| Age | Commit message (Collapse) | Author | Files | Lines |
|---|
|
There's a pattern throughout LLVM of cl::opts being exported. That in
itself is probably a bit unfortunate, but what's especially bad about it
is that a lot of those symbols are in the global namespace. Move them
into the llvm namespace.
While doing this, I noticed some other variables in the global namespace
and moved them as well.
|
|
Currently there are two serialization modes for bitstream Remarks:
standalone and separate. The separate mode splits remark metadata (e.g.
the string table) from actual remark data. The metadata is written into
the object file by the AsmPrinter, while the remark data is stored in a
separate remarks file. This means we can't use bitstream remarks with
tools like opt that don't generate an object file. Also, it is confusing
to post-process bitstream remarks files, because only the standalone
files can be read by llvm-remarkutil. We always need to use dsymutil
to convert the separate files to standalone files, which only works for
MachO. It is not possible for clang/opt to directly emit bitstream
remark files in standalone mode, because the string table can only be
serialized after all remarks were emitted.
Therefore, this change completely removes the separate serialization
mode. Instead, the remark string table is now always written to the end
of the remarks file. This requires us to tell the serializer when to
finalize remark serialization. This automatically happens when the
serializer goes out of scope. However, often the remark file goes out of
scope before the serializer is destroyed. To diagnose this, I have added
an assert to alert users that they need to explicitly call
finalizeLLVMOptimizationRemarks.
This change paves the way for further improvements to the remark
infrastructure, including more tooling (e.g. #159784), size optimizations
for bitstream remarks, and more.
Pull Request: https://github.com/llvm/llvm-project/pull/156715
|
|
In order to better see what's going on during ThinLTO linking, this PR
adds more profile tags when using `--time-trace` on a `lld-link.exe`
invocation.
After PR, linking `clang.exe`:
<img width="3839" height="2026" alt="Capture d’écran 2025-09-02 082021"
src="https://github.com/user-attachments/assets/bf0c85ba-2f85-4bbf-a5c1-800039b56910"
/>
Linking a custom (Unreal Engine game) binary gives a completly
different picture, probably because of using Unity files, and the sheer
amount of input files (here, providing over 60 GB of .OBJs/.LIBs).
<img width="1940" height="1008" alt="Capture d’écran 2025-09-02 102048"
src="https://github.com/user-attachments/assets/60b28630-7995-45ce-9e8c-13f3cb5312e0"
/>
|
|
(#153864)
This reverts commit 334e9bf2dd01fbbfe785624c0de477b725cde6f2.
Check if llvm-nm exists before building the benchmark.
|
|
(#153864)
…210)"
This reverts commit 9a14b1d254a43dc0d4445c3ffa3d393bca007ba3.
Revert "RuntimeLibcalls: Return StringRef for libcall names (#153209)"
This reverts commit cb1228fbd535b8f9fe78505a15292b0ba23b17de.
Revert "TableGen: Emit statically generated hash table for runtime
libcalls (#150192)"
This reverts commit 769a9058c8d04fc920994f6a5bbb03c8a4fbcd05.
Reverted three changes because of a CMake error while building llvm-nm
as reported in the following PR:
https://github.com/llvm/llvm-project/pull/150192#issuecomment-3192223073
|
|
Does not yet fully propagate this down into the TargetLowering
uses, many of which are relying on null checks on the returned
value.
|
|
|
|
With the current aliases metadata we lose information about which groups
of aliases survive symbol resolution. This causes various problems such
as #150075 where symbol resolution breaks the link between alias groups.
In this redesign of the aliases metadata, we stop representing the
individual aliases in !aliases. Instead, the individual aliases are
represented in !cfi.functions in the same way as functions, and the
alias groups (i.e. groups of symbols with the same address) are stored
in !aliases. At symbol resolution time, we filter out all non-prevailing
members of !aliases; the resulting set is used by LowerTypeTests to
recreate the aliases.
With this change it is now possible for a jump table entry to refer
to an alias in one of the ThinLTO object files (e.g. if a function is
non-prevailing but its alias is prevailing), so instead of deleting them,
rename them with the ".cfi" suffix.
Fixes #150070.
Fixes #150075.
