llvm-project/llvm/lib/LTO/LTOModule.cpp

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//===-- 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 "llvm/LTO/LTOModule.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCTargetAsmParser.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.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/TargetLowering.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Transforms/Utils/GlobalStatus.h"
using namespace llvm;
LTOModule::LTOModule(llvm::Module *m, llvm::TargetMachine *t)
: _module(m), _target(t),
_context(_target->getMCAsmInfo(), _target->getRegisterInfo(), &ObjFileInfo),
_mangler(t->getDataLayout()) {
ObjFileInfo.InitMCObjectFileInfo(t->getTargetTriple(),
t->getRelocationModel(), t->getCodeModel(),
_context);
}
/// isBitcodeFile - Returns 'true' if the file (or memory contents) is LLVM
/// bitcode.
bool LTOModule::isBitcodeFile(const void *mem, size_t length) {
return sys::fs::identify_magic(StringRef((const char *)mem, length)) ==
sys::fs::file_magic::bitcode;
}
bool LTOModule::isBitcodeFile(const char *path) {
sys::fs::file_magic type;
if (sys::fs::identify_magic(path, type))
return false;
return type == sys::fs::file_magic::bitcode;
}
/// isBitcodeFileForTarget - Returns 'true' if the file (or memory contents) is
/// LLVM bitcode for the specified triple.
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) {
std::unique_ptr<MemoryBuffer> buffer;
if (MemoryBuffer::getFile(path, buffer))
return false;
return isTargetMatch(buffer.release(), triplePrefix);
}
/// isTargetMatch - Returns 'true' if the memory buffer is for the specified
/// target triple.
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;
}
/// makeLTOModule - Create an LTOModule. N.B. These methods take ownership of
/// the buffer.
LTOModule *LTOModule::makeLTOModule(const char *path, TargetOptions options,
std::string &errMsg) {
std::unique_ptr<MemoryBuffer> buffer;
if (error_code ec = MemoryBuffer::getFile(path, buffer)) {
errMsg = ec.message();
return nullptr;
}
return makeLTOModule(buffer.release(), options, errMsg);
}
LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
size_t size, TargetOptions options,
std::string &errMsg) {
return makeLTOModule(fd, path, size, 0, options, errMsg);
}
LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
size_t map_size,
off_t offset,
TargetOptions options,
std::string &errMsg) {
std::unique_ptr<MemoryBuffer> buffer;
if (error_code ec =
MemoryBuffer::getOpenFileSlice(fd, path, buffer, map_size, offset)) {
errMsg = ec.message();
return nullptr;
}
return makeLTOModule(buffer.release(), options, errMsg);
}
LTOModule *LTOModule::makeLTOModule(const void *mem, size_t length,
TargetOptions options,
std::string &errMsg, StringRef path) {
std::unique_ptr<MemoryBuffer> buffer(makeBuffer(mem, length, path));
if (!buffer)
return nullptr;
return makeLTOModule(buffer.release(), options, errMsg);
}
LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
TargetOptions options,
std::string &errMsg) {
// parse bitcode buffer
ErrorOr<Module *> ModuleOrErr =
getLazyBitcodeModule(buffer, getGlobalContext());
if (error_code EC = ModuleOrErr.getError()) {
errMsg = EC.message();
delete buffer;
return nullptr;
}
std::unique_ptr<Module> m(ModuleOrErr.get());
std::string TripleStr = m->getTargetTriple();
if (TripleStr.empty())
TripleStr = sys::getDefaultTargetTriple();
llvm::Triple Triple(TripleStr);
// find machine architecture for this module
const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
if (!march)
return nullptr;
2011-04-21 09:54:08 +08:00
// construct LTOModule, hand over ownership of module and target
SubtargetFeatures Features;
Features.getDefaultSubtargetFeatures(Triple);
std::string FeatureStr = Features.getString();
// Set a default CPU for Darwin triples.
