llvm-project/lld/wasm/Symbols.cpp

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//===- Symbols.cpp --------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Symbols.h"
#include "Config.h"
#include "InputChunks.h"
#include "InputEvent.h"
#include "InputFiles.h"
#include "InputGlobal.h"
#include "OutputSections.h"
#include "OutputSegment.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Strings.h"
#define DEBUG_TYPE "lld"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::wasm;
namespace lld {
std::string toString(const wasm::Symbol &sym) {
return maybeDemangleSymbol(sym.getName());
}
std::string maybeDemangleSymbol(StringRef name) {
// WebAssembly requires caller and callee signatures to match, so we mangle
// `main` in the case where we need to pass it arguments.
if (name == "__main_argc_argv")
return "main";
if (wasm::config->demangle)
return demangleItanium(name);
return std::string(name);
}
std::string toString(wasm::Symbol::Kind kind) {
switch (kind) {
case wasm::Symbol::DefinedFunctionKind:
return "DefinedFunction";
case wasm::Symbol::DefinedDataKind:
return "DefinedData";
case wasm::Symbol::DefinedGlobalKind:
return "DefinedGlobal";
case wasm::Symbol::DefinedEventKind:
return "DefinedEvent";
case wasm::Symbol::UndefinedFunctionKind:
return "UndefinedFunction";
case wasm::Symbol::UndefinedDataKind:
return "UndefinedData";
case wasm::Symbol::UndefinedGlobalKind:
return "UndefinedGlobal";
case wasm::Symbol::LazyKind:
return "LazyKind";
case wasm::Symbol::SectionKind:
return "SectionKind";
case wasm::Symbol::OutputSectionKind:
return "OutputSectionKind";
}
llvm_unreachable("invalid symbol kind");
}
namespace wasm {
DefinedFunction *WasmSym::callCtors;
DefinedFunction *WasmSym::initMemory;
DefinedFunction *WasmSym::applyRelocs;
[WebAssembly] Implement thread-local storage (local-exec model) Summary: Thread local variables are placed inside a `.tdata` segment. Their symbols are offsets from the start of the segment. The address of a thread local variable is computed as `__tls_base` + the offset from the start of the segment. `.tdata` segment is a passive segment and `memory.init` is used once per thread to initialize the thread local storage. `__tls_base` is a wasm global. Since each thread has its own wasm instance, it is effectively thread local. Currently, `__tls_base` must be initialized at thread startup, and so cannot be used with dynamic libraries. `__tls_base` is to be initialized with a new linker-synthesized function, `__wasm_init_tls`, which takes as an argument a block of memory to use as the storage for thread locals. It then initializes the block of memory and sets `__tls_base`. As `__wasm_init_tls` will handle the memory initialization, the memory does not have to be zeroed. To help allocating memory for thread-local storage, a new compiler intrinsic is introduced: `__builtin_wasm_tls_size()`. This instrinsic function returns the size of the thread-local storage for the current function. The expected usage is to run something like the following upon thread startup: __wasm_init_tls(malloc(__builtin_wasm_tls_size())); Reviewers: tlively, aheejin, kripken, sbc100 Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, jfb, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D64537 llvm-svn: 366272
2019-07-17 06:00:45 +08:00
DefinedFunction *WasmSym::initTLS;
DefinedData *WasmSym::dsoHandle;
DefinedData *WasmSym::dataEnd;
DefinedData *WasmSym::globalBase;
DefinedData *WasmSym::heapBase;
DefinedData *WasmSym::initMemoryFlag;
GlobalSymbol *WasmSym::stackPointer;