Reviewers: teresajohnson, vitalybuka
Reviewed By: vitalybuka
Pull Request: https://github.com/llvm/llvm-project/pull/150690
|
|
|
|
&I is already of const uint8_t *.
|
|
Work towards separating the ABI existence of libcalls vs. the
lowering selection. Set libcall selection through enums, rather
than through raw string names.
|
|
This flag was used to let us incrementally introduce debug records
into LLVM, however everything is now using records. It serves no
purpose now, so delete it.
|
|
Start removing debug intrinsics support -- starting with the flag that
controls production of their replacement, debug records. This patch
removes the command-line-flag and with it the ability to switch back to
intrinsics. The module / function / block level "IsNewDbgInfoFormat"
flags get hardcoded to true, I'll to incrementally remove things that
depend on those flags.
|
|
## Purpose
This patch is one in a series of code-mods that annotate LLVM’s public
interface for export. This patch annotates the `llvm/LTO` library. These
annotations currently have no meaningful impact on the LLVM build;
however, they are a prerequisite to support an LLVM Windows DLL (shared
library) build.
## Background
This effort is tracked in #109483. Additional context is provided in
[this
discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307),
and documentation for `LLVM_ABI` and related annotations is found in the
LLVM repo
[here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst).
The bulk of these changes were generated automatically using the
[Interface Definition Scanner (IDS)](https://github.com/compnerd/ids)
tool, followed formatting with `git clang-format`.
The following manual adjustments were also applied after running IDS on
Linux:
- Add `LLVM_ABI` to a small number of symbols that require export but
are not declared in headers
## Validation
Local builds and tests to validate cross-platform compatibility. This
included llvm, clang, and lldb on the following configurations:
- Windows with MSVC
- Windows with Clang
- Linux with GCC
- Linux with Clang
- Darwin with Clang
|
|
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
|
|
This patch adds initial support for Integrated Distributed ThinLTO
(DTLTO) in LLVM, which manages distribution internally during the
traditional link step. This enables compatibility with any build
system that supports in-process ThinLTO. In contrast, existing
approaches to distributed ThinLTO, which split the thin-link
(--thinlto-index-only), backend compilation, and final link into
separate steps, require build system support, e.g. Bazel.
This patch implements the core DTLTO mechanism, which enables
delegation of ThinLTO backend jobs to an external process (the
distributor). The distributor can then manage job distribution through
systems like Incredibuild. A generic JSON interface is used to
communicate with the distributor, allowing for the creation of new
distributors (and thus integration with different distribution
systems) without modifying LLVM.
Please see llvm/docs/dtlto.rst for more details.
RFC: https://discourse.llvm.org/t/rfc-integrated-distributed-thinlto/69641
Design Review: https://github.com/llvm/llvm-project/pull/126654
|
|
|
|
See https://discourse.llvm.org/t/rfc-keep-globalvalue-guids-stable/84801
for context.
This is a non-functional change which just changes the interface of
GlobalValue, in preparation for future functional changes. This part
touches a fair few users, so is split out for ease of review. Future
changes to the GlobalValue implementation can then be focused purely on
that class.
This does the following:
* Rename GlobalValue::getGUID(StringRef) to
getGUIDAssumingExternalLinkage. This is simply making explicit at the
callsite what is currently implicit.
* Where possible, migrate users to directly calling getGUID on a
GlobalValue instance.
* Otherwise, where possible, have them call the newly renamed
getGUIDAssumingExternalLinkage, to make the assumption explicit.
There are a few cases where neither of the above are possible, as the
caller saves and reconstructs the necessary information to compute the
GUID themselves. We want to migrate these callers eventually, but for
this first step we leave them be.
|
|
enabled (#134541)
On one hand, we intend to force import all functions when the option is
enabled.
On the other hand, we currently drop definitions of some functions and
convert
them to declarations, which contradicts this intent.
With this PR, functions will no longer be converted to declarations when
`force-import-all` is enabled.
|
|
DenseSet, SmallPtrSet, SmallSet, SetVector, and StringSet recently
gained C++23-style insert_range. This patch uses insert_range with
iterator ranges. For each case, I've verified that foos is defined as
make_range(foo_begin(), foo_end()) or in a similar manner.
|
|
prevailing definition of this class (#131721)
Before this patch, whole program devirtualization is suppressed on a
class if any superclass is visible to regular object files, by recording
the class GUID in `VisibleToRegularObjSymbols`.