std::string CPU;
if (Triple.isOSDarwin()) {
if (Triple.getArch() == llvm::Triple::x86_64)
CPU = "core2";
else if (Triple.getArch() == llvm::Triple::x86)
CPU = "yonah";
else if (Triple.getArch() == llvm::Triple::arm64)
CPU = "cyclone";
}
TargetMachine *target = march->createTargetMachine(TripleStr, CPU, FeatureStr,
options);
m->materializeAllPermanently();
LTOModule *Ret = new LTOModule(m.release(), target);
// We need a MCContext set up in order to get mangled names of private
// symbols. It is a bit odd that we need to report uses and definitions
// of private symbols, but it does look like ld64 expects to be informed
// of at least the ones with an 'l' prefix.
MCContext &Context = Ret->_context;
const TargetLoweringObjectFile &TLOF =
target->getTargetLowering()->getObjFileLowering();
const_cast<TargetLoweringObjectFile &>(TLOF).Initialize(Context, *target);
if (Ret->parseSymbols(errMsg)) {
delete Ret;
return nullptr;
}
Ret->parseMetadata();
return Ret;
}
/// Create a MemoryBuffer from a memory range with an optional name.
MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length,
StringRef name) {
const char *startPtr = (const char*)mem;
return MemoryBuffer::getMemBuffer(StringRef(startPtr, length), name, false);
}
/// objcClassNameFromExpression - Get string that the data pointer points to.
bool
LTOModule::objcClassNameFromExpression(const Constant *c, std::string &name) {
if (const ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
Constant *op = ce->getOperand(0);
if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
Constant *cn = gvn->getInitializer();
if (ConstantDataArray *ca = dyn_cast<ConstantDataArray>(cn)) {
if (ca->isCString()) {
name = ".objc_class_name_" + ca->getAsCString().str();
return true;
}
}
}
}
return false;
}
/// addObjCClass - Parse i386/ppc ObjC class data structure.
void LTOModule::addObjCClass(const GlobalVariable *clgv) {
const ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
if (!c) return;
// 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;
info.isFunction = false;
info.symbol = clgv;
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_PERMISSIONS_DATA |
LTO_SYMBOL_DEFINITION_REGULAR | LTO_SYMBOL_SCOPE_DEFAULT;
info.isFunction = false;
info.symbol = clgv;
_symbols.push_back(info);
}
}
/// addObjCCategory - Parse i386/ppc ObjC category data structure.
void LTOModule::addObjCCategory(const GlobalVariable *clgv) {
const ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
if (!c) return;
// second slot in __OBJC,__category is pointer to target class name
std::string targetclassName;
if (!objcClassNameFromExpression(c->getOperand(1), targetclassName))
return;
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;
info.isFunction = false;
info.symbol = clgv;
entry.setValue(info);
}
/// addObjCClassRef - Parse i386/ppc ObjC class list data structure.
void LTOModule::addObjCClassRef(const GlobalVariable *clgv) {
std::string targetclassName;
if (!objcClassNameFromExpression(clgv->getInitializer(), targetclassName))
return;
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;
info.isFunction = false;
info.symbol = clgv;
entry.setValue(info);
}
/// addDefinedDataSymbol - Add a data symbol as defined to the list.
void LTOModule::addDefinedDataSymbol(const GlobalValue *v) {
// Add to list of defined symbols.
addDefinedSymbol(v, false);
if (!v->hasSection() /* || !isTargetDarwin */)
return;
// 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.
