llvm-project/llvm/tools/lto/LTOModule.cpp

730 lines
23 KiB
C++

//===-- LTOModule.cpp - LLVM Link Time Optimizer --------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Link Time Optimization library. This library is
// intended to be used by linker to optimize code at link time.
//
//===----------------------------------------------------------------------===//
#include "LTOModule.h"
#include "llvm/Constants.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/system_error.h"
#include "llvm/Target/Mangler.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/MC/MCTargetAsmParser.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegisterInfo.h"
using namespace llvm;
bool LTOModule::isBitcodeFile(const void *mem, size_t length) {
return llvm::sys::IdentifyFileType((char*)mem, length)
== llvm::sys::Bitcode_FileType;
}
bool LTOModule::isBitcodeFile(const char *path) {
return llvm::sys::Path(path).isBitcodeFile();
}
bool LTOModule::isBitcodeFileForTarget(const void *mem, size_t length,
const char *triplePrefix) {
MemoryBuffer *buffer = makeBuffer(mem, length);
if (!buffer)
return false;
return isTargetMatch(buffer, triplePrefix);
}
bool LTOModule::isBitcodeFileForTarget(const char *path,
const char *triplePrefix) {
OwningPtr<MemoryBuffer> buffer;
if (MemoryBuffer::getFile(path, buffer))
return false;
return isTargetMatch(buffer.take(), triplePrefix);
}
// Takes ownership of buffer.
bool LTOModule::isTargetMatch(MemoryBuffer *buffer, const char *triplePrefix) {
std::string Triple = getBitcodeTargetTriple(buffer, getGlobalContext());
delete buffer;
return (strncmp(Triple.c_str(), triplePrefix,
strlen(triplePrefix)) == 0);
}
LTOModule::LTOModule(Module *m, TargetMachine *t)
: _module(m), _target(t)
{
}
LTOModule *LTOModule::makeLTOModule(const char *path,
std::string &errMsg) {
OwningPtr<MemoryBuffer> buffer;
if (error_code ec = MemoryBuffer::getFile(path, buffer)) {
errMsg = ec.message();
return NULL;
}
return makeLTOModule(buffer.take(), errMsg);
}
LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
size_t size,
std::string &errMsg) {
return makeLTOModule(fd, path, size, size, 0, errMsg);
}
LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
size_t file_size,
size_t map_size,
off_t offset,
std::string &errMsg) {
OwningPtr<MemoryBuffer> buffer;
if (error_code ec = MemoryBuffer::getOpenFile(fd, path, buffer, file_size,
map_size, offset, false)) {
errMsg = ec.message();
return NULL;
}
return makeLTOModule(buffer.take(), errMsg);
}
/// makeBuffer - Create a MemoryBuffer from a memory range.
MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length) {
const char *startPtr = (char*)mem;
return MemoryBuffer::getMemBuffer(StringRef(startPtr, length), "", false);
}
LTOModule *LTOModule::makeLTOModule(const void *mem, size_t length,
std::string &errMsg) {
OwningPtr<MemoryBuffer> buffer(makeBuffer(mem, length));
if (!buffer)
return NULL;
return makeLTOModule(buffer.take(), errMsg);
}
LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
std::string &errMsg) {
static bool Initialized = false;
if (!Initialized) {
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmParsers();
Initialized = true;
}
// parse bitcode buffer
OwningPtr<Module> m(getLazyBitcodeModule(buffer, getGlobalContext(),
&errMsg));
if (!m) {
delete buffer;
return NULL;
}
std::string Triple = m->getTargetTriple();
if (Triple.empty())
Triple = sys::getHostTriple();
// find machine architecture for this module
const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
if (!march)
return NULL;
// construct LTOModule, hand over ownership of module and target
SubtargetFeatures Features;
Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
std::string FeatureStr = Features.getString();
std::string CPU;
TargetMachine *target = march->createTargetMachine(Triple, CPU, FeatureStr);
LTOModule *Ret = new LTOModule(m.take(), target);
bool Err = Ret->ParseSymbols();
if (Err) {
delete Ret;
return NULL;
}
return Ret;
}
const char *LTOModule::getTargetTriple() {
return _module->getTargetTriple().c_str();
}
void LTOModule::setTargetTriple(const char *triple) {
_module->setTargetTriple(triple);
}
void LTOModule::addDefinedFunctionSymbol(Function *f, Mangler &mangler) {
// add to list of defined symbols
addDefinedSymbol(f, mangler, true);
}
// Get string that data pointer points to.
