Changes

[lldb/DWARF] More DW_AT_const_value fixes

This fixes several issues in handling of DW_AT_const_value attributes:
- the first is that the size of the data given by data forms does not
  need to match the size of the underlying variable. We already had the
  case to handle this for DW_FORM_(us)data -- this extends the handling
  to other data forms. The main reason this was not picked up is because
  clang uses leb forms in these cases while gcc prefers the fixed-size
  ones.
- The handling of DW_AT_strp form was completely broken -- we would end
  up using the pointer value as the result. I've reorganized this code
  so that it handles all string forms uniformly.
- In case of a completely bogus form we would crash due to
  strlen(nullptr).

Depends on D86311.

Differential Revision: https://reviews.llvm.org/D86348

[obj2yaml] - Cleanup error reporting (remove Error.cpp/.h files)

This removes Error.cpp/.h files from obj2yaml.
These files are not needed because we are
using `Error`s instead of error codes widely and do
not need a logic related to obj2yaml specific
error codes anymore.

I had to adjust just a few lines of tool's code
to remove remaining dependencies.

Differential revision: https://reviews.llvm.org/D86536

Copy m_plan_is_for_signal_trap member.

Otherwise it would stay uninitialized. Found by msan.

[libunwind] Convert x86, x86_64, arm64 register restore functions to C calling convention and name mangling

Currently, the assembly functions for restoring register state have
been direct implementations of the Registers_*::jumpto() method
(contrary to the functions for saving register state, which are
implementations of the extern C function __unw_getcontext). This has
included having the assembly function name match the C++ mangling of
that method name (and having the function match the C++ member
function calling convention). To simplify the interface of the assembly
implementations, make the functions have C calling conventions and
name mangling.

This fixes building the library in with a MSVC C++ ABI with clang-cl,
which uses a significantly different method name mangling scheme.
(The library might not be of much use as C++ exception unwinder in such
an environment, but the libunwind.h interface for stepwise unwinding
still is usable, as is the _Unwind_Backtrace function.)

Differential Revision: https://reviews.llvm.org/D86041

[gn build] Port 357dc1ed125

[RDA] Don't visit the BB of the instruction in getReachingUniqueMIDef

If the basic block of the instruction passed to getUniqueReachingMIDef
is a transitive predecessor of itself and has a definition of the
register, the function will return that definition even if it is after
the instruction given to the function. This patch stops the function
from scanning the instruction's basic block to prevent this.

Differential Revision: https://reviews.llvm.org/D86607

[llvm-readobj/elf][test] - Add testing for EM_* specific OS/ABI values.

We have no tests for OS/ABI values specific to
EM_TI_C6000, ELFOSABI_AMDGPU_MESA3D and ELFOSABI_ARM machines.

Also, related arrays in the code are not grouped together.
(That is why such testing was missed I guess).

The patch fixes that all.

Differential revision: https://reviews.llvm.org/D86341

[llvm-readobj][test] - Commit trivial.obj.elf-amdhsa-gfx803 binary back.

It was removed in rGcbedbd12e9837e049f0a936636a82ff39b75692b by mistake.

[ARM] Increase MVE gather/scatter cost by MVECostFactor.

MVE Gather scatter codegeneration is looking a lot better than it used
to, but still has some issues. The instructions we currently model as 1
cycle per element, which is a bit low for some cases. Increasing the
cost by the MVECostFactor brings them in-line with our other instruction
costs. This will have the effect of only generating then when the extra
benefit is more likely to overcome some of the issues. Notably in
running out of registers and vectorizing loops that could otherwise be
SLP vectorized.

In the short-term whilst we look at other ways of dealing with those
more directly, we can increase the costs of gathers to make them more
likely to be beneficial when created.

Differential Revision: https://reviews.llvm.org/D86444

[llvm/Object] - Make dyn_cast<XCOFFObjectFile> work as it should.

Currently, `dyn_cast<XCOFFObjectFile>` always does cast and returns a pointer,
even when we pass `ELF`/`Wasm`/`Mach-O` or `COFF` instead of `XCOFF`.

It happens because `XCOFFObjectFile` class does not implement `classof`.
I've fixed it and added a unit test.

