D152340 has split WinCOFFObjectWriter to WinCOFFWriter. This patch adds
another WinCOFFWriter as DwoWriter to write Dwo sections to dwo file.
Driver options are also updated accordingly to support -gsplit-dwarf in
CL mode.
e.g. $ clang-cl -c -gdwarf -gsplit-dwarf foo.c
Like what -gsplit-dwarf did in ELF, using this option will create DWARF object
(.dwo) file. DWARF debug info is split between COFF object and DWARF object
file. It can reduce the executable file size especially for large project.
Reviewed By: skan, MaskRay
Differential Revision: https://reviews.llvm.org/D152785
We'd like to support -gsplit-dwarf for Windows COFF. It requires to
write Dwo and NonDwo sections to different output streams.The original
implementation is not designed to do that and there can be only one
MCObjectWriter. This patch split WinCOFFObjectWriter to WinCOFFWriter so
that:
1. WinCOFFObjectWriter can create multiple WinCOFFWriter.
2. Each WinCOFFWriter can separately collect sections it is interested.
3. Each WinCOFFWriter can write to it's own output stream.
Reviewed By: skan
Differential Revision: https://reviews.llvm.org/D152340
This is mostly useful for ARM64EC, which uses such symbols extensively.
One interesting quirk of ARM64EC is that we need to be able to emit weak
symbols that point at each other (so if either symbol is defined
elsewhere, both symbols point at the definition). This handling is
currently restricted to weak_anti_dep symbols, because we depend on the
current behavior of resolving weak symbols in some cases.
Differential Revision: https://reviews.llvm.org/D145208
Set public specifiers only for constructor and inherited methods from
MCObjectWriter and leave others as private. Also change the order of
MCObjectWriter methods' definition according to it's declaration order.
Reviewed By: skan
Differential Revision: https://reviews.llvm.org/D152229
Each COFFSection bind MCSection when created. No need to iterate
throught MCAssembler when writeSection.
Reviewed By: skan
Differential Revision: https://reviews.llvm.org/D151793
This reverts commit 10c17c97ebaf81ac26f6830e51a7a57ddcf63cd2. It causes undefined symbol error on chromium windows build. A small repro was uploaded to the code review.
This is mostly useful for ARM64EC, which uses such symbols extensively.
One interesting quirk of ARM64EC is that we need to be able to emit weak
symbols that point at each other (so if either symbol is defined
elsewhere, both symbols point at the definition). This required a few
changes to the way we handle weak symbols on Windows.
Differential Revision: https://reviews.llvm.org/D145208
This is mostly useful for ARM64EC, which uses such symbols extensively.
One interesting quirk of ARM64EC is that we need to be able to emit weak
symbols that point at each other (so if either symbol is defined
elsewhere, both symbols point at the definition). This required a few
changes to the way we handle weak symbols on Windows.
Differential Revision: https://reviews.llvm.org/D145208
Use deduction guides instead of helper functions.
The only non-automatic changes have been:
1. ArrayRef(some_uint8_pointer, 0) needs to be changed into ArrayRef(some_uint8_pointer, (size_t)0) to avoid an ambiguous call with ArrayRef((uint8_t*), (uint8_t*))
2. CVSymbol sym(makeArrayRef(symStorage)); needed to be rewritten as CVSymbol sym{ArrayRef(symStorage)}; otherwise the compiler is confused and thinks we have a (bad) function prototype. There was a few similar situation across the codebase.
3. ADL doesn't seem to work the same for deduction-guides and functions, so at some point the llvm namespace must be explicitly stated.
4. The "reference mode" of makeArrayRef(ArrayRef<T> &) that acts as no-op is not supported (a constructor cannot achieve that).
Per reviewers' comment, some useless makeArrayRef have been removed in the process.
This is a follow-up to https://reviews.llvm.org/D140896 that introduced
the deduction guides.
Differential Revision: https://reviews.llvm.org/D140955
.addrsig_sym forces registering the symbol regardless whether it is otherwise
registered. This creates an undefined symbol which is inconvenient/undesired:
* `extern int x; void f() { (void)x; }` has inconsistent behavior whether `x` is emitted as an undefined symbol.
`-O0 -faddrsig` makes `x` undefined while other -O levels and -fno-addrsig eliminate the symbol.
* In ThinLTO, after a non-prevailing linkonce_odr definition is converted to available_externally, and then a declaration,
the addrsig code emits a symbol while the symbol is otherwise unseen.
