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Differential D29104 Diff 88967 lib/CodeGen/TargetLoweringObjectFileImpl.cpp

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lib/CodeGen/TargetLoweringObjectFileImpl.cpp

Show First 20 Lines • Show All 205 Lines • ▼ Show 20 Linesstatic const Comdat *getELFComdat(const GlobalValue *GV) {
if (C->getSelectionKind() != Comdat::Any) if (C->getSelectionKind() != Comdat::Any)
report_fatal_error("ELF COMDATs only support SelectionKind::Any, '" + report_fatal_error("ELF COMDATs only support SelectionKind::Any, '" +
C->getName() + "' cannot be lowered."); C->getName() + "' cannot be lowered.");
return C; return C;
} }
static const MCSymbolELF *getAssociatedSymbol(MDNode *MD, const TargetMachine &TM) {
auto *VM = dyn_cast<ValueAsMetadata>(MD->getOperand(0));
if (!VM)
report_fatal_error("MD_associated operand is not ValueAsMetadata");
GlobalObject *GO = dyn_cast<GlobalObject>(VM->getValue());
return dyn_cast<MCSymbolELF>(TM.getSymbol(GO));
pccUnsubmitted
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What if GO is null? (This could happen if we RAUW the GlobalObject with some other constant.)

I think the right behavior in that case would be to return null from this function.

pcc: What if GO is null? (This could happen if we RAUW the GlobalObject with some other constant.)…
}
MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal( MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const { const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
StringRef SectionName = GO->getSection(); StringRef SectionName = GO->getSection();
// Infer section flags from the section name if we can. // Infer section flags from the section name if we can.
Kind = getELFKindForNamedSection(SectionName, Kind); Kind = getELFKindForNamedSection(SectionName, Kind);
StringRef Group = ""; StringRef Group = "";
unsigned Flags = getELFSectionFlags(Kind); unsigned Flags = getELFSectionFlags(Kind);
if (const Comdat *C = getELFComdat(GO)) { if (const Comdat *C = getELFComdat(GO)) {
Group = C->getName(); Group = C->getName();
Flags |= ELF::SHF_GROUP; Flags |= ELF::SHF_GROUP;
} }
return getContext().getELFSection(SectionName,
getELFSectionType(SectionName, Kind), Flags, // A section can have at most one associated section. Put each global with
/*EntrySize=*/0, Group); // MD_associated in a unique section.
unsigned UniqueID = MCContext::GenericSectionID;
const MCSymbolELF *AssociatedSymbol = nullptr;
if (MDNode *MD = GO->getMetadata(LLVMContext::MD_associated)) {
UniqueID = NextUniqueID++;
Flags |= ELF::SHF_LINK_ORDER;
AssociatedSymbol = getAssociatedSymbol(MD, TM);
pccUnsubmitted
Done
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I think you need to make sure AssociatedSymbol is non-null before setting the flag. Please also add a negative test for a non-GlobalObject constant.