This patch suppresses whole program devirtualization on a class if the
LTO unit doesn't have the prevailing definition of this class (e.g., the
prevailing definition is in a shared library)
Implementation summaries:
1. In llvm/lib/LTO/LTO.cpp, `IsVisibleToRegularObj` is updated to look
at the global resolution's `IsPrevailing` bit for ThinLTO and
regularLTO.
2. In llvm/tools/llvm-lto2/llvm-lto2.cpp,
- three command line options are added so `llvm-lto2` can override
`Conf.HasWholeProgramVisibility`, `Conf.ValidateAllVtablesHaveTypeInfos`
and `Conf.AllVtablesHaveTypeInfos`.
The test case is reduced from a small C++ program (main.cc, lib.cc/h
pasted below in [1]). To reproduce the program failure without this
patch, compile lib.cc into a shared library, and provide it to a ThinLTO
build of main.cc (commands are pasted in [2]).
[1]
* lib.h
```
#include <cstdio>
class Derived {
public:
void dispatch();
virtual void print();
virtual void sum();
};
void Derived::dispatch() {
static_cast<Derived*>(this)->print();
static_cast<Derived*>(this)->sum();
}
void Derived::sum() {
printf("Derived::sum\n");
}
__attribute__((noinline)) void* create(int i);
__attribute__((noinline)) void* getPtr(int i);
```
* lib.cc
```
#include "lib.h"
#include <cstdio>
#include <iostream>
class Derived2 : public Derived {
public:
void print() override {
printf("DerivedSharedLib\n");
}
void sum() override {
printf("DerivedSharedLib::sum\n");
}
};
void Derived::print() {
printf("Derived\n");
}
__attribute__((noinline)) void* create(int i) {
if (i & 1)
return new Derived2();
return new Derived();
}
```
* main.cc
```
cat main.cc
#include "lib.h"
class DerivedN : public Derived {
public:
};
__attribute__((noinline)) void* getPtr(int x) {
return new DerivedN();
}
int main() {
Derived*b = static_cast<Derived*>(create(201));
b->dispatch();
delete b;
Derived* a = static_cast<Derived*>(getPtr(202));
a->dispatch();
delete a;
return 0;
}
```
[2]
```
# compile lib.o in a shared library.
$ ./bin/clang++ -O2 -fPIC -c lib.cc -o lib.o
$ ./bin/clang++ -shared -o libdata.so lib.o
# Provide the shared library in `-ldata`
$ ./bin/clang++ -v -g -ldata --save-temps -fno-discard-value-names -Wl,-mllvm,-print-before=wholeprogramdevirt -Wl,-mllvm,-wholeprogramdevirt-check=trap -Rpass=wholeprogramdevirt -Wl,--lto-whole-program-visibility -Wl,--lto-validate-all-vtables-have-type-infos -mllvm -disable-icp=true -Wl,-mllvm,-disable-icp=false -flto=thin -fwhole-program-vtables -fno-split-lto-unit -fuse-ld=lld main.cc -L . -o main >/tmp/wholeprogramdevirt.ir 2>&1
# Run the program hits a segmentation fault with `-Wl,-mllvm,-wholeprogramdevirt-check=trap`
$ LD_LIBRARY_PATH=. ./main
DerivedSharedLib
Trace/breakpoint trap (core dumped)
```
|
|
Preparation for CFI Index refactoring,
which will fix O(N^2) in ThinLTO indexing.
|
|
The module currently stores the target triple as a string. This means
that any code that wants to actually use the triple first has to
instantiate a Triple, which is somewhat expensive. The change in #121652
caused a moderate compile-time regression due to this. While it would be
easy enough to work around, I think that architecturally, it makes more
sense to store the parsed Triple in the module, so that it can always be
directly queried.
For this change, I've opted not to add any magic conversions between
std::string and Triple for backwards-compatibilty purses, and instead
write out needed Triple()s or str()s explicitly. This is because I think
a decent number of them should be changed to work on Triple as well, to
avoid unnecessary conversions back and forth.
