[JITLink] Switch to SymbolStringPtr for Symbol names (#115796)

Use SymbolStringPtr for Symbol names in LinkGraph. This reduces string interning
on the boundary between JITLink and ORC, and allows p

[JITLink] Switch to SymbolStringPtr for Symbol names (#115796)

Use SymbolStringPtr for Symbol names in LinkGraph. This reduces string interning
on the boundary between JITLink and ORC, and allows pointer comparisons (rather
than string comparisons) between Symbol names. This should improve the
performance and readability of code that bridges between JITLink and ORC (e.g.
ObjectLinkingLayer and ObjectLinkingLayer::Plugins).

To enable use of SymbolStringPtr a std::shared_ptr<SymbolStringPool> is added to
LinkGraph and threaded through to its construction sites in LLVM and Bolt. All
LinkGraphs that are to have symbol names compared by pointer equality must point
to the same SymbolStringPool instance, which in ORC sessions should be the pool
attached to the ExecutionSession.
---------

Co-authored-by: Lang Hames <lhames@gmail.com>

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Re-apply "[ORC][JITLink] Add jitlink::Scope::SideEffectsOnly" with fixes.

This reapplies aba6bb0820b, which was reverted in 28e2a891210 due to bot
failures. It contains fixes to silence warnings for

Re-apply "[ORC][JITLink] Add jitlink::Scope::SideEffectsOnly" with fixes.

This reapplies aba6bb0820b, which was reverted in 28e2a891210 due to bot
failures. It contains fixes to silence warnings for uncovered switches,
and for incorrect initializer-symbol handling on ELF and COFF.

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[ExecutionEngine] Remove unused includes (NFC) (#116749)

Identified with misc-include-cleaner.

[ORC] Add absoluteSymbolsLinkGraph to expose absolute symbols to platform (#77008)

Adds a function to create a LinkGraph of absolute symbols, and a
callback in dynamic library search generators to

[ORC] Add absoluteSymbolsLinkGraph to expose absolute symbols to platform (#77008)

Adds a function to create a LinkGraph of absolute symbols, and a
callback in dynamic library search generators to enable using it to
expose its symbols to the platform/orc runtime. This allows e.g. using
__orc_rt_run_program to run a precompiled function that was found via
dlsym. Ideally we would use this in llvm-jitlink's own search generator,
but it will require more work to align with the Process/Platform
JITDylib split, so not handled here.

As part of this change we need to handle LinkGraphs that only have
absolute symbols.

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[JITLink] Don't try to abandon non-existent allocations.

If JITLinkGeneric::linkPhase2 receives an Error rather than an InFlightAlloc
then we need to call JITLinkContext::notifyFailed, rather than c

[JITLink] Don't try to abandon non-existent allocations.

If JITLinkGeneric::linkPhase2 receives an Error rather than an InFlightAlloc
then we need to call JITLinkContext::notifyFailed, rather than calling
abandonAllocAndBailOut -- the latter asserts that there is an allocation to
abandon, and this was turning allocation errors into assertion failures in
debug mode.

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[ORC] Move most ORC APIs to ExecutorAddr, introduce ExecutorSymbolDef.

ExecutorAddr was introduced in b8e5f918166 as an eventual replacement for
JITTargetAddress. ExecutorSymbolDef is introduced in

[ORC] Move most ORC APIs to ExecutorAddr, introduce ExecutorSymbolDef.

ExecutorAddr was introduced in b8e5f918166 as an eventual replacement for
JITTargetAddress. ExecutorSymbolDef is introduced in this patch as a
replacement for JITEvaluatedSymbol: ExecutorSymbolDef is an (ExecutorAddr,
JITSymbolFlags) pair, where JITEvaluatedSymbol was a (JITTargetAddress,
JITSymbolFlags) pair.

A number of APIs had already migrated from JITTargetAddress to ExecutorAddr,
but many of ORC's internals were still using the older type. This patch aims
to address that.