bool LTOModule::objcClassNameFromExpression(Constant *c, std::string &name) {
if (ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
Constant *op = ce->getOperand(0);
if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
Constant *cn = gvn->getInitializer();
if (ConstantArray *ca = dyn_cast<ConstantArray>(cn)) {
if (ca->isCString()) {
name = ".objc_class_name_" + ca->getAsCString();
return true;
}
}
}
}
return false;
}
// Parse i386/ppc ObjC class data structure.
void LTOModule::addObjCClass(GlobalVariable *clgv) {
if (ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer())) {
// second slot in __OBJC,__class is pointer to superclass name
std::string superclassName;
if (objcClassNameFromExpression(c->getOperand(1), superclassName)) {
NameAndAttributes info;
StringMap<NameAndAttributes>::value_type &entry =
_undefines.GetOrCreateValue(superclassName);
if (!entry.getValue().name) {
const char *symbolName = entry.getKey().data();
info.name = symbolName;
info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
entry.setValue(info);
}
}
// third slot in __OBJC,__class is pointer to class name
std::string className;
if (objcClassNameFromExpression(c->getOperand(2), className)) {
StringSet::value_type &entry =
_defines.GetOrCreateValue(className);
entry.setValue(1);
NameAndAttributes info;
info.name = entry.getKey().data();
info.attributes = (lto_symbol_attributes)
(LTO_SYMBOL_PERMISSIONS_DATA |
LTO_SYMBOL_DEFINITION_REGULAR |
LTO_SYMBOL_SCOPE_DEFAULT);
_symbols.push_back(info);
}
}
}
// Parse i386/ppc ObjC category data structure.
void LTOModule::addObjCCategory(GlobalVariable *clgv) {
if (ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer())) {
// second slot in __OBJC,__category is pointer to target class name
std::string targetclassName;
if (objcClassNameFromExpression(c->getOperand(1), targetclassName)) {
NameAndAttributes info;
StringMap<NameAndAttributes>::value_type &entry =
_undefines.GetOrCreateValue(targetclassName);
if (entry.getValue().name)
return;
const char *symbolName = entry.getKey().data();
info.name = symbolName;
info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
entry.setValue(info);
}
}
}
// Parse i386/ppc ObjC class list data structure.
void LTOModule::addObjCClassRef(GlobalVariable *clgv) {
std::string targetclassName;
if (objcClassNameFromExpression(clgv->getInitializer(), targetclassName)) {
NameAndAttributes info;
StringMap<NameAndAttributes>::value_type &entry =
_undefines.GetOrCreateValue(targetclassName);
if (entry.getValue().name)
return;
const char *symbolName = entry.getKey().data();
info.name = symbolName;
info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
entry.setValue(info);
}
}
void LTOModule::addDefinedDataSymbol(GlobalValue *v, Mangler &mangler) {
// Add to list of defined symbols.
addDefinedSymbol(v, mangler, false);
// Special case i386/ppc ObjC data structures in magic sections:
// The issue is that the old ObjC object format did some strange
// contortions to avoid real linker symbols. For instance, the
// ObjC class data structure is allocated statically in the executable
// that defines that class. That data structures contains a pointer to
// its superclass. But instead of just initializing that part of the
// struct to the address of its superclass, and letting the static and
// dynamic linkers do the rest, the runtime works by having that field
// instead point to a C-string that is the name of the superclass.