[WebAssembly] Implement thread-local storage (local-exec model) Summary: Thread local variables are placed inside a `.tdata` segment. Their symbols are offsets from the start of the segment. The address of a thread local variable is computed as `__tls_base` + the offset from the start of the segment. `.tdata` segment is a passive segment and `memory.init` is used once per thread to initialize the thread local storage. `__tls_base` is a wasm global. Since each thread has its own wasm instance, it is effectively thread local. Currently, `__tls_base` must be initialized at thread startup, and so cannot be used with dynamic libraries. `__tls_base` is to be initialized with a new linker-synthesized function, `__wasm_init_tls`, which takes as an argument a block of memory to use as the storage for thread locals. It then initializes the block of memory and sets `__tls_base`. As `__wasm_init_tls` will handle the memory initialization, the memory does not have to be zeroed. To help allocating memory for thread-local storage, a new compiler intrinsic is introduced: `__builtin_wasm_tls_size()`. This instrinsic function returns the size of the thread-local storage for the current function. The expected usage is to run something like the following upon thread startup: __wasm_init_tls(malloc(__builtin_wasm_tls_size())); Reviewers: tlively, aheejin, kripken, sbc100 Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, jfb, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D64537 llvm-svn: 366272
2019-07-17 06:00:45 +08:00
GlobalSymbol *WasmSym::tlsBase;
GlobalSymbol *WasmSym::tlsSize;
GlobalSymbol *WasmSym::tlsAlign;
UndefinedGlobal *WasmSym::tableBase;
DefinedData *WasmSym::definedTableBase;
UndefinedGlobal *WasmSym::memoryBase;
DefinedData *WasmSym::definedMemoryBase;
WasmSymbolType Symbol::getWasmType() const {
if (isa<FunctionSymbol>(this))
return WASM_SYMBOL_TYPE_FUNCTION;
if (isa<DataSymbol>(this))
return WASM_SYMBOL_TYPE_DATA;
if (isa<GlobalSymbol>(this))
return WASM_SYMBOL_TYPE_GLOBAL;
if (isa<EventSymbol>(this))
return WASM_SYMBOL_TYPE_EVENT;
if (isa<SectionSymbol>(this) || isa<OutputSectionSymbol>(this))
return WASM_SYMBOL_TYPE_SECTION;
llvm_unreachable("invalid symbol kind");
}
const WasmSignature *Symbol::getSignature() const {
if (auto* f = dyn_cast<FunctionSymbol>(this))
return f->signature;
if (auto *l = dyn_cast<LazySymbol>(this))
return l->signature;
return nullptr;
}
InputChunk *Symbol::getChunk() const {
if (auto *f = dyn_cast<DefinedFunction>(this))
return f->function;
if (auto *d = dyn_cast<DefinedData>(this))
return d->segment;
return nullptr;
}
bool Symbol::isDiscarded() const {
if (InputChunk *c = getChunk())
return c->discarded;
return false;
}
bool Symbol::isLive() const {
if (auto *g = dyn_cast<DefinedGlobal>(this))
return g->global->live;
if (auto *e = dyn_cast<DefinedEvent>(this))
return e->event->live;
if (InputChunk *c = getChunk())
return c->live;
return referenced;
}
void Symbol::markLive() {
assert(!isDiscarded());
if (auto *g = dyn_cast<DefinedGlobal>(this))
g->global->live = true;
if (auto *e = dyn_cast<DefinedEvent>(this))
e->event->live = true;
if (InputChunk *c = getChunk())
c->live = true;
referenced = true;
}
uint32_t Symbol::getOutputSymbolIndex() const {
assert(outputSymbolIndex != INVALID_INDEX);
return outputSymbolIndex;
}
void Symbol::setOutputSymbolIndex(uint32_t index) {
LLVM_DEBUG(dbgs() << "setOutputSymbolIndex " << name << " -> " << index
<< "\n");
assert(outputSymbolIndex == INVALID_INDEX);
outputSymbolIndex = index;
}
void Symbol::setGOTIndex(uint32_t index) {
LLVM_DEBUG(dbgs() << "setGOTIndex " << name << " -> " << index << "\n");
assert(gotIndex == INVALID_INDEX);
if (config->isPic) {
// Any symbol that is assigned a GOT entry must be exported otherwise the
// dynamic linker won't be able create the entry that contains it.