Some public APIs are affected as well. If you need to migrate your APIs you can
use the following operations:

* ExecutorAddr::toPtr replaces jitTargetAddressToPointer and
jitTargetAddressToFunction.

* ExecutorAddr::fromPtr replace pointerToJITTargetAddress.

* ExecutorAddr(JITTargetAddress) creates an ExecutorAddr value from a
JITTargetAddress.

* ExecutorAddr::getValue() creates a JITTargetAddress value from an
ExecutorAddr.

JITTargetAddress and JITEvaluatedSymbol will remain in JITSymbol.h for now, but
the aim will be to eventually deprecate and remove these types (probably when
MCJIT and RuntimeDyld are deprecated).

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[JITLink] Ensure that in-flight alloc is abandoned on error in post-alloc phase.

If an error occurs during the post-allocation phase (JITLinkerBase::linkPhase2)
then we need to call JITLinkMemoryMan

[JITLink] Ensure that in-flight alloc is abandoned on error in post-alloc phase.

If an error occurs during the post-allocation phase (JITLinkerBase::linkPhase2)
then we need to call JITLinkMemoryManager::InFlightAlloc::abandon so that the
allocation has a chance to clean up. This was already handled for later phases,
but we were skipping the abandon step when we bailed out of phase 2.

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[JITLink] Update external symbol scopes to reflect scopes of resolved defs.

This is a counterpart to ffe2dda29f3, and does for scope what that commit did
for linkage.

Making the scope of external d

[JITLink] Update external symbol scopes to reflect scopes of resolved defs.

This is a counterpart to ffe2dda29f3, and does for scope what that commit did
for linkage.

Making the scope of external definitions visible to JITLink plugins will
allow us to distinguish hidden weak defs (which do not need to be tracked by
default) from default-scoped weak defs (which need to be updated to point at
a single chosen definition at runtime).

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[ORC][JITLink] Retain Weak flags in JITDylib interfaces, propagate to LinkGraph.

Previously we stripped Weak flags from JITDylib symbol table entries once they
were resolved (there was no particular

[ORC][JITLink] Retain Weak flags in JITDylib interfaces, propagate to LinkGraph.

Previously we stripped Weak flags from JITDylib symbol table entries once they
were resolved (there was no particularly good reason for this). Now we want to
retain them and query them when setting the Linkage on external symbols in
LinkGraphs during symbol resolution (this was the motivation for 75404e9ef88).
Making weak linkage of external definitions discoverable in the LinkGraph will
in turn allow future plugins to implement correct handling for them (by
recording locations that depend on exported weak definitions and pointing all
of these at one chosen definition at runtime).

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[JITLink] Introduce new weakly-referenced concept separate from linkage.

Introduces two new methods on Symbol: isWeaklyReferenced and
setWeaklyReferenced. These are now used to track/set whether an

[JITLink] Introduce new weakly-referenced concept separate from linkage.

Introduces two new methods on Symbol: isWeaklyReferenced and
setWeaklyReferenced. These are now used to track/set whether an external symbol
is weakly referenced, rather than having the Symbol's linkage set to weak.

This change is a first step towards proper handling of weak defs used across
JITDylib boundaries: It frees up the Linkage field on external symbols so that
it can be used to represent the linkage of the definition that the symbol resolves
to. It is expected that Platform plugins will use this information to track
locations that need to be updated if the selected weak definition changes (e.g.
because JITDylibs were dlclosed and then dlopened again in a different order).

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Revert "[JITLink] Fix some C++17 related fixmes."

This reverts commit 6ea5bf436a983ea9e16a5fe7534c87beca0a61b7.

6ea5bf436a983ea9e16a5fe7534c87beca0a61b7 made use of new c++17 rules regarding
order

Revert "[JITLink] Fix some C++17 related fixmes."

This reverts commit 6ea5bf436a983ea9e16a5fe7534c87beca0a61b7.

