After outputting block scalar string, the indent will be wrong.
This patch fixes Padding after block scalar string to ensure the correct
format of yaml.

The new added ut will fail in main.
```diff
@@ -3,4 +3,4 @@
     Just a block
     scalar doc
-scalar:          a
+  scalar:          a
 ...\n
```

Fix bug that `mir-strip-debug` pass does not remove debug location from
bundled instructions.

Problem arises during testing that debug info does not affect
optimization passes output (`llvm-lit` with ` -Dllc="llc
-debugify-and-strip-all-safe"`), when pass operates on MIR with bundled
instructions + memory operands.

Let mir test check looks like:

```
CHECK-NEXT: BUNDLE {
CHECK-NEXT:   $r3 = LD $r1, $r2 :: (load (s64) from %ir.a, !tbaa !2)
CHECK-NEXT: }
```

So as `mir-strip-debug` pass does not process bundled instructions,
running `llc -debugify-and-strip-all-safe` on the test will produce the
following output:

```
BUNDLE {
  $r3 = LD $r1, $r2, debug-location !DILocation(line: 3, column: 1, scope: <0x608cb2b99b10>) :: (load (s64) from %ir.a, !tbaa !2)
}
```

And test will fail, but it shouldn't.

Seems like the root cause is that `mir-strip-debug` pass should remove
debug location from bundled instructions.

This patch makes the final major change of the RemoveDIs project, changing the
default IR output from debug intrinsics to debug records. This is expected to
break a large number of tests: every single one that tests for uses or
declarations of debug intrinsics and does not explicitly disable writing
records. 

If this patch has broken your downstream tests (or upstream tests on a
configuration I wasn't able to run):
1. If you need to immediately unblock a build, pass
`--write-experimental-debuginfo=false` to LLVM's option processing for all
failing tests (remember to use `-mllvm` for clang/flang to forward arguments to
LLVM).
2. For most test failures, the changes are trivial and mechanical, enough that
they can be done by script; see the migration guide for a guide on how to do
this: https://llvm.org/docs/RemoveDIsDebugInfo.html#test-updates
3. If any tests fail for reasons other than FileCheck check lines that need
updating, such as assertion failures, that is most likely a real bug with this
patch and should be reported as such.

For more information, see the recent PSA:
https://discourse.llvm.org/t/psa-ir-output-changing-from-debug-intrinsics-to-debug-records/79578

In 85e8e6246e0fcc62ba727e8fb5990f1a632125d0, these tests were modified
to work with AVR, but the regex matchers were finicky and required a
fix forward patch, being this.

This fixes the vast majority of remaining failing AVR Generic CodeGen
tests.

https://reviews.llvm.org/D78411 introduced test changes which relied on
the ability to strip debugify metadata even if module-level metadata is
missing. This introduces a more targeted test for that ability.

Summary:
A few tests start out with debug info and expect it to reach
the output. For these tests we shouldn't strip the debug info

Reviewers: aprantl, vsk, bogner

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77886

Summary:
Removes:
* All LLVM-IR level debug info using StripDebugInfo()
* All debugify metadata
* 'Debug Info Version' module flag
* All (valid*) DEBUG_VALUE MachineInstrs
* All DebugLocs from MachineInstrs

This is a more complete solution than the previous MIRPrinter
option that just causes it to neglect to print debug-locations.

* The qualifier 'valid' is used here because AArch64 emits
  an invalid one and tests depend on it

Reviewers: vsk, aprantl, bogner

Subscribers: mgorny, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77747