forceExport = true;
}
gotIndex = index;
}
bool Symbol::isWeak() const {
return (flags & WASM_SYMBOL_BINDING_MASK) == WASM_SYMBOL_BINDING_WEAK;
}
bool Symbol::isLocal() const {
return (flags & WASM_SYMBOL_BINDING_MASK) == WASM_SYMBOL_BINDING_LOCAL;
}
bool Symbol::isHidden() const {
return (flags & WASM_SYMBOL_VISIBILITY_MASK) == WASM_SYMBOL_VISIBILITY_HIDDEN;
}
void Symbol::setHidden(bool isHidden) {
LLVM_DEBUG(dbgs() << "setHidden: " << name << " -> " << isHidden << "\n");
flags &= ~WASM_SYMBOL_VISIBILITY_MASK;
if (isHidden)
flags |= WASM_SYMBOL_VISIBILITY_HIDDEN;
else
flags |= WASM_SYMBOL_VISIBILITY_DEFAULT;
}
bool Symbol::isExported() const {
if (!isDefined() || isLocal())
return false;
if (forceExport || config->exportAll)
return true;
if (config->exportDynamic && !isHidden())
return true;
return flags & WASM_SYMBOL_EXPORTED;
}
bool Symbol::isNoStrip() const {
return flags & WASM_SYMBOL_NO_STRIP;
}
uint32_t FunctionSymbol::getFunctionIndex() const {
if (auto *f = dyn_cast<DefinedFunction>(this))
return f->function->getFunctionIndex();
assert(functionIndex != INVALID_INDEX);
return functionIndex;
}
void FunctionSymbol::setFunctionIndex(uint32_t index) {
LLVM_DEBUG(dbgs() << "setFunctionIndex " << name << " -> " << index << "\n");
assert(functionIndex == INVALID_INDEX);
functionIndex = index;
}
bool FunctionSymbol::hasFunctionIndex() const {
if (auto *f = dyn_cast<DefinedFunction>(this))
return f->function->hasFunctionIndex();
return functionIndex != INVALID_INDEX;
}
uint32_t FunctionSymbol::getTableIndex() const {
if (auto *f = dyn_cast<DefinedFunction>(this))
return f->function->getTableIndex();
assert(tableIndex != INVALID_INDEX);
return tableIndex;
}
bool FunctionSymbol::hasTableIndex() const {
if (auto *f = dyn_cast<DefinedFunction>(this))
return f->function->hasTableIndex();
return tableIndex != INVALID_INDEX;
}
void FunctionSymbol::setTableIndex(uint32_t index) {
// For imports, we set the table index here on the Symbol; for defined
// functions we set the index on the InputFunction so that we don't export
// the same thing twice (keeps the table size down).
if (auto *f = dyn_cast<DefinedFunction>(this)) {
f->function->setTableIndex(index);
return;
}
LLVM_DEBUG(dbgs() << "setTableIndex " << name << " -> " << index << "\n");
assert(tableIndex == INVALID_INDEX);
tableIndex = index;
}
DefinedFunction::DefinedFunction(StringRef name, uint32_t flags, InputFile *f,
InputFunction *function)
: FunctionSymbol(name, DefinedFunctionKind, flags, f,
function ? &function->signature : nullptr),
function(function) {}
uint64_t DefinedData::getVirtualAddress() const {
LLVM_DEBUG(dbgs() << "getVirtualAddress: " << getName() << "\n");
[WebAssembly] Implement thread-local storage (local-exec model) Summary: Thread local variables are placed inside a `.tdata` segment. Their symbols are offsets from the start of the segment. The address of a thread local variable is computed as `__tls_base` + the offset from the start of the segment. `.tdata` segment is a passive segment and `memory.init` is used once per thread to initialize the thread local storage. `__tls_base` is a wasm global. Since each thread has its own wasm instance, it is effectively thread local. Currently, `__tls_base` must be initialized at thread startup, and so cannot be used with dynamic libraries. `__tls_base` is to be initialized with a new linker-synthesized function, `__wasm_init_tls`, which takes as an argument a block of memory to use as the storage for thread locals. It then initializes the block of memory and sets `__tls_base`. As `__wasm_init_tls` will handle the memory initialization, the memory does not have to be zeroed. To help allocating memory for thread-local storage, a new compiler intrinsic is introduced: `__builtin_wasm_tls_size()`. This instrinsic function returns the size of the thread-local storage for the current function. The expected usage is to run something like the following upon thread startup: __wasm_init_tls(malloc(__builtin_wasm_tls_size())); Reviewers: tlively, aheejin, kripken, sbc100 Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, jfb, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D64537 llvm-svn: 366272
2019-07-17 06:00:45 +08:00
if (segment) {
// For thread local data, the symbol location is relative to the start of
// the .tdata section, since they are used as offsets from __tls_base.
// Hence, we do not add in segment->outputSeg->startVA.
