Created using spr 1.3.6

[skip ci]

Lit's internal shell does not support -b (properly). This patch rewrites
the tests to conform to their existing semantics (using
--implicit-check-not) using diff -u. This allows for enabling lit's
internal shell by default on all platforms.

Fixes #106249.

Reviewers: compnerd, ilovepi, petrhosek, DougGregor

Reviewed By: ilovepi, compnerd

Pull Request: https://github.com/llvm/llvm-project/pull/157588

Prepare to use this with HwMode. This is mostly code copied from x86.

Mips has an exceptionally broken system where the target-abi option
can be used to change the pointer size. i.e., you can mix and match
32-bit base triples with an explicit request to use 32-bit or 64-bit
pointers such that you cannot rely on the triple reported pointer size.
This hack manages to only work for codegen. The MC subtarget
constructors
do not have access to the target-abi name so those will continue to not
have the appropriate feature set.

Resolves #157075 

This was causing an assertion failure on
`_attribute__((swift_name("")))`. Fix ensures this case shows the
warn_attr_swift_name_function diagnostic as expected.

Added in #154660 which ported #145899, but only the AllTargetsCodeGens
dep actually seems necessary here.

InstCombine will hoist an fneg through an fmul, but not for fadd/fsub.
This prevents us from matching fmsub and fnmadd in some cases.

This patch adds a DAG combine to undo this in InstCombine, which helps
some hot loops in 508.namd_r:

@@ -983,18 +983,15 @@
        fld     ft2, 48(a5)
        fld     ft3, 64(a5)
        fld     ft4, 72(a5)
-       fneg.d  fa0, fa0
-       fneg.d  ft0, ft0
-       fneg.d  ft2, ft2
        fmul.d  fa3, ft5, fa3
        fmul.d  fa0, fa3, fa0
        fmul.d  ft0, fa3, ft0
        fmul.d  fa3, fa3, ft2
        fld     ft2, 0(s1)
        fmul.d  fa4, ft5, fa4
-       fmadd.d fa2, fa4, fa2, fa0
-       fmadd.d ft6, fa4, ft6, ft0
-       fmadd.d fa4, fa4, ft1, fa3
+       fmsub.d fa2, fa4, fa2, fa0
+       fmsub.d ft6, fa4, ft6, ft0
+       fmsub.d fa4, fa4, ft1, fa3

This gives a [1.77% improvement in both instruction count and runtime on
508.namd_r](https://lnt.lukelau.me/db_default/v4/nts/profile/1/1022/1021)

This also causes some more fnegs to be sunk after a bitcast to integer,
so they're now done as xor. From glancing at some of the schedules for
WriteFSGN my guess is that this is also profitable.

In https://github.com/llvm/llvm-project/pull/155741 I broke the cardinal
rule of CMake: nothing happens when you think it happens 🤷. Meaning:
`declare_mlir_python_sources(SOURCES_GLOB
"_mlir_libs/${_module_name}/**/*.pyi")` wasn't picking up any sources
_because they aren't generated yet_. This of course makes sense in
retrospect (the stubs are generated as part of the build process, post
extension compile, rather than the configure process).

Thus, the API needs to be:

```
GENERATE_TYPE_STUBS: List of generated type stubs expected from stubgen, relative to _mlir_libs.
```

Partially as a result of this omission, the stubs weren't being
installed into either the build dir nor the install dir. That is also
fixed now:

**Source dir (for easy reference):**

<img width="300" height="674" alt="image"
src="https://github.com/user-attachments/assets/a569f066-c2bd-4361-91f3-1c75181e51da"
/>

**Build dir (for forthcoming typechecker tests):**

<img width="398" height="551" alt="image"
src="https://github.com/user-attachments/assets/017859f9-fddb-49ee-85e5-915f5b5f7377"
/>

**Install dir:**

<img width="456" height="884" alt="image"
src="https://github.com/user-attachments/assets/8051be7e-898c-4ec8-a11e-e2408b241a56"
/>