Before this, if an inline function was defined in several input files,
lld would write each copy of the inline function the output. With this
patch, it only writes one copy.
Reduces the size of Chromium Framework from 378MB to 345MB (compared
to 290MB linked with ld64, which also does dead-stripping, which we
don't do yet), and makes linking it faster:
N Min Max Median Avg Stddev
x 10 3.9957051 4.3496981 4.1411121 4.156837 0.10092097
+ 10 3.908154 4.169318 3.9712729 3.9846753 0.075773012
Difference at 95.0% confidence
-0.172162 +/- 0.083847
-4.14165% +/- 2.01709%
(Student's t, pooled s = 0.0892373)
Implementation-wise, when merging two weak symbols, this sets a
"canOmitFromOutput" on the InputSection belonging to the weak symbol not put in
the symbol table. We then don't write InputSections that have this set, as long
as they are not referenced from other symbols. (This happens e.g. for object
files that don't set .subsections_via_symbols or that use .alt_entry.)
Some restrictions:
- not yet done for bitcode inputs
- no "comdat" handling (`kindNoneGroupSubordinate*` in ld64) --
Frame Descriptor Entries (FDEs), Language Specific Data Areas (LSDAs)
(that is, catch block unwind information) and Personality Routines
associated with weak functions still not stripped. This is wasteful,
but harmless.
- However, this does strip weaks from __unwind_info (which is needed for
correctness and not just for size)
- This nopes out on InputSections that are referenced form more than
one symbol (eg from .alt_entry) for now
Things that work based on symbols Just Work:
- map files (change in MapFile.cpp is no-op and not needed; I just
found it a bit more explicit)
- exports
Things that work with inputSections need to explicitly check if
an inputSection is written (e.g. unwind info).
This patch is useful in itself, but it's also likely also a useful foundation
for dead_strip.
I used to have a "canoncialRepresentative" pointer on InputSection instead of
just the bool, which would be handy for ICF too. But I ended up not needing it
for this patch, so I removed that again for now.
Differential Revision: https://reviews.llvm.org/D102076
GNU as documentation states that a `.thumb_func` directive implies `.thumb`, teach the asm parser to switch mode whenever it's encountered. On the other hand the labeled form, exclusive to Apple's toolchain, doesn't switch mode at all.
Reviewed By: nickdesaulniers, peter.smith
Differential Revision: https://reviews.llvm.org/D101975
This fixes an issue where mixed TOC / NOTOC calls can call the incorrect
thunks if a previous thunk already exists. The issue appears when a TOC
funciton calls a NOTOC callee and then a different NOTOC function calls the same
NOTOC callee. In this case the linker would sometimes incorrectly call the
same thunk for both cases.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D101837
ld64 can emit dylibs that support more than one platform (typically macOS and
macCatalyst). This diff allows LLD to read in those dylibs. Note that this is a
super bare-bones implementation -- in particular, I haven't added support for
LLD to emit those multi-platform dylibs, nor have I added a variety of
validation checks that ld64 does. Until we have a use-case for emitting zippered
dylibs, I think this is good enough.
Fixes PR49597.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D101954
It doesn't seem like TBDv3 allows for specifying multiple platforms, so I'm
upgrading us to TBDv4. (We need to support multiple platforms in order to test
that we can handle zippered dylibs; that functionality will be added in an
upcoming diff.)
Differential Revision: https://reviews.llvm.org/D101953
This is a slight improvement to the help text, as I was slightly
surprised when strip-all did more than remove the symbol table.
Currently, we match gold's help text for strip-all and strip-debug.
I think that the GNU documentation for these options is not particularly
clear. However, I have opted to make only a minor change here and keep
the help text similar to gold's as these are mature options that are
well understood.
ld.bfd (https://sourceware.org/binutils/docs/ld/Options.html) has a
similar implication although it defines strip-debug as a subset of
strip-all. However, felt that noting that strip-all implies strip-debug
is better; because, with the ld.bfd approach you have to read both the
--strip-debug and the --strip-all help text to understand the behaviour
of --strip-all (and the --strip-all help text doesn't indicate that he
--strip-debug help text is related).
Differential Revision: https://reviews.llvm.org/D101890
The Halide project uses `#pragma comment(linker, "/STACK:...")` to set
the stack size high enough for our embedded compiler to run in end-user
programs on Windows.
Unfortunately, lld-link.exe breaks on this when embedded in a COFF
object, despite supporting the flag on the command line. MSVC's link.exe
supports this fine. This patch extends support for this to lld-link.exe
for better compatibility with MSVC projects.
Differential Revision: https://reviews.llvm.org/D99680
Currently the linker causes unnecessary errors when either the target or the config's platform is a simulator.
Differential Revision: https://reviews.llvm.org/D101855
Otherwise I get the following error on windows.