// At runtime the objc initialization updates that pointer and sets
// it to point to the actual super class. As far as the linker
// knows it is just a pointer to a string. But then someone wanted the
// linker to issue errors at build time if the superclass was not found.
// So they figured out a way in mach-o object format to use an absolute
// symbols (.objc_class_name_Foo = 0) and a floating reference
// (.reference .objc_class_name_Bar) to cause the linker into erroring when
// a class was missing.
// The following synthesizes the implicit .objc_* symbols for the linker
// from the ObjC data structures generated by the front end.
if (v->hasSection() /* && isTargetDarwin */) {
// special case if this data blob is an ObjC class definition
if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
addObjCClass(gv);
}
}
// special case if this data blob is an ObjC category definition
else if (v->getSection().compare(0, 18, "__OBJC,__category,") == 0) {
if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
addObjCCategory(gv);
}
}
// special case if this data blob is the list of referenced classes
else if (v->getSection().compare(0, 18, "__OBJC,__cls_refs,") == 0) {
if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
addObjCClassRef(gv);
}
}
}
}
void LTOModule::addDefinedSymbol(GlobalValue *def, Mangler &mangler,
bool isFunction) {
// ignore all llvm.* symbols
if (def->getName().startswith("llvm."))
return;
// string is owned by _defines
SmallString<64> Buffer;
mangler.getNameWithPrefix(Buffer, def, false);
// set alignment part log2() can have rounding errors
uint32_t align = def->getAlignment();
uint32_t attr = align ? CountTrailingZeros_32(def->getAlignment()) : 0;
// set permissions part
if (isFunction)
attr |= LTO_SYMBOL_PERMISSIONS_CODE;
else {
GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
if (gv && gv->isConstant())
attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
else
attr |= LTO_SYMBOL_PERMISSIONS_DATA;
}
// set definition part
if (def->hasWeakLinkage() || def->hasLinkOnceLinkage() ||
def->hasLinkerPrivateWeakLinkage() ||
def->hasLinkerPrivateWeakDefAutoLinkage())
attr |= LTO_SYMBOL_DEFINITION_WEAK;
else if (def->hasCommonLinkage())
attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
else
attr |= LTO_SYMBOL_DEFINITION_REGULAR;
// set scope part
if (def->hasHiddenVisibility())
attr |= LTO_SYMBOL_SCOPE_HIDDEN;
else if (def->hasProtectedVisibility())
attr |= LTO_SYMBOL_SCOPE_PROTECTED;
else if (def->hasExternalLinkage() || def->hasWeakLinkage() ||
def->hasLinkOnceLinkage() || def->hasCommonLinkage() ||
def->hasLinkerPrivateWeakLinkage())
attr |= LTO_SYMBOL_SCOPE_DEFAULT;
else if (def->hasLinkerPrivateWeakDefAutoLinkage())
attr |= LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
else
attr |= LTO_SYMBOL_SCOPE_INTERNAL;
// add to table of symbols
NameAndAttributes info;
StringSet::value_type &entry = _defines.GetOrCreateValue(Buffer);
entry.setValue(1);
StringRef Name = entry.getKey();
info.name = Name.data();
assert(info.name[Name.size()] == '\0');
info.attributes = (lto_symbol_attributes)attr;
_symbols.push_back(info);
}
void LTOModule::addAsmGlobalSymbol(const char *name,
lto_symbol_attributes scope) {
StringSet::value_type &entry = _defines.GetOrCreateValue(name);
// only add new define if not already defined
if (entry.getValue())
return;
entry.setValue(1);
const char *symbolName = entry.getKey().data();
uint32_t attr = LTO_SYMBOL_DEFINITION_REGULAR;
attr |= scope;
NameAndAttributes info;
info.name = symbolName;
info.attributes = (lto_symbol_attributes)attr;
_symbols.push_back(info);
}
void LTOModule::addAsmGlobalSymbolUndef(const char *name) {
StringMap<NameAndAttributes>::value_type &entry =
_undefines.GetOrCreateValue(name);
_asm_undefines.push_back(entry.getKey().data());
// we already have the symbol
if (entry.getValue().name)
return;
uint32_t attr = LTO_SYMBOL_DEFINITION_UNDEFINED;;
attr |= LTO_SYMBOL_SCOPE_DEFAULT;
NameAndAttributes info;
info.name = entry.getKey().data();
info.attributes = (lto_symbol_attributes)attr;
entry.setValue(info);
}
void LTOModule::addPotentialUndefinedSymbol(GlobalValue *decl,
Mangler &mangler) {
// ignore all llvm.* symbols
if (decl->getName().startswith("llvm."))
