Right now, the createTargetMachine function in LTOBackend.cpp (used by llvm-lto, and other components) selects the default Relocation Model when none is specified in the module.
Other components (such as opt and llc) that construct a TargetMachine delegate the decision on the default value to the polymorphic TargetMachine's constructor.
This commit aligns llvm-lto with other components.
Reviewed By: daltenty, fhahn
Differential Revision: https://reviews.llvm.org/D97507
IR symbol table does not parse inline asm. A symbol only referenced by inline
asm is not in the IR symbol table, so LTO does not know that the definition (in
another translation unit) is referenced and may internalize it, even if that
definition has `__attribute__((used))` (which lowers to `llvm.compiler.used` on
ELF targets since D97446).
```
// cabac.c
__attribute__((used)) const uint8_t ff_h264_cabac_tables[...] = {...};
// h264_cabac.c
asm("lea ff_h264_cabac_tables(%rip), %0" : ...);
```
`__attribute__((used))` is the recommended way to tell the compiler there may
be inline asm references, so the usage is perfectly fine. This patch
conservatively sets the `FB_used` bit on `llvm.compiler.used` symbols to work
around the IR symbol table limitation. Note: before D97446, Clang never emitted
symbols in the `llvm.compiler.used` list, so this change does not punish any
Clang emitted global object.
Without the patch, `ff_h264_cabac_tables` may be assigned to a non-external
partition and get internalized. Then we will get a linker error because the
`cabac.c` definition is not exposed.
Differential Revision: https://reviews.llvm.org/D97755
This version of the patch includes a fix for the cfi failures.
(undoes the revert commit 7db390cc77)
It also undoes reverts of follow-up patches that also needed reverting
originally:
* [LTO] Add option enable NewPM with LTOCodeGenerator.
(undoes revert commit 0a17664b47)
* [LTOCodeGenerator] Use lto::Config for options (NFC)."
(undoes revert commit b0a8e41cff)
Perform DSOLocal propagation within summary list of every GV. This
avoids the repeated query of this information during function
importing.
Differential Revision: https://reviews.llvm.org/D96398
I've already witnessed two separate changes missing runNewPMPasses()
because runNewPMCustomPasses() is so similar.
This cleans up some duplicated code.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D96553
This patch removes some options that have been duplicated in
LTOCodeGenerator and instead use lto::Config directly to manage the
options.
This is a cleanup after 6a59f05606.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D95738
This patch adds an option to enable the new pass manager in
LTOCodeGenerator. It also updates a few tests with legacy PM specific
tests, which started failing after 6a59f05606 when
LLVM_ENABLE_NEW_PASS_MANAGER=true.
This patch updates LTOCodeGenerator to use the utilities provided by
LTOBackend to run middle-end optimizations and backend code generation.
This is a first step towards unifying the code used by libLTO's C API
and the newer, C++ interface (see PR41541).
The immediate motivation is to allow using the new pass manager when
doing LTO using libLTO's C API, which is used on Darwin, among others.
With the changes, there are no codegen/stats differences when building
MultiSource/SPEC2000/SPEC2006 on Darwin X86 with LTO, compared
to without the patch.
Reviewed By: steven_wu
Differential Revision: https://reviews.llvm.org/D94487
splitCodeGen does not need to take ownership of the module, as it
currently clones the original module for each split operation.
There is an ~4 year old fixme to change that, but until this is
addressed, the function can just take a reference to the module.
This makes the transition of LTOCodeGenerator to use LTOBackend a bit
easier, because under some circumstances, LTOCodeGenerator needs to
write the original module back after codegen.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D95222
Identify dynamically exported symbols (--export-dynamic[-symbol=],
--dynamic-list=, or definitions needed to preempt shared objects) and
prevent their LTO visibility from being upgraded.
This helps avoid use of whole program devirtualization when there may
be overrides in dynamic libraries.
Differential Revision: https://reviews.llvm.org/D91583
Imported functions and variable get the visibility from the module supplying the
definition. However, non-imported definitions do not get the visibility from
(ELF) the most constraining visibility among all modules (Mach-O) the visibility
of the prevailing definition.
This patch
* adds visibility bits to GlobalValueSummary::GVFlags
* computes the result visibility and propagates it to all definitions
Protected/hidden can imply dso_local which can enable some optimizations (this
is stronger than GVFlags::DSOLocal because the implied dso_local can be
leveraged for ELF -shared while default visibility dso_local has to be cleared
for ELF -shared).
