llvm-project/lld/MachO/CMakeLists.txt

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set(LLVM_TARGET_DEFINITIONS Options.td)
tablegen(LLVM Options.inc -gen-opt-parser-defs)
add_public_tablegen_target(MachOOptionsTableGen)
include_directories(${LLVM_MAIN_SRC_DIR}/../libunwind/include)
add_lld_library(lldMachO
Arch/ARM.cpp
Arch/ARM64.cpp
Arch/ARM64Common.cpp
Arch/ARM64_32.cpp
Arch/X86_64.cpp
ConcatOutputSection.cpp
Driver.cpp
DriverUtils.cpp
[lld-macho] Emit STABS symbols for debugging, and drop debug sections Debug sections contain a large amount of data. In order not to bloat the size of the final binary, we remove them and instead emit STABS symbols for `dsymutil` and the debugger to locate their contents in the object files. With this diff, `dsymutil` is able to locate the debug info. However, we need a few more features before `lldb` is able to work well with our binaries -- e.g. having `LC_DYSYMTAB` accurately reflect the number of local symbols, emitting `LC_UUID`, and more. Those will be handled in follow-up diffs. Note also that the STABS we emit differ slightly from what ld64 does. First, we emit the path to the source file as one `N_SO` symbol instead of two. (`ld64` emits one `N_SO` for the dirname and one of the basename.) Second, we do not emit `N_BNSYM` and `N_ENSYM` STABS to mark the start and end of functions, because the `N_FUN` STABS already serve that purpose. @clayborg recommended these changes based on his knowledge of what the debugging tools look for. Additionally, this current implementation doesn't accurately reflect the size of function symbols. It uses the size of their containing sectioins as a proxy, but that is only accurate if `.subsections_with_symbols` is set, and if there isn't an `N_ALT_ENTRY` in that particular subsection. I think we have two options to solve this: 1. We can split up subsections by symbol even if `.subsections_with_symbols` is not set, but include constraints to ensure those subsections retain their order in the final output. This is `ld64`'s approach. 2. We could just add a `size` field to our `Symbol` class. This seems simpler, and I'm more inclined toward it, but I'm not sure if there are use cases that it doesn't handle well. As such I'm punting on the decision for now. Reviewed By: clayborg Differential Revision: https://reviews.llvm.org/D89257
2020-12-02 06:45:01 +08:00
Dwarf.cpp
ExportTrie.cpp
ICF.cpp
InputFiles.cpp
InputSection.cpp
LTO.cpp
MapFile.cpp
[lld/mac] Implement -dead_strip 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
2021-05-08 05:10:05 +08:00
MarkLive.cpp
ObjC.cpp
OutputSection.cpp
OutputSegment.cpp
Relocations.cpp
SymbolTable.cpp
Symbols.cpp
SyntheticSections.cpp
Target.cpp
UnwindInfoSection.cpp
Writer.cpp
LINK_COMPONENTS
${LLVM_TARGETS_TO_BUILD}
BinaryFormat
BitReader
Core
DebugInfoDWARF
LTO
MC
ObjCARCOpts
Object
Option
Passes
Support
TextAPI
LINK_LIBS
lldCommon
${LLVM_PTHREAD_LIB}
${XAR_LIB}
DEPENDS
MachOOptionsTableGen
${tablegen_deps}
)
if(LLVM_HAVE_LIBXAR)
target_link_libraries(lldMachO PRIVATE ${XAR_LIB})
endif()