llvm-6502/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

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#include "DwarfCompileUnit.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instruction.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
namespace llvm {
DwarfCompileUnit::DwarfCompileUnit(unsigned UID, DICompileUnit Node,
AsmPrinter *A, DwarfDebug *DW,
DwarfFile *DWU)
: DwarfUnit(UID, dwarf::DW_TAG_compile_unit, Node, A, DW, DWU) {
insertDIE(Node, &getUnitDie());
}
/// addLabelAddress - Add a dwarf label attribute data and value using
/// DW_FORM_addr or DW_FORM_GNU_addr_index.
///
void DwarfCompileUnit::addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
const MCSymbol *Label) {
// Don't use the address pool in non-fission or in the skeleton unit itself.
// FIXME: Once GDB supports this, it's probably worthwhile using the address
// pool from the skeleton - maybe even in non-fission (possibly fewer
// relocations by sharing them in the pool, but we have other ideas about how
// to reduce the number of relocations as well/instead).
if (!DD->useSplitDwarf() || !Skeleton)
return addLocalLabelAddress(Die, Attribute, Label);
if (Label)
DD->addArangeLabel(SymbolCU(this, Label));
unsigned idx = DD->getAddressPool().getIndex(Label);
DIEValue *Value = new (DIEValueAllocator) DIEInteger(idx);
Die.addValue(Attribute, dwarf::DW_FORM_GNU_addr_index, Value);
}
void DwarfCompileUnit::addLocalLabelAddress(DIE &Die,
dwarf::Attribute Attribute,
const MCSymbol *Label) {
if (Label)
DD->addArangeLabel(SymbolCU(this, Label));
Die.addValue(Attribute, dwarf::DW_FORM_addr,
Label ? (DIEValue *)new (DIEValueAllocator) DIELabel(Label)
: new (DIEValueAllocator) DIEInteger(0));
}
unsigned DwarfCompileUnit::getOrCreateSourceID(StringRef FileName,
StringRef DirName) {
// If we print assembly, we can't separate .file entries according to
// compile units. Thus all files will belong to the default compile unit.
// FIXME: add a better feature test than hasRawTextSupport. Even better,
// extend .file to support this.
return Asm->OutStreamer.EmitDwarfFileDirective(
0, DirName, FileName,
Asm->OutStreamer.hasRawTextSupport() ? 0 : getUniqueID());
}
// Return const expression if value is a GEP to access merged global
// constant. e.g.
// i8* getelementptr ({ i8, i8, i8, i8 }* @_MergedGlobals, i32 0, i32 0)
static const ConstantExpr *getMergedGlobalExpr(const Value *V) {
const ConstantExpr *CE = dyn_cast_or_null<ConstantExpr>(V);
if (!CE || CE->getNumOperands() != 3 ||
CE->getOpcode() != Instruction::GetElementPtr)
return nullptr;
// First operand points to a global struct.
Value *Ptr = CE->getOperand(0);
if (!isa<GlobalValue>(Ptr) ||
!isa<StructType>(cast<PointerType>(Ptr->getType())->getElementType()))
return nullptr;
// Second operand is zero.
const ConstantInt *CI = dyn_cast_or_null<ConstantInt>(CE->getOperand(1));
if (!CI || !CI->isZero())
return nullptr;
// Third operand is offset.
if (!isa<ConstantInt>(CE->getOperand(2)))
return nullptr;
return CE;
}
/// getOrCreateGlobalVariableDIE - get or create global variable DIE.
DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(DIGlobalVariable GV) {
// Check for pre-existence.
if (DIE *Die = getDIE(GV))
return Die;
assert(GV.isGlobalVariable());
DIScope GVContext = GV.getContext();
DIType GTy = DD->resolve(GV.getType());
// If this is a static data member definition, some attributes belong
// to the declaration DIE.