Differential revision: https://reviews.llvm.org/D86542

[mlir][PDL] Add a PDL Interpreter Dialect

The PDL Interpreter dialect provides a lower level abstraction compared to the PDL dialect, and is targeted towards low level optimization and interpreter code generation. The dialect operations encapsulates low-level pattern match and rewrite "primitives", such as navigating the IR (Operation::getOperand), creating new operations (OpBuilder::create), etc. Many of the operations within this dialect also fuse branching control flow with some form of a predicate comparison operation. This type of fusion reduces the amount of work that an interpreter must do when executing.

An example of this representation is shown below:

```mlir
// The following high level PDL pattern:
pdl.pattern : benefit(1) {
  %resultType = pdl.type
  %inputOperand = pdl.input
  %root, %results = pdl.operation "foo.op"(%inputOperand) -> %resultType
  pdl.rewrite %root {
    pdl.replace %root with (%inputOperand)
  }
}

// May be represented in the interpreter dialect as follows:
module {
  func @matcher(%arg0: !pdl.operation) {
    pdl_interp.check_operation_name of %arg0 is "foo.op" -> ^bb2, ^bb1
  ^bb1:
    pdl_interp.return
  ^bb2:
    pdl_interp.check_operand_count of %arg0 is 1 -> ^bb3, ^bb1
  ^bb3:
    pdl_interp.check_result_count of %arg0 is 1 -> ^bb4, ^bb1
  ^bb4:
    %0 = pdl_interp.get_operand 0 of %arg0
    pdl_interp.is_not_null %0 : !pdl.value -> ^bb5, ^bb1
  ^bb5:
    %1 = pdl_interp.get_result 0 of %arg0
    pdl_interp.is_not_null %1 : !pdl.value -> ^bb6, ^bb1
  ^bb6:
    pdl_interp.record_match @rewriters::@rewriter(%0, %arg0 : !pdl.value, !pdl.operation) : benefit(1), loc([%arg0]), root("foo.op") -> ^bb1
  }
  module @rewriters {
    func @rewriter(%arg0: !pdl.value, %arg1: !pdl.operation) {
      pdl_interp.replace %arg1 with(%arg0)
      pdl_interp.return
    }
  }
}
```

Differential Revision: https://reviews.llvm.org/D84579

[Scheduling] Implement a new way to cluster loads/stores

Before calling target hook to determine if two loads/stores are clusterable,
we put them into different groups to avoid fake cluster due to dependency.
For now, we are putting the loads/stores into the same group if they have
the same predecessor. We assume that, if two loads/stores have the same
predecessor, it is likely that, they didn't have dependency for each other.

However, one SUnit might have several predecessors and for now, we just
pick up the first predecessor that has non-data/non-artificial dependency,
which is too arbitrary. And we are struggling to fix it.

So, I am proposing some better implementation.
1. Collect all the loads/stores that has memory info first to reduce the complexity.
2. Sort these loads/stores so that we can stop the seeking as early as possible.
3. For each load/store, seeking for the first non-dependency instruction with the
   sorted order, and check if they can cluster or not.

Reviewed By: Jay Foad

Differential Revision: https://reviews.llvm.org/D85517

[DWARFYAML] Make the unit_length and header_length fields optional.

This patch makes the unit_length and header_length fields of line tables
optional. yaml2obj is able to infer them for us.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D86590

[AMDGPU][GlobalISel] Eliminate barrier if workgroup size is not greater than wavefront size

If a workgroup size is known to be not greater than wavefront size
the s_barrier instruction is not needed since all threads are guaranteed
to come to the same point at the same time.

This is the same optimization that was implemented for SelectionDAG in
D31731.

Differential Revision: https://reviews.llvm.org/D86609

GlobalISel: Combine G_ADD of G_PTRTOINT to G_PTR_ADD

This produces less work for addressing mode matching. I think this is
safe since I don't think machine IR is supposed to give the same
aliasing properties as getelementptr in the IR.

AMDGPU/GlobalISel: Tolerate negated control flow intrinsic outputs

If the condition output is negated, swap the branch targets. This is
similar to what SelectionDAG does for when SelectionDAGBuilder
decides to invert the condition and swap the branches.

This is leaving behind a dead constant def for some reason.

Add clang-cl "vctoolsdir" option to specify the location of the msvc toolchain

Add an option to directly specify where the msvc toolchain lives for
clang-cl and avoid unwanted file and registry probes.

Differential revision: https://reviews.llvm.org/D85998

AMDGPU: Use Subtarget reference in SIInstrInfo

[Support] Allow printing the stack trace only for a given depth

Differential Revision: https://reviews.llvm.org/D85458