Also sync help texts for the option between elf and coff ports.
Decisions:
- Do this even if /lldignoreenv is passed. /reproduce: does not affect
the main output, and this makes the env var more convenient to use.
(On the other hand, it's now possible to set this env var and forget
about it, and all future builds in the same shell will be much slower.
That's true for ld.lld, but posix shells have an easy way to set an
env var for a single command; in cmd.exe this is not possible without
contortions. Then again, lld-link runs in posix shells too.)
Original patch rebased across D68378 and D68381.
Differential Revision: https://reviews.llvm.org/D67707
In https://reviews.llvm.org/D89072 I added static const data members
to the debug subsection for globals. It skipped emitting an S_CONSTANT if it
didn't have a value, which meant the subsection could be empty.
This patch fixes the empty subsection issue.
Differential Revision: https://reviews.llvm.org/D92049
Also use "unknown flag 'flag'" instead of "unknown flag: flag" for
consistency with the other ports.
Differential Revision: https://reviews.llvm.org/D91970
This patch adds support for creating Guard Address-Taken IAT Entry Tables (.giats$y sections) in object files, matching the behavior of MSVC. These contain lists of address-taken imported functions, which are used by the linker to create the final GIATS table.
Additionally, if any DLLs are delay-loaded, the linker must look through the .giats tables and add the respective load thunks of address-taken imports to the GFIDS table, as these are also valid call targets.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D87544
This adds `--[no-]color-diagnostics[=auto,never,always]` to
the MachO port and harmonizes the flag in the other ports:
- Consistently use MetaVarName
- Consistently document the non-eq version as alias of the eq version
- Use B<> in the ports that have it (no-op, shorter)
- Fix oversight in COFF port that made the --no flag have the wrong
prefix
Differential Revision: https://reviews.llvm.org/D91640
This broke both Firefox and Chromium (PR47905) due to what seems like dllimport
function not being handled correctly.
> This patch adds support for creating Guard Address-Taken IAT Entry Tables (.giats$y sections) in object files, matching the behavior of MSVC. These contain lists of address-taken imported functions, which are used by the linker to create the final GIATS table.
> Additionally, if any DLLs are delay-loaded, the linker must look through the .giats tables and add the respective load thunks of address-taken imports to the GFIDS table, as these are also valid call targets.
>
> Reviewed By: rnk
>
> Differential Revision: https://reviews.llvm.org/D87544
This reverts commit cfd8481da1.
This is more or less a port of rL329598 (D45275) to the COFF linker.
Since there were already LTO-related settings under -opt:, I added
them there instead of new flags.
Differential Revision: https://reviews.llvm.org/D90624
Match MSVC linker output - align all debug directories on four bytes,
while removing debug directory alignment. This would have the same
effect on CETCOMPAT support as D89919.
Chromium bug: https://crbug.com/1136664
Differential Revision: https://reviews.llvm.org/D89921
I had envisioned the ghash step as a big up front step, but as currently
written, the timers are nested, and we are notionally adding types from
objects, so we might as well arrange the timers this way.
Add a simple forwarding option in the MinGW frontend, and implement
the private -wrap option in the COFF linker.
The feature in lld-link isn't gated by the -lldmingw option, but
the option is left as a private, undocumented option primarily
used by the MinGW driver.
The implementation is significantly based on the support for --wrap
in the ELF linker, but many small nuance details are different
between the ELF and COFF linkers, ending up with more than a few
implementation differences.
This fixes https://bugs.llvm.org/show_bug.cgi?id=47384.
Differential Revision: https://reviews.llvm.org/D89004
Reapplied with the bitfield member canInline fixed so it doesn't break
builds targeting windows.
This reverts commit a012c704b5.
Breaks Windows builds.
C:\src\llvm-mint\lld\COFF\Symbols.cpp(26,1): error: static_assert failed due to requirement 'sizeof(lld::coff::SymbolUnion) <= 48' "symbols should be optimized for memory usage"
static_assert(sizeof(SymbolUnion) <= 48,
Add a simple forwarding option in the MinGW frontend, and implement
the private -wrap option in the COFF linker.
The feature in lld-link isn't gated by the -lldmingw option, but
the option is left as a private, undocumented option primarily
used by the MinGW driver.
The implementation is significantly based on the support for --wrap
in the ELF linker, but many small nuance details are different
between the ELF and COFF linkers, ending up with more than a few
implementation differences.
This fixes https://bugs.llvm.org/show_bug.cgi?id=47384.
