These cannot be detected by reading the ID_AA64ISAR1_EL1 register since
their corresponding bitfields are hidden. Additionally the instructions
that these features enable are unusable from EL0.
ACLE: https://github.com/ARM-software/acle/pull/382
Currently we need at least one more version other than the default to
trigger FMV. However we would like a header file declaration
__attribute__((target_version("default"))) void f(void);
to guarantee that there will be f.default
According to the Arm Architecture Reference Manual for A-profile
architecture you can't have one feature without having the other:
ID_AA64ZFR0_EL1.AES, bits [7:4]
> FEAT_SVE_AES implements the functionality identified by the value
0b0001.
> FEAT_SVE_PMULL128 implements the functionality identified by the value
0b0010.
> The permitted values are 0b0000 and 0b0010.
(The following was removed from the latest release of the specification,
but it appears to be a mistake that was not intended to relax the
architecture constraints. The discrepancy has been reported)
ID_AA64ISAR0_EL1.AES, bits [7:4]
> FEAT_AES implements the functionality identified by the value 0b0001.
> FEAT_PMULL implements the functionality identified by the value
0b0010.
> From Armv8, the permitted values are 0b0000 and 0b0010.
Approved in ACLE as https://github.com/ARM-software/acle/pull/352
Fixes a crash and cleans up some dead code.
namespace Foo {
int bar();
__attribute((target_version("default"))) int bar() { return 0; }
__attribute((target_version("mops"))) int bar() { return 1; }
}
$ clang++ --target=aarch64-linux-gnu --rtlib=compiler-rt fmv.cpp
None multiversion type isn't valid here
UNREACHABLE executed at clang/lib/CodeGen/CodeGenModule.cpp:1840! ...
getMangledNameImpl
clang::CodeGen::CodeGenModule::getMangledName
clang::CodeGen::CodeGenModule::EmitGlobal
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.
On AArch64 for function multiversioning target_version/target_clones
attributes should be used. The patch fixes the defect allowing target
attribute to cause multiversioning.
Differential Revision: https://reviews.llvm.org/D150867
This reverts commit e43924a75145d2f9e722f74b673145c3e62bfd07.
Reason: Patch broke the MSan buildbots. More information is available on
the original phabricator review: https://reviews.llvm.org/D127812
