Implementation of Pass and Dialect Plugins that mirrors LLVM Pass Plugin  implementation from the new pass manager.

Currently the implementation only supports using the pass-pipeline option for adding passes. This restriction is imposed by the `PassPipelineCLParser` variable in mlir/lib/Tools/mlir-opt/MlirOptMain.cpp:114 that loads the parse options statically before parsing the cmd line args.

```
mlir-opt stanalone-plugin.mlir --load-dialect-plugin=lib/libStandalonePlugin.so --pass-pipeline="builtin.module(standalone-switch-bar-foo)"
```

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D147053

This lets tablegen generated the code and avoids a string lookup
of the CSR name at runtime.

ORC's ELF platform support prefers the newer libunwind registration functions
(__unw_add_dynamic_eh_frame_section, __unw_remove_dynamic_eh_frame_section) when
they're available, and falls back to the older registration functions
(__register_frame, __deregister_frame) when they're not.

Until now the choice of registration functions has been made on the controller
side in ELFNixPlatform: The platform JITDylib was searched for the registration
functions and aliases set depending on which ones were found. This patch drops
that selection logic from ELFNixPlatform and instead uses weak imports of the
registration functions in elfnix_platform.cpp to identify which ones are
available and choose which ones to use.

This has a few small benefits:
(1) The registration functions don't need to be defined in the same JITDylib as
the ORC runtime -- it's sufficient for them to be defined in a JITDylib that the
ORC runtime's JITDylib links against.

(2) THe elfnix_platfrom code is more readable, as we don't have to dig into
ELFNixPlatform.cpp on the controller side to discover the definition of the
registration aliases.

(3) We may save a separate round-trip to look up the registration APIs (the
lookup will be folded into the ordinary external symbol lookup when linking the
runtime).

Currently the use of bare pointer calling convention is controlled
globally through use of an option in the `LLVMTypeConverter`. To allow
more fine-grained control use an attribute on a function to drive the
calling convention to use.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D147494

Made the condition for the erasing of the gathered extractelements
stricter, remove it only if it has single vectorized use, otherwise
leave it for instcombiner/instsimplify analysis.

generateUnrolledLoop was assuming that the yielded value is always generated in
the Block corresponding to the loop being unrolled. Thus, it was updating the
last yielded values with it's cloned value. However, if the yielded value is not
generated in the same Block then the cloned value and it's corresponding mapping
won't exist, resulting in a crash. Fix this.

Reviewed By: bondhugula

Differential Revision: https://reviews.llvm.org/D146931

test-affine-parametric-tile pass was crashing on an incorrect input.
Instead it should emit an error message and exit.

Fixes: https://github.com/llvm/llvm-project/issues/61528

Reviewed By: mehdi_amini, bondhugula

Differential Revision: https://reviews.llvm.org/D147595

Update the design document to reflect the actual implementation
of polymorphic entities.

Reviewed By: jeanPerier, PeteSteinfeld

Differential Revision: https://reviews.llvm.org/D147665

Revert D146987 for the 2nd time.

This reverts commit 91a07404

Buildbot: https://lab.llvm.org/buildbot/#/builders/70/builds/36007

And more importantly, move the fixme to the sole caller where it actually makes sense in context.

This reverts commit 3b5ff3a6.

This reverts commit f6059243.

Based on info from https://github.com/llvm/llvm-project/issues/54964

Re-land D146987.

This reverts commit 43825d19 (revert)
which reverts aa32490b (original commit).

Correctly handle the case of splitting an alloca which backs contiguous
distinct variables, where a slice's size equals the size of a backed variable.

We need to ensure that we don't generate fragments expressions with fragments
of the same size as the variable as this is a verifier error.

Prior to this patch a fragment expression would be created in this
situation. e.g. splitting an alloca i64 with two adjacent 32-bit variables into
two 32-bit allocas, the new dbg.assign expressions would contain
(DW_OP_LLVM_fragment, 0, 32) and (DW_OP_LLVM_fragment, 32, 32) even though
those fragments cover each variable entirely.

