This re-applies 133f86e954, which was reverted in
c5965a411c 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.
This patch makes jitlink to report an out of range error when the fixup value out of range
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D107328
Address the advice proposed at patch D105429 . Use [Low, Low+size) to represent bits.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D107250
R_X86_64_PLT32 explicitly represents the '-4' PC-adjustment in the relocation's
addend, but JITLink's x86_64::Branch32PCRel includes the PC-adjustment
implicitly. We have been zeroing the addend to account for the difference, but
this breaks for branches to non-zero offsets past labels. This patch updates the
relocation parsing code to unconditionally adjust the offset by '+4' instead.
For branches directly to labels the result is still 0, for branches to offsets
past labels the result is the correct addend for x86_64::Branch32PCRel.
Size 0 sections can have symbols that have size 0. Build those sections
and symbols into the LinkGraph so they can be used properly if needed.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D114749
Add support for reading extended table in ELF object file. This allows
JITLink to support ELF object files with many sections.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D114747
Fix `splitBlock` so that it can handle the case when the block being
split has symbols span across the split boundary. This is an error
case in general but for EHFrame splitting on macho platforms, there is an
anonymous symbol that marks the entire block. Current implementation
will leave a symbol that is out of bound of the underlying block. Fix
the problem by dropping such symbols when the block is split.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D113912
This reapplies e1933a0488 (which was reverted in
f55ba3525e due to bot failures, e.g.
https://lab.llvm.org/buildbot/#/builders/117/builds/2768).
The bot failures were due to a missing symbol error: We use the input object's
mangling to decide how to mangle the debug-info registration function name. This
caused lookup of the registration function to fail when the input object
mangling didn't match the host mangling.
Disbaling the test on non-Darwin platforms is the easiest short-term solution.
I have filed https://llvm.org/PR52503 with a proposed longer term solution.
This commit adds a new plugin, GDBJITDebugInfoRegistrationPlugin, that checks
for objects containing debug info and registers any debug info found via the
GDB JIT registration API.
To enable this registration without redundantly representing non-debug sections
this plugin synthesizes a new embedded object within a section of the LinkGraph.
An allocation action is used to make the registration call.
Currently MachO only. ELF users can still use the DebugObjectManagerPlugin. The
two are likely to be merged in the near future.
Only search within the requested section, and allow one-past-then-end addresses.
This is needed to support section-end-address references to sections with no
symbols in them.
We need to skip the length field when generating error strings.
No test case: This hand-hacked deserializer should be removed in the near future
once JITLink can use generic ORC APIs (including SPS and WrapperFunction).
Alloc actions should return a CWrapperFunctionResult. JITLink does not have
access to this type yet, due to library layering issues, so add a cut-down
version with a fixme.
Enables the arm64 MachO platform, adds basic tests, and implements the
missing TLV relocations and runtime wrapper function. The TLV
relocations are just handled as GOT accesses.
rdar://84671534
Differential Revision: https://reviews.llvm.org/D112656
This lifts the global offset table and procedure linkage table builders out of
ELF_x86_64.h and into x86_64.h, renaming them with generic names
x86_64::GOTTableBuilder and x86_64::PLTTableBuilder. MachO_x86_64.cpp is updated
to use these classes instead of the older PerGraphGOTAndStubsBuilder tool.
Moves visitEdge into the TableManager derivatives, replacing the fixEdgeKind
methods in those classes. The visitEdge method takes on responsibility for
updating the edge target, as well as its kind.
This patch add a TableManager which reponsible for fixing edges that need entries to reference the target symbol and constructing such entries.
In the past, the PerGraphGOTAndPLTStubsBuilder pass was used to build GOT and PLT entry, and the PerGraphTLSInfoEntryBuilder pass was used to build TLSInfo entry. By generalizing the behavior of building entry, I added a TableManager which could be reused when built GOT, PLT and TLSInfo entries.
If this patch makes sense and can be accepted, I will apply the TableManager to other targets(MachO_x86_64, MachO_arm64, ELF_riscv), and delete the file PerGraphGOTAndPLTStubsBuilder.h
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D110383
Negative deltas for LDRLiteral19 have their high bits set. If these bits aren't
masked out then they will overwrite other instruction bits, leading to a bogus
encoding.
