- Remove custom handling of jumptables by the elf writter (this was
a dirty hack and isn't need anymore since the last x86 code emitter patch)
- Add a target-dependent modifier to addend calculation
- Use R_X86_64_32S relocation for X86::reloc_absolute_word_sext
- Use getELFSectionFlags whenever possible
- fix getTextSection to use TLOF and emit the right text section
- Handle global emission for static ctors, dtors and Type::PointerTyID
- Some minor fixes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78176 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ELFWriter.cpp b/lib/CodeGen/ELFWriter.cpp
index 3122564..93e8415 100644
--- a/lib/CodeGen/ELFWriter.cpp
+++ b/lib/CodeGen/ELFWriter.cpp
@@ -76,6 +76,7 @@
ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
: MachineFunctionPass(&ID), O(o), TM(tm),
OutContext(*new MCContext()),
+ TLOF(TM.getTargetLowering()->getObjFileLowering()),
is64Bit(TM.getTargetData()->getPointerSizeInBits() == 64),
isLittleEndian(TM.getTargetData()->isLittleEndian()),
ElfHdr(isLittleEndian, is64Bit) {
@@ -99,8 +100,6 @@
// the module to the ELF file.
bool ELFWriter::doInitialization(Module &M) {
// Initialize TargetLoweringObjectFile.
- const TargetLoweringObjectFile &TLOF =
- TM.getTargetLowering()->getObjFileLowering();
const_cast<TargetLoweringObjectFile&>(TLOF).Initialize(OutContext, TM);
Mang = new Mangler(M);
@@ -160,11 +159,13 @@
return false;
}
-// addGlobalSymbol - Add a global to be processed and to the
-// global symbol lookup, use a zero index for non private symbols
-// because the table index will be determined later.
-void ELFWriter::addGlobalSymbol(const GlobalValue *GV) {
+// addGlobalSymbol - Add a global to be processed and to the global symbol
+// lookup, use a zero index because the table index will be determined later.
+void ELFWriter::addGlobalSymbol(const GlobalValue *GV,
+ bool AddToLookup /* = false */) {
PendingGlobals.insert(GV);
+ if (AddToLookup)
+ GblSymLookup[GV] = 0;
}
// addExternalSymbol - Add the external to be processed and to the
@@ -175,20 +176,39 @@
ExtSymLookup[External] = 0;
}
-// Get jump table section on the section name returned by TAI
-ELFSection &ELFWriter::getJumpTableSection() {
- unsigned Align = TM.getTargetData()->getPointerABIAlignment();
-
- const TargetLoweringObjectFile &TLOF =
- TM.getTargetLowering()->getObjFileLowering();
-
- return getSection(TLOF.getSectionForConstant(SectionKind::getReadOnly())
- ->getName(),
- ELFSection::SHT_PROGBITS,
- ELFSection::SHF_ALLOC, Align);
+// getCtorSection - Get the static constructor section
+ELFSection &ELFWriter::getCtorSection() {
+ const MCSection *Ctor = TLOF.getStaticCtorSection();
+ return getSection(Ctor->getName(), ELFSection::SHT_PROGBITS,
+ getElfSectionFlags(Ctor->getKind()));
}
-// Get a constant pool section based on the section name returned by TAI
+// getDtorSection - Get the static destructor section
+ELFSection &ELFWriter::getDtorSection() {
+ const MCSection *Dtor = TLOF.getStaticDtorSection();
+ return getSection(Dtor->getName(), ELFSection::SHT_PROGBITS,
+ getElfSectionFlags(Dtor->getKind()));
+}
+
+// getTextSection - Get the text section for the specified function
+ELFSection &ELFWriter::getTextSection(Function *F) {
+ const MCSection *Text = TLOF.SectionForGlobal(F, Mang, TM);
+ return getSection(Text->getName(), ELFSection::SHT_PROGBITS,
+ getElfSectionFlags(Text->getKind()));
+}
+
+// getJumpTableSection - Get a read only section for constants when
+// emitting jump tables. TODO: add PIC support
+ELFSection &ELFWriter::getJumpTableSection() {
+ const MCSection *JT = TLOF.getSectionForConstant(SectionKind::getReadOnly());
+ return getSection(JT->getName(),
+ ELFSection::SHT_PROGBITS,
+ getElfSectionFlags(JT->getKind()),
+ TM.getTargetData()->getPointerABIAlignment());
+}
+
+// getConstantPoolSection - Get a constant pool section based on the machine
+// constant pool entry type and relocation info.