Differential Revision: https://reviews.llvm.org/D89004
This should fix cases when e.g. auto import is enabled without
mingw mode in total being enabled.
Differential Revision: https://reviews.llvm.org/D89006
Fixes https://bugs.llvm.org/show_bug.cgi?id=46473
LLD wasn't previously specifying any specific alignment in the TLS table's Characteristics field so the loader would just assume the default value (16 bytes). This works most of the time except if you have thread locals that want specific higher alignments (e.g. 32 as in the bug) *even* if they specify an alignment on the thread local. This change updates LLD to take the max alignment from tls section.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D88637
Revert individual wip commits and will instead follow up with a
single commit with all the changes. Makes cherry-picking easier
and will contain all the right tags.
This reverts commit 32a4ad3b6c.
This reverts commit 7fe13af676.
This reverts commit 51fbc1bef6.
This reverts commit f80950a8bb.
This reverts commit 0778cad9f3.
This reverts commit 8b70d527d7.
Fixes https://bugs.llvm.org/show_bug.cgi?id=46473
LLD wasn't previously specifying any specific alignment in the TLS table's Characteristics field so the loader would just assume the default value (16 bytes). This works most of the time except if you have thread locals that want specific higher alignments (e.g. 32 as in the bug) *even* if they specify an alignment on the thread local. This change updates LLD to take the max alignment from tls section.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D88637
This patch adds support for creating Guard Address-Taken IAT Entry Tables (.giats$y sections) in object files, matching the behavior of MSVC. These contain lists of address-taken imported functions, which are used by the linker to create the final GIATS table.
Additionally, if any DLLs are delay-loaded, the linker must look through the .giats tables and add the respective load thunks of address-taken imports to the GFIDS table, as these are also valid call targets.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D87544
As they can be set independently after D88802, we can get rid of a bit
of extra code - simplifying the logic here before adding more
complication to it later.
Differential Revision: https://reviews.llvm.org/D88803
The MinGW driver has separate options for OS and subsystem version.
Having this available in lld-link allows the MinGW driver to both match
GNU ld better and simplifies the code for merging two (potentially
mismatching) arguments into one.
Differential Revision: https://reviews.llvm.org/D88802
Parse the components as decimal, instead of decuding the base from
the string. This avoids ambiguity if the second number contains leading
zeros, which previously were parsed as indicating an octal number.
MS link.exe doesn't support hexadecimal numbers in the version numbers,
neither in /version nor in /subsystem.
Differential Revision: https://reviews.llvm.org/D88801
This adds the following two new lines to /summary:
21351 Input OBJ files (expanded from all cmd-line inputs)
61 PDB type server dependencies
38 Precomp OBJ dependencies
1420669231 Input type records <<<<
78665073382 Input type records bytes <<<<
8801393 Merged TPI records
3177158 Merged IPI records
59194 Output PDB strings
71576766 Global symbol records
25416935 Module symbol records
2103431 Public symbol records
Differential Revision: https://reviews.llvm.org/D88703
Before this patch /summary was crashing with some .PCH.OBJ files, because tpiMap[srcIdx++] was reading at the wrong location. When the TpiSource depends on a .PCH.OBJ file, the types should be offset by the previously merged PCH.OBJ set of indices.
Differential Revision: https://reviews.llvm.org/D88678
This patch adds support for creating Guard Address-Taken IAT Entry Tables (.giats$y sections) in object files, matching the behavior of MSVC. These contain lists of address-taken imported functions, which are used by the linker to create the final GIATS table.
Additionally, if any DLLs are delay-loaded, the linker must look through the .giats tables and add the respective load thunks of address-taken imports to the GFIDS table, as these are also valid call targets.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D87544
Stored Error objects have to be checked, even if they are success
values.
This reverts commit 8d250ac3cd.
Relands commit 49b3459930655d879b2dc190ff8fe11c38a8be5f..
Original commit message:
-----------------------------------------
This makes type merging much faster (-24% on chrome.dll) when multiple
threads are available, but it slightly increases the time to link (+10%)
when /threads:1 is passed. With only one more thread, the new type
merging is faster (-11%). The output PDB should be identical to what it
was before this change.
To give an idea, here is the /time output placed side by side:
BEFORE | AFTER
Input File Reading: 956 ms | 968 ms
Code Layout: 258 ms | 190 ms
Commit Output File: 6 ms | 7 ms
PDB Emission (Cumulative): 6691 ms | 4253 ms
Add Objects: 4341 ms | 2927 ms
Type Merging: 2814 ms | 1269 ms -55%!