DIE *VariableDIE = nullptr;
bool IsStaticMember = false;
DIDerivedType SDMDecl = GV.getStaticDataMemberDeclaration();
if (SDMDecl.Verify()) {
assert(SDMDecl.isStaticMember() && "Expected static member decl");
// We need the declaration DIE that is in the static member's class.
VariableDIE = getOrCreateStaticMemberDIE(SDMDecl);
IsStaticMember = true;
}
// If this is not a static data member definition, create the variable
// DIE and add the initial set of attributes to it.
if (!VariableDIE) {
// Construct the context before querying for the existence of the DIE in
// case such construction creates the DIE.
DIE *ContextDIE = getOrCreateContextDIE(GVContext);
// Add to map.
VariableDIE = &createAndAddDIE(GV.getTag(), *ContextDIE, GV);
// Add name and type.
addString(*VariableDIE, dwarf::DW_AT_name, GV.getDisplayName());
addType(*VariableDIE, GTy);
// Add scoping info.
if (!GV.isLocalToUnit())
addFlag(*VariableDIE, dwarf::DW_AT_external);
// Add line number info.
addSourceLine(*VariableDIE, GV);
}
// Add location.
bool addToAccelTable = false;
DIE *VariableSpecDIE = nullptr;
bool isGlobalVariable = GV.getGlobal() != nullptr;
if (isGlobalVariable) {
addToAccelTable = true;
DIELoc *Loc = new (DIEValueAllocator) DIELoc();
const MCSymbol *Sym = Asm->getSymbol(GV.getGlobal());
if (GV.getGlobal()->isThreadLocal()) {
// FIXME: Make this work with -gsplit-dwarf.
unsigned PointerSize = Asm->getDataLayout().getPointerSize();
assert((PointerSize == 4 || PointerSize == 8) &&
"Add support for other sizes if necessary");
// Based on GCC's support for TLS:
if (!DD->useSplitDwarf()) {
// 1) Start with a constNu of the appropriate pointer size
addUInt(*Loc, dwarf::DW_FORM_data1,
PointerSize == 4 ? dwarf::DW_OP_const4u : dwarf::DW_OP_const8u);
// 2) containing the (relocated) offset of the TLS variable
// within the module's TLS block.
addExpr(*Loc, dwarf::DW_FORM_udata,
Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
} else {
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
addUInt(*Loc, dwarf::DW_FORM_udata,
DD->getAddressPool().getIndex(Sym, /* TLS */ true));
}
// 3) followed by a custom OP to make the debugger do a TLS lookup.
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_push_tls_address);
} else {
DD->addArangeLabel(SymbolCU(this, Sym));
addOpAddress(*Loc, Sym);
}
// A static member's declaration is already flagged as such.
if (!SDMDecl.Verify() && !GV.isDefinition())
addFlag(*VariableDIE, dwarf::DW_AT_declaration);
// Do not create specification DIE if context is either compile unit
// or a subprogram.
if (GVContext && GV.isDefinition() && !GVContext.isCompileUnit() &&
!GVContext.isFile() && !DD->isSubprogramContext(GVContext)) {
// Create specification DIE.
VariableSpecDIE = &createAndAddDIE(dwarf::DW_TAG_variable, UnitDie);
addDIEEntry(*VariableSpecDIE, dwarf::DW_AT_specification, *VariableDIE);
addBlock(*VariableSpecDIE, dwarf::DW_AT_location, Loc);
// A static member's declaration is already flagged as such.
if (!SDMDecl.Verify())
addFlag(*VariableDIE, dwarf::DW_AT_declaration);
} else {
addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
}
// Add the linkage name.