D135427 fixed a bug that a non-prevailing `__cxx_global_var_init` was
incorrectly retained. However, the IR declaration causes an undesired
`.addrsig_sym __cxx_global_var_init`. This can be addressed in a way similar
to D101512 (`isTransitiveUsedByMetadataOnly`) but the increased
`OutStreamer->emitAddrsigSym(getSymbol(&GV));` complexity makes me nervous.
Just ignoring unregistered symbols circumvents the problem.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D135642
When using weak symbols, the WinCOFFObjectWriter keeps a list (`WeakDefaults`)
that's used to make names unique. This list should be reset when the object
writer is reset, because otherwise reuse of the object writer can result in
freed symbols being accessed. With some added output, this becomes clear when
using `llc` in `--run-twice` mode:
```
$ ./llc --compile-twice -mtriple=x86_64-pc-win32 trivial.ll -filetype=obj
DefineSymbol::WeakDefaults
- .weak.foo.default
- .weak.bar.default
DefineSymbol::WeakDefaults
- .weak.foo.default
- áÑJij⌂ p§┼Ø┐☺
- .debug_macinfo.dw
- .weak.bar.default
```
This does not seem to leak into the output object file though, so I couldn't
come up with a test. I added one that just does `--run-twice` (and verified
that it does access freed memory), which should result in detecting the
invalid memory accesses when running under ASAN.
Observed in a Julia PR where we started using weak symbols:
https://github.com/JuliaLang/julia/pull/45649
Reviewed By: mstorsjo
Differential Revision: https://reviews.llvm.org/D129840
It's a fairly common issue that the generating code incorrectly marks
instructions as narrow or wide; check that the instruction lengths
add up to the expected value, and error out if it doesn't. This allows
catching code generation bugs.
Also check that prologs and epilogs are properly terminated, to
catch other code generation issues.
Differential Revision: https://reviews.llvm.org/D125647
The __llvm_addrsig section is a section that the linker needs for safe icf.
This was not yet implemented for MachO - this is the implementation.
It has been tested with a safe deduplication implementation inside lld.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D123751
Large COFF section names are moved into the string table and the
section header field is the offset into the string table encoded in
ASCII for offset smaller than 7 digits and in base64 for larger
offsets.
The operation of taking the string table offsets is done in a few
places in the codebase, so it is helpful to move this operation into
`BinaryFormat` so that it can be shared everywhere it's done.
So this patch takes the implementation of this operation from
`llvm/lib/MC/WinCOFFObjectWriter.cpp` and moves it into `BinaryFormat`.
Reviewed By: jhenderson, rnk
Differential Revision: https://reviews.llvm.org/D118793
There's a few relevant forward declarations in there that may require downstream
adding explicit includes:
llvm/MC/MCContext.h no longer includes llvm/BinaryFormat/ELF.h, llvm/MC/MCSubtargetInfo.h, llvm/MC/MCTargetOptions.h
llvm/MC/MCObjectStreamer.h no longer include llvm/MC/MCAssembler.h
llvm/MC/MCAssembler.h no longer includes llvm/MC/MCFixup.h, llvm/MC/MCFragment.h
Counting preprocessed lines required to rebuild llvm-project on my setup:
before: 1052436830
after: 1049293745
Which is significant and backs up the change in addition to the usual benefits of
decreasing coupling between headers and compilation units.
Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D119244
For relocations against temporary symbols (that don't persist in
the object file), we normally adjust them to reference the start of
the section.
For adrp relocations, the immediate offset from the referenced
symbol is stored in the opcode as the 21 bit signed immediate; this
means that the symbol referenced must be within +/- 1 MB from the
referenced symbol.
Create label symbols with regular intervals (1 MB intervals). For
relocations against temporary symbols, pick the preceding added
offset symbol and make the relocation against that instead of
against the start of the section.
This should fix the root issue behind
https://bugs.llvm.org/show_bug.cgi?id=52378.
Differential Revision: https://reviews.llvm.org/D114340
This matches how they are defined on X86.
This should fix the relative lookup tables pass for COFF, allowing
it to be reenabled.
Differential Revision: https://reviews.llvm.org/D102217
Avoid introducing unnecessary indirection for weak-external references.
We only need to introduce ".weak.<SYMBOL>.default" when referencing a
symbol that is defined, but not external.
Reviewed By: mstorsjo
Differential Revision: https://reviews.llvm.org/D88305
For comdats (e.g. caused by -ffunction-sections), Section is already
set here; make sure it's null, for the weak external symbol to be undefined.