This long-standing relocation bug was exposed by e50aea58d5, "[JITLink][ORC]
Major JITLinkMemoryManager refactor.", which caused memory layouts to be
reordered, which in turn lead to a previously unseen negative delta. (Unseen
because LDRLiteral19s were only created in JITLink passes where they always
pointed at segments that were layed-out-after in the old layout).
No testcase yet: Our existing regression test infrastructure is good at checking
that operand bits are correct, but provides no easy way to test for bad opcode
bits. I'll have a think about the right way to approach this.
https://llvm.org/PR52153
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 6641d29b70.
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.
This patch add a TableManager which reponsible for fixing edges that need entries to reference the target symbol and constructing such entries.
In the past, the PerGraphGOTAndPLTStubsBuilder pass was used to build GOT and PLT entry, and the PerGraphTLSInfoEntryBuilder pass was used to build TLSInfo entry. By generalizing the behavior of building entry, I added a TableManager which could be reused when built GOT, PLT and TLSInfo entries.
If this patch makes sense and can be accepted, I will apply the TableManager to other targets(MachO_x86_64, MachO_arm64, ELF_riscv), and delete the file PerGraphGOTAndPLTStubsBuilder.h
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D110383
CompactUnwindSplitter splits compact-unwind sections on record boundaries and
adds keep-alive edges from target functions back to their respective records.
In MachO_arm64.cpp, a CompactUnwindSplitter pass is added to the pre-prune pass
list when setting up the standard pipeline.
This patch does not provide runtime support for compact-unwind, but is a first
step towards enabling it.
Following D109516, this patch re-uses the new helper function for ELF relocation traversal in the RISCV backend.
Reviewed By: StephenFan
Differential Revision: https://reviews.llvm.org/D109522
Following D109516, this patch re-uses the new helper function for ELF relocation traversal in the x86-64 backend.
Reviewed By: StephenFan
Differential Revision: https://reviews.llvm.org/D109520
First step in reducing redundancy in `addRelocations()` implementations across ELF JITLink backends. The patch factors out common logic for ELF relocation traversal into the new helper function `forEachRelocation()` in the `ELFLinkGraphBuilder` base class. For now, this is applied to the Aarch64 implementation. Others may follow soon.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D109516
This patch use the same way as the https://reviews.llvm.org/rGfe1fa43f16beac1506a2e73a9f7b3c81179744eb to handle the thread local variable.
It allocates 2 * pointerSize space in GOT to represent the thread key and data address. Instead of using the _tls_get_addr function, I customed a function __orc_rt_elfnix_tls_get_addr to get the address of thread local varible. Currently, this is a wip patch, only one TLS relocation R_X86_64_TLSGD is supported and I need to add the corresponding test cases.
To allocate the TLS descriptor in GOT, I need to get the edge kind information in PerGraphGOTAndPLTStubBuilder, So I add a `Edge::Kind K` argument in some functions in PerGraphGOTAndPLTStubBuilder.h. If it is not suitable, I can think further to solve this problem.
Differential Revision: https://reviews.llvm.org/D109293
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.
Set up basic infrastructure for 64-bit ARM architecture support in JITLink. It allows for loading a minimal object file and resolving a single relocation. Advanced features like GOT and PLT handling or relaxations were intentionally left out for the moment.
This patch follows the idea to keep implementations for ARM (32-bit) and Aaarch64 (64-bit) separate, because:
* it might be easier to share code with the MachO "arm64" JITLink backend
* LLVM has individual targets for ARM and Aaarch64 as well
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D108986
This patch add the R_RISCV_GOT_HI20 and R_RISCV_CALL_PLT relocation support. And the basic got/plt was implemented. Because of riscv32 and riscv64 has different pointer size, the got entry size and instructions of plt entry is different. This patch is the basic support, the optimization pass at preFixup stage has not been implemented.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D107688
This patch supported the R_X86_64_32S relocation and add the Pointer32Signed generic edge kind.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D108446
This patch optimize the GOTPCRELX Reloations, which is described in X86-64 psabi chapter B.2. And Not all optimization of this chapter is implemented.
1. Convert call and jmp has been implemented
2. Convert mov, but the optimization that when the symbol is defined in the lower 32-bit address space, memory operand in `mov` can be convertted into immediate operand has not been implemented.
