MaterializationUnits may contain arbitrary resources that need cleanup. We want
to do this outside the JIT's session lock.
This should fix a lock-order-inversion warning in clang-repl (for details see
https://github.com/llvm/llvm-project/issues/124215).
For Darwin/arm64 (including Apple Silicon Macs) this will enable exception
handling and stack unwinding in JIT'd code.
Darwin supports two unwind-info formats: DWARF eh-frames and compact-unwind. On
Darwin/x86-64 compilers usually produce both by default, and ORC supported
exceptions and unwinding via eh-frames (same as on Linux), discarding the
redundant compact-unwind info. On Darwin/arm64 compilers typically default to
producing compact-unwind only, with DWARF eh-frames as a fallback for functions
that can't be described in compact-unwind. Since ORC did not previously support
the compact-unwind format and eh-frames were not present ORC was unable to
handle exceptions or unwinding by default in Darwin/arm64 JIT'd code.
This patch enables support for the compact-unwind-info format, and contains
three major moving parts:
(1) The JITLink CompactUnwindManager class is responsible for transforming the
__compact_unwind records produced by the linker into the __unwind_info
tables that libunwind parses during unwinding. To enable this the
CompactUnwindManager class provides three JITLink passes: The
prepareForPrune pass that splits the __compact_unwind section into
single-record blocks, allowing unused records to be dead-stripped; the
processAndReserveUnwindInfo pass that reserves space for the final
__unwind_info section, and the writeUnwindInfo pass that writes the
__unwind_info section.
(2) The OrcTargetProcess UnwindInfoManager class maintains a table of
registered JIT'd __unwind_info and __eh_frame sections, and handles
requests from libunwind for unwind info sections (by registering a callback
with libunwind's __unw_add_find_dynamic_unwind_sections function).
(3) The Orc UnwindInfoRegistrationPlugin, which scans LinkGraphs for
__unwind_info and __eh_frame sections to register with the
UnwindInfoManager.
This commit adds the CompactUnwindManager passes to the default JITLink
pipelines for Darwin/arm64 and Darwin/x86-64, and UnwindInfoManager intances to
the SelfExecutorProcessControl class (when built for apple platforms) and the
llvm-jitlink-executor tool.
The LLJIT class will now create an UnwindInfoRegistrationPlugin when targeting
a process running on Darwin if it detects that an UnwindInfoManager is
available to handle the registrations.
The ORC runtime macho_platform class already supported libunwind callbacks, so
out-of-process execution and unwinding support will work when loading the ORC
runtime.
The llvm-jitlink tool will only support compact-unwind when the orc-runtime is
loaded, as the UnwindInfoRegistrationPlugin requires access to an IR compiler
to load a helper module and llvm-jitlink does not provide an IR compiler.
The MachOPlatform::MachOPlatformPlugin class will now inject a
"__jitlink$libunwind_dso_base" symbol into each LinkGraph pointing to the Mach
header for the containing JITDylib. The compact-unwind support plugin will use
this symbol as the dso-base for the __unwind_info sections. (Failure to inject
this symbol would result in the compact-unwind support plugin creating a new
header for every graph).
This function can be called on a LinkGraph to get an anonymous symbol pointing
to the start of a mach_header / mach_header_64 block with suitable cputype and
cpusubtype values for the LinkGraph, and with filetype = MachO::MH_OBJECT.
This functionality will be used in the upcoming compact-unwind support patch:
For graphs that do not have a suitable existing header to use (indicated by the
presence of a "__jitlink$libunwind_dso_base" symbol) the compact-unwind support
plugin will create a local header to use as the dso-base to report to
libunwind.
Enable ELFNixPlatform support for loongarch64. These are few simple
changes, but it allows us to use the orc runtime in ELF/LoongArch64
backend.
This change adds test cases targeting the LoongArch64 Linux platform to
the ORC runtime integration test suite. Since jitlink for loongarch64 is
ready for general use, and ELF-based platforms support defining multiple
static initializer table sections with differing priorities, some
relevant test cases in compiler-rt for ELFNixPlatform support can be
enabled.
x86_64::GOTTableManager and x86_64::PLTTableManager will now look for existing
GOT and PLT sections and re-use existing entries if they're present.