if (segment->outputSeg->name == ".tdata")
return segment->outputSegmentOffset + offset;
return segment->outputSeg->startVA + segment->outputSegmentOffset + offset;
[WebAssembly] Implement thread-local storage (local-exec model) Summary: Thread local variables are placed inside a `.tdata` segment. Their symbols are offsets from the start of the segment. The address of a thread local variable is computed as `__tls_base` + the offset from the start of the segment. `.tdata` segment is a passive segment and `memory.init` is used once per thread to initialize the thread local storage. `__tls_base` is a wasm global. Since each thread has its own wasm instance, it is effectively thread local. Currently, `__tls_base` must be initialized at thread startup, and so cannot be used with dynamic libraries. `__tls_base` is to be initialized with a new linker-synthesized function, `__wasm_init_tls`, which takes as an argument a block of memory to use as the storage for thread locals. It then initializes the block of memory and sets `__tls_base`. As `__wasm_init_tls` will handle the memory initialization, the memory does not have to be zeroed. To help allocating memory for thread-local storage, a new compiler intrinsic is introduced: `__builtin_wasm_tls_size()`. This instrinsic function returns the size of the thread-local storage for the current function. The expected usage is to run something like the following upon thread startup: __wasm_init_tls(malloc(__builtin_wasm_tls_size())); Reviewers: tlively, aheejin, kripken, sbc100 Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, jfb, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D64537 llvm-svn: 366272
2019-07-17 06:00:45 +08:00
}
return offset;
}
void DefinedData::setVirtualAddress(uint64_t value) {
LLVM_DEBUG(dbgs() << "setVirtualAddress " << name << " -> " << value << "\n");
assert(!segment);
offset = value;
}
uint64_t DefinedData::getOutputSegmentOffset() const {
LLVM_DEBUG(dbgs() << "getOutputSegmentOffset: " << getName() << "\n");
return segment->outputSegmentOffset + offset;
}
uint64_t DefinedData::getOutputSegmentIndex() const {
LLVM_DEBUG(dbgs() << "getOutputSegmentIndex: " << getName() << "\n");
return segment->outputSeg->index;
}
uint32_t GlobalSymbol::getGlobalIndex() const {
if (auto *f = dyn_cast<DefinedGlobal>(this))
return f->global->getGlobalIndex();
assert(globalIndex != INVALID_INDEX);
return globalIndex;
}
void GlobalSymbol::setGlobalIndex(uint32_t index) {
LLVM_DEBUG(dbgs() << "setGlobalIndex " << name << " -> " << index << "\n");
assert(globalIndex == INVALID_INDEX);
globalIndex = index;
}
bool GlobalSymbol::hasGlobalIndex() const {
if (auto *f = dyn_cast<DefinedGlobal>(this))
return f->global->hasGlobalIndex();
return globalIndex != INVALID_INDEX;
}
DefinedGlobal::DefinedGlobal(StringRef name, uint32_t flags, InputFile *file,
InputGlobal *global)
: GlobalSymbol(name, DefinedGlobalKind, flags, file,
global ? &global->getType() : nullptr),
global(global) {}
uint32_t EventSymbol::getEventIndex() const {
if (auto *f = dyn_cast<DefinedEvent>(this))
return f->event->getEventIndex();
assert(eventIndex != INVALID_INDEX);
return eventIndex;
}
void EventSymbol::setEventIndex(uint32_t index) {
LLVM_DEBUG(dbgs() << "setEventIndex " << name << " -> " << index << "\n");
assert(eventIndex == INVALID_INDEX);
eventIndex = index;
}
bool EventSymbol::hasEventIndex() const {
if (auto *f = dyn_cast<DefinedEvent>(this))
return f->event->hasEventIndex();
return eventIndex != INVALID_INDEX;
}
DefinedEvent::DefinedEvent(StringRef name, uint32_t flags, InputFile *file,
InputEvent *event)
: EventSymbol(name, DefinedEventKind, flags, file,
event ? &event->getType() : nullptr,
event ? &event->signature : nullptr),
event(event) {}
const OutputSectionSymbol *SectionSymbol::getOutputSectionSymbol() const {
assert(section->outputSec && section->outputSec->sectionSym);
return section->outputSec->sectionSym;
}
void LazySymbol::fetch() { cast<ArchiveFile>(file)->addMember(&archiveSymbol); }
MemoryBufferRef LazySymbol::getMemberBuffer() {
Archive::Child c =
CHECK(archiveSymbol.getMember(),
"could not get the member for symbol " + toString(*this));
return CHECK(c.getMemoryBufferRef(),
"could not get the buffer for the member defining symbol " +
toString(*this));
}
void printTraceSymbolUndefined(StringRef name, const InputFile* file) {
message(toString(file) + ": reference to " + name);
}
// Print out a log message for --trace-symbol.
void printTraceSymbol(Symbol *sym) {
// Undefined symbols are traced via printTraceSymbolUndefined
if (sym->isUndefined())
return;
std::string s;
if (sym->isLazy())
s = ": lazy definition of ";
else
s = ": definition of ";
message(toString(sym->getFile()) + s + sym->getName());
}
const char *defaultModule = "env";
const char *functionTableName = "__indirect_function_table";
} // namespace wasm
} // namespace lld