// special case if this data blob is an ObjC class definition
if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
if (const 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 (const 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 (const GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
addObjCClassRef(gv);
}
}
}
/// addDefinedFunctionSymbol - Add a function symbol as defined to the list.
void LTOModule::addDefinedFunctionSymbol(const Function *f) {
// add to list of defined symbols
addDefinedSymbol(f, true);
}
static bool canBeHidden(const GlobalValue *GV) {
// FIXME: this is duplicated with another static function in AsmPrinter.cpp
GlobalValue::LinkageTypes L = GV->getLinkage();
if (L != GlobalValue::LinkOnceODRLinkage)
return false;
if (GV->hasUnnamedAddr())
return true;
// If it is a non constant variable, it needs to be uniqued across shared
// objects.
if (const GlobalVariable *Var = dyn_cast<GlobalVariable>(GV)) {
if (!Var->isConstant())
return false;
}
GlobalStatus GS;
if (GlobalStatus::analyzeGlobal(GV, GS))
return false;
return !GS.IsCompared;
}
/// addDefinedSymbol - Add a defined symbol to the list.
void LTOModule::addDefinedSymbol(const GlobalValue *def, bool isFunction) {
// ignore all llvm.* symbols
if (def->getName().startswith("llvm."))
return;
// string is owned by _defines
SmallString<64> Buffer;
_target->getNameWithPrefix(Buffer, def, _mangler);
// set alignment part log2() can have rounding errors
uint32_t align = def->getAlignment();
uint32_t attr = align ? countTrailingZeros(def->getAlignment()) : 0;
// set permissions part
if (isFunction) {
attr |= LTO_SYMBOL_PERMISSIONS_CODE;
} else {
const GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
if (gv && gv->isConstant())
attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
else
attr |= LTO_SYMBOL_PERMISSIONS_DATA;
}
// set definition part
Remove the linker_private and linker_private_weak linkages. These linkages were introduced some time ago, but it was never very clear what exactly their semantics were or what they should be used for. Some investigation found these uses: * utf-16 strings in clang. * non-unnamed_addr strings produced by the sanitizers. It turns out they were just working around a more fundamental problem. For some sections a MachO linker needs a symbol in order to split the section into atoms, and llvm had no idea that was the case. I fixed that in r201700 and it is now safe to use the private linkage. When the object ends up in a section that requires symbols, llvm will use a 'l' prefix instead of a 'L' prefix and things just work. With that, these linkages were already dead, but there was a potential future user in the objc metadata information. I am still looking at CGObjcMac.cpp, but at this point I am convinced that linker_private and linker_private_weak are not what they need. The objc uses are currently split in * Regular symbols (no '\01' prefix). LLVM already directly provides whatever semantics they need. * Uses of a private name (start with "\01L" or "\01l") and private linkage. We can drop the "\01L" and "\01l" prefixes as soon as llvm agrees with clang on L being ok or not for a given section. I have two patches in code review for this. * Uses of private name and weak linkage. The last case is the one that one could think would fit one of these linkages. That is not the case. The semantics are * the linker will merge these symbol by *name*. * the linker will hide them in the final DSO. Given that the merging is done by name, any of the private (or internal) linkages would be a bad match. They allow llvm to rename the symbols, and that is really not what we want. From the llvm point of view, these objects should really be (linkonce|weak)(_odr)?. For now, just keeping the "\01l" prefix is probably the best for these symbols. If we one day want to have a more direct support in llvm, IMHO what we should add is not a linkage, it is just a hidden_symbol attribute. It would be applicable to multiple linkages. For example, on weak it would produce the current behavior we have for objc metadata. On internal, it would be equivalent to private (and we should then remove private). llvm-svn: 203866
2014-03-14 07:18:37 +08:00
if (def->hasWeakLinkage() || def->hasLinkOnceLinkage())
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 (canBeHidden(def))
attr |= LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
else if (def->hasExternalLinkage() || def->hasWeakLinkage() ||