The only interesting part in this patch is that the default triple is
Triple("") instead of Triple() to preserve existing behavior. The former
defaults to using the ELF object format instead of unknown object
format. We should fix that as well.
|
|
Add `Intrinsic::getDeclarationIfExists` to lookup an existing
declaration of an intrinsic in a `Module`.
|
|
Rounds (#90933)
|
|
This feature is enabled by `-codegen-data-thinlto-two-rounds`, which
effectively runs the `-codegen-data-generate` and `-codegen-data-use` in
two rounds to enable global outlining with ThinLTO.
1. The first round: Run both optimization + codegen with a scratch
output.
Before running codegen, we serialize the optimized bitcode modules to a
temporary path.
2. From the scratch object files, we merge them into the codegen data.
3. The second round: Read the optimized bitcode modules and start the
codegen only this time.
Using the codegen data, the machine outliner effectively performs the
global outlining.
Depends on #90934, #110461 and #110463.
This is a patch for
https://discourse.llvm.org/t/rfc-enhanced-machine-outliner-part-2-thinlto-nolto/78753.
|
|
This is a prep for https://github.com/llvm/llvm-project/pull/90933.
- Change `ThinBackend` from a function to a type.
- Store the parallelism level in the type, which will be used when creating two-codegen round backends that inherit this value.
- `ThinBackendProc` is hoisted to `LTO.h` from `LTO.cpp` to provide its body for `ThinBackend`. However, `emitFiles()` is still implemented separately in `LTO.cpp`, distinct from its parent class.
|
|
We've noticed that for large builds executing thin-link can take on the
order of 10s of minutes. We are only using a single thread to write the
sharded indices and import files for each input bitcode file. While we
need to ensure the index file produced lists modules in a deterministic
order, that doesn't prevent us from executing the rest of the work in
parallel.
In this change we use a thread pool to execute as much of the backend's
work as possible in parallel. In local testing on a machine with 80
cores, this change makes a thin-link for ~100,000 input files run in ~2
minutes. Without this change it takes upwards of 10 minutes.
---------
Co-authored-by: Nuri Amari <nuriamari@fb.com>
|
|
This is a prep for https://github.com/llvm/llvm-project/pull/90933.
- Change `FileCache` from a function to a type.
- Store the cache directory in the type, which will be used when creating additional caches for two-codegen round runs that inherit this value.
|
|
This is NFC for https://github.com/llvm/llvm-project/pull/90933.
- Create a lambda function, `RunBackends`, to group the backend
operations into a single function.
- Explicitly pass the `CodeGenOnly` argument to thinBackend, instead of
depending on a configuration value.
Depends on https://github.com/llvm/llvm-project/pull/90304.
This is a patch for
https://discourse.llvm.org/t/rfc-enhanced-machine-outliner-part-2-thinlto-nolto/78753.
|
|
clangd reports these as unused headers. My manual inspection agrees
with the findings.
|
|
resolution in ELF" (#107792)
Fix the use-after-free bug and re-apply
https://github.com/llvm/llvm-project/pull/106193
* Without the fix, the string referenced by `objSym.Name` could be
destroyed even if string saver keeps a copy of the referenced string.
This caused use-after-free.
* The fix ([latest
commit](https://github.com/llvm/llvm-project/pull/107792/commits/9776ed44cfb26172480145aed8f59ba78a6fa2ea))
updates `objSym.Name` to reference (via `StringRef`) the string saver's
copy.
Test:
1. For `lld/test/ELF/lto/asmundef.ll`, its test failure is reproducible
with `-DLLVM_USE_SANITIZER=Address` and gone with the fix.
3. Run all tests by following
https://github.com/google/sanitizers/wiki/SanitizerBotReproduceBuild#try-local-changes.
* Without the fix, `ELF/lto/asmundef.ll` aborted the multi-stage test at
`@@@BUILD_STEP stage2/asan_ubsan check@@@`, defined
[here](https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/sanitizers/buildbot_fast.sh#L30)
* With the fix, the [multi-stage
test](https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/sanitizers/buildbot_fast.sh)
pass stage2 {asan, ubsan, masan}. This is also the test used by
https://lab.llvm.org/buildbot/#/builders/169
**Original commit message**
`StringMap<T>` creates a [copy of the
string](https://github.com/llvm/llvm-project/blob/d4c519e7b2ac21350ec08b23eda44bf4a2d3c974/llvm/include/llvm/ADT/StringMapEntry.h#L55-L58)
for entry insertions and intentionally keep copies [since the
implementation optimizes string memory
usage](https://github.com/llvm/llvm-project/blob/d4c519e7b2ac21350ec08b23eda44bf4a2d3c974/llvm/include/llvm/ADT/StringMap.h#L124).