6ea5bf436a983ea9e16a5fe7534c87beca0a61b7 made use of new c++17 rules regarding
order of evaluation (specifically: in function calls the expression naming the
function should be sequenced before the evalution of any operands) to simplify
some continuation-passing calls. Unfortunately this appears to break at least
one MSVC bot: https://lab.llvm.org/buildbot/#/builders/123/builds/12149 .

Includes an update to the comments to note that the workaround is now based on
MSVC limitations, not on LLVM adopting c++17.

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[JITLink] Fix some C++17 related fixmes.

[llvm] Use = default (NFC)

Re-apply "[JITLink] Update JITLink to use ExecutorAddr rather... " with fixes.

This re-applies 133f86e95492b2a00b944e070878424cfa73f87c, which was reverted in
c5965a411c635106a47738b8d2e24db822b7416

Re-apply "[JITLink] Update JITLink to use ExecutorAddr rather... " with fixes.

This re-applies 133f86e95492b2a00b944e070878424cfa73f87c, which was reverted in
c5965a411c635106a47738b8d2e24db822b7416f while I investigated bot failures.

The original failure contained an arithmetic conversion think-o (on line 419 of
EHFrameSupport.cpp) that could cause failures on 32-bit platforms. The issue
should be fixed in this patch.

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Revert "[JITLink] Update JITLink to use ExecutorAddr rather than..."

This reverts commit 133f86e95492b2a00b944e070878424cfa73f87c while I investigate
the bot failures at https://lab.llvm.org/buildbo

Revert "[JITLink] Update JITLink to use ExecutorAddr rather than..."

This reverts commit 133f86e95492b2a00b944e070878424cfa73f87c while I investigate
the bot failures at https://lab.llvm.org/buildbot#builders/186/builds/3370.

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[JITLink] Update JITLink to use ExecutorAddr rather than JITTargetAddress.

ExecutorAddr is the preferred representation for executor process addresses now.

Re-apply e50aea58d59, "Major JITLinkMemoryManager refactor". with fixes.

Adds explicit narrowing casts to JITLinkMemoryManager.cpp.

Honors -slab-address option in llvm-jitlink.cpp, which was accide

Re-apply e50aea58d59, "Major JITLinkMemoryManager refactor". with fixes.

Adds explicit narrowing casts to JITLinkMemoryManager.cpp.

Honors -slab-address option in llvm-jitlink.cpp, which was accidentally
dropped in the refactor.

This effectively reverts commit 6641d29b70993bce6dbd7e0e0f1040753d38842f.

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Revert "[JITLink][ORC] Major JITLinkMemoryManager refactor."

This reverts commit e50aea58d59c8cfae807a7fee21c4227472c0678 while I
investigate bot failures.

[JITLink][ORC] Major JITLinkMemoryManager refactor.

This commit substantially refactors the JITLinkMemoryManager API to: (1) add
asynchronous versions of key operations, (2) give memory manager impl

[JITLink][ORC] Major JITLinkMemoryManager refactor.

This commit substantially refactors the JITLinkMemoryManager API to: (1) add
asynchronous versions of key operations, (2) give memory manager implementations
full control over link graph address layout, (3) enable more efficient tracking
of allocated memory, and (4) support "allocation actions" and finalize-lifetime
memory.

Together these changes provide a more usable API, and enable more powerful and
efficient memory manager implementations.

To support these changes the JITLinkMemoryManager::Allocation inner class has
been split into two new classes: InFlightAllocation, and FinalizedAllocation.
The allocate method returns an InFlightAllocation that tracks memory (both
working and executor memory) prior to finalization. The finalize method returns
a FinalizedAllocation object, and the InFlightAllocation is discarded. Breaking
Allocation into InFlightAllocation and FinalizedAllocation allows
InFlightAllocation subclassses to be written more naturally, and FinalizedAlloc
to be implemented and used efficiently (see (3) below).

