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 bc5b7217dc,
and this was originally explicitly fixed in
732eeaf2a9).
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.
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
Summary:
r327219 added wrappers to std::sort which randomly shuffle the container before sorting.
This will help in uncovering non-determinism caused due to undefined sorting
order of objects having the same key.
To make use of that infrastructure we need to invoke llvm::sort instead of std::sort.
Note: This patch is one of a series of patches to replace *all* std::sort to llvm::sort.
Refer the comments section in D44363 for a list of all the required patches.
Reviewers: grosbach, void, ruiu
Reviewed By: ruiu
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45138
llvm-svn: 330058
Summary:
We already emit relocations in this case when the "incremental linker
compatible" flag is set, but it turns out these relocations are also
required for /guard:cf. Now that we have two use cases for this
behavior, let's make it unconditional to try to keep things simple.
We never hit this problem in Clang because it always sets the
"incremental linker compatible" flag when targeting MSVC. However, LLD
LTO doesn't set this flag, so we'd get CFG failures at runtime when
using ThinLTO and /guard:cf. We probably don't want LLD LTO to set the
"incremental linker compatible" assembler flag, since this has nothing
to do with incremental linking, and we don't need to timestamp LTO
temporary objects.
Fixes PR36624.
Reviewers: inglorion, espindola, majnemer
Subscribers: mehdi_amini, llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D44485
llvm-svn: 327557
functions.
This makes the ownership of the resulting MCObjectWriter clear, and allows us
to remove one instance of MCObjectStreamer's bizarre "holding ownership via
someone else's reference" trick.
llvm-svn: 315327
createWinCOFFObjectWriter to WinCOFFObjectWriter's constructor.
Fixes the same ownership issue for COFF that r315245 did for MachO:
WinCOFFObjectWriter takes ownership of its MCWinCOFFObjectTargetWriter, so we
want to pass this through to the constructor via a unique_ptr, rather than a
raw ptr.
llvm-svn: 315257
X86_64 COFF only has support for 32 bit pcrel relocations. Produce an
error on all others.
Note that gnu as has extended the relocation values to support
this. It is not clear if we should support the gnu extension.
llvm-svn: 306082
For whatever reason, when processing
.globl foo
foo:
.data
bar:
.long foo-bar
llvm-mc creates a relocation with the section:
0x0 IMAGE_REL_I386_REL32 .text
This is different than when the relocation is relative from the
beginning. For example, a file with
call foo
produces
0x0 IMAGE_REL_I386_REL32 foo
I would like to refactor the logic for converting "foo - ." into a
relative relocation so that it is shared with ELF. This is the first
step and just changes the coff implementation to match what ELF (and
COFF in the case of calls) does.
llvm-svn: 306063
It looks like that when this code was written recordRelocation could
be called with A-B where A and B are in the same section. The
expression evaluation logic these days makes sure those are folded, so
some of this code was dead.
llvm-svn: 306053
This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.
Differential Revision: https://reviews.llvm.org/D33843
llvm-svn: 304864
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.
I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.
This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.
Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).
llvm-svn: 304787
MSVC link.exe cannot handle associative sections that refer later
sections in the section header. Technically, such COFF object doesn't
violate the Microsoft COFF spec, as the spec doesn't say anything
about that, but still we should avoid doing that to make it compatible
with MS tools.
This patch assigns smaller section numbers to non-associative sections
and larger numbers to associative sections. This should resolve the
compatibility issue.
Differential Revision: https://reviews.llvm.org/D30080
llvm-svn: 295464
Simon Pilgrim