Symbol Merging: 1509 ms | 1645 ms
Publics Stream Layout: 111 ms | 112 ms
TPI Stream Layout: 764 ms | 26 ms trivial
Commit to Disk: 1322 ms | 1036 ms -300ms
----------------------------------------- --------
Total Link Time: 8416 ms 5882 ms -30% overall
The main source of the additional overhead in the single-threaded case
is the need to iterate all .debug$T sections up front to check which
type records should go in the IPI stream. See fillIsItemIndexFromDebugT.
With changes to the .debug$H section, we could pre-calculate this info
and eliminate the need to do this walk up front. That should restore
single-threaded performance back to what it was before this change.
This change will cause LLD to be much more parallel than it used to, and
for users who do multiple links in parallel, it could regress
performance. However, when the user is only doing one link, it's a huge
improvement. In the future, we can use NT worker threads to avoid
oversaturating the machine with work, but for now, this is such an
improvement for the single-link use case that I think we should land
this as is.
Algorithm
----------
Before this change, we essentially used a
DenseMap<GloballyHashedType, TypeIndex> to check if a type has already
been seen, and if it hasn't been seen, insert it now and use the next
available type index for it in the destination type stream. DenseMap
does not support concurrent insertion, and even if it did, the linker
must be deterministic: it cannot produce different PDBs by using
different numbers of threads. The output type stream must be in the same
order regardless of the order of hash table insertions.
In order to create a hash table that supports concurrent insertion, the
table cells must be small enough that they can be updated atomically.
The algorithm I used for updating the table using linear probing is
described in this paper, "Concurrent Hash Tables: Fast and General(?)!":
https://dl.acm.org/doi/10.1145/3309206
The GHashCell in this change is essentially a pair of 32-bit integer
indices: <sourceIndex, typeIndex>. The sourceIndex is the index of the
TpiSource object, and it represents an input type stream. The typeIndex
is the index of the type in the stream. Together, we have something like
a ragged 2D array of ghashes, which can be looked up as:
tpiSources[tpiSrcIndex]->ghashes[typeIndex]
By using these side tables, we can omit the key data from the hash
table, and keep the table cell small. There is a cost to this: resolving
hash table collisions requires many more loads than simply looking at
the key in the same cache line as the insertion position. However, most
supported platforms should have a 64-bit CAS operation to update the
cell atomically.
To make the result of concurrent insertion deterministic, the cell
payloads must have a priority function. Defining one is pretty
straightforward: compare the two 32-bit numbers as a combined 64-bit
number. This means that types coming from inputs earlier on the command
line have a higher priority and are more likely to appear earlier in the
final PDB type stream than types from an input appearing later on the
link line.
After table insertion, the non-empty cells in the table can be copied
out of the main table and sorted by priority to determine the ordering
of the final type index stream. At this point, item and type records
must be separated, either by sorting or by splitting into two arrays,
and I chose sorting. This is why the GHashCell must contain the isItem
bit.
Once the final PDB TPI stream ordering is known, we need to compute a
mapping from source type index to PDB type index. To avoid starting over
from scratch and looking up every type again by its ghash, we save the
insertion position of every hash table insertion during the first
insertion phase. Because the table does not support rehashing, the
insertion position is stable. Using the array of insertion positions
indexed by source type index, we can replace the source type indices in
the ghash table cells with the PDB type indices.
Once the table cells have been updated to contain PDB type indices, the
mapping for each type source can be computed in parallel. Simply iterate
the list of cell positions and replace them with the PDB type index,
since the insertion positions are no longer needed.
Once we have a source to destination type index mapping for every type
source, there are no more data dependencies. We know which type records
are "unique" (not duplicates), and what their final type indices will
be. We can do the remapping in parallel, and accumulate type sizes and
type hashes in parallel by type source.
Lastly, TPI stream layout must be done serially. Accumulate all the type
records, sizes, and hashes, and add them to the PDB.
Differential Revision: https://reviews.llvm.org/D87805
This makes type merging much faster (-24% on chrome.dll) when multiple
threads are available, but it slightly increases the time to link (+10%)
when /threads:1 is passed. With only one more thread, the new type
merging is faster (-11%). The output PDB should be identical to what it
was before this change.
To give an idea, here is the /time output placed side by side:
BEFORE | AFTER
Input File Reading: 956 ms | 968 ms
Code Layout: 258 ms | 190 ms
Commit Output File: 6 ms | 7 ms
PDB Emission (Cumulative): 6691 ms | 4253 ms
Add Objects: 4341 ms | 2927 ms
Type Merging: 2814 ms | 1269 ms -55%!