In addition to the memory manager changes this commit also introduces a new
MemProt type to represent memory protections (MemProt replaces use of
sys::Memory::ProtectionFlags in JITLink), and a new MemDeallocPolicy type that
can be used to indicate when a section should be deallocated (see (4) below).

Plugin/pass writers who were using sys::Memory::ProtectionFlags will have to
switch to MemProt -- this should be straightworward. Clients with out-of-tree
memory managers will need to update their implementations. Clients using
in-tree memory managers should mostly be able to ignore it.

Major features:

(1) More asynchrony:

The allocate and deallocate methods are now asynchronous by default, with
synchronous convenience wrappers supplied. The asynchronous versions allow
clients (including JITLink) to request and deallocate memory without blocking.

(2) Improved control over graph address layout:

Instead of a SegmentRequestMap, JITLinkMemoryManager::allocate now takes a
reference to the LinkGraph to be allocated. The memory manager is responsible
for calculating the memory requirements for the graph, and laying out the graph
(setting working and executor memory addresses) within the allocated memory.
This gives memory managers full control over JIT'd memory layout. For clients
that don't need or want this degree of control the new "BasicLayout" utility can
be used to get a segment-based view of the graph, similar to the one provided by
SegmentRequestMap. Once segment addresses are assigned the BasicLayout::apply
method can be used to automatically lay out the graph.

(3) Efficient tracking of allocated memory.

The FinalizedAlloc type is a wrapper for an ExecutorAddr and requires only
64-bits to store in the controller. The meaning of the address held by the
FinalizedAlloc is left up to the memory manager implementation, but the
FinalizedAlloc type enforces a requirement that deallocate be called on any
non-default values prior to destruction. The deallocate method takes a
vector<FinalizedAlloc>, allowing for bulk deallocation of many allocations in a
single call.

Memory manager implementations will typically store the address of some
allocation metadata in the executor in the FinalizedAlloc, as holding this
metadata in the executor is often cheaper and may allow for clean deallocation
even in failure cases where the connection with the controller is lost.

(4) Support for "allocation actions" and finalize-lifetime memory.

Allocation actions are pairs (finalize_act, deallocate_act) of JITTargetAddress
triples (fn, arg_buffer_addr, arg_buffer_size), that can be attached to a
finalize request. At finalization time, after memory protections have been
applied, each of the "finalize_act" elements will be called in order (skipping
any elements whose fn value is zero) as

((char*(*)(const char *, size_t))fn)((const char *)arg_buffer_addr,
(size_t)arg_buffer_size);

At deallocation time the deallocate elements will be run in reverse order (again
skipping any elements where fn is zero).

The returned char * should be null to indicate success, or a non-null
heap-allocated string error message to indicate failure.

These actions allow finalization and deallocation to be extended to include
operations like registering and deregistering eh-frames, TLS sections,
initializer and deinitializers, and language metadata sections. Previously these
operations required separate callWrapper invocations. Compared to callWrapper
invocations, actions require no extra IPC/RPC, reducing costs and eliminating
a potential source of errors.

Finalize lifetime memory can be used to support finalize actions: Sections with
finalize lifetime should be destroyed by memory managers immediately after
finalization actions have been run. Finalize memory can be used to support
finalize actions (e.g. with extra-metadata, or synthesized finalize actions)
without incurring permanent memory overhead.

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[JITLink] Working memory shouldn't be subject to alignment constraints.

Refactors copyBlockContentToWorkingMemory to use offsets rather than direct
pointers to working memory. This simplifies the pr

[JITLink] Working memory shouldn't be subject to alignment constraints.

Refactors copyBlockContentToWorkingMemory to use offsets rather than direct
pointers to working memory. This simplifies the problem of maintaining
alignments between blocks in working memory, without requiring the working
memory itself to be aligned.

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[JITLink] Enable creation and management of mutable block content.

This patch introduces new operations on jitlink::Blocks: setMutableContent,
getMutableContent and getAlreadyMutableContent. The set

[JITLink] Enable creation and management of mutable block content.

