a5645513db
Also adds support for live_support sections, no_dead_strip sections, .no_dead_strip symbols. Chromium Framework 345MB unstripped -> 250MB stripped (vs 290MB unstripped -> 236M stripped with ld64). Doing dead stripping is a bit faster than not, because so much less data needs to be processed: % ministat lld_* x lld_nostrip.txt + lld_strip.txt N Min Max Median Avg Stddev x 10 3.929414 4.07692 4.0269079 4.0089678 0.044214794 + 10 3.8129408 3.9025559 3.8670411 3.8642573 0.024779651 Difference at 95.0% confidence -0.144711 +/- 0.0336749 -3.60967% +/- 0.839989% (Student's t, pooled s = 0.0358398) This interacts with many parts of the linker. I tried to add test coverage for all added `isLive()` checks, so that some test will fail if any of them is removed. I checked that the test expectations for the most part match ld64's behavior (except for live-support-iterations.s, see the comment in the test). Interacts with: - debug info - export tries - import opcodes - flags like -exported_symbol(s_list) - -U / dynamic_lookup - mod_init_funcs, mod_term_funcs - weak symbol handling - unwind info - stubs - map files - -sectcreate - undefined, dylib, common, defined (both absolute and normal) symbols It's possible it interacts with more features I didn't think of, of course. I also did some manual testing: - check-llvm check-clang check-lld work with lld with this patch as host linker and -dead_strip enabled - Chromium still starts - Chromium's base_unittests still pass, including unwind tests Implemenation-wise, this is InputSection-based, so it'll work for object files with .subsections_via_symbols (which includes all object files generated by clang). I first based this on the COFF implementation, but later realized that things are more similar to ELF. I think it'd be good to refactor MarkLive.cpp to look more like the ELF part at some point, but I'd like to get a working state checked in first. Mechanical parts: - Rename canOmitFromOutput to wasCoalesced (no behavior change) since it really is for weak coalesced symbols - Add noDeadStrip to Defined, corresponding to N_NO_DEAD_STRIP (`.no_dead_strip` in asm) Fixes PR49276. Differential Revision: https://reviews.llvm.org/D103324
78 lines
2.5 KiB
C++
78 lines
2.5 KiB
C++
//===- SymbolTable.h --------------------------------------------*- C++ -*-===//
|
|
//
|
|
// 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
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLD_MACHO_SYMBOL_TABLE_H
|
|
#define LLD_MACHO_SYMBOL_TABLE_H
|
|
|
|
#include "Symbols.h"
|
|
|
|
#include "lld/Common/LLVM.h"
|
|
#include "llvm/ADT/CachedHashString.h"
|
|
#include "llvm/ADT/DenseMap.h"
|
|
#include "llvm/Object/Archive.h"
|
|
|
|
namespace lld {
|
|
namespace macho {
|
|
|
|
class ArchiveFile;
|
|
class DylibFile;
|
|
class InputFile;
|
|
class ObjFile;
|
|
class InputSection;
|
|
class MachHeaderSection;
|
|
class Symbol;
|
|
class Defined;
|
|
class Undefined;
|
|
|
|
/*
|
|
* Note that the SymbolTable handles name collisions by calling
|
|
* replaceSymbol(), which does an in-place update of the Symbol via `placement
|
|
* new`. Therefore, there is no need to update any relocations that hold
|
|
* pointers the "old" Symbol -- they will automatically point to the new one.
|
|
*/
|
|
class SymbolTable {
|
|
public:
|
|
Defined *addDefined(StringRef name, InputFile *, InputSection *,
|
|
uint64_t value, uint64_t size, bool isWeakDef,
|
|
bool isPrivateExtern, bool isThumb,
|
|
bool isReferencedDynamically, bool noDeadStrip);
|
|
|
|
Symbol *addUndefined(StringRef name, InputFile *, bool isWeakRef);
|
|
|
|
Symbol *addCommon(StringRef name, InputFile *, uint64_t size, uint32_t align,
|
|
bool isPrivateExtern);
|
|
|
|
Symbol *addDylib(StringRef name, DylibFile *file, bool isWeakDef, bool isTlv);
|
|
Symbol *addDynamicLookup(StringRef name);
|
|
|
|
Symbol *addLazy(StringRef name, ArchiveFile *file,
|
|
const llvm::object::Archive::Symbol &sym);
|
|
|
|
Defined *addSynthetic(StringRef name, InputSection *, uint64_t value,
|
|
bool isPrivateExtern, bool includeInSymtab,
|
|
bool referencedDynamically);
|
|
|
|
ArrayRef<Symbol *> getSymbols() const { return symVector; }
|
|
Symbol *find(llvm::CachedHashStringRef name);
|
|
Symbol *find(StringRef name) { return find(llvm::CachedHashStringRef(name)); }
|
|
|
|
private:
|
|
std::pair<Symbol *, bool> insert(StringRef name, const InputFile *);
|
|
llvm::DenseMap<llvm::CachedHashStringRef, int> symMap;
|
|
std::vector<Symbol *> symVector;
|
|
};
|
|
|
|
void treatUndefinedSymbol(const Undefined &, StringRef source = "");
|
|
|
|
extern SymbolTable *symtab;
|
|
|
|
} // namespace macho
|
|
} // namespace lld
|
|
|
|
#endif
|