ELFSection &ELFWriter::getConstantPoolSection(MachineConstantPoolEntry &CPE) {
SectionKind Kind;
switch (CPE.getRelocationInfo()) {
@@ -206,17 +226,14 @@
}
}
- const TargetLoweringObjectFile &TLOF =
- TM.getTargetLowering()->getObjFileLowering();
-
return getSection(TLOF.getSectionForConstant(Kind)->getName(),
ELFSection::SHT_PROGBITS,
- ELFSection::SHF_MERGE | ELFSection::SHF_ALLOC,
+ getElfSectionFlags(Kind),
CPE.getAlignment());
}
-// Return the relocation section of section 'S'. 'RelA' is true
-// if the relocation section contains entries with addends.
+// getRelocSection - Return the relocation section of section 'S'. 'RelA'
+// is true if the relocation section contains entries with addends.
ELFSection &ELFWriter::getRelocSection(ELFSection &S) {
unsigned SectionHeaderTy = TEW->hasRelocationAddend() ?
ELFSection::SHT_RELA : ELFSection::SHT_REL;
@@ -248,7 +265,7 @@
if (GV->hasInternalLinkage())
return ELFSym::STB_LOCAL;
- if (GV->hasWeakLinkage())
+ if (GV->isWeakForLinker())
return ELFSym::STB_WEAK;
return ELFSym::STB_GLOBAL;
@@ -267,9 +284,11 @@
// getElfSectionFlags - Get the ELF Section Header flags based
// on the flags defined in SectionKind.h.
-unsigned ELFWriter::getElfSectionFlags(SectionKind Kind) {
- unsigned ElfSectionFlags = ELFSection::SHF_ALLOC;
-
+unsigned ELFWriter::getElfSectionFlags(SectionKind Kind, bool IsAlloc) {
+ unsigned ElfSectionFlags = 0;
+
+ if (IsAlloc)
+ ElfSectionFlags |= ELFSection::SHF_ALLOC;
if (Kind.isText())
ElfSectionFlags |= ELFSection::SHF_EXECINSTR;
if (Kind.isWriteable())
@@ -287,7 +306,8 @@
// isELFUndefSym - the symbol has no section and must be placed in
// the symbol table with a reference to the null section.
static bool isELFUndefSym(const GlobalValue *GV) {
- return GV->isDeclaration();
+ // Functions which make up until this point references are an undef symbol
+ return GV->isDeclaration() || (isa<Function>(GV));
}
// isELFBssSym - for an undef or null value, the symbol must go to a bss
@@ -305,7 +325,7 @@
}
// isELFDataSym - if the symbol is an initialized but no null constant
-// it must go to some kind of data section gathered from TAI
+// it must go to some kind of data section
static bool isELFDataSym(const Constant *CV) {
return (!(CV->isNullValue() || isa<UndefValue>(CV)));
}
@@ -317,27 +337,22 @@
if (GblSymLookup.find(GV) != GblSymLookup.end())
return;
- // If the global is a function already emited in the text section
- // just add it to the global symbol lookup with a zero index to be
- // patched up later.
- if (isa<Function>(GV) && !GV->isDeclaration()) {
- GblSymLookup[GV] = 0;
- return;
- }
-
// Handle ELF Bind, Visibility and Type for the current symbol
unsigned SymBind = getGlobalELFBinding(GV);
- ELFSym *GblSym = ELFSym::getGV(GV, SymBind, getGlobalELFType(GV),
- getGlobalELFVisibility(GV));
+ unsigned SymType = getGlobalELFType(GV);
- if (isELFUndefSym(GV)) {
- GblSym->SectionIdx = ELFSection::SHN_UNDEF;
- } else {
+ // All undef symbols have the same binding, type and visibily and
+ // are classified regardless of their type.