On the other hand, linker keeps copies of symbol names [1] in
`lld::elf::parseFiles` [2] before invoking `compileBitcodeFiles` [3].
This change proposes to optimize away string copies inside
[LTO::GlobalResolutions](https://github.com/llvm/llvm-project/blob/24e791b4164986a1ca7776e3ae0292ef20d20c47/llvm/include/llvm/LTO/LTO.h#L409),
which will make LTO indexing more memory efficient for ELF. There are
similar opportunities for other (COFF, wasm, MachO) formats.
The optimization takes place for lld (ELF) only. For the rest of use
cases (gold plugin, `llvm-lto2`, etc), LTO owns a string saver to keep
copies and use global resolution key for de-duplication.
Together with @kazutakahirata's work to make `ComputeCrossModuleImport`
more memory efficient, we see a ~20% peak memory usage reduction in a
binary where peak memory usage needs to go down. Thanks to the
optimization in
https://github.com/llvm/llvm-project/commit/329ba523ccbbe68a12434926c92fd9a86494d958,
the max (as opposed to the sum) of `ComputeCrossModuleImport` or
`GlobalResolution` shows up in peak memory usage.
* Regarding correctness, the set of
[resolved](https://github.com/llvm/llvm-project/blob/80c47ad3aec9d7f22e1b1bdc88960a91b66f89f1/llvm/lib/LTO/LTO.cpp#L739)
[per-module
symbols](https://github.com/llvm/llvm-project/blob/80c47ad3aec9d7f22e1b1bdc88960a91b66f89f1/llvm/include/llvm/LTO/LTO.h#L188-L191)
is a subset of
[llvm::lto::InputFile::Symbols](https://github.com/llvm/llvm-project/blob/80c47ad3aec9d7f22e1b1bdc88960a91b66f89f1/llvm/include/llvm/LTO/LTO.h#L120).
And bitcode symbol parsing saves symbol name when iterating
`obj->symbols` in `BitcodeFile::parse` already. This change updates
`BitcodeFile::parseLazy` to keep copies of per-module undefined symbols.
* Presumably the undefined symbols in a LTO unit (copied in this patch
in linker unique saver) is a small set compared with the set of symbols
in global-resolution (copied before this patch), making this a
worthwhile trade-off. Benchmarking this change alone shows measurable
memory savings across various benchmarks.
[1] ELF
https://github.com/llvm/llvm-project/blob/1cea5c2138bef3d8fec75508df6dbb858e6e3560/lld/ELF/InputFiles.cpp#L1748
[2]
https://github.com/llvm/llvm-project/blob/ef7b18a53c0d186dcda1e322be6035407fdedb55/lld/ELF/Driver.cpp#L2863
[3]
https://github.com/llvm/llvm-project/blob/ef7b18a53c0d186dcda1e322be6035407fdedb55/lld/ELF/Driver.cpp#L2995
|
|
resolution in ELF" (#107788)
Reverts llvm/llvm-project#106193 while investigating bot failures
https://lab.llvm.org/buildbot/#/builders/169/builds/2989/steps/9/logs/stdio
|
|
ELF (#106193)
`StringMap<T>` creates a [copy of the
string](https://github.com/llvm/llvm-project/blob/d4c519e7b2ac21350ec08b23eda44bf4a2d3c974/llvm/include/llvm/ADT/StringMapEntry.h#L55-L58)
for entry insertions and intentionally keep copies [since the
implementation optimizes string memory
usage](https://github.com/llvm/llvm-project/blob/d4c519e7b2ac21350ec08b23eda44bf4a2d3c974/llvm/include/llvm/ADT/StringMap.h#L124).
On the other hand, linker keeps copies of symbol names [1] in
`lld::elf::parseFiles` [2] before invoking `compileBitcodeFiles` [3].
This change proposes to optimize away string copies inside
[LTO::GlobalResolutions](https://github.com/llvm/llvm-project/blob/24e791b4164986a1ca7776e3ae0292ef20d20c47/llvm/include/llvm/LTO/LTO.h#L409),
which will make LTO indexing more memory efficient for ELF. There are
similar opportunities for other (COFF, wasm, MachO) formats.