3. Conver Test and Binop has not been implemented.
The new test file named ELF_got_plt_optimizations.s has been added, and I moved some test cases about optimization of got/plt from ELF_x86_64_small_pic_relocations.s to the new test file.
By referencing the lld, so, the optimization `Convert call and jmp` is not same as what psabi says, and I have explained it in the comment.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D108280
This patch unify optimizeELF_x86_64_GOTAndStubs and optimizeMachO_x86_64_GOTAndStubs into a pure optimize_x86_64_GOTAndStubs
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D108025
This patch uses a switch statement to map the ELF_x86_64's edge kind to generic edge kind, and merge the ELF_x86_64 's applyFixup function to the x86_64 's applyFixup function. Some edge kinds were not have corresponding generic edge kinds, so I added three generic edge kinds asa follows:
1. RequestGOTAndTransformToDelta64, which is similar to RequestGOTAndTransformToDelta32.
2. GOTDelta64. This generic kind is similar to Delta64, except the GOTDelta64 computes the delta relative to GOTSymbol
3. RequestGOTAndTransformToGOTDelta64. This edge kind was used to deal with ELF_x86_64's GOT64 edge kind, it request the fixGOTEdge function to change the target to GOT entry, and set the edge kind to generic edge kind GOTDelta64.
These added generic edge kinds may named haphazardly, or can't express its meaning well.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D107967
Some files still contained the old University of Illinois Open Source
Licence header. This patch replaces that with the Apache 2 with LLVM
Exception licence.
Differential Revision: https://reviews.llvm.org/D107528
This patch is the initial support, it implements translation from object file to JIT link graph, and very few relocations were supported. Currently, the test file ELF_pc_indirect.s is passed, the HelloWorld program(compiled with mno-relax flag) can be linked correctly and run on instruction emulator correctly.
In the downstream implementation, I have implemented the GOT, PLT function, and EHFrame and some optimization will be implement soon. I will organize the code in to patches, then gradually send it to upstream.
Differential Revision: https://reviews.llvm.org/D105429
This reverts commit 6b2a96285b.
The ccache builders are still failing. Looks like they need to be updated to
get the llvm-zorg config change in 490633945677656ba75d42ff1ca9d4a400b7b243.
I'll re-apply this as soon as the builders are updated.
This reapplies commit a7733e9556 ("Re-apply
[ORC][ORC-RT] Add initial native-TLV support to MachOPlatform."), and
d4abdefc99 ("[ORC-RT] Rename macho_tlv.x86-64.s
to macho_tlv.x86-64.S (uppercase suffix)").
These patches were reverted in 48aa82cacb while I
investigated bot failures (e.g.
https://lab.llvm.org/buildbot/#/builders/109/builds/18981). The fix was to
disable building of the ORC runtime on buliders using ccache (which is the same
fix used for other compiler-rt projects containing assembly code). This fix was
commited to llvm-zorg in 490633945677656ba75d42ff1ca9d4a400b7b243.
This reverts commit d4abdefc99 ("[ORC-RT] Rename
macho_tlv.x86-64.s to macho_tlv.x86-64.S (uppercase suffix)", and
a7733e9556 ("Re-apply "[ORC][ORC-RT] Add initial
native-TLV support to MachOPlatform."), while I investigate failures on
ccache builders (e.g. https://lab.llvm.org/buildbot/#/builders/109/builds/18981)
Reapplies fe1fa43f16, which was reverted in
6d8c63946c, with fixes:
1. Remove .subsections_via_symbols directive from macho_tlv.x86-64.s (it's
not needed here anyway).
2. Return error from pthread_key_create to the MachOPlatform to silence unused
variable warning.
Adds code to LLVM (MachOPlatform) and the ORC runtime to support native MachO
thread local variables. Adding new TLVs to a JITDylib at runtime is supported.
On the LLVM side MachOPlatform is updated to:
1. Identify thread local variables in the LinkGraph and lower them to GOT
accesses to data in the __thread_data or __thread_bss sections.
2. Merge and report the address range of __thread_data and thread_bss sections
to the runtime.
On the ORC runtime a MachOTLVManager class introduced which records the address
range of thread data/bss sections, and creates thread-local instances from the
initial data on demand. An orc-runtime specific tlv_get_addr implementation is
included which saves all register state then calls the MachOTLVManager to get
the address of the requested variable for the current thread.