Remove the linker_private and linker_private_weak linkages. These linkages were introduced some time ago, but it was never very clear what exactly their semantics were or what they should be used for. Some investigation found these uses: * utf-16 strings in clang. * non-unnamed_addr strings produced by the sanitizers. It turns out they were just working around a more fundamental problem. For some sections a MachO linker needs a symbol in order to split the section into atoms, and llvm had no idea that was the case. I fixed that in r201700 and it is now safe to use the private linkage. When the object ends up in a section that requires symbols, llvm will use a 'l' prefix instead of a 'L' prefix and things just work. With that, these linkages were already dead, but there was a potential future user in the objc metadata information. I am still looking at CGObjcMac.cpp, but at this point I am convinced that linker_private and linker_private_weak are not what they need. The objc uses are currently split in * Regular symbols (no '\01' prefix). LLVM already directly provides whatever semantics they need. * Uses of a private name (start with "\01L" or "\01l") and private linkage. We can drop the "\01L" and "\01l" prefixes as soon as llvm agrees with clang on L being ok or not for a given section. I have two patches in code review for this. * Uses of private name and weak linkage. The last case is the one that one could think would fit one of these linkages. That is not the case. The semantics are * the linker will merge these symbol by *name*. * the linker will hide them in the final DSO. Given that the merging is done by name, any of the private (or internal) linkages would be a bad match. They allow llvm to rename the symbols, and that is really not what we want. From the llvm point of view, these objects should really be (linkonce|weak)(_odr)?. For now, just keeping the "\01l" prefix is probably the best for these symbols. If we one day want to have a more direct support in llvm, IMHO what we should add is not a linkage, it is just a hidden_symbol attribute. It would be applicable to multiple linkages. For example, on weak it would produce the current behavior we have for objc metadata. On internal, it would be equivalent to private (and we should then remove private). llvm-svn: 203866
2014-03-14 07:18:37 +08:00
def->hasLinkOnceLinkage() || def->hasCommonLinkage())
attr |= LTO_SYMBOL_SCOPE_DEFAULT;
else
attr |= LTO_SYMBOL_SCOPE_INTERNAL;
StringSet::value_type &entry = _defines.GetOrCreateValue(Buffer);
entry.setValue(1);
// fill information structure
NameAndAttributes info;
StringRef Name = entry.getKey();
info.name = Name.data();
assert(info.name[Name.size()] == '\0');
info.attributes = attr;
info.isFunction = isFunction;
info.symbol = def;
// add to table of symbols
_symbols.push_back(info);
}
/// addAsmGlobalSymbol - Add a global symbol from module-level ASM to the
/// defined list.
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);
NameAndAttributes &info = _undefines[entry.getKey().data()];
if (info.symbol == nullptr) {
// FIXME: This is trying to take care of module ASM like this:
//
// module asm ".zerofill __FOO, __foo, _bar_baz_qux, 0"
//
// but is gross and its mother dresses it funny. Have the ASM parser give us
// more details for this type of situation so that we're not guessing so
// much.
// fill information structure
info.name = entry.getKey().data();
info.attributes =
LTO_SYMBOL_PERMISSIONS_DATA | LTO_SYMBOL_DEFINITION_REGULAR | scope;
info.isFunction = false;
info.symbol = nullptr;
// add to table of symbols
_symbols.push_back(info);
return;
}
if (info.isFunction)
addDefinedFunctionSymbol(cast<Function>(info.symbol));
else
addDefinedDataSymbol(info.symbol);
_symbols.back().attributes &= ~LTO_SYMBOL_SCOPE_MASK;
_symbols.back().attributes |= scope;
}
/// addAsmGlobalSymbolUndef - Add a global symbol from module-level ASM to the
/// undefined list.
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 = attr;
info.isFunction = false;
info.symbol = nullptr;
entry.setValue(info);
}
/// addPotentialUndefinedSymbol - Add a symbol which isn't defined just yet to a
/// list to be resolved later.
void
LTOModule::addPotentialUndefinedSymbol(const GlobalValue *decl, bool isFunc) {
// ignore all llvm.* symbols
if (decl->getName().startswith("llvm."))
return;
// ignore all aliases
if (isa<GlobalAlias>(decl))
return;
SmallString<64> name;
_target->getNameWithPrefix(name, decl, _mangler);
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;
info.isFunction = isFunc;
info.symbol = decl;
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) {}
void EmitInstruction(const MCInst &Inst,
const MCSubtargetInfo &STI) override {
// Scan for values.