The optimization takes place for lld (ELF) only. For the rest of use
cases (gold plugin, `llvm-lto2`, etc), LTO owns a string saver to keep
copies and use global resolution key for de-duplication.
Together with @kazutakahirata's work to make `ComputeCrossModuleImport`
more memory efficient, we see a ~20% peak memory usage reduction in a
binary where peak memory usage needs to go down. Thanks to the
optimization in
https://github.com/llvm/llvm-project/commit/329ba523ccbbe68a12434926c92fd9a86494d958,
the max (as opposed to the sum) of `ComputeCrossModuleImport` or
`GlobalResolution` shows up in peak memory usage.
* Regarding correctness, the set of
[resolved](https://github.com/llvm/llvm-project/blob/80c47ad3aec9d7f22e1b1bdc88960a91b66f89f1/llvm/lib/LTO/LTO.cpp#L739)
[per-module
symbols](https://github.com/llvm/llvm-project/blob/80c47ad3aec9d7f22e1b1bdc88960a91b66f89f1/llvm/include/llvm/LTO/LTO.h#L188-L191)
is a subset of
[llvm::lto::InputFile::Symbols](https://github.com/llvm/llvm-project/blob/80c47ad3aec9d7f22e1b1bdc88960a91b66f89f1/llvm/include/llvm/LTO/LTO.h#L120).
And bitcode symbol parsing saves symbol name when iterating
`obj->symbols` in `BitcodeFile::parse` already. This change updates
`BitcodeFile::parseLazy` to keep copies of per-module undefined symbols.
* Presumably the undefined symbols in a LTO unit (copied in this patch
in linker unique saver) is a small set compared with the set of symbols
in global-resolution (copied before this patch), making this a
worthwhile trade-off. Benchmarking this change alone shows measurable
memory savings across various benchmarks.
[1] ELF
https://github.com/llvm/llvm-project/blob/1cea5c2138bef3d8fec75508df6dbb858e6e3560/lld/ELF/InputFiles.cpp#L1748
[2]
https://github.com/llvm/llvm-project/blob/ef7b18a53c0d186dcda1e322be6035407fdedb55/lld/ELF/Driver.cpp#L2863
[3]
https://github.com/llvm/llvm-project/blob/ef7b18a53c0d186dcda1e322be6035407fdedb55/lld/ELF/Driver.cpp#L2995
|
|
synthetic count passes. (#107471)
The primary motivation is to remove `EntryCount` from `FunctionSummary`.
This frees 8 bytes out of `sizeof(FunctionSummary)` (136 bytes as of
https://github.com/llvm/llvm-project/commit/64498c54831bed9cf069e0923b9b73678c6451d8).
While I'm at it, this PR clean up {SummaryBasedOptimizations,
SyntheticCountsPropagation} since they were not used and there are no
plans to further invest on them.
With this patch, bitcode writer writes a placeholder 0 at the byte
offset of `EntryCount` and bitcode reader can parse the function entry
count at the correct byte offset. Added a TODO to stop writing
`EntryCount` and bump bitcode version
|
|
Nothing went wrong in this case, we just successfully matched a module
by identifier. No need to print to std::error like we would for
something that should be user-visible.
Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>
|
|
This patch reduces the memory usage for import lists by employing
memory-efficient data structures.
With this patch, an import list for a given destination module is
basically DenseSet<uint32_t> with each element indexing into the
deduplication table containing tuples of:
{SourceModule, GUID, Definition/Declaration}
In one of our large applications, the peak memory usage goes down by
9.2% from 6.120GB to 5.555GB during the LTO indexing step.
This patch addresses several sources of space inefficiency associated
with std::unordered_map:
- std::unordered_map<GUID, ImportKind> takes up 16 bytes because of
padding even though ImportKind only carries one bit of information.
- std::unordered_map uses pointers to elements, both in the hash table
proper and for collision chains.