This will be used for an upcoming MachO patch to enable compact unwind support.
This patch is the x86-64 counterpart 42595bdaefb, which added the same
functionality to the GOT and PLT managers for aarch64.
These are unneeded even on AIX, PURE_WINDOWS, and ZOS (per #104706)
* HAVE_ERRNO_H: introduced by 1a93330ffa2ae2aa0b49461f05e6f0d51e8443f8 (2009) but unneeded.
The guarded ABI is unconditionally used by lldb.
* HAVE_FCNTL_H
* HAVE_FENV_H
* HAVE_SYS_STAT_H
Pull Request: https://github.com/llvm/llvm-project/pull/123087
On platfarms where some relocations for eh-frame sections are implicit (e.g.
MachO/x86-64) EHFrameEdgeFixer is responsible for adding edges for the
implicit relocations.
Adds new convenience methods findDefinedSymbolByName, findExternalSymbolByName
and findAbsoluteSymbolByName to the LinkGraph class. These should be used to
find symbols of the given types by name.
COFFLinkGraphBuilder and MachOPlatform are updated to take advantage of the
new methods.
aarch64::GOTTableManager and aarch64::PLTTableManager will now look for
existing GOT and PLT sections and re-use existing entries if they're present.
This will be used for an upcoming MachO patch to enable compact unwind support.
DeferredAAs should only capture bootstrap actions, but after 30b73ed7bd it was
capturing all actions, including those from other plugins. This is problematic
as other plugins may introduce actions that need to run before the platform
actions (e.g. on arm64e we need pointer signing to run before we access any
global pointers in the graph).
Note that this effectively undoes 30b73ed7bd, which was a buggy attempt to
synchronize writes to the DeferredAAs vector. This patch fixes that issue the
obvious way by locking the bootstrap mutex while accessing the DeferredAAs
vector.
No testcase yet: So far I've only seen this fail during bootstrap of arm64e
JIT'd programs.
This reapplies 6d72bf47606, which was reverted in 57447d3ddf to investigate
build failures, e.g. https://lab.llvm.org/buildbot/#/builders/3/builds/10114.
The original patch contained an invalid unused friend declaration of
std::make_shared. This has been removed.
Also adds a new IdleTask type and updates DynamicThreadPoolTaskDispatcher to
schedule IdleTasks whenever the total number of threads running is less than
the maximum number of MaterializationThreads.
A SimpleLazyReexportsSpeculator instance maintains a list of speculation
suggestions ((JITDylib, Function) pairs) and registered lazy reexports. When
speculation opportunities are available (having been added via
addSpeculationSuggestions or when lazy reexports were created) it schedules
an IdleTask that triggers the next speculative lookup as soon as resources
are available. Speculation suggestions are processed first, followed by
lookups for lazy reexport bodies. A callback can be registered at object
construction time to record lazy reexport executions as they happen, and these
executions can be fed back into the speculator as suggestions on subsequent
executions.
The llvm-jitlink tool is updated to support speculation when lazy linking is
used via three new arguments:
-speculate=[none|simple] : When the 'simple' value is specified a
SimpleLazyReexportsSpeculator instances is used
for speculation.
-speculate-order <path> : Specifies a path to a CSV containing
(jit dylib name, function name) triples to use
as speculative suggestions in the current run.
-record-lazy-execs <path> : Specifies a path in which to record lazy function
executions as a CSV of (jit dylib name, function
name) pairs, suitable for use with
-speculate-order.
The same path can be passed to -speculate-order and -record-lazy-execs, in
which case the file will be overwritten at the end of the execution.
No testcase yet: Speculative linking is difficult to test (since by definition
execution behavior should be unaffected by speculation) and this is an new
prototype of the concept*. Tests will be added in the future once the interface
and behavior settle down.