Note: we don't have summaries for declarations, so for ELF if a declaration has
the most constraining visibility, the result visibility may not be that one.
Differential Revision: https://reviews.llvm.org/D92900
To simplify the transition to using LTOBackend, move DisableVerify to
the LTOCodeGenerator class, like most/all other options.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D95223
The target features are obtained as a list of features/attributes.
Instead of storing them in a single string, store the vector. This
matches lto::Config's behavior and simplifies the transition to
lto::backend().
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D95224
lto::Config has a field to control whether the build is "freestanding"
(no builtins) or not, but it is not hooked up to the code actually
running the passes.
This patch adds support for the flag to both the code that runs
optimization with the new and old pass managers, by explicitly adding a
TargetLibraryInfo instance. If Freestanding is true, all library functions
are disabled.
Reviewed By: steven_wu
Differential Revision: https://reviews.llvm.org/D94630
Run the ObjCARCContractPass during LTO. The legacy LTO backend (under
LTO/ThinLTOCodeGenerator.cpp) already does this; this diff just adds that
behavior to the new LTO backend. Without that pass, the objc.clang.arc.use
intrinsic will get passed to the instruction selector, which doesn't know how to
handle it.
In order to test both the new and old pass managers, I've also added support for
the `--[no-]lto-legacy-pass-manager` flags.
P.S. Not sure if the ordering of the pass within the pipeline matters...
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D94547
This patch removes some ancient options as a clean-up before moving
code-gen to use LTOBackend in D94487.
I think it would preferable to remove those ancient options, because
1. There are no corresponding options in LTOBackend based tools,
2. There are no unit tests for them,
3. They are not passed through by Clang,
4. At least for GNVLoadPRE, users could just use GVN's `enable-load-pre`.
Alternatively we could add support for those options to lto::Config &
co, but I think it would be better to remove them, unless they are
actually used in practice.
Reviewed By: steven_wu, tejohnson
Differential Revision: https://reviews.llvm.org/D94783
Only class declarations should be inside anonymous namespaces
(https://llvm.org/docs/CodingStandards.html#anonymous-namespaces)
Instead of using a anonymous namespace, just mark the functions in it as
static (some of them already were).
This simplifies the diff for D94486.
This also teaches MachO writers/readers about the MachO cpu subtype,
beyond the minimal subtype reader support present at the moment.
This also defines a preprocessor macro to allow users to distinguish
__arm64__ from __arm64e__.
arm64e defaults to an "apple-a12" CPU, which supports v8.3a, allowing
pointer-authentication codegen.
It also currently defaults to ios14 and macos11.
Differential Revision: https://reviews.llvm.org/D87095
1. Removed #include "...AliasAnalysis.h" in other headers and modules.
2. Cleaned up includes in AliasAnalysis.h.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D92489
This is the #1 of 2 changes that make remarks hotness threshold option
available in more tools. The changes also allow the threshold to sync with
hotness threshold from profile summary with special value 'auto'.
This change modifies the interface of lto::setupLLVMOptimizationRemarks() to
accept remarks hotness threshold. Update all the tools that use it with remarks
hotness threshold options:
* lld: '--opt-remarks-hotness-threshold='
* llvm-lto2: '--pass-remarks-hotness-threshold='
* llvm-lto: '--lto-pass-remarks-hotness-threshold='
* gold plugin: '-plugin-opt=opt-remarks-hotness-threshold='
Differential Revision: https://reviews.llvm.org/D85809
All these potential null pointer dereferences are reported by my static analyzer for null smart pointer dereferences, which has a different implementation from `alpha.cplusplus.SmartPtr`.
The checked pointers in this patch are initialized by Target::createXXX functions. When the creator function pointer is not correctly set, a null pointer will be returned, or the creator function may originally return a null pointer.
Some of them may not make sense as they may be checked before entering the function, but I fixed them all in this patch. I submit this fix because 1) similar checks are found in some other places in the LLVM codebase for the same return value of the function; and, 2) some of the pointers are dereferenced before they are checked, which may definitely trigger a null pointer dereference if the return value is nullptr.
Reviewed By: tejohnson, MaskRay, jpienaar
Differential Revision: https://reviews.llvm.org/D91410
No longer rely on an external tool to build the llvm component layout.