- We allocate an instance of std::unordered_map for each
{Destination Module, Source Module} pair for which we have at least
one import. Most import lists have less than 10 imports, so the
metadata like the size of std::unordered_map and the pointer to the
hash table costs a lot relative to the actual contents.
|
|
The background is as follows. I'm planning to reduce the memory
footprint of ThinLTO indexing by changing ImportMapTy, the data
structure used for an import list. Once this patch lands, I'm
planning to change the type slightly. The new type alias allows us to
update the type without touching many places.
|
|
This patch introduces type alias ModuleToSummariesForIndexTy.
I'm planning to change the type slightly to allow heterogeneous lookup
(that is, std::map<K, V, std::less<>>) in a subsequent patch. The
problem is that changing the type affects many places. Using a type
alias reduces the impact.
|
|
This patch turns type alias ImportMapTy into a proper class to provide
a more intuitive interface like:
ImportList.addDefinition(...)
as opposed to:
FunctionImporter::addDefinition(ImportList, ...)
Also, this patch requires all non-const accesses to go through
addDefinition, maybeAddDeclaration, and addGUID while providing const
accesses via:
const ImportMapTyImpl &getImportMap() const { return ImportMap; }
I realize ImportMapTy may not be the best name as a class (maybe OK as
a type alias). I am not renaming ImportMapTy in this patch at least
because there are 47 mentions of ImportMapTy under llvm/.
|
|
|
|
The two instances of std::set are used only for membership checking
purposes in computeLTOCacheKey. We do not need std::set's strengths
like iterators staying valid or the ability to traverse in a sorted
order. This patch changes them to DenseSet.
While I am at it, this patch replaces count with contains for slightly
increased readability.
|
|
Without this patch, computeLTOCacheKey computes SHA1, creates its
hexadecimal representation with toHex, which returns std::string, and
then copies it to an output parameter of type SmallString.
This patch removes the redirection and teaches computeLTOCacheKey to
directly return std::string computed by toHex. With the move
semantics, no buffer copy should be involved.
While I am at it, this patch adds a Twine to concatenate two strings.
|
|
(#98512)"
This reverts commit 740161a9b98c9920dedf1852b5f1c94d0a683af5.
I moved the `ISD` dependencies into the CodeGen portion of the handling,
it's a little awkward but it's the easiest solution I can think of for
now.
|
|
|
|
(#98512)"
This reverts commit c05126bdfc3b02daa37d11056fa43db1a6cdef69.
(llvmorg-19-init-17714-gc05126bdfc3b)
See #99610
|
|
Summary:
The LTO pass and LLD linker have logic in them that forces extraction
and prevent internalization of needed runtime calls. However, these
currently take all RTLibcalls into account, even if the target does not
support them. The target opts-out of a libcall if it sets its name to
nullptr. This patch pulls this logic out into a class in the header so
that LTO / lld can use it to determine if a symbol actually needs to be
kept.
This is important for targets like AMDGPU that want to be able to use
`lld` to perform the final link step, but does not want the overhead of
uncalled functions. (This adds like a second to the link time trivially)
|
|
https://github.com/llvm/llvm-project/pull/87600 was reverted in order to
revert
https://github.com/llvm/llvm-project/commit/6262763341fcd71a2b0708cf7485f9abd1d26ba8.
Now https://github.com/llvm/llvm-project/pull/95482 is fix forward for
https://github.com/llvm/llvm-project/commit/6262763341fcd71a2b0708cf7485f9abd1d26ba8.
This patch is a reland for
https://github.com/llvm/llvm-project/pull/87600
**Changes on top of original patch**
In `llvm/include/llvm/IR/ModuleSummaryIndex.h`, make the type of
`GVSummaryPtrSet` an `unordered_set` which is more memory efficient when
the number of elements is smaller than 128 [1]
**Original commit message**
For distributed ThinLTO, the LTO indexing step generates combined
summary for each module, and postlink pipeline reads the combined
summary which stores the information for link-time optimization.
This patch populates the 'import type' of a summary in bitcode, and
updates bitcode reader to parse the bit correctly.
[1]
https://github.com/llvm/llvm-project/blob/393eff4e02e7ab3d234d246a8d6912c8e745e6f9/llvm/lib/Support/SmallPtrSet.cpp#L43
|
|
https://github.com/llvm/llvm-project/pull/95482 is a reland of
https://github.com/llvm/llvm-project/pull/88024.
https://github.com/llvm/llvm-project/pull/95482 keeps indexing memory
usage reasonable by using unordered_map and doesn't make other changes
to originally reviewed code.