for (unsigned i = Inst.getNumOperands(); i--; )
if (Inst.getOperand(i).isExpr())
AddValueSymbols(Inst.getOperand(i).getExpr());
}
void EmitLabel(MCSymbol *Symbol) override {
Symbol->setSection(*getCurrentSection().first);
markDefined(*Symbol);
}
void EmitDebugLabel(MCSymbol *Symbol) override {
This patch is needed to make c++ exceptions work for mips16. Mips16 is really a processor decoding mode (ala thumb 1) and in the same program, mips16 and mips32 functions can exist and can call each other. If a jal type instruction encounters an address with the lower bit set, then the processor switches to mips16 mode (if it is not already in it). If the lower bit is not set, then it switches to mips32 mode. The linker knows which functions are mips16 and which are mips32. When relocation is performed on code labels, this lower order bit is set if the code label is a mips16 code label. In general this works just fine, however when creating exception handling tables and dwarf, there are cases where you don't want this lower order bit added in. This has been traditionally distinguished in gas assembly source by using a different syntax for the label. lab1: ; this will cause the lower order bit to be added lab2=. ; this will not cause the lower order bit to be added In some cases, it does not matter because in dwarf and debug tables the difference of two labels is used and in that case the lower order bits subtract each other out. To fix this, I have added to mcstreamer the notion of a debuglabel. The default is for label and debug label to be the same. So calling EmitLabel and EmitDebugLabel produce the same result. For various reasons, there is only one set of labels that needs to be modified for the mips exceptions to work. These are the "$eh_func_beginXXX" labels. Mips overrides the debug label suffix from ":" to "=." . This initial patch fixes exceptions. More changes most likely will be needed to DwarfCFException to make all of this work for actual debugging. These changes will be to emit debug labels in some places where a simple label is emitted now. Some historical discussion on this from gcc can be found at: http://gcc.gnu.org/ml/gcc-patches/2008-08/msg00623.html http://gcc.gnu.org/ml/gcc-patches/2008-11/msg01273.html llvm-svn: 170279
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EmitLabel(Symbol);
}
void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override {
// FIXME: should we handle aliases?
markDefined(*Symbol);
AddValueSymbols(Value);
}
bool EmitSymbolAttribute(MCSymbol *Symbol,
MCSymbolAttr Attribute) override {
if (Attribute == MCSA_Global)
markGlobal(*Symbol);
return true;
}
void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size , unsigned ByteAlignment) override {
markDefined(*Symbol);
}
void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) override {
markDefined(*Symbol);
}
void EmitBundleAlignMode(unsigned AlignPow2) override {}
void EmitBundleLock(bool AlignToEnd) override {}
void EmitBundleUnlock() override {}
// Noop calls.
void ChangeSection(const MCSection *Section,
const MCExpr *Subsection) override {}
void EmitAssemblerFlag(MCAssemblerFlag Flag) override {}
void EmitThumbFunc(MCSymbol *Func) override {}
void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override {}
void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override {}
void BeginCOFFSymbolDef(const MCSymbol *Symbol) override {}
void EmitCOFFSymbolStorageClass(int StorageClass) override {}
void EmitCOFFSymbolType(int Type) override {}
void EndCOFFSymbolDef() override {}
void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) override {}
void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) override {}
void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) override {}
void EmitBytes(StringRef Data) override {}
void EmitValueImpl(const MCExpr *Value, unsigned Size,
const SMLoc &Loc) override {}
void EmitULEB128Value(const MCExpr *Value) override {}
void EmitSLEB128Value(const MCExpr *Value) override {}
void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
unsigned ValueSize,
unsigned MaxBytesToEmit) override {}
void EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit) override {}
bool EmitValueToOffset(const MCExpr *Offset,
unsigned char Value) override { return false; }
void EmitFileDirective(StringRef Filename) override {}
void EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel,
const MCSymbol *Label,
unsigned PointerSize) override {}
void FinishImpl() override {}
void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override {
RecordProcEnd(Frame);
}
};
} // end anonymous namespace
/// addAsmGlobalSymbols - Add global symbols from module-level ASM to the
/// defined or undefined lists.