return;
// ignore all aliases
if (isa<GlobalAlias>(decl))
return;
SmallString<64> name;
mangler.getNameWithPrefix(name, decl, false);
StringMap<NameAndAttributes>::value_type &entry =
_undefines.GetOrCreateValue(name);
// we already have the symbol
if (entry.getValue().name)
return;
NameAndAttributes info;
info.name = entry.getKey().data();
if (decl->hasExternalWeakLinkage())
info.attributes = LTO_SYMBOL_DEFINITION_WEAKUNDEF;
else
info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
entry.setValue(info);
}
namespace {
class RecordStreamer : public MCStreamer {
public:
enum State { NeverSeen, Global, Defined, DefinedGlobal, Used};
private:
StringMap<State> Symbols;
void markDefined(const MCSymbol &Symbol) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Global:
S = DefinedGlobal;
break;
case NeverSeen:
case Defined:
case Used:
S = Defined;
break;
}
}
void markGlobal(const MCSymbol &Symbol) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Defined:
S = DefinedGlobal;
break;
case NeverSeen:
case Global:
case Used:
S = Global;
break;
}
}
void markUsed(const MCSymbol &Symbol) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Defined:
case Global:
break;
case NeverSeen:
case Used:
S = Used;
break;
}
}
// FIXME: mostly copied for the obj streamer.
void AddValueSymbols(const MCExpr *Value) {
switch (Value->getKind()) {
case MCExpr::Target:
// FIXME: What should we do in here?
break;
case MCExpr::Constant:
break;
case MCExpr::Binary: {
const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
AddValueSymbols(BE->getLHS());
AddValueSymbols(BE->getRHS());
break;
}
case MCExpr::SymbolRef:
markUsed(cast<MCSymbolRefExpr>(Value)->getSymbol());
break;
case MCExpr::Unary:
AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
break;
}
}
public:
typedef StringMap<State>::const_iterator const_iterator;
const_iterator begin() {
return Symbols.begin();
}
const_iterator end() {
return Symbols.end();
}
RecordStreamer(MCContext &Context) : MCStreamer(Context) {}
virtual void ChangeSection(const MCSection *Section) {}
virtual void InitSections() {}
virtual void EmitLabel(MCSymbol *Symbol) {
Symbol->setSection(*getCurrentSection());
markDefined(*Symbol);
}
virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
virtual void EmitThumbFunc(MCSymbol *Func) {}
virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
// FIXME: should we handle aliases?
markDefined(*Symbol);
}
virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
if (Attribute == MCSA_Global)
markGlobal(*Symbol);
}
virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
virtual void EmitCOFFSymbolStorageClass(int StorageClass) {}
virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
unsigned Size , unsigned ByteAlignment) {
markDefined(*Symbol);
}
virtual void EmitCOFFSymbolType(int Type) {}
virtual void EndCOFFSymbolDef() {}
virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
markDefined(*Symbol);
}
virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {}
virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {}
virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {}
virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {}
virtual void EmitULEB128Value(const MCExpr *Value) {}
virtual void EmitSLEB128Value(const MCExpr *Value) {}
virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
unsigned ValueSize,
unsigned MaxBytesToEmit) {}
virtual void EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit) {}
virtual void EmitValueToOffset(const MCExpr *Offset,
unsigned char Value ) {}
virtual void EmitFileDirective(StringRef Filename) {}
virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
const MCSymbol *LastLabel,
const MCSymbol *Label,
unsigned PointerSize) {}
virtual void EmitInstruction(const MCInst &Inst) {
// Scan for values.