+ ELFSym *GblSym = isELFUndefSym(GV) ? ELFSym::getUndefGV(GV)
+ : ELFSym::getGV(GV, SymBind, SymType, getGlobalELFVisibility(GV));
+
+ if (!isELFUndefSym(GV)) {
assert(isa<GlobalVariable>(GV) && "GV not a global variable!");
const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
- const TargetLoweringObjectFile &TLOF =
- TM.getTargetLowering()->getObjFileLowering();
+ // Handle special llvm globals
+ if (EmitSpecialLLVMGlobal(GVar))
+ return;
// Get the ELF section where this global belongs from TLOF
const MCSection *S = TLOF.SectionForGlobal(GV, Mang, TM);
@@ -474,39 +489,106 @@
for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
EmitGlobalConstant(CP->getOperand(I), GblS);
return;
- } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
- // This is a constant address for a global variable or function and
- // therefore must be referenced using a relocation entry.
-
- // Check if the referenced symbol is already emitted
- if (GblSymLookup.find(GV) == GblSymLookup.end())
- EmitGlobal(GV);
-
- // Create the relocation entry for the global value
- MachineRelocation MR =
- MachineRelocation::getGV(GblS.getCurrentPCOffset(),
- TEW->getAbsoluteLabelMachineRelTy(),
- const_cast<GlobalValue*>(GV));
-
- // Fill the data entry with zeros
- for (unsigned i=0; i < Size; ++i)
- GblS.emitByte(0);
-
- // Add the relocation entry for the current data section
- GblS.addRelocation(MR);
- return;
} else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
if (CE->getOpcode() == Instruction::BitCast) {
EmitGlobalConstant(CE->getOperand(0), GblS);
return;
}
- // See AsmPrinter::EmitConstantValueOnly for other ConstantExpr types
- llvm_unreachable("Unsupported ConstantExpr type");
+ std::string msg(CE->getOpcodeName());
+ raw_string_ostream ErrorMsg(msg);
+ ErrorMsg << ": Unsupported ConstantExpr type";
+ llvm_report_error(ErrorMsg.str());
+ } else if (CV->getType()->getTypeID() == Type::PointerTyID) {
+ // Fill the data entry with zeros or emit a relocation entry
+ if (isa<ConstantPointerNull>(CV)) {
+ for (unsigned i=0; i < Size; ++i)
+ GblS.emitByte(0);
+ } else {
+ emitGlobalDataRelocation(cast<const GlobalValue>(CV),
+ TD->getPointerSize(), GblS);
+ }
+ return;
+ } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
+ // This is a constant address for a global variable or function and
+ // therefore must be referenced using a relocation entry.
+ emitGlobalDataRelocation(GV, Size, GblS);
+ return;
}
- llvm_unreachable("Unknown global constant type");
+ std::string msg;
+ raw_string_ostream ErrorMsg(msg);
+ ErrorMsg << "Constant unimp for type: " << *CV->getType();
+ llvm_report_error(ErrorMsg.str());
}
+void ELFWriter::emitGlobalDataRelocation(const GlobalValue *GV, unsigned Size,
+ ELFSection &GblS) {
+ // Create the relocation entry for the global value
+ MachineRelocation MR =
+ MachineRelocation::getGV(GblS.getCurrentPCOffset(),
+ TEW->getAbsoluteLabelMachineRelTy(),
+ const_cast<GlobalValue*>(GV));
+
+ // Fill the data entry with zeros
+ for (unsigned i=0; i < Size; ++i)
+ GblS.emitByte(0);
+
+ // Add the relocation entry for the current data section
+ GblS.addRelocation(MR);
+}
+
+/// EmitSpecialLLVMGlobal - Check to see if the specified global is a
+/// special global used by LLVM. If so, emit it and return true, otherwise
+/// do nothing and return false.