bool LTOModule::addAsmGlobalSymbols(std::string &errMsg) {
const std::string &inlineAsm = _module->getModuleInlineAsm();
if (inlineAsm.empty())
return false;
std::unique_ptr<RecordStreamer> Streamer(new RecordStreamer(_context));
MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(inlineAsm);
SourceMgr SrcMgr;
SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
std::unique_ptr<MCAsmParser> Parser(
createMCAsmParser(SrcMgr, _context, *Streamer, *_target->getMCAsmInfo()));
const Target &T = _target->getTarget();
std::unique_ptr<MCInstrInfo> MCII(T.createMCInstrInfo());
std::unique_ptr<MCSubtargetInfo> STI(T.createMCSubtargetInfo(
_target->getTargetTriple(), _target->getTargetCPU(),
_target->getTargetFeatureString()));
std::unique_ptr<MCTargetAsmParser> TAP(
T.createMCAsmParser(*STI, *Parser.get(), *MCII,
_target->Options.MCOptions));
if (!TAP) {
errMsg = "target " + std::string(T.getName()) +
" does not define AsmParser.";
return true;
}
Parser->setTargetParser(*TAP);
if (Parser->Run(false))
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;
}
/// isDeclaration - Return 'true' if the global value is a declaration.
static bool isDeclaration(const GlobalValue &V) {
if (V.hasAvailableExternallyLinkage())
return true;
if (V.isMaterializable())
return false;
return V.isDeclaration();
}
/// parseSymbols - Parse the symbols from the module and model-level ASM and add
/// them to either the defined or undefined lists.
bool LTOModule::parseSymbols(std::string &errMsg) {
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// add functions
for (Module::iterator f = _module->begin(), e = _module->end(); f != e; ++f) {
if (isDeclaration(*f))
addPotentialUndefinedSymbol(f, true);
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else
addDefinedFunctionSymbol(f);
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}
// add data
for (Module::global_iterator v = _module->global_begin(),
e = _module->global_end(); v != e; ++v) {
if (isDeclaration(*v))
addPotentialUndefinedSymbol(v, false);
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else
addDefinedDataSymbol(v);
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}
// add asm globals
if (addAsmGlobalSymbols(errMsg))
return true;
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// add aliases
for (Module::alias_iterator a = _module->alias_begin(),
e = _module->alias_end(); a != e; ++a) {
if (isDeclaration(*a->getAliasedGlobal()))
// Is an alias to a declaration.
addPotentialUndefinedSymbol(a, false);
else
addDefinedDataSymbol(a);
}
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// make symbols for all undefines
for (StringMap<NameAndAttributes>::iterator u =_undefines.begin(),
e = _undefines.end(); u != e; ++u) {
// If this symbol also has a definition, then don't make an undefine because
// it is a tentative definition.
if (_defines.count(u->getKey())) continue;
NameAndAttributes info = u->getValue();
_symbols.push_back(info);
}
return false;
}
/// parseMetadata - Parse metadata from the module
void LTOModule::parseMetadata() {
// Linker Options
if (Value *Val = _module->getModuleFlag("Linker Options")) {
MDNode *LinkerOptions = cast<MDNode>(Val);
for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
StringRef Op = _linkeropt_strings.
GetOrCreateValue(MDOption->getString()).getKey();
StringRef DepLibName = _target->getTargetLowering()->
getObjFileLowering().getDepLibFromLinkerOpt(Op);
if (!DepLibName.empty())
_deplibs.push_back(DepLibName.data());
else if (!Op.empty())
_linkeropts.push_back(Op.data());
}
}
}
// Add other interesting metadata here.
}