LineNum) + " Col " +
std::to_string(LineInfo.ColumnNum));
OS.EmitIntValue(LineInfo.LineNum << 10 | LineInfo.ColumnNum, 4);
}
}
}
void BTFDebug::beginFunctionImpl(const MachineFunction *MF) {
auto *SP = MF->getFunction().getSubprogram();
auto *Unit = SP->getUnit();
if (Unit->getEmissionKind() == DICompileUnit::NoDebug) {
SkipInstruction = true;
return;
}
SkipInstruction = false;
// Collect all types locally referenced in this function.
// Use RetainedNodes so we can collect all argument names
// even if the argument is not used.
std::unordered_map<uint32_t, StringRef> FuncArgNames;
for (const DINode *DN : SP->getRetainedNodes()) {
if (const auto *DV = dyn_cast<DILocalVariable>(DN)) {
// Collect function arguments for subprogram func type.
uint32_t Arg = DV->getArg();
if (Arg) {
visitTypeEntry(DV->getType().resolve());
FuncArgNames[Arg] = DV->getName();
}
}
}
// Construct subprogram func proto type.
uint32_t ProtoTypeId;
visitSubroutineType(SP->getType(), true, FuncArgNames, ProtoTypeId);
// Construct subprogram func type
auto FuncTypeEntry =
llvm::make_unique<BTFTypeFunc>(SP->getName(), ProtoTypeId);
uint32_t FuncTypeId = addType(std::move(FuncTypeEntry));
// Construct funcinfo and the first lineinfo for the function.
MCSymbol *FuncLabel = Asm->getFunctionBegin();
BTFFuncInfo FuncInfo;
FuncInfo.Label = FuncLabel;
FuncInfo.TypeId = FuncTypeId;
if (FuncLabel->isInSection()) {
MCSection &Section = FuncLabel->getSection();
const MCSectionELF *SectionELF = dyn_cast<MCSectionELF>(&Section);
assert(SectionELF && "Null section for Function Label");
SecNameOff = addString(SectionELF->getSectionName());
} else {
SecNameOff = addString(".text");
}
FuncInfoTable[SecNameOff].push_back(FuncInfo);
}
void BTFDebug::endFunctionImpl(const MachineFunction *MF) {
SkipInstruction = false;
LineInfoGenerated = false;
SecNameOff = 0;
}
void BTFDebug::beginInstruction(const MachineInstr *MI) {
DebugHandlerBase::beginInstruction(MI);
if (SkipInstruction || MI->isMetaInstruction() ||
MI->getFlag(MachineInstr::FrameSetup))
return;
if (MI->isInlineAsm()) {
// Count the number of register definitions to find the asm string.
unsigned NumDefs = 0;
for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
++NumDefs)
;
// Skip this inline asm instruction if the asmstr is empty.
const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
if (AsmStr[0] == 0)
return;
}
// Skip this instruction if no DebugLoc or the DebugLoc
// is the same as the previous instruction.
const DebugLoc &DL = MI->getDebugLoc();
if (!DL || PrevInstLoc == DL) {
// This instruction will be skipped, no LineInfo has
// been generated, construct one based on function signature.
if (LineInfoGenerated == false) {
auto *S = MI->getMF()->getFunction().getSubprogram();
MCSymbol *FuncLabel = Asm->getFunctionBegin();
constructLineInfo(S, FuncLabel, S->getLine(), 0);
LineInfoGenerated = true;
}
return;
}
// Create a temporary label to remember the insn for lineinfo.
MCSymbol *LineSym = OS.getContext().createTempSymbol();
OS.EmitLabel(LineSym);
// Construct the lineinfo.
auto SP = DL.get()->getScope()->getSubprogram();
constructLineInfo(SP, LineSym, DL.getLine(), DL.getCol());
LineInfoGenerated = true;
PrevInstLoc = DL;
}
void BTFDebug::endModule() {
// Collect all types referenced by globals.
const Module *M = MMI->getModule();
for (const GlobalVariable &Global : M->globals()) {
// Ignore external globals for now.
if (!Global.getInitializer())
continue;
SmallVector<DIGlobalVariableExpression *, 1> GVs;
Global.getDebugInfo(GVs);
for (auto *GVE : GVs) {
visitTypeEntry(GVE->getVariable()->getType().resolve());
}
}
// Complete BTF type cross refereences.
for (const auto &TypeEntry : TypeEntries)
TypeEntry->completeType(*this);
// Emit BTF sections.
emitBTFSection();
emitBTFExtSection();
}