For dwarf debug info, an executable normally either contains the debug
info, or it is stripped out. To reduce the storage needed (slightly)
for the debug info kept separately from the released, stripped binaries,
one can choose to only copy the debug data from the original executable
(essentially the reverse of the strip operation), producing a file with
only debug info.
When copying the debug data from an executable with GNU objcopy,
the build id and debug directory need to reside in a separate section,
as this will be kept while the rest of the .rdata section is removed.
Differential Revision: https://reviews.llvm.org/D49352
llvm-svn: 337526
This patch changes relative path for source files in obj files to
absolute path in PDB when linking with added flag.
I will make obj file generated by clang-cl independent from build
directory for chromium build. But I don't want to confuse visual studio
debugger or require additional configuration. To attain this goal, I
added flag to convert relative source file path in obj to absolute path
when emitting PDB.
By removing absolute path from obj files, we can share build cache
between chromium developers even when they are doing debug build.
That will make build time faster.
More context:
https://bugs.chromium.org/p/chromium/issues/detail?id=712796https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/5HXSVX-7fPc
llvm-svn: 337439
Dwarf debug info contains some data that contains absolute addresses.
Since these sections are discardable and aren't loaded at runtime,
there's no point in adding base relocations for them.
This makes sure that after stripping out dwarf debug info, there are no
base relocations that point to nonexistent sections.
Differential Revision: https://reviews.llvm.org/D49350
llvm-svn: 337438
Some Microsoft tools (e.g. new versions of WPA) fail when the
COFF Debug Directory contains a path to the PDB that contains
dots, such as D:\foo\./bar.pdb. Remove dots before writing this
path.
This fixes pr38126.
llvm-svn: 336873
Future symbol insertions can potentially change the type of these
symbols - keep pointers to the base class to reflect this, and
use dynamic casts to inspect them before using as the subclass
type.
This fixes crashes that were possible before, by touching these
symbols that now are populated as e.g. a DefinedRegular, via
the old pointers with DefinedImportThunk type.
Differential Revision: https://reviews.llvm.org/D48953
llvm-svn: 336652
With this set, we retain the symbol table, but skip the actual debug
information.
This is meant to be used by the MinGW frontend.
Differential Revision: https://reviews.llvm.org/D48745
llvm-svn: 335946
Summary:
Control flow guard works best when targets it checks are 16-byte aligned.
Microsoft's link.exe helps ensure this by aligning code from sections
that are referenced from the gfids table to 16 bytes when linking with
-guard:cf, even if the original section specifies a smaller alignment.
This change implements that behavior in lld-link.
See https://crbug.com/857012 for more details.
Reviewers: ruiu, hans, thakis, zturner
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D48690
llvm-svn: 335864
`lld-link foo.lib /wholearchive:foo.lib` should work the same way as
`lld-link /wholearchive:foo.lib foo.lib`. Previously, /wholearchive in
the former case was ignored.
Differential Revision: https://reviews.llvm.org/D47565
llvm-svn: 334552
When running with linker GC (`-opt:ref`), defined imported symbols that
are referenced but then dropped by GC end up with their `Location`
member being nullptr, which means `getChunk()` returns nullptr for them
and attempting to call `getChunk()->getOutputSection()` causes a crash
from the nullptr dereference. Check for `getChunk()` being nullptr and
bail out early to avoid the crash.
Differential Revision: https://reviews.llvm.org/D48092
llvm-svn: 334548
This simplifies some code which had StringRefs to begin with, and
makes other code more complicated which had const char* to begin
with.
In the end, I think this makes for a more idiomatic and platform
agnostic API. Not all platforms launch process with null terminated
c-string arrays for the environment pointer and argv, but the api
was designed that way because it allowed easy pass-through for
posix-based platforms. There's a little additional overhead now
since on posix based platforms we'll be takign StringRefs which
were constructed from null terminated strings and then copying
them to null terminate them again, but from a readability and
usability standpoint of the API user, I think this API signature
is strictly better.
llvm-svn: 334518
Summary:
When reporting an unsupported relocation type, let's also report the
file we encountered it in to aid diagnosis.