Symbol Merging: 1509 ms | 1645 ms
Publics Stream Layout: 111 ms | 112 ms
TPI Stream Layout: 764 ms | 26 ms trivial
Commit to Disk: 1322 ms | 1036 ms -300ms
----------------------------------------- --------
Total Link Time: 8416 ms 5882 ms -30% overall
The main source of the additional overhead in the single-threaded case
is the need to iterate all .debug$T sections up front to check which
type records should go in the IPI stream. See fillIsItemIndexFromDebugT.
With changes to the .debug$H section, we could pre-calculate this info
and eliminate the need to do this walk up front. That should restore
single-threaded performance back to what it was before this change.
This change will cause LLD to be much more parallel than it used to, and
for users who do multiple links in parallel, it could regress
performance. However, when the user is only doing one link, it's a huge
improvement. In the future, we can use NT worker threads to avoid
oversaturating the machine with work, but for now, this is such an
improvement for the single-link use case that I think we should land
this as is.
Algorithm
----------
Before this change, we essentially used a
DenseMap<GloballyHashedType, TypeIndex> to check if a type has already
been seen, and if it hasn't been seen, insert it now and use the next
available type index for it in the destination type stream. DenseMap
does not support concurrent insertion, and even if it did, the linker
must be deterministic: it cannot produce different PDBs by using
different numbers of threads. The output type stream must be in the same
order regardless of the order of hash table insertions.
In order to create a hash table that supports concurrent insertion, the
table cells must be small enough that they can be updated atomically.
The algorithm I used for updating the table using linear probing is
described in this paper, "Concurrent Hash Tables: Fast and General(?)!":
https://dl.acm.org/doi/10.1145/3309206
The GHashCell in this change is essentially a pair of 32-bit integer
indices: <sourceIndex, typeIndex>. The sourceIndex is the index of the
TpiSource object, and it represents an input type stream. The typeIndex
is the index of the type in the stream. Together, we have something like
a ragged 2D array of ghashes, which can be looked up as:
tpiSources[tpiSrcIndex]->ghashes[typeIndex]
By using these side tables, we can omit the key data from the hash
table, and keep the table cell small. There is a cost to this: resolving
hash table collisions requires many more loads than simply looking at
the key in the same cache line as the insertion position. However, most
supported platforms should have a 64-bit CAS operation to update the
cell atomically.
To make the result of concurrent insertion deterministic, the cell
payloads must have a priority function. Defining one is pretty
straightforward: compare the two 32-bit numbers as a combined 64-bit
number. This means that types coming from inputs earlier on the command
line have a higher priority and are more likely to appear earlier in the
final PDB type stream than types from an input appearing later on the
link line.
After table insertion, the non-empty cells in the table can be copied
out of the main table and sorted by priority to determine the ordering
of the final type index stream. At this point, item and type records
must be separated, either by sorting or by splitting into two arrays,
and I chose sorting. This is why the GHashCell must contain the isItem
bit.
Once the final PDB TPI stream ordering is known, we need to compute a
mapping from source type index to PDB type index. To avoid starting over
from scratch and looking up every type again by its ghash, we save the
insertion position of every hash table insertion during the first
insertion phase. Because the table does not support rehashing, the
insertion position is stable. Using the array of insertion positions
indexed by source type index, we can replace the source type indices in
the ghash table cells with the PDB type indices.
Once the table cells have been updated to contain PDB type indices, the
mapping for each type source can be computed in parallel. Simply iterate
the list of cell positions and replace them with the PDB type index,
since the insertion positions are no longer needed.
Once we have a source to destination type index mapping for every type
source, there are no more data dependencies. We know which type records
are "unique" (not duplicates), and what their final type indices will
be. We can do the remapping in parallel, and accumulate type sizes and
type hashes in parallel by type source.
Lastly, TPI stream layout must be done serially. Accumulate all the type
records, sizes, and hashes, and add them to the PDB.
Differential Revision: https://reviews.llvm.org/D87805
Library users should not need to call errorHandler().reset() explicitly.
google/iree calls lld:🧝:link and without the patch some global
variables are not cleaned up in the next invocation.
In lit tests, we run each LLD invocation twice (LLD_IN_TEST=2), without shutting down the process in-between. This ensures a full cleanup is properly done between runs.
Only active for the COFF driver for now. Other drivers still use LLD_IN_TEST=1 which executes just one iteration with full cleanup, like before.