* An earlier implementation of the speculation concept can be found in
llvm/include/llvm/ExecutionEngine/Orc/Speculation.h. Both systems have the
same goal (hiding compilation latency) but different mechanisms. This patch
relies entirely on information available in the controller, where the old
system could receive additional information from the JIT'd runtime via
callbacks. I aim to combine the two in the future, but want to gain more
practical experience with speculation first.
Threads created by DynamicThreadPoolTaskDispatcher::dispatch had been holding a
unique_ptr to the most recent Task, meaning that the Task would be destroyed
when the thread object was destroyed, but this would happen *after* the thread
signaled the Dispatcher that it was finished. This could cause
DynamicThreadPoolTaskDispatcher::shutdown to return (and consequently
ExecutionSession to be destroyed) before all Tasks were destroyed, with Task
destructors accessing ExecutionSession and related objects after they were
freed.
The fix is to reset the Task pointer immediately after it is run to trigger
cleanup, *then* (if there are no other tasks to run) signal the Dispatcher that
the thread is finished.
This patch also updates DynamicThreadPoolTaskDispatcher::dispatch to reject any
new Tasks dispatched after DynamicThreadPoolTaskDispatcher::shutdown is called.
ORC and JITLink debugging output write the dbgs() raw_ostream, which isn't
thread-safe. Use -num-threads=0 to force single-threaded linking for tests that
produce debugging output.
The llvm-jitlink tool is updated to suggest -num-threads=0 when debugging
output is enabled.
Similar to a9e75b1d4d1: During MachOPlatform bootstrap we need to defer actions
until essential platform functionality has been loaded, but the platform itself
may be loaded under a concurrent dispatcher so we have to guard against the
deferred actions vector being accessed concurrently.
This fixes a probablistic failure in the ORC runtime regression tests on
Darwin/x86-64 that was spotted after edca1d9bad2 (which turned on concurrent
linking by default in llvm-jitlink).
The debug section map was using MachO section names (with the "__" prefix), but
DWARFContext expects section names with the object format prefix stripped off.
This was preventing DWARFContext from accessing the debug_str section,
resulting in bogus source name strings.
This fixes a concurrency bug in the COFF_x86_64 backend: lookupAsync was used
to find __ImageBase without blocking to wait for the result.
Rather than adding promises / futures, this patch just adds an external
__ImageBase symbol if needed. This is the canonical JITLink solution for
resolving external symbols, and is simpler and more concurrency friendly than
using promises / futures with lookupAsync.
Cleanup to recent LazyReexportManager changes: KeyToReentryAddr now maps to
multiple addrs, so make its name plural. Use vector insert rather than a for
loop.
NFC.
Introduces a new layer interface, LinkGraphLayer, that can be used to
add LinkGraphs to an ExecutionSession.
This patch moves most of ObjectLinkingLayer's functionality into a new
LinkGraphLinkingLayer which should (in the future) be able to be used
without linking libObject. ObjectLinkingLayer now inherits from
LinkGraphLinkingLayer and just handles conversion of object files to
LinkGraphs, which are then handed down to LinkGraphLinkingLayer to be
linked.
Apologies for the large change, I looked for ways to break this up and
all of the ones I saw added real complexity. This change focuses on the
option's prefixed names and the array of prefixes. These are present in
every option and the dominant source of dynamic relocations for PIE or
PIC users of LLVM and Clang tooling. In some cases, 100s or 1000s of
them for the Clang driver which has a huge number of options.
This PR addresses this by building a string table and a prefixes table
that can be referenced with indices rather than pointers that require
dynamic relocations. This removes almost 7k dynmaic relocations from the
`clang` binary, roughly 8% of the remaining dynmaic relocations outside
of vtables. For busy-boxing use cases where many different option tables
are linked into the same binary, the savings add up a bit more.
The string table is a straightforward mechanism, but the prefixes
required some subtlety. They are encoded in a Pascal-string fashion with
a size followed by a sequence of offsets. This works relatively well for
the small realistic prefixes arrays in use.
Lots of code has to change in order to land this though: both all the
option library code has to be updated to use the string table and
prefixes table, and all the users of the options library have to be
updated to correctly instantiate the objects.