StringRef LinkageName = GV.getLinkageName();
if (!LinkageName.empty())
// From DWARF4: DIEs to which DW_AT_linkage_name may apply include:
// TAG_common_block, TAG_constant, TAG_entry_point, TAG_subprogram and
// TAG_variable.
addString(IsStaticMember && VariableSpecDIE ? *VariableSpecDIE
: *VariableDIE,
DD->getDwarfVersion() >= 4 ? dwarf::DW_AT_linkage_name
: dwarf::DW_AT_MIPS_linkage_name,
GlobalValue::getRealLinkageName(LinkageName));
} else if (const ConstantInt *CI =
dyn_cast_or_null<ConstantInt>(GV.getConstant())) {
// AT_const_value was added when the static member was created. To avoid
// emitting AT_const_value multiple times, we only add AT_const_value when
// it is not a static member.
if (!IsStaticMember)
addConstantValue(*VariableDIE, CI, GTy);
} else if (const ConstantExpr *CE = getMergedGlobalExpr(GV.getConstant())) {
addToAccelTable = true;
// GV is a merged global.
DIELoc *Loc = new (DIEValueAllocator) DIELoc();
Value *Ptr = CE->getOperand(0);
MCSymbol *Sym = Asm->getSymbol(cast<GlobalValue>(Ptr));
DD->addArangeLabel(SymbolCU(this, Sym));
addOpAddress(*Loc, Sym);
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
SmallVector<Value *, 3> Idx(CE->op_begin() + 1, CE->op_end());
addUInt(*Loc, dwarf::DW_FORM_udata,
Asm->getDataLayout().getIndexedOffset(Ptr->getType(), Idx));
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
}
DIE *ResultDIE = VariableSpecDIE ? VariableSpecDIE : VariableDIE;
if (addToAccelTable) {
DD->addAccelName(GV.getName(), *ResultDIE);
// If the linkage name is different than the name, go ahead and output
// that as well into the name table.
if (GV.getLinkageName() != "" && GV.getName() != GV.getLinkageName())
DD->addAccelName(GV.getLinkageName(), *ResultDIE);
}
addGlobalName(GV.getName(), *ResultDIE, GV.getContext());
return ResultDIE;
}
void DwarfCompileUnit::addRange(RangeSpan Range) {
bool SameAsPrevCU = this == DD->getPrevCU();
DD->setPrevCU(this);
// If we have no current ranges just add the range and return, otherwise,
// check the current section and CU against the previous section and CU we
// emitted into and the subprogram was contained within. If these are the
// same then extend our current range, otherwise add this as a new range.
if (CURanges.empty() || !SameAsPrevCU ||
(&CURanges.back().getEnd()->getSection() !=
&Range.getEnd()->getSection())) {
CURanges.push_back(Range);
return;
}
CURanges.back().setEnd(Range.getEnd());
}
void DwarfCompileUnit::addSectionLabel(DIE &Die, dwarf::Attribute Attribute,
const MCSymbol *Label,
const MCSymbol *Sec) {
if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
addLabel(Die, Attribute,
DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
: dwarf::DW_FORM_data4,
Label);
else
addSectionDelta(Die, Attribute, Label, Sec);
}
void DwarfCompileUnit::initStmtList(MCSymbol *DwarfLineSectionSym) {
// Define start line table label for each Compile Unit.
MCSymbol *LineTableStartSym =
Asm->OutStreamer.getDwarfLineTableSymbol(getUniqueID());
stmtListIndex = UnitDie.getValues().size();
// DW_AT_stmt_list is a offset of line number information for this
// compile unit in debug_line section. For split dwarf this is
// left in the skeleton CU and so not included.
// The line table entries are not always emitted in assembly, so it
// is not okay to use line_table_start here.
addSectionLabel(UnitDie, dwarf::DW_AT_stmt_list, LineTableStartSym,
DwarfLineSectionSym);
}
void DwarfCompileUnit::applyStmtList(DIE &D) {
D.addValue(dwarf::DW_AT_stmt_list,
UnitDie.getAbbrev().getData()[stmtListIndex].getForm(),
UnitDie.getValues()[stmtListIndex]);
}
void DwarfCompileUnit::attachLowHighPC(DIE &D, const MCSymbol *Begin,
const MCSymbol *End) {
assert(Begin && "Begin label should not be null!");
assert(End && "End label should not be null!");
assert(Begin->isDefined() && "Invalid starting label");
assert(End->isDefined() && "Invalid end label");
addLabelAddress(D, dwarf::DW_AT_low_pc, Begin);
if (DD->getDwarfVersion() < 4)
addLabelAddress(D, dwarf::DW_AT_high_pc, End);
else
addLabelDelta(D, dwarf::DW_AT_high_pc, End, Begin);
}
// Find DIE for the given subprogram and attach appropriate DW_AT_low_pc
// and DW_AT_high_pc attributes. If there are global variables in this
// scope then create and insert DIEs for these variables.