This fixes PR46779.
Differential Revision: https://reviews.llvm.org/D84507
These symbols need to be external (MSVC tools error out if a weak
external points at a symbol that isn't external; this was tried before
but had to be reverted in bc5b7217dceecd3eec69593026a9e38dfbfd6908,
and this was originally explicitly fixed in
732eeaf2a930ad2755cb4eb5d99a3deae0de4a72).
If multiple object files have weak symbols with defaults, their
defaults could cause linker errors due to duplicate definitions,
unless the names of the defaults are unique.
GNU binutils handles this by appending the name of another symbol
from the same object file to the name of the default symbol. Try
to implement something similar; before writing the object file,
locate a symbol that should have a unique name and use the name of
that one for making the weak defaults unique.
Differential Revision: https://reviews.llvm.org/D75989
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.
This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.
This doesn't actually modify StringRef yet, I'll do that in a follow-up.
This reverts commit 7ca86ee6494d4307333b300bae80e42df4a5140f.
Apparently this change causes MS link.exe to error out with
"LNK1235: corrupt or invalid COFF symbol table".
If we have references to the same extern_weak in multiple objects,
all of them would generate external symbols with the same name. Make
them static to avoid duplicate definitions; nothing should need to
refer to this symbol outside of the current object.
GCC/binutils seems to handle the same by not using a fixed string
for the ".default" suffix, but instead using the name of some other
defined external symbol from the same object (which is supposed to
be unique among objects unless there's other duplicate definitions).
Differential Revision: https://reviews.llvm.org/D71711
David added the JamCRC implementation in r246590. More recently, Eugene
added a CRC-32 implementation in r357901, which falls back to zlib's
crc32 function if present.
These checksums are essentially the same, so having multiple
implementations seems unnecessary. This replaces the CRC-32
implementation with the simpler one from JamCRC, and implements the
JamCRC interface in terms of CRC-32 since this means it can use zlib's
implementation when available, saving a few bytes and potentially making
it faster.
JamCRC took an ArrayRef<char> argument, and CRC-32 took a StringRef.
This patch changes it to ArrayRef<uint8_t> which I think is the best
choice, and simplifies a few of the callers nicely.
Differential revision: https://reviews.llvm.org/D68570
llvm-svn: 374148
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
llvm-svn: 369013
The weak alias should have the characteristics set to
`IMAGE_EXTERN_WEAK_SEARCH_ALIAS` to indicate that the weak external here
is a symbol alias and that the symbol is aliased to a locally defined
symbol. We were previously setting the characteristics to
`IMAGE_EXTERN_WEAK_SEARCH_LIBRARY` which indicates that the symbol
should be looked for in the libraries.
llvm-svn: 364370
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Aligning section contents is not required, but only
recommended, by the specification. Microsoft's documentation says
(https://docs.microsoft.com/en-us/windows/desktop/debug/pe-format#section-table-section-headers):
"For object files, the value should be aligned on a 4-byte boundary
for best performance."
However, according to my measurements, aligning section contents has
a neutral to negative effect on performance.
I measured the median run time of 100 links of Chromium's
base_unittests on Linux with lld-link and on Windows with link.exe with
both aligned and unaligned sections. On Linux I didn't see a measurable
performance difference, and on Windows the link was slightly faster
with unaligned sections (presumably because on Windows the bottleneck
is I/O).
Also, the sections created by cl.exe are unaligned, so we should expect
tools to broadly accept unaligned sections.
Differential Revision: https://reviews.llvm.org/D51149
llvm-svn: 340514
The format is the same as in ELF: a sequence of ULEB128-encoded
symbol indexes.
Differential Revision: https://reviews.llvm.org/D51047
llvm-svn: 340499
Remove code for writing auxiliary symbols of type function definition
and begin function. These types of symbols are associated with
pre-CodeView debug info and we never emit them.
llvm-svn: 340113
Handle the case when the symbol is private. Private symbols are not in
the COFF object file symbol table, so they aren't inserted into
SymbolMap. We can't look up the section of the symbol that way. Instead,
get the MCSection from the MCSymbol and map that to the object file
section.
Print a better error message when the symbol has no section, like when
the symbol is undefined.
Fixes PR38607
llvm-svn: 339942
Also clean up a couple of hacks where we were writing the section
contents to another stream by setting the object writer's stream,
writing and setting it back.
Part of PR37466.
Differential Revision: https://reviews.llvm.org/D47038
llvm-svn: 332858
