The 256-bit maximum vector register size control was removed from AVX10
whitepaper, ref: https://cdrdv2.intel.com/v1/dl/getContent/784343

We have warned these options in LLVM21 through #132542. This patch
removes underlying implementations in LLVM22.

Let Clang emit `dead_on_return` attribute on pointer arguments
that are passed indirectly, namely, large aggregates that the
ABI mandates be passed by value; thus, the parameter is destroyed
within the callee. Writes to such arguments are not observable by
the caller after the callee returns.

This should desirably enable further MemCpyOpt/DSE optimizations.

Previous discussion: https://discourse.llvm.org/t/rfc-add-dead-on-return-attribute/86871.

Set the writable and dead_on_unwind attributes for sret arguments. These
indicate that the argument points to writable memory (and it's legal to
introduce spurious writes to it on entry to the function) and that the
argument memory will not be used if the call unwinds.

This enables additional MemCpyOpt/DSE/LICM optimizations.

This is an alternative of D157485 and a pre-feature to support AVX10.

AVX10 Architecture Specification: https://cdrdv2.intel.com/v1/dl/getContent/784267
AVX10 Technical Paper: https://cdrdv2.intel.com/v1/dl/getContent/784343
RFC: https://discourse.llvm.org/t/rfc-design-for-avx10-feature-support/72661

Based on the feedbacks from LLVM and GCC community, we have agreed to
start from supporting `-m[no-]evex512` on existing AVX512 features.
The option `-mno-evex512` can be used with `-mavx512xxx` to build
binaries that can run on both legacy AVX512 targets and AVX10-256.

There're still arguments about what's the expected behavior when this
option as well as `-mavx512xxx` used together with `-mavx10.1-256`. We
decided to defer the support of `-mavx10.1` after we made consensus.
Or furthermore, we start from supporting AVX10.2 and not providing any
AVX10.1 options.

Reviewed By: RKSimon, skan

Differential Revision: https://reviews.llvm.org/D159250

This reverts commit 7dd48cc24de2d54d40527432cbee8a9d97a8a4f7.

Causing buildbot failure.

This is an alternative of D157485 and a pre-feature to support AVX10.

AVX10 Architecture Specification: https://cdrdv2.intel.com/v1/dl/getContent/784267
AVX10 Technical Paper: https://cdrdv2.intel.com/v1/dl/getContent/784343
RFC: https://discourse.llvm.org/t/rfc-design-for-avx10-feature-support/72661

Based on the feedbacks from LLVM and GCC community, we have agreed to
start from supporting `-m[no-]evex512` on existing AVX512 features.
The option `-mno-evex512` can be used with `-mavx512xxx` to build
binaries that can run on both legacy AVX512 targets and AVX10-256.

There're still arguments about what's the expected behavior when this
option as well as `-mavx512xxx` used together with `-mavx10.1-256`. We
decided to defer the support of `-mavx10.1` after we made consensus.
Or furthermore, we start from supporting AVX10.2 and not providing any
AVX10.1 options.

Reviewed By: RKSimon, skan

Differential Revision: https://reviews.llvm.org/D159250

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.

Conversion performed using the script at:
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34

These are only tests where no manual fixup was required.

This adds -no-opaque-pointers to clang tests whose output will
change when opaque pointers are enabled by default. This is
intended to be part of the migration approach described in
https://discourse.llvm.org/t/enabling-opaque-pointers-by-default/61322/9.

The patch has been produced by replacing %clang_cc1 with
%clang_cc1 -no-opaque-pointers for tests that fail with opaque
pointers enabled. Worth noting that this doesn't cover all tests,
there's a remaining ~40 tests not using %clang_cc1 that will need
a followup change.

Differential Revision: https://reviews.llvm.org/D123115

Currently, the regcall calling conversion in Clang doesn't match with
ICC when passing / returning structures. https://godbolt.org/z/axxKMKrW7

This patch tries to fix the problem to match with ICC.

Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D122104