Reviewers: ruiu, rnk
Reviewed By: rnk
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45911
llvm-svn: 334154
Peter Collingbourne suggested moving the switch to the top of the
function, so that all the code that cares about the output section for a
symbol is in the same place.
Differential Revision: https://reviews.llvm.org/D47497
llvm-svn: 333472
Rather than using a loop to compare symbol RVAs to the starting RVAs of
sections to determine which section a symbol belongs to, just get the
output section of a symbol directly via its chunk, and bail if the
symbol doesn't have an output section, which avoids having to hardcode
logic for handling dead symbols, CodeView symbols, etc. This was
suggested by Reid Kleckner; thank you.
This also fixes writing out symbol tables in the presence of RVA table
input sections (e.g. .sxdata and .gfids). Such sections aren't written
to the output file directly, so their RVA is 0, and the loop would thus
fail to find an output section for them, resulting in a segfault. Extend
some existing tests to cover this case.
Fixes PR37584.
Differential Revision: https://reviews.llvm.org/D47391
llvm-svn: 333450
- Move some common code into Common/rrorHandler.cpp and
Common/Strings.h.
- Don't use `fatal` when incompatible bitcode files are
encountered.
- Rename NameRef variable to just Name
See D47162
Differential Revision: https://reviews.llvm.org/D47206
llvm-svn: 333021
Previously we emitted 20-byte SHA1 hashes. This is overkill
for identifying debug info records, and has the negative side
effect of making object files bigger and links slower. By
using only the last 8 bytes of a SHA1, we get smaller object
files and ~10% faster links.
This modifies the format of the .debug$H section by adding a new
value for the hash algorithm field, so that the linker will still
work when its object files have an old format.
Differential Revision: https://reviews.llvm.org/D46855
llvm-svn: 332669
Previously we would always write a hash of the binary into the
PE file, for reproducible builds. This breaks AppCompat, which
is a feature of Windows that relies on the timestamp in the PE
header being set to a real value (or at the very least, a value
that satisfies certain properties).
To address this, we put the old behavior of writing the hash
behind the /Brepro flag, which mimics MSVC linker behavior. We
also match MSVC default behavior, which is to write an actual
timestamp to the PE header. Finally, we add the /TIMESTAMP
option (an lld extension) so that the user can specify the exact
value to be used in case he/she manually constructs a value which
is both reproducible and satisfies AppCompat.
Differential Revision: https://reviews.llvm.org/D46966
llvm-svn: 332613
This is needed to avoid merging two functions with identical
instructions but different xdata. It also reduces binary size by
deduplicating identical pdata sections.
Fixes PR35337.
Differential Revision: https://reviews.llvm.org/D46672
llvm-svn: 332169
We discovered (crbug.com/838449#c24) that string tail merging can
negatively affect compressed binary size, so provide a flag to turn
it off for users who care more about compressed size than uncompressed
size.
Differential Revision: https://reviews.llvm.org/D46780
llvm-svn: 332149
This is most useful when using lld-link on a non-Win host (but it might become
useful on Windows too if lld also grows a fansi-escape-codes flag).
Also make the help for --color-diagnostic mention the valid values in ELF and
wasm, and print the flag name with two dashes in diags, since the one-dash form
is seen as a list of many one-letter flags in some contexts.
https://reviews.llvm.org/D46693
llvm-svn: 332012
Previously this was only supported when specified on the command line
or in directives.
Differential Revision: https://reviews.llvm.org/D46244
llvm-svn: 331900
The operator == used for exporting a function with a different
name in the DLL compared to the name in the import library
(which is useful for adding linker level aliases for function
in the import library) is a feature distinct and different from
the operator = used for exporting a function with a different
name (both in import library and DLL) than in the implementation
producing the DLL.
When creating an import library using dlltool, from a def file that
contains forwards (Func = OtherDll.Func), this shouldn't affect the
produced import library, which should still behave just as if it
was a normal exported function.
This clears a lot of confusion and subtle misunderstandings, and
avoids a parameter that was used to avoid creating weak aliases
when invoked from lld. (This parameter was added previously due to
the existing conflation of the two features.)