pcc: I think you need to make sure AssociatedSymbol is non-null before setting the flag. Please also…
}
MCSectionELF *Section = getContext().getELFSection(
SectionName, getELFSectionType(SectionName, Kind), Flags,
/*EntrySize=*/0, Group, UniqueID, AssociatedSymbol);
// Make sure that we did not get some other section with incompatible sh_link.
// This should not be possible due to UniqueID code above.
assert(Section->getAssociatedSymbol() == AssociatedSymbol);
return Section;
} }
/// Return the section prefix name used by options FunctionsSections and /// Return the section prefix name used by options FunctionsSections and
/// DataSections. /// DataSections.
static StringRef getSectionPrefixForGlobal(SectionKind Kind) { static StringRef getSectionPrefixForGlobal(SectionKind Kind) {
if (Kind.isText()) if (Kind.isText())
return ".text"; return ".text";
if (Kind.isReadOnly()) if (Kind.isReadOnly())
return ".rodata"; return ".rodata";
if (Kind.isBSS()) if (Kind.isBSS())
return ".bss"; return ".bss";
if (Kind.isThreadData()) if (Kind.isThreadData())
return ".tdata"; return ".tdata";
if (Kind.isThreadBSS()) if (Kind.isThreadBSS())
return ".tbss"; return ".tbss";
if (Kind.isData()) if (Kind.isData())
return ".data"; return ".data";
assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
return ".data.rel.ro"; return ".data.rel.ro";
} }
static MCSectionELF * static MCSectionELF *selectELFSectionForGlobal(
selectELFSectionForGlobal(MCContext &Ctx, const GlobalObject *GO, MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
SectionKind Kind, Mangler &Mang, const TargetMachine &TM, bool EmitUniqueSection, unsigned Flags,
const TargetMachine &TM, bool EmitUniqueSection, unsigned *NextUniqueID, const MCSymbolELF *AssociatedSymbol) {
unsigned Flags, unsigned *NextUniqueID) {
unsigned EntrySize = 0; unsigned EntrySize = 0;
if (Kind.isMergeableCString()) { if (Kind.isMergeableCString()) {
if (Kind.isMergeable2ByteCString()) { if (Kind.isMergeable2ByteCString()) {
EntrySize = 2; EntrySize = 2;
} else if (Kind.isMergeable4ByteCString()) { } else if (Kind.isMergeable4ByteCString()) {
EntrySize = 4; EntrySize = 4;
} else { } else {
EntrySize = 1; EntrySize = 1;
▲ Show 20 Lines • Show All 50 Lines • ▼ Show 20 Linesstatic MCSectionELF *selectELFSectionForGlobal(
if (EmitUniqueSection && !UniqueSectionNames) { if (EmitUniqueSection && !UniqueSectionNames) {
UniqueID = *NextUniqueID; UniqueID = *NextUniqueID;
(*NextUniqueID)++; (*NextUniqueID)++;
} }
// Use 0 as the unique ID for execute-only text // Use 0 as the unique ID for execute-only text
if (Kind.isExecuteOnly()) if (Kind.isExecuteOnly())
UniqueID = 0; UniqueID = 0;
return Ctx.getELFSection(Name, getELFSectionType(Name, Kind), Flags, return Ctx.getELFSection(Name, getELFSectionType(Name, Kind), Flags,
EntrySize, Group, UniqueID); EntrySize, Group, UniqueID, AssociatedSymbol);
} }
MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal( MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const { const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
unsigned Flags = getELFSectionFlags(Kind); unsigned Flags = getELFSectionFlags(Kind);
// If we have -ffunction-section or -fdata-section then we should emit the // If we have -ffunction-section or -fdata-section then we should emit the
// global value to a uniqued section specifically for it. // global value to a uniqued section specifically for it.
bool EmitUniqueSection = false; bool EmitUniqueSection = false;
if (!(Flags & ELF::SHF_MERGE) && !Kind.isCommon()) { if (!(Flags & ELF::SHF_MERGE) && !Kind.isCommon()) {
if (Kind.isText()) if (Kind.isText())
EmitUniqueSection = TM.getFunctionSections(); EmitUniqueSection = TM.getFunctionSections();
else else
EmitUniqueSection = TM.getDataSections(); EmitUniqueSection = TM.getDataSections();
} }
EmitUniqueSection |= GO->hasComdat(); EmitUniqueSection |= GO->hasComdat();
return selectELFSectionForGlobal(getContext(), GO, Kind, getMangler(), TM, const MCSymbolELF *AssociatedSymbol = nullptr;
EmitUniqueSection, Flags, &NextUniqueID); if (MDNode *MD = GO->getMetadata(LLVMContext::MD_associated)) {
EmitUniqueSection = true;
Flags |= ELF::SHF_LINK_ORDER;
AssociatedSymbol = getAssociatedSymbol(MD, TM);
pccUnsubmitted
Not Done
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Same here.

pcc: Same here.
}
EmitUniqueSection |= GO->getMetadata(LLVMContext::MD_associated) != nullptr;
pccUnsubmitted
Done
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Remove this line.

pcc: Remove this line.
MCSectionELF *Section = selectELFSectionForGlobal(
getContext(), GO, Kind, getMangler(), TM, EmitUniqueSection, Flags,
&NextUniqueID, AssociatedSymbol);
assert(Section->getAssociatedSymbol() == AssociatedSymbol);
return Section;
} }
MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable( MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable(
const Function &F, const TargetMachine &TM) const { const Function &F, const TargetMachine &TM) const {
// If the function can be removed, produce a unique section so that // If the function can be removed, produce a unique section so that
// the table doesn't prevent the removal. // the table doesn't prevent the removal.
const Comdat *C = F.getComdat(); const Comdat *C = F.getComdat();
bool EmitUniqueSection = TM.getFunctionSections() || C; bool EmitUniqueSection = TM.getFunctionSections() || C;
if (!EmitUniqueSection) if (!EmitUniqueSection)
return ReadOnlySection; return ReadOnlySection;
return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(), return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(),
getMangler(), TM, EmitUniqueSection, ELF::SHF_ALLOC, getMangler(), TM, EmitUniqueSection,
&NextUniqueID); ELF::SHF_ALLOC, &NextUniqueID,
/* AssociatedSymbol */ nullptr);
} }
bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection( bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection(
bool UsesLabelDifference, const Function &F) const { bool UsesLabelDifference, const Function &F) const {
// We can always create relative relocations, so use another section // We can always create relative relocations, so use another section
// that can be marked non-executable. // that can be marked non-executable.
return false; return false;
} }
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