Some follow-up patches in the works to provide an abstraction for this
style of code, and to start using the same technique for some of the
other strings here now that the infrastructure is in place.
This re-applies 570ecdcf8b4, which was reverted in 74e8a37ff32 due to bot
failures. This commit renames sysv_resolve.cpp to resolve.cpp, which was the
cause of the config errors.
This reapplies 570ecdcf8b4, which was reverted in 6073dd923b8 due to bot
failures.
The test failures on Linux were fixed by:
1. Removing an overly restrictive assertion (query dependence on a symbol no
longer implies a MaterializingInfo for that symbol)
2. Adding reentry and resolver files to the ORC runtime CMakeLists.txt for
Linux.
3. Adding the __orc_rt_reentry -> __orc_rt_sysv_reentry alias to ELFNixPlatform.
…d reentry.
These utilities provide new, more generic and easier to use support for
lazy compilation in ORC.
LazyReexportsManager is an alternative to LazyCallThroughManager. It
takes requests for lazy re-entry points in the form of an alias map:
lazy-reexports = {
( <entry point symbol #1>, <implementation symbol #1> ),
( <entry point symbol #2>, <implementation symbol #2> ),
...
( <entry point symbol #n>, <implementation symbol #n> )
}
LazyReexportsManager then:
1. binds the entry points to the implementation names in an internal
table.
2. creates a JIT re-entry trampoline for each entry point.
3. creates a redirectable symbol for each of the entry point name and
binds redirectable symbol to the corresponding reentry trampoline.
When an entry point symbol is first called at runtime (which may be on
any thread of the JIT'd program) it will re-enter the JIT via the
trampoline and trigger a lookup for the implementation symbol stored in
LazyReexportsManager's internal table. When the lookup completes the
entry point symbol will be updated (via the RedirectableSymbolManager)
to point at the implementation symbol, and execution will proceed to the
implementation symbol.
Actual construction of the re-entry trampolines and redirectable symbols
is delegated to an EmitTrampolines functor and the
RedirectableSymbolsManager respectively.
JITLinkReentryTrampolines.h provides a JITLink-based implementation of
the EmitTrampolines functor. (AArch64 only in this patch, but other
architectures will be added in the near future).
Register state save and reentry functionality is added to the ORC
runtime in the __orc_rt_sysv_resolve and __orc_rt_resolve_implementation
functions (the latter is generic, the former will need custom
implementations for each ABI and architecture to be supported, however
this should be much less effort than the existing OrcABISupport
approach, since the ORC runtime allows this code to be written as native
assembly).
The resulting system:
1. Works equally well for in-process and out-of-process JIT'd code.
2. Requires less boilerplate to set up.
Given an ObjectLinkingLayer and PlatformJD (JITDylib containing the ORC
runtime), setup is just:
```c++
auto RSMgr = JITLinkRedirectableSymbolManager::Create(OLL);
if (!RSMgr)
return RSMgr.takeError();
auto LRMgr = createJITLinkLazyReexportsManager(OLL, **RSMgr, PlatformJD);
if (!LRMgr)
return LRMgr.takeError();
```
after which lazy reexports can be introduced with:
```c++
JD.define(lazyReexports(LRMgr, <alias map>));
```
LazyObectLinkingLayer is updated to use this new method, but the LLVM-IR
level CompileOnDemandLayer will continue to use LazyCallThroughManager
and OrcABISupport until the new system supports a wider range of
architectures and ABIs.
The llvm-jitlink utility's -lazy option now uses the new scheme. Since
it depends on the ORC runtime, the lazy-link.ll testcase and associated
helpers are moved to the ORC runtime.
Make EPCGenericMemoryAccess the default implementation for the MemoryAccess
object in SimpleRemoteEPC, and add support for the WritePointers operation to
OrcTargetProcess (previously this operation was unimplemented and would have
triggered an error if accessed in a remote-JIT setup).
No testcase yet: This functionality requires cross-process JITing to test (or a
much more elaborate unit-test setup). It can be tested once the new top-level
ORC runtime project lands.