Differential Revision: https://reviews.llvm.org/D46245
llvm-svn: 331860
Now only IMAGE_REL_ARM64_ABSOLUTE and IMAGE_REL_ARM64_TOKEN
are unhandled.
Also add range checks for the existing BRANCH26 relocation.
Differential Revision: https://reviews.llvm.org/D46354
llvm-svn: 331505
Summary:
When a symbol refers to a special section or a section that doesn't
exist, lld would fatal with "broken object file". This change gives a
different message for each scenario, and includes the name of the
file, name of the symbol, and the section being referred to.
Reviewers: pcc, ruiu
Reviewed By: ruiu
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D46090
llvm-svn: 330883
Summary:
In a number of places in the COFF linker, we were calling
MemoryBuffer::getFile() with default parameters. This causes LLVM to
NUL-terminate the buffers, which can prevent them from being memory
mapped. Since we operate on binary and do not use NUL as an indicator
of the end of the file content, this change causes us to not require
the NUL terminator anymore.
Reviewers: ruiu, pcc
Reviewed By: ruiu
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45909
llvm-svn: 330786
With MSVC linker, /DEBUG is an alias of /DEBUG:FASTLINK, and if
you don't want /DEBUG:FASTLINK you have to explicitly specify
/DEBUG:FULL.
LLD doesn't support /DEBUG:FASTLINK, and so our standard /DEBUG
option is what MSVC calls /DEBUG:FULL. To provide command line
compatibility with MSVC, we should also support /DEBUG:FULL, and
since it's the same as what LLD already does for /DEBUG, just
alias it.
llvm-svn: 330647
Summary:
ubsan found that we sometimes pass nullptr to memcpy in
SectionChunk::writeTo(). This change adds a check that avoids that.
Reviewers: ruiu
Reviewed By: ruiu
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45789
llvm-svn: 330490
This is what link.exe does and lets us avoid needing to worry about
merging output characteristics while adding input sections to output
sections.
With this change we can't process /merge in the same way as before
because sections with different output characteristics can still
be merged into one another. So this change moves the processing of
/merge to just before we assign addresses. In the case where there
are multiple output sections with the same name, link.exe only merges
the first section with the source name into the first section with
the target name, and we do the same.
At the same time I also implemented transitive merging (which means
that /merge:.c=.b /merge:.b=.a merges both .c and .b into .a).
This isn't quite enough though because link.exe has a special case for
.CRT in 32-bit mode: it processes sections whose output characteristics
are DATA | R | W as though the output characteristics were DATA | R
(so that they get merged into things like constructor lists in the
expected way). Chromium has a few such sections, and it turns out
that those sections were causing the problem that resulted in r318699
(merge .xdata into .rdata) being reverted: because of the previous
permission merging semantics, the .CRT sections were causing the entire
.rdata section to become writable, which caused the SEH runtime to
crash because it apparently requires .xdata to be read-only. This
change also implements the same special case.
This should unblock being able to merge .xdata into .rdata by default,
as well as .bss into .data, both of which will be done in followups.
Differential Revision: https://reviews.llvm.org/D45801
llvm-svn: 330479
It's possible to have an empty object file, for example if you
just compile an empty .c file. This file won't have any sections
so asserting that a file has chunks is definitely wrong.
llvm-svn: 330461
Part of the DBI stream is a list of variable length structures
describing each module that contributes to the final executable.
One member of this structure is a section contribution entry that
describes the first section contribution in the output file for
the given module.
We have been leaving this structure unpopulated until now, so with
this patch it is now filled out correctly.
Differential Revision: https://reviews.llvm.org/D45832
llvm-svn: 330457
In an upcoming change I will need to make a distinction between section
type (code, data, bss) and permissions. The term that I use for both
of these things is "output characteristics".
Differential Revision: https://reviews.llvm.org/D45799
llvm-svn: 330361
Summary:
DLLs and executables with no exception handlers need to be marked with
IMAGE_DLL_CHARACTERISTICS_NO_SEH, even if they have a load config.
Discovered here when building Chromium with LLD on Windows:
https://crbug.com/833951
Reviewers: ruiu, mstorsjo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45778
llvm-svn: 330300