LinkGraph::transferBlock can be used to move a block and all associated symbols
from one section to another.
LinkGraph::mergeSections moves all blocks and sections from a source section to
a destination section.
ELFLinkGraphBuilder<ELFT> will hold generic parsing and LinkGraph-building code
that can be shared between JITLink ELF backends for different architectures.
For now it's just a stub. The plan is to incrementally move functionality down
from ELFLinkGraphBuilder_x86_64 into the new template.
The C-string section splitting support added in f9649d123d triggered an assert
("Duplicate canonical symbol at address") when multiple symbols were defined at
the the same offset within a C-string block (this triggered on arm64, where we
always add a block start symbol). The bug was caused by a failure to update the
record of the last canonical symbol address. The fix was to maintain this record
correctly, and move the auto-generation of the block-start symbol above the
handling for symbols defined in the object itself so that all symbols
(auto-generated and defined) are processed in address order.
MachO C-string literal sections should be split on null-terminator boundaries,
rather than the usual symbol boundaries. This patch updates
MachOLinkGraphBuilder to do that.
During the generic x86-64 support refactor in ecf6466f01 the implementation
of MachO_arm64_GOTAndStubsBuilder::isGOTEdgeToFix was altered to only return
true for external symbols. This behavior is incorrect: GOT entries may be
required for defined symbols (e.g. in the large code model).
This patch fixes the bug and adds a test case for it (renaming an old test
case to avoid any ambiguity).
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.
These can be used to create eh-frame section fixing passes outside the usual
linker pipeline, which can be useful for tests and tools that just want to
verify or dump graphs.
This commit reorders some fields and fixes the width of others to try to
maintain more consistent columns. It also switches to long-hand scope
and linkage names, since LinkGraph dumps aren't read often enough for
single-character codes to be memorable.
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. ;)
JITLink now requires section names to be unique. In MachO section names are only
guaranteed to be unique within their containing segment (e.g. a '__const' section
in the '__DATA' segment does not clash with a '__const' section in the '__TEXT'
segment), so we need to use the fully qualified <segment>,<section> section
names (e.g. '__DATA,__const' or '__TEXT,__const') when constructing
jitlink::Sections for MachO objects.
Introduces DefineExternalSectionStartAndEndSymbols.h, which defines a template
for a JITLink pass that transforms external symbols meeting a user-supplied
predicate into defined symbols pointing at the start and end of a Section
identified by the predicate. JITLink.h is updated with a new makeAbsolute
function to support this pass.
Also renames BasicGOTAndStubsBuilder to PerGraphGOTAndPLTStubsBuilder -- the new
name better describes the intent of this GOT and PLT stubs builder, and will
help to distinguish it from future GOT and PLT stub builders that build entries
that may be shared between multiple graphs.
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.
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
This makes the target triple, graph name, and full graph content available
when making decisions about how to populate the linker pass pipeline.
Also updates the LLJITWithObjectLinkingLayerPlugin example to show more
API use, including use of the API changes in this patch.
GCC warning:
```
In file included from /usr/include/c++/9/cassert:44,
from /home/vsts/work/1/llvm-project/llvm/include/llvm/ADT/BitVector.h:21,
from /home/vsts/work/1/llvm-project/llvm/include/llvm/Support/Program.h:17,
from /home/vsts/work/1/llvm-project/llvm/include/llvm/Support/Process.h:32,
from /home/vsts/work/1/llvm-project/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp:11:
/home/vsts/work/1/llvm-project/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp: In member function ‘virtual llvm::Expected<std::unique_ptr<llvm::jitlink::JITLinkMemoryManager::Allocation> > llvm::jitlink::InProcessMemoryManager::allocate(const llvm::jitlink::JITLinkDylib*, const SegmentsRequestMap&)’:
/home/vsts/work/1/llvm-project/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp:129:40: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
129 | assert(SlabRemaining.allocatedSize() >= 0 && "Mapping exceeds allocation");
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
```
The return type of `allocatedSize()` is `size_t`, thus the expression
`SlabRemaining.allocatedSize() >= 0` always evaluate to `true`.
Kazu Hirata