Changes

[X86] Fix tile register spill issue.

The tile register spill need 2 instructions.
%46:gr64_nosp = MOV64ri 64
TILESTORED %stack.2, 1, killed %46:gr64_nosp, 0, $noreg, %43:tile
The first instruction load the stride to a GPR, and the second
instruction store tile register to stack slot. The optimization of merge
spill instruction is done after register allocation. And spill tile
register need create a new virtual register to for stride, so we can't
hoist tile spill instruction in postOptimization() of register
allocation. We can't hoist TILESTORED alone and we can't hoist the 2
instuctions together because MOV64ri will clobber some GPR. This patch
is to disble the spill merge for any spill which need 2 instructions.

Differential Revision: https://reviews.llvm.org/D93898

Require chained analyses in BasicAA and AAResults to be transitive

This patch fixes a bug that could result in miscompiles (at least
in an OOT target). The problem could be seen by adding checks that
the DominatorTree used in BasicAliasAnalysis and ValueTracking was
valid (e.g. by adding DT->verify() call before every DT dereference
and then running all tests in test/CodeGen).

Problem was that the LegacyPassManager calculated "last user"
incorrectly for passes such as the DominatorTree when not telling
the pass manager that there was a transitive dependency between
the different analyses. And then it could happen that an incorrect
dominator tree was used when doing alias analysis (which was a pretty
serious bug as the alias analysis result could be invalid).

Fixes: https://bugs.llvm.org/show_bug.cgi?id=48709

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D94138

[SVE][CodeGen] Fix legalisation of floating-point masked gathers

Changes in this patch:
- When lowering floating-point masked gathers, cast the result of the
  gather back to the original type with reinterpret_cast before returning.
- Added patterns for reinterpret_casts from integer to floating point, and
  concat_vector patterns for bfloat16.
- Tests for various legalisation scenarios with floating point types.

Reviewed By: sdesmalen, david-arm

Differential Revision: https://reviews.llvm.org/D94171

Revert rGd43a264a5dd3 "Revert "[X86][SSE] Fold unpack(hop(),hop()) -> permute(hop())""

This reapplies commit rG80dee7965dffdfb866afa9d74f3a4a97453708b2.

[X86][SSE] Fold unpack(hop(),hop()) -> permute(hop())

UNPCKL/UNPCKH only uses one op from each hop, so we can merge the hops and then permute the result.

REAPPLIED with a fix for unary unpacks of HOP.

[X86][SSE] Add missing SSE test coverage for permute(hop,hop) folds

Should help avoid bugs like reported in rG80dee7965dff

[VE] Support intrinsic to isnert/extract_subreg of v512i1

Support insert/extract_subreg intrinsic instructions for v512i1
registers and add regression tests.

Reviewed By: simoll

Differential Revision: https://reviews.llvm.org/D94298

[VE] Support additional VMRGW and VMV intrinsic instructions

Support missing VMRGW and VMV intrinsic instructions and add regression
tests.

Reviewed By: simoll

Differential Revision: https://reviews.llvm.org/D94300

[obj2yaml] - Fix the crash in getUniquedSectionName().

`getUniquedSectionName(const Elf_Shdr *Sec)` assumes that
`Sec` is not `nullptr`.

I've found one place in `getUniquedSymbolName` where it is
not true (because of that we crash when trying to dump
unnamed null section symbols).

Patch fixes the crash and changes the signature of the
`getUniquedSectionName` section to accept a reference.

Differential revision: https://reviews.llvm.org/D93754

[clang][AArch64][SVE] Avoid going through memory for coerced VLST return values

VLST return values are coerced to VLATs in the function epilog for
consistency with the VLAT ABI. Previously, this coercion was done
through memory. It is preferable to use the
llvm.experimental.vector.insert intrinsic to avoid going through memory
here.

Reviewed By: c-rhodes

Differential Revision: https://reviews.llvm.org/D94290

[llvm-readelf/obj] - Index phdrs and relocations from 0 when reporting warnings.

As was mentioned in comments here:
https://reviews.llvm.org/D92636#inline-864967

we are not consistent and sometimes index things from 0, but sometimes
from 1 in warnings.

This patch fixes 2 places: messages reported for
program headers and messages reported for relocations.

Differential revision: https://reviews.llvm.org/D93805

[VPlan] Move initial quote emission from ::print to ::dumpBasicBlock.

This means there will be no stray " when printing individual recipes
using print()/dump() in a debugger, for example.

[obj2yaml][test] - Improve and fix section-group.yaml test.

It has multiple issues fixed by this patch:
1) It shouldn't test how llvm-readelf/yaml2obj works.
2) It should use "-NEXT" prefix for check lines.
3) It can use YAML macros, that allows to use a single YAML.
4) It should probably test the case when a group member is a null section.

Differential revision: https://reviews.llvm.org/D93753