While discussing possible ways to minimize indexing memory usage, Teresa
asked whether I need `ExportSetTy` as a map or a set is sufficient. This
PR implements the idea. It uses a set rather than a map to track exposed
ValueInfos.
Currently, `ExportLists` has two use cases, and neither needs to track a
ValueInfo's import/export status. So using a set is sufficient and
correct.
1) In both in-process and distributed ThinLTO, it's used to decide if a
function or global variable is visible [1] from another module after importing
creates additional cross-module references.
* If a cross-module call edge is seen today, the callee must be visible
to another module without keeping track of its export status already.
For instance, this [2] is how callees of direct calls get exported.
2) For in-process ThinLTO [3], it's used to compute lto cache key.
* The cache key computation already hashes [4] 'ImportList' , and 'ExportList' is
determined by 'ImportList'. So it's fine to not track 'import type' for export list.
[1] https://github.com/llvm/llvm-project/blob/66cd8ec4c08252ebc73c82e4883a8da247ed146b/llvm/lib/LTO/LTO.cpp#L1815-L1819
[2] https://github.com/llvm/llvm-project/blob/66cd8ec4c08252ebc73c82e4883a8da247ed146b/llvm/lib/LTO/LTO.cpp#L1783-L1794
[3] https://github.com/llvm/llvm-project/blob/66cd8ec4c08252ebc73c82e4883a8da247ed146b/llvm/lib/LTO/LTO.cpp#L1494-L1496
[4] https://github.com/llvm/llvm-project/blob/b76100e220591fab2bf0a4917b216439f7aa4b09/llvm/lib/LTO/LTO.cpp#L194-L222
|
|
ThinLTO under a default-off new option" (#95482)
Make `FunctionsToImportTy` an `unordered_map` rather than `DenseMap`.
Credit goes to jvoung@ for the 'DenseMap -> unordered_map' change. This
is a reland of https://github.com/llvm/llvm-project/pull/92718
* `DenseMap` allocates space for a large number of key/value pairs and
wastes space when the number of elements are small.
* While init bucket size is zero [1], it quickly allocates buckets for 64 elements [2]
when the number of elements is small (for example, 3 or 4 elements). The programmer
manual [3] also mentions it could waste space.
* Experiments show `FunctionsToImportTy.size()` is smaller than 4 for
multiple binaries with high indexing ram usage. `unordered_map` grows
factor is at most 2 in llvm libc [4] for insert operations.
With this change, `ComputeCrossModuleImport` ram increase is smaller
than 0.5G on a couple of binaries with high indexing ram usage. A wider
range of (pre-release) tests pass.
[1] https://github.com/llvm/llvm-project/blob/ad79a14c9e5ec4a369eed4adf567c22cc029863f/llvm/include/llvm/ADT/DenseMap.h#L431-L432
[2] https://github.com/llvm/llvm-project/blob/ad79a14c9e5ec4a369eed4adf567c22cc029863f/llvm/include/llvm/ADT/DenseMap.h#L849
[3] https://llvm.org/docs/ProgrammersManual.html#llvm-adt-densemap-h
[4] https://github.com/llvm/llvm-project/blob/ad79a14c9e5ec4a369eed4adf567c22cc029863f/libcxx/include/__hash_table#L1525-L1526
**Original commit message**
The goal is to populate `declaration` import status if a new flag
`-import-declaration` is on.
* For in-process ThinLTO, the `declaration` status is visible to backend
`function-import` pass, so `FunctionImporter::importFunctions` should
read the import status and be no-op for declaration summaries.
Basically, the postlink pipeline is updated to keep its current behavior
(import definitions), but not updated to handle `declaration` summaries.
Two use cases ([better call-graph
sort](https://discourse.llvm.org/t/rfc-for-better-call-graph-sort-build-a-more-complete-call-graph-by-adding-more-indirect-call-edges/74029#support-cross-module-function-declaration-import-5)
or [cross-module
auto-init](https://github.com/llvm/llvm-project/pull/87597#discussion_r1556067195))
would use this bit differently.
* For distributed ThinLTO, the `declaration` status is not serialized to
bitcode. As discussed, https://github.com/llvm/llvm-project/pull/87600
will do this.
|