Instead, leverage the existing `add_llvm_componentlibrary` cmake function and
introduce `add_llvm_component_group` to accurately describe component behavior.
These function store extra properties in the created targets. These properties
are processed once all components are defined to resolve library dependencies
and produce the header expected by llvm-config.
Differential Revision: https://reviews.llvm.org/D90848
Make DebugLogging a member variable so that users of PassBuilder don't
need to pass it around so much.
Move call to TargetMachine::registerPassBuilderCallbacks() within
PassBuilder so users don't need to remember to call it.
Reviewed By: asbirlea
Differential Revision: https://reviews.llvm.org/D90437
llvm::EmbedBitcodeInModule needs (what used to be called) EmbedMarker
set, in order to emit .llvmcmd. EmbedMarker is really about embedding the
command line, so renamed the parameter accordingly, too.
This was not caught at test because the check-prefix was incorrect, but
FileCheck does not report that when multiple prefixes are provided. A
separate patch will address that.
Differential Revision: https://reviews.llvm.org/D90278
This reverts 9b5b305023 and fixes the unwanted re-ordering when generating ThinLTO indexes.
The goal of this patch is to better balance thread utilization during ThinLTO in-process linking (in llvm-lto2 or in LLD). Before this patch, large modules would often be scheduled late during execution, taking a long time to complete, thus starving the thread pool.
We now sort modules in descending order, based on each module's bitcode size, so that larger modules are processed first. By doing so, smaller modules have a better chance to keep the thread pool active, and thus avoid starvation when the bitcode compilation is almost complete.
In our case (on dual Intel Xeon Gold 6140, Windows 10 version 2004, two-stage build), this saves 15 sec when linking `clang.exe` with LLD & -flto=thin, /opt:lldltojobs=all, no ThinLTO cache, -DLLVM_INTEGRATED_CRT_ALLOC=d:\git\rpmalloc.
Before patch: 100 sec
After patch: 85 sec
Inspired by the work done by David Callahan in D60495.
Differential Revision: https://reviews.llvm.org/D87966
This reverts commit 6537004913. This is causing test failures internally, and while a few of the cases turned out to be bad user code (relying on a specific order of static initialization across translation units), some cases are less clear. Temporarily reverting for now, and Teresa is going to follow up with more details.
This completes the circle, complementing -lto-embed-bitcode
(specifically, post-merge-pre-opt). Using -thinlto-assume-merged skips
function importing. The index file is still needed for the other data it
contains.
Differential Revision: https://reviews.llvm.org/D87949
Re-use an optimizition from the old LTO API (used by ld64).
This sorts modules in ascending order, based on bitcode size, so that larger modules are processed first. This allows for smaller modules to be process last, and better fill free threads 'slots', and thusly allow for better multi-thread load balancing.
In our case (on dual Intel Xeon Gold 6140, Windows 10 version 2004, two-stage build), this saves 15 sec when linking `clang.exe` with LLD & `-flto=thin`, `/opt:lldltojobs=all`, no ThinLTO cache, -DLLVM_INTEGRATED_CRT_ALLOC=d:\git\rpmalloc.
Before patch: 102 sec
After patch: 85 sec
Inspired by the work done by David Callahan in D60495.
Differential Revision: https://reviews.llvm.org/D87966
This will embed bitcode after (Thin)LTO merge, but before optimizations.
In the case the thinlto backend is called from clang, the .llvmcmd
section is also produced. Doing so in the case where the caller is the
linker doesn't yet have a motivation, and would require plumbing through
command line args.
Differential Revision: https://reviews.llvm.org/D87636
The current behavior of -lto-embed-bitcode is not quite the same as that
of -fembed-bitcode. While both populate .llvmbc with bitcode, the latter
populates it with pre-optimized bitcode(*), while the former with
post-optimized. The scenarios driving them are different - the latter's
goal is to allow re-compilation, while the former, IIUC, is execution.
I plan to add a third mode for thinlto cases, closely-related to
-fembed-bitcode's scenario: adding the bitcode pre-optimization, but
post-merging. This would allow re-compilation without requiring the
other .bc files that were merged (akin to how -fembed-bitcode allows
recompilation without all the .h files)
The third mode can't co-exist with the current -lto-embed-bitcode mode,
because the latter would overwrite it. For clarity, we change
-lto-embed-bitcode to be an enum.