```
CMake Error at D:/bld/lld_1569206597988/work/build/CMakeFiles/CMakeTmp/CMakeLists.txt:2 (set):
Syntax error in cmake code at
D:/bld/lld_1569206597988/work/build/CMakeFiles/CMakeTmp/CMakeLists.txt:2
when parsing string
D:\bld\lld_1569206597988\_h_env\Library\lib\cmake\llvm
Invalid character escape '\b'.
CMake Error at D:/bld/lld_1569206597988/_build_env/Library/share/cmake-3.15/Modules/CheckSymbolExists.cmake:100 (try_compile):
Failed to configure test project build system.
Call Stack (most recent call first):
D:/bld/lld_1569206597988/_build_env/Library/share/cmake-3.15/Modules/CheckSymbolExists.cmake:57 (__CHECK_SYMBOL_EXISTS_IMPL)
D:/bld/lld_1569206597988/_h_env/Library/lib/cmake/llvm/HandleLLVMOptions.cmake:943 (check_symbol_exists)
CMakeLists.txt:56 (include)
```
Reviewed By: sbc100
Differential Revision: https://reviews.llvm.org/D68158
ARM_RELOC_BR24 is used for BL/BLX instructions from within ARM (i.e. not
Thumb) code. This diff just handles the basic case: branches from ARM to
ARM, or from ARM to Thumb where no shimming is required. (See comments
in ARM.cpp for why shims are required.)
Note: I will likely be deprioritizing ARM work for the near future to
focus on other parts of LLD. Apologies for the half-done state of this;
I'm just trying to wrap up what I've already worked on.
Reviewed By: #lld-macho, alexshap
Differential Revision: https://reviews.llvm.org/D101814
We need to account for path rerooting when generating the response
file. We could either reroot the paths before generating the file, or pass
through the original filenames and change just the syslibroot. I've opted for
the latter, in order that the reproduction run more closely mirrors the
original.
We must also be careful *not* to make an absolute path relative if it is
shadowed by a rerooted path. See repro6.tar in reroot-path.s for
details.
I've moved the call to `createResponseFile()` after the initialization of
`config->systemLibraryRoots`, since it now needs to know what those roots are.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D101224
This is a followup to 2b01a417d7ccb001ccc1185ef5fdc967c9fac8d7;
previously the RVAs of the exported symbols from comdats were left
zero.
Thanks to Kleis Auke Wolthuizen for the fix suggestion and pointing
out the omission.
Differential Revision: https://reviews.llvm.org/D101615
When dumping multiple pieces of information (e.g. --all-headers),
there is sometimes no separator between two pieces.
This patch uses the "\nheader:\n" style, which generally improves
compatibility with GNU objdump.
Note: objdump -t/-T does not add a newline before "SYMBOL TABLE:" and "DYNAMIC SYMBOL TABLE:".
We add a newline to be consistent with other information.
`objdump -d` prints two empty lines before the first 'Disassembly of section'.
We print just one with this patch.
Differential Revision: https://reviews.llvm.org/D101796
ld64 automatically renames many sections depending on output type and assorted flags. Here, we implement the most common configs. We can add more obscure flags and behaviors as needed.
Depends on D101393
Differential Revision: https://reviews.llvm.org/D101395
`shouldImport` was not returning true in PIC mode even though out
assumption elsewhere (in Relocations.cpp:scanRelocations) is that we
don't report undefined symbols in PIC mode today. This was resulting
functions that were undefined and but also not imported which hits an
assert later on that all functions have valid indexes.
Differential Revision: https://reviews.llvm.org/D101716
Two of these are trivial. The third (shared.s) did have some
expectations changes but only due to two data symbols being re-ordered.
Differential Revision: https://reviews.llvm.org/D101711
When running in relocatable mode any input data segments that are part
of a comdat group should not be merged with other segments of the same
name. This is because the final linker needs to keep the separate so
they can be included/excluded individually.
Often this is not a problem since normally only one section with a given
name `foo` ends up in the output object file. However, the problem
occurs when one input contains `foo` which part of a comdat and another
object contains a local symbol `foo` we were attempting to merge them.
This behaviour matches (I believe) that of the ELF linker. See
`LinkerScript.cpp:addInputSec`.
Fixes: https://github.com/emscripten-core/emscripten/issues/9726
Differential Revision: https://reviews.llvm.org/D101703
@thakis pointed out that `mach_header` and `mach_header_64`
actually have the same set of (used) fields, with the 64-bit version
having extra padding. So we can access the fields we need using the
single `mach_header` type instead of using templates to switch between
the two.
I also spotted a potential issue where hasObjCSection tries to parse a
file w/o checking if it does indeed match the target arch... As such,
I've added a quick magic number check to ensure we don't access invalid
memory during `findCommand()`.
Addresses PR50180.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D101724
Adopt my suggestion in https://reviews.llvm.org/D91426#2653926 ,
generalizing the ppc64 specific code.
GNU ld and glibc ld.so has a contract about the first few entries of .got .