DIE &DwarfCompileUnit::updateSubprogramScopeDIE(DISubprogram SP) {
DIE *SPDie = getOrCreateSubprogramDIE(SP);
attachLowHighPC(*SPDie, DD->getFunctionBeginSym(), DD->getFunctionEndSym());
if (!DD->getCurrentFunction()->getTarget().Options.DisableFramePointerElim(
*DD->getCurrentFunction()))
addFlag(*SPDie, dwarf::DW_AT_APPLE_omit_frame_ptr);
// Only include DW_AT_frame_base in full debug info
if (getCUNode().getEmissionKind() != DIBuilder::LineTablesOnly) {
const TargetRegisterInfo *RI =
Asm->TM.getSubtargetImpl()->getRegisterInfo();
MachineLocation Location(RI->getFrameRegister(*Asm->MF));
addAddress(*SPDie, dwarf::DW_AT_frame_base, Location);
}
// Add name to the name table, we do this here because we're guaranteed
// to have concrete versions of our DW_TAG_subprogram nodes.
DD->addSubprogramNames(SP, *SPDie);
return *SPDie;
}
// Construct a DIE for this scope.
void DwarfCompileUnit::constructScopeDIE(
LexicalScope *Scope, SmallVectorImpl<std::unique_ptr<DIE>> &FinalChildren) {
if (!Scope || !Scope->getScopeNode())
return;
DIScope DS(Scope->getScopeNode());
assert((Scope->getInlinedAt() || !DS.isSubprogram()) &&
"Only handle inlined subprograms here, use "
"constructSubprogramScopeDIE for non-inlined "
"subprograms");
SmallVector<std::unique_ptr<DIE>, 8> Children;
// We try to create the scope DIE first, then the children DIEs. This will
// avoid creating un-used children then removing them later when we find out
// the scope DIE is null.
std::unique_ptr<DIE> ScopeDIE;
if (Scope->getParent() && DS.isSubprogram()) {
ScopeDIE = DD->constructInlinedScopeDIE(*this, Scope);
if (!ScopeDIE)
return;
// We create children when the scope DIE is not null.
DD->createScopeChildrenDIE(*this, Scope, Children);
} else {
// Early exit when we know the scope DIE is going to be null.
if (DD->isLexicalScopeDIENull(Scope))
return;
unsigned ChildScopeCount;
// We create children here when we know the scope DIE is not going to be
// null and the children will be added to the scope DIE.
DD->createScopeChildrenDIE(*this, Scope, Children, &ChildScopeCount);
// There is no need to emit empty lexical block DIE.
for (const auto &E : DD->findImportedEntitiesForScope(DS))
Children.push_back(
constructImportedEntityDIE(DIImportedEntity(E.second)));
// If there are only other scopes as children, put them directly in the
// parent instead, as this scope would serve no purpose.
if (Children.size() == ChildScopeCount) {
FinalChildren.insert(FinalChildren.end(),
std::make_move_iterator(Children.begin()),
std::make_move_iterator(Children.end()));
return;
}
ScopeDIE = DD->constructLexicalScopeDIE(*this, Scope);
assert(ScopeDIE && "Scope DIE should not be null.");
}
// Add children
for (auto &I : Children)
ScopeDIE->addChild(std::move(I));
FinalChildren.push_back(std::move(ScopeDIE));
}
} // end llvm namespace