(*) That's the compiler semantics. The driver splits compilation in 2
phases, so if -fembed-bitcode is given to the driver, the .llvmbc is
optimized bitcode; if the option is passed to the compiler (after -cc1),
the section is pre-optimized.
Differential Revision: https://reviews.llvm.org/D87477
llvm::EmbedBitcodeInModule handles serializing the passed-in module, if
the provided MemoryBufferRef is invalid. This is already the path taken
in one of the uses of the API - clang::EmbedBitcode, when called from
BackendConsumer::HandleTranslationUnit - so might as well do the same
here and reduce (by very little) code duplication.
The only difference this patch introduces is that the serialization happens
with ShouldPreserveUseListOrder set to true.
Differential Revision: https://reviews.llvm.org/D87339
Instead, passing in the command line options, initialized to nullptr. In
an upcoming patch, we can then use the parameter to pass actual command
line options.
Differential Revision: https://reviews.llvm.org/D87336
This is a presumed fix for FireFox thinLTO bot fix which hits assertion
failure for invalid index when access StringRef. Techinically, `IRName`
in the symtab should not be empty string for the entries we cared about
but this will help to fix the bot before more information can be
provided. Otherwise, NFCI.
For `ld64` which uses legacy LTOCodeGenerator, it relies on
writeMergedModule to perform `ld -r` (generates a linked object file).
If all the inputs to `ld -r` is fullLTO bitcode, `ld64` will linked the
bitcode module, internalize all the symbols and write out another
fullLTO bitcode object file. This bitcode file doesn't have all the
bitcode inputs and it should not have LTOPostLink module flag. It will
also cause error when this bitcode object file is linked with other LTO
object file.
Fix the issue by not applying LTOPostLink flag during writeMergedModule
function. The flag should only be added when all the bitcode are linked
and ready to be optimized.
rdar://problem/58462798
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D84789
Instead of computing GUID based on some assumption about symbol mangling
rule from IRName to symbol name, lookup the IRName from all the symtabs
from all the input files to see if there are any matching symbols entry
provides the IRName for GUID computation.
rdar://65853754
Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D84803
Dead function has its body stripped away, and can cause various
analyses to panic. Also it does not make sense to apply analyses on
such function.
Reviewed By: xazax.hun, MaskRay, wenlei, hoy
Differential Revision: https://reviews.llvm.org/D84715
OptNoneInstrumentation is part of StandardInstrumentations. It skips
functions (or loops) that are marked optnone.
The feature of skipping optional passes for optnone functions under NPM
is gated on a -enable-npm-optnone flag. Currently it is by default
false. That is because we still need to mark all required passes to be
required. Otherwise optnone functions will start having incorrect
semantics. After that is done in following changes, we can remove the
flag and always enable this.
Reviewed By: ychen
Differential Revision: https://reviews.llvm.org/D83519
This function is deceptive at best: it doesn't return what you'd expect.
If you have an arbitrary GlobalValue and you want to determine the
alignment of that pointer, Value::getPointerAlignment() returns the
correct value. If you want the actual declared alignment of a function
or variable, GlobalObject::getAlignment() returns that.
This patch switches all the users of GlobalValue::getAlignment to an
appropriate alternative.
Differential Revision: https://reviews.llvm.org/D80368
Fixes an issue with missing nul-terminators and saves us some string
copying, compared to a version which would insert nul-terminators.
Differential Revision: https://reviews.llvm.org/D82033
This is a fix for PR #46392 (Diagnostic message (error) related to
ThinLTO caching needs to be downgraded to a remark).
There are diagnostic messages related to ThinLTO caching that contain
the word "error", but they are really just notices/remarks for users,
and they don't cause a build failure. The word "error" appearing can be
confusing to users, and may even cause deeper problems.
User's build system might be designed to interpret any error messages
(even a benign error message as the one above) reported by the compiler
as a build failure, thus causing the build to fail "needlessly". In
short, the term "error" in this diagnostic is misleading at best, and
may be causing build systems to fail at worst.
Differential Revision: https://reviews.llvm.org/D82138
Summary:
ThinLTO linking runs dataflow processing on collected
function parameters. Then StackSafetyGlobalInfoWrapperPass
in ThinLTO backend will run as usual looking up to external
symbol in the summary if needed.
Depends on D80985.
Reviewers: eugenis, pcc
Reviewed By: eugenis
Subscribers: inglorion, hiraditya, steven_wu, dexonsmith, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D81242
Wael Yehia