We have a dedicated test to check the target-features for FMV
(clang/test/CodeGen/aarch64-fmv-dependencies.c) therefore I am removing
the autogenerated checks from irrelevant tests since the noise is making
it harder to review actual codegen changes.
It was raised in https://github.com/llvm/llvm-project/issues/81494 that
we are not generating correct code when there is no TU-local caller.
The suggestion was to emit a resolver:
* Whenever there is a use in the TU.
* When the TU has a definition of the default version.
See the comment for more details:
https://github.com/llvm/llvm-project/issues/81494#issuecomment-1985963497
This got addressed with https://github.com/llvm/llvm-project/pull/84405.
Generating a resolver on use means that we may end up with multiple
resolvers across different translation units. Those resolvers may not be
the same because each translation unit may contain different version
declarations (user's fault). Therefore the order of linking the final
image determines which of these weak symbols gets selected, resulting in
non consisted behavior. I am proposing to stop emitting a resolver on
use and only do so in the translation unit which contains the default
definition. This way we guarantee the existence of a single resolver.
Now, when a versioned function is used we want to emit a declaration of
the function symbol omitting the multiversion mangling.
I have added a requirement to ACLE mandating that all the function
versions are declared in the translation unit which contains the default
definition: https://github.com/ARM-software/acle/pull/328
Long story short the interaction of two optimizations happening in
GlobalOpt results in a crash. For more details look at the issue
https://github.com/llvm/llvm-project/issues/96197. I will be fixing this
in GlobalOpt but it is a conservative solution since it won't allow us
to optimize resolvers which return a pointer to a function whose
definition is in another TU when compiling without LTO:
```
__attribute__((target_version("simd"))) void bar(void);
__attribute__((target_version("default"))) void bar(void);
int foo() { bar(); }
```
fixes: #96197
Reverts llvm/llvm-project#88965
This caused a test suite failure:
https://lab.llvm.org/buildbot/#/builders/185/builds/6583
NOEXE: test-suite::aarch64-acle-fmv-features.test
```
/home/tcwg-buildbot/worker/clang-aarch64-lld-2stage/test/test-suite/SingleSource/UnitTests/AArch64/acle-fmv-features.c:98:1: error: redefinition of 'check_sha1'
98 | CHECK(sha1, {
| ^
/home/tcwg-buildbot/worker/clang-aarch64-lld-2stage/test/test-suite/SingleSource/UnitTests/AArch64/acle-fmv-features.c:36:17: note: expanded from macro 'CHECK'
36 | static void check_##X(void) { \
| ^
<scratch space>:150:1: note: expanded from here
150 | check_sha1
| ^
```
I presume that the useless features need to be removed from the fmv test
as well.
As explained in https://github.com/ARM-software/acle/pull/315 we
are deprecating features which aren't adding any value. These are:
sha1, pmull, dit, dgh, ebf16, sve-bf16, sve-ebf16, sve-i8mm,
sve2-pmull128, memtag2, memtag3, ssbs2, bti, ls64_v, ls64_accdata
This was a limitation which has now been lifted. Please read the
thread below for more details:
https://github.com/llvm/llvm-project/pull/84405#discussion_r1525583647
Basically it allows to separate versioned implementations across
different TUs without having to share private header files which
contain the default declaration.
The ACLE spec has been updated accordingly to make this explicit:
"Each version declaration should be visible at the translation
unit in which the corresponding function version resides."
https://github.com/ARM-software/acle/pull/310
If a resolver is required (because there is a caller in the TU),
then a default declaration is implicitly generated.
…ion.
This was reverted because the resolver didn't look as expected in one of
the tests. I believe it had some interaction with #84146. I have now
regenerated it using -target-feature -fp-armv8.
Reverts llvm/llvm-project#84405
In between of passing the precommit tests on github and being merged
some change (perhaps in the AArch64 backend?) landed which resulted
in altering the generated resolver. I will regenerate the tests
perhaps using a less sensitive runline to such changes.
We would like the resolver to be generated eagerly, even if the
versioned function is not called from the current translation
unit. Fixes#81494. It further allows Multi Versioning to work
even if the default target version attribute is omitted from
function declarations.
This decouples feature priorities from name mangling. Doing so will
prevent ABI breakages in case we change the feature priorities.
Formalized in ACLE here: https://github.com/ARM-software/acle/pull/303.
AArch64 part of https://github.com/llvm/llvm-project/pull/71706.
Default version is now mangled with .default.
Resolver for the TargetVersion need to be emitted from the
CodeGenModule::EmitMultiVersionFunctionDefinition.
The patch fixes Function Multi Versioning features detection by ifunc
resolver on Android API levels < 30.
Ifunc hwcaps parameters are not supported on Android API levels 23-29,
so all CPU features are set unsupported if they were not initialized
before ifunc resolver call.
There is no support for ifunc on Android API levels < 23, so Function
Multi Versioning is disabled in this case.
Also use two underscore prefix for FMV runtime support functions to
avoid conflict with user program ones.
Differential Revision: https://reviews.llvm.org/D158641
This is the default behavior and cuts down on attribute spam.
Probably should also do something to consolidate the option spellings;
printing and parsing it is repeated in at least 3 different places.
In the OpenMP tests, I had to manually delete some metadata check
lines update_cc_test_checks was inserting that included the local
build revision.
This reverts commit e43924a75145d2f9e722f74b673145c3e62bfd07.
Reason: Patch broke the MSan buildbots. More information is available on
the original phabricator review: https://reviews.llvm.org/D127812