When the environment variable LLD_IN_TEST is unset, a shortcut is taken, only one iteration is executed, no cleanup for faster exit, like before.
A public API, lld::safeLldMain(), is also available when using LLD as a library.
Differential Revision: https://reviews.llvm.org/D70378
Extending the lifetime of these type index mappings does increase memory
usage (+2% in my case), but it decouples type merging from symbol
merging. This is a pre-requisite for two changes that I have in mind:
- parallel type merging: speeds up slow type merging
- defered symbol merging: avoid heap allocating (relocating) all symbols
This eliminates CVIndexMap and moves its data into TpiSource. The maps
are also split into a SmallVector and ArrayRef component, so that the
ipiMap can alias the tpiMap for /Z7 object files, and so that both maps
can simply alias the PDB type server maps for /Zi files.
Splitting TypeServerSource establishes that all input types to be merged
can be identified with two 32-bit indices:
- The index of the TpiSource object
- The type index of the record
This is useful, because this information can be stored in a single
64-bit atomic word to enable concurrent hashtable insertion.
One last change is that now all object files with debugChunks get a
TpiSource, even if they have no type info. This avoids some null checks
and special cases.
Differential Revision: https://reviews.llvm.org/D87736
Binutils generated sections seem to be padded to a multiple of 16 bytes,
but the aux section definition contains the original, unpadded section
length.
The size check used for IMAGE_COMDAT_SELECT_SAME_SIZE previously
only checked the size of the section itself. When checking the
currently processed object file against the previously chosen
comdat section, we easily have access to the aux section definition
of the currently processed section, but we have to iterate over the
symbols of the previously selected object file to find the section
definition of the previously picked section. (We don't want to
inflate SectionChunk to carry more data, for something that is only
needed in corner cases.) Only do this when the mingw flag is set.
This fixes statically linking clang-built C++ object files against
libstdc++ built with GCC, if the object files contain e.g. typeinfo.
Differential Revision: https://reviews.llvm.org/D86659
The global variable outputSections in the COFF writer was not
cleared between runs which caused successive calls to lld::coff::link
to generate invalid binaries. These binaries when loaded would result
in "invalid win32 applications" and/or "bad image" errors.
Differential Revision: https://reviews.llvm.org/D86401
This patch adds the missing information to the LF_BUILDINFO record, which allows for rebuilding a .CPP without any external dependency but the .OBJ itself (other than the compiler).
Some external tools that we are using (Recode, Live++) are extracting the information to reproduce a build without any knowledge of the build system. The LF_BUILDINFO stores a full path to the compiler, the PWD (CWD at program startup), a relative or absolute path to the TU, and the full CC1 command line. The command line needs to be freestanding (not depend on any environment variables). In the same way, MSVC doesn't store the provided command-line, but an expanded version (somehow their equivalent of CC1) which is also freestanding.
For more information see PR36198 and D43002.
Differential Revision: https://reviews.llvm.org/D80833
Previously this flag was just ignored. If set, set the
IMAGE_DLL_CHARACTERISTICS_NO_SEH bit, regardless of the normal safeSEH
machinery.
In mingw configurations, the safeSEH bit might not be set in e.g. object
files built from handwritten assembly, making it impossible to use the
normal safeseh flag. As mingw setups don't generally use SEH on 32 bit
x86 at all, it should be fine to set that flag bit though - hook up
the existing GNU ld flag for controlling that.
Differential Revision: https://reviews.llvm.org/D84701
For a weak symbol func in a comdat, the actual leader symbol ends up
named like .weak.func.default*. Likewise, for stdcall on i386, the symbol
may be named _func@4, while the section suffix only is "func", which the
previous implementation didn't handle.
This fixes unwinding through weak functions when using
-ffunction-sections in mingw environments.
Differential Revision: https://reviews.llvm.org/D84607
The "undefined symbol" error message from lld-link displays up to 3 references to that symbol, and the number of extra references not shown.
This patch removes the computation of the strings for those extra references.
It fixes a freeze of lld-link we accidentally encountered when activating asan on a large project, without linking with the asan library.
In that case, __asan_report_load8 was referenced more than 2 million times, causing the computation of that many display strings, of which only 3 were used.
Differential Revision: https://reviews.llvm.org/D83510
The `intrinsics_gen` target exists in the CMake exports since r309389
(see LLVMConfig.cmake.in), hence projects can depend on `intrinsics_gen`
even it they are built separately from LLVM.
Reviewed By: MaskRay, JDevlieghere
Differential Revision: https://reviews.llvm.org/D83454
Fangrui Song