for (unsigned i = Inst.getNumOperands(); i--; )
if (Inst.getOperand(i).isExpr())
AddValueSymbols(Inst.getOperand(i).getExpr());
}
virtual void Finish() {}
};
}
bool LTOModule::addAsmGlobalSymbols(MCContext &Context) {
const std::string &inlineAsm = _module->getModuleInlineAsm();
OwningPtr<RecordStreamer> Streamer(new RecordStreamer(Context));
MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(inlineAsm);
SourceMgr SrcMgr;
SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
OwningPtr<MCAsmParser> Parser(createMCAsmParser(SrcMgr,
Context, *Streamer,
*_target->getMCAsmInfo()));
OwningPtr<MCSubtargetInfo> STI(_target->getTarget().
createMCSubtargetInfo(_target->getTargetTriple(),
_target->getTargetCPU(),
_target->getTargetFeatureString()));
OwningPtr<MCTargetAsmParser>
TAP(_target->getTarget().createMCAsmParser(*STI, *Parser.get()));
Parser->setTargetParser(*TAP);
int Res = Parser->Run(false);
if (Res)
return true;
for (RecordStreamer::const_iterator i = Streamer->begin(),
e = Streamer->end(); i != e; ++i) {
StringRef Key = i->first();
RecordStreamer::State Value = i->second;
if (Value == RecordStreamer::DefinedGlobal)
addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_DEFAULT);
else if (Value == RecordStreamer::Defined)
addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_INTERNAL);
else if (Value == RecordStreamer::Global ||
Value == RecordStreamer::Used)
addAsmGlobalSymbolUndef(Key.data());
}
return false;
}
static bool isDeclaration(const GlobalValue &V) {
if (V.hasAvailableExternallyLinkage())
return true;
if (V.isMaterializable())
return false;
return V.isDeclaration();
}
static bool isAliasToDeclaration(const GlobalAlias &V) {
return isDeclaration(*V.getAliasedGlobal());
}
bool LTOModule::ParseSymbols() {
// Use mangler to add GlobalPrefix to names to match linker names.
MCContext Context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(),NULL);
Mangler mangler(Context, *_target->getTargetData());
// add functions
for (Module::iterator f = _module->begin(); f != _module->end(); ++f) {
if (isDeclaration(*f))
addPotentialUndefinedSymbol(f, mangler);
else
addDefinedFunctionSymbol(f, mangler);
}
// add data
for (Module::global_iterator v = _module->global_begin(),
e = _module->global_end(); v != e; ++v) {
if (isDeclaration(*v))
addPotentialUndefinedSymbol(v, mangler);
else
addDefinedDataSymbol(v, mangler);
}
// add asm globals
if (addAsmGlobalSymbols(Context))
return true;
// add aliases
for (Module::alias_iterator i = _module->alias_begin(),
e = _module->alias_end(); i != e; ++i) {
if (isAliasToDeclaration(*i))
addPotentialUndefinedSymbol(i, mangler);
else
addDefinedDataSymbol(i, mangler);
}
// make symbols for all undefines
for (StringMap<NameAndAttributes>::iterator it=_undefines.begin();
it != _undefines.end(); ++it) {
// if this symbol also has a definition, then don't make an undefine
// because it is a tentative definition
if (_defines.count(it->getKey()) == 0) {
NameAndAttributes info = it->getValue();
_symbols.push_back(info);
}
}
return false;
}
uint32_t LTOModule::getSymbolCount() {
return _symbols.size();
}
lto_symbol_attributes LTOModule::getSymbolAttributes(uint32_t index) {
if (index < _symbols.size())
return _symbols[index].attributes;
else
return lto_symbol_attributes(0);
}
const char *LTOModule::getSymbolName(uint32_t index) {
if (index < _symbols.size())
return _symbols[index].name;
else
return NULL;
}