There are somewhat complex conditions when the header is needed. This patch
switches to a simpler approach: add a header unconditionally if
_GLOBAL_OFFSET_TABLE_ is used or the number of entries is more than just the
header.
The right symbol flag mask is ~0x7, not ~0xf.
Also emit string names for the other flags (we were missing some).
Reviewed By: #lld-macho, gkm
Differential Revision: https://reviews.llvm.org/D101548
This just parses the `-arch armv7` and emits the right header flags.
The rest will be slowly fleshed out in upcoming diffs.
Reviewed By: #lld-macho, gkm
Differential Revision: https://reviews.llvm.org/D101557
Stop using the compatibility spellings of `OF_{None,Text,Append}`
left behind by 1f67a3cba9. A follow-up
will remove them.
Differential Revision: https://reviews.llvm.org/D101650
as a way of not running it on Windows, where the file paths when
extracting repro2.tar can become longer than the maximum file length
limit (depending on the build dir name) and cause the test to fail.
(See https://crbug.com/1204463 for example test failure.)
When looking for the "all" symbols that are supposed to be exported,
we can't look at the live flag - the symbols we mark as to be
exported will become GC roots even if they aren't yet marked as live.
With this in place, building an LLVM library with BUILD_SHARED_LIBS
produces the same set of symbols exported regardless of whether the
--gc-sections flag is specified, both with and without being built
with -ffunction-sections.
Differential Revision: https://reviews.llvm.org/D101522
I don't think it's super worthwhile to test the dylib headers outputs of
all the different archs when x86_64 is the only one that has interesting
behavior.
Motivated by my upcoming addition of arm32...
Modern versions of macOS (>= 10.7) and in general all modern Mach-O
target archs want PIEs by default. ld64 defaults to PIE for iOS >= 4.3,
as well as for all versions of watchOS and simulators. Basically all the
platforms LLD is likely to target want PIE. So instead of cluttering LLD's
code with legacy version checks, I think it's simpler to just default to
PIE for everything.
Note that `-no_pie` still works, so users can still opt out of it.
Reviewed By: #lld-macho, thakis, MaskRay
Differential Revision: https://reviews.llvm.org/D101513
GNU ld -r can create .rela.eh_frame with unordered r_offset values.
(With LLD, we can craft such a case by reordering sections in .eh_frame.)
This is currently unsupported and will trigger
`assert(pieces[i].inputOff <= off ...` in `OffsetGetter::get`
(the content is corrupted in a -DLLVM_ENABLE_ASSERTIONS=off build).
This patch supports this case.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D101116
Just like the in case for function and data symbols this is needed to
support relocations in debug info sections which are allowed contains
relocations against non-live symbols.
The motivating use case is an object file that contains debug info that
references `__stack_pointer` (a local symbol) but does not actually
contain any uses of `__stack_pointer`.
Fixes: https://github.com/emscripten-core/emscripten/issues/14025
Differential Revision: https://reviews.llvm.org/D101399
The original page no longer works, so use a web.archive.org link instead.
Reviewed By: atanasyan
Differential Revision: https://reviews.llvm.org/D100949
As preparation for a subsequent diff that implements builtin section renaming, define more `constexpr` strings in namespaces `lld::macho::segment_names` and `lld::macho::section_names`, and use them to replace string literals.
Differential Revision: https://reviews.llvm.org/D101393
This is the same problem as 127176e59e, but for static TLS rather than
dynamic TLS. Although we know the symbol will be the one in our own TLS
segment, and thus the offset of it within that, we don't know where in
the static TLS block our data will be allocated and thus we must emit a
dynamic relocation for this case.
Reviewed By: MaskRay, atanasyan
Differential Revision: https://reviews.llvm.org/D101381
Whilst not wrong (unless using static PIE where the relocations are
likely not implemented by the runtime), this is inefficient, as the TLS
module indices and offsets are independent of the executable's load
address.
Reviewed By: MaskRay, atanasyan
Differential Revision: https://reviews.llvm.org/D101382
Add option to limit (or remove limits) on the number of errors printed before exiting. This option exists in the other lld ports: COFF & ELF.
Differential Revision: https://reviews.llvm.org/D101274
When I added this assert in D93609, it asserted that a symbol that
is privateExtern is also isExternal().
In D98381 the privateExtern check moved into shouldExportSymbol()
but the assert didn't -- now it checked that _every_ non-exported
symbol is isExternal(), which isn't true. Move the assert into the
privateExtern check where it used to be.
Fixes PR50098.
Differential Revision: https://reviews.llvm.org/D101223
- the macro seems needlessly clever -- shorter and imho clearer without it
- give all filenames an extension so they look like filenames
- rename .private_extern symbol from _private to _private_extern
to prepare for follow-up that adds a truly private symbol
No behavior change.
Differential Revision: https://reviews.llvm.org/D101222
Nico Weber