+bool ELFWriter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
+ if (GV->getName() == "llvm.used")
+ llvm_unreachable("not implemented yet");
+
+ // Ignore debug and non-emitted data. This handles llvm.compiler.used.
+ if (GV->getSection() == "llvm.metadata" ||
+ GV->hasAvailableExternallyLinkage())
+ return true;
+
+ if (!GV->hasAppendingLinkage()) return false;
+
+ assert(GV->hasInitializer() && "Not a special LLVM global!");
+
+ const TargetData *TD = TM.getTargetData();
+ unsigned Align = TD->getPointerPrefAlignment();
+ if (GV->getName() == "llvm.global_ctors") {
+ ELFSection &Ctor = getCtorSection();
+ Ctor.emitAlignment(Align);
+ EmitXXStructorList(GV->getInitializer(), Ctor);
+ return true;
+ }
+
+ if (GV->getName() == "llvm.global_dtors") {
+ ELFSection &Dtor = getDtorSection();
+ Dtor.emitAlignment(Align);
+ EmitXXStructorList(GV->getInitializer(), Dtor);
+ return true;
+ }
+
+ return false;
+}
+
+/// EmitXXStructorList - Emit the ctor or dtor list. This just emits out the
+/// function pointers, ignoring the init priority.
+void ELFWriter::EmitXXStructorList(Constant *List, ELFSection &Xtor) {
+ // Should be an array of '{ int, void ()* }' structs. The first value is the
+ // init priority, which we ignore.
+ if (!isa<ConstantArray>(List)) return;
+ ConstantArray *InitList = cast<ConstantArray>(List);
+ for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
+ if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
+ if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
+
+ if (CS->getOperand(1)->isNullValue())
+ return; // Found a null terminator, exit printing.
+ // Emit the function pointer.
+ EmitGlobalConstant(CS->getOperand(1), Xtor);
+ }
+}
bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
// Nothing to do here, this is all done through the ElfCE object above.
@@ -638,7 +720,8 @@
Addend = PrivateSyms[SymIdx]->Value;
SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
} else {
- Addend = TEW->getDefaultAddendForRelTy(RelType);
+ int64_t GlobalOffset = MR.getConstantVal();
+ Addend = TEW->getDefaultAddendForRelTy(RelType, GlobalOffset);
}
} else if (MR.isExternalSymbol()) {
const char *ExtSym = MR.getExternalSymbol();
@@ -648,29 +731,26 @@
// Get the symbol index for the section symbol
unsigned SectionIdx = MR.getConstantVal();
SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
- Addend = (uint64_t)MR.getResultPointer();
+
+ // The symbol offset inside the section
+ int64_t SymOffset = (int64_t)MR.getResultPointer();
// For pc relative relocations where symbols are defined in the same
// section they are referenced, ignore the relocation entry and patch
// the relocatable field with the symbol offset directly.
if (S.SectionIdx == SectionIdx && TEW->isPCRelativeRel(RelType)) {
- int64_t Value = TEW->computeRelocation(Addend, RelOffset, RelType);
+ int64_t Value = TEW->computeRelocation(SymOffset, RelOffset, RelType);
RelocateField(S, RelOffset, Value, RelTySize);
continue;
}
- // Handle Jump Table Index relocation
- if ((SectionIdx == getJumpTableSection().SectionIdx) &&
- TEW->hasCustomJumpTableIndexRelTy()) {
- RelType = TEW->getJumpTableIndexRelTy();
- RelTySize = TEW->getRelocationTySize(RelType);
- }
+ Addend = TEW->getDefaultAddendForRelTy(RelType, SymOffset);
}
// The target without addend on the relocation symbol must be
// patched in the relocation place itself to contain the addend
- if (!HasRelA)
- RelocateField(S, RelOffset, Addend, RelTySize);
+ // otherwise write zeros to make sure there is no garbage there
+ RelocateField(S, RelOffset, HasRelA ? 0 : Addend, RelTySize);
// Get the relocation entry and emit to the relocation section
ELFRelocation Rel(RelOffset, SymIdx, RelType, HasRelA, Addend);