This patch introduces new operations on jitlink::Blocks: setMutableContent,
getMutableContent and getAlreadyMutableContent. The setMutableContent method
will set the block content data and size members and flag the content as
mutable. The getMutableContent method will return a mutable copy of the existing
content value, auto-allocating and populating a new mutable copy if the existing
content is marked immutable. The getAlreadyMutableMethod asserts that the
existing content is already mutable and returns it.

setMutableContent should be used when updating the block with totally new
content backed by mutable memory. It can be used to change the size of the
block. The argument value should *not* be shared with any other block.

getMutableContent should be used when clients want to modify the existing
content and are unsure whether it is mutable yet.

getAlreadyMutableContent should be used when clients want to modify the existing
content and know from context that it must already be immutable.

These operations reduce copy-modify-update boilerplate and unnecessary copies
introduced when clients couldn't me sure whether the existing content was
mutable or not.

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[JITLink] Switch from StringRef to ArrayRef<char>, add some generic x86-64 utils

Adds utilities for creating anonymous pointers and jump stubs to x86_64.h. These
are used by the GOT and Stubs builde

[JITLink] Switch from StringRef to ArrayRef<char>, add some generic x86-64 utils

Adds utilities for creating anonymous pointers and jump stubs to x86_64.h. These
are used by the GOT and Stubs builder, but may also be used by pass writers who
want to create pointer stubs for indirection.

This patch also switches the underlying type for LinkGraph content from
StringRef to ArrayRef<char>. This avoids any confusion when working with buffers
that contain null bytes in the middle like, for example, a newly added null
pointer content array. ;)

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[JITLink] Don't issue lookups for empty symbol sets.

Issuing a lookup for an empty symbol set is legal, but can actually result in
unrelated work being done if there was a work queue left over from

[JITLink] Don't issue lookups for empty symbol sets.

Issuing a lookup for an empty symbol set is legal, but can actually result in
unrelated work being done if there was a work queue left over from the previous
lookup. We can avoid doing this unrelated work (reducing stack depth and
interleaving of debugging output) by not issuing these no-op lookups in the
first place.

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[JITLink][MachO][x86-64] Introduce generic x86-64 support.

This patch introduces generic x86-64 edge kinds, and refactors the MachO/x86-64
backend to use these edge kinds. This simplifies the implem

[JITLink][MachO][x86-64] Introduce generic x86-64 support.

This patch introduces generic x86-64 edge kinds, and refactors the MachO/x86-64
backend to use these edge kinds. This simplifies the implementation of the
MachO/x86-64 backend and makes it possible to write generic x86-64 passes and
utilities.

The new edge kinds are different from the original set used in the MachO/x86-64
backend. Several edge kinds that were not meaningfully distinguished in that
backend (e.g. the PCRelMinusN edges) have been merged into single edge kinds in
the new scheme (these edge kinds can be reintroduced later if we find a use for
them). At the same time, new edge kinds have been introduced to convey extra
information about the state of the graph. E.g. The Request*AndTransformTo**
edges represent GOT/TLVP relocations prior to synthesis of the GOT/TLVP
entries, and the 'Relaxable' suffix distinguishes edges that are candidates for
optimization from edges which should be left as-is (e.g. to enable runtime
redirection).

ELF/x86-64 will be refactored to use these generic edges at some point in the
future, and I anticipate a similar refactor to create a generic arm64 support
header too.

Differential Revision: https://reviews.llvm.org/D98305

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[JITLink] Add a new PostAllocationPasses list.

Passes in the new PostAllocationPasses list will run immediately after memory
allocation and address assignment for defined symbols, and before
JITLink

[JITLink] Add a new PostAllocationPasses list.

Passes in the new PostAllocationPasses list will run immediately after memory
allocation and address assignment for defined symbols, and before
JITLinkContext::notifyResolved is called. These passes can set up state
associated with the addresses of defined symbols before any query for these
addresses completes.

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