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D147696

All users of MCCodeEmitter::encodeInstruction use a raw_svector_ostream
to encode the instruction into a SmallVector. The raw_ostream however
incurs some overhead for the actual encoding.

This change allows an MCCodeEmitter to directly emit an instruction into
a SmallVector without using a raw_ostream and therefore allow for
performance improvments in encoding. A default path that uses existing
raw_ostream implementations is provided.

Reviewed By: MaskRay, Amir

Differential Revision: https://reviews.llvm.org/D145791

We were trying to mangle templated names and the Microsoft mangler does
not have an implementation for mangling dependent names. Instead, we
now skip trying to print the mangled name if the AST node is still a
templated node rather than a fully resolved node.

Fixes https://github.com/llvm/llvm-project/issues/61440

It is easier to introduce header-only library.

Let RISCV64 targets math implementations with and without FMA
automatically.

Reviewed By: michaelrj

Differential Revision: https://reviews.llvm.org/D146730

This patch is mainly to deal with folding trunci with ext，as flows：
    trunci(zexti(a)) -> trunci(a)
    trunci(zexti(a)) -> trunci(a)

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D140604

COMPILER_RT_DEFAULT_TARGET_ONLY is the goto workaround for building
only one of a multilib setup while still being able to autodetect the native target.
For example only building 64 bit libraries on Intel instead of 32 and 64 bit.
Which may fail without 32 bit compatibility libs installed.

As reported in https://discourse.llvm.org/t/configuring-compiler-rt-to-use-default-target-only-does-not-work/62727
this build config hasn't worked in a while.

It relies on a variable usually set during cross compliation,
though my testing shows you can set it in other scenarios too.
https://cmake.org/cmake/help/latest/variable/CMAKE_LANG_COMPILER_TARGET.html

So the options you need to provide are:
-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON -DCMAKE_C_COMPILER_TARGET="aarch64-unknown-linux-gnu"

And we should error if CMAKE_C_COMPILER_TARGET isn't set.

Reviewed By: glaubitz

Differential Revision: https://reviews.llvm.org/D147598

[DAG] combineSelect - select(i1,vXi1,vXi1) - only cast <X x i1> constants to iX pre-legalization or if its a legal type

Fixes #61524

Currently llvm-exegesis fails to do this which causes every snippet to crash

~~

Huawei RRI, OS Lab

Reviewed By: courbet

Differential Revision: https://reviews.llvm.org/D147699

Remove the file copied from the source tree before overwriting it. If
the source code is stored with readonly (0444) permissions, then
the copied files are also readonly and attempting to overwrite them
fails.

Reviewed By: yubing

Differential Revision: https://reviews.llvm.org/D147527

Looks like it can benefit from this mode.

1. Simplify code by using conditional operator
2. Add comments for "kz" and "store" cases
3. Rename variables to match flags

The LDR and STR instructions must have the same value for imm4(second operand)
and offset(fourth operand).
The disassembly guarantees that happens, but the Asm parser was not checking that.
This patch fixes that by checking if the second operand and fourth operand are
immediate and have the same value.

Reviewed By: david-arm

Differential Revision: https://reviews.llvm.org/D147617

Due to not resetting that, clang still thinks that it is in immediate
function context even if it already entered non-consteval function.
This caused consteval functions reaching codegen in some cases.

Fixes https://github.com/llvm/llvm-project/issues/61142

Reviewed By: cor3ntin, aaron.ballman

Differential Revision: https://reviews.llvm.org/D147531

FCMP may use ISD::SETNE when nnan, we don't want to end up with cases where we mismatch signed zeros etc.

Thanks to @pengfei for the test case from D147688

This reverts commit efd34ba6.

Reapplies 8ff48326. Missed a failing test. Needed to just
update test checks.