[llvm] [win] Replace the .seh_startchained and .sehendchained instructions with .seh_splitchained (PR #172895)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 167345 tests passed
* 2964 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### LLVM
<details>
<summary>LLVM.MC/ARM/seh-checks2.s</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 3
not /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llvm-mc -triple thumbv7-pc-win32 -filetype=obj -o /dev/null /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/MC/ARM/seh-checks2.s 2>&1 | /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/MC/ARM/seh-checks2.s
# executed command: not /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llvm-mc -triple thumbv7-pc-win32 -filetype=obj -o /dev/null /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/MC/ARM/seh-checks2.s
# note: command had no output on stdout or stderr
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/MC/ARM/seh-checks2.s
# .---command stderr------------
# | /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/MC/ARM/seh-checks2.s:6:11: error: CHECK: expected string not found in input
# | // CHECK: error: Prologue in func2 not correctly terminated
# |           ^
# | <stdin>:1:52: note: scanning from here
# | <unknown>:0: error: Stray .seh_endepilogue in func1
# |                                                    ^
# | <stdin>:10:14: note: possible intended match here
# | <unknown>:0: error: Epilogue in func3 not correctly terminated
# |              ^
# | 
# | Input file: <stdin>
# | Check file: /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/MC/ARM/seh-checks2.s
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1: <unknown>:0: error: Stray .seh_endepilogue in func1 
# | check:6'0                                                        X error: no match found
# |            2: <unknown>:0: error: Incorrect size for func1 prologue: 2 bytes of instructions in range, but .seh directives corresponding to 6 bytes 
# | check:6'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            3:  
# | check:6'0     ~
# |            4: <unknown>:0: error: starting epilogue (.seh_startepilogue) before prologue has ended (.seh_endprologue) in func2 
# | check:6'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            5: <unknown>:0: error: Incorrect size for func2 prologue: 4 bytes of instructions in range, but .seh directives corresponding to 2 bytes 
# | check:6'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            6:  
# | check:6'0     ~
# |            7: /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/MC/ARM/seh-checks2.s:53:9: error: Missing .seh_endepilogue in func3 
# | check:6'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            8:  .seh_endproc 
# | check:6'0     ~~~~~~~~~~~~~~
# |            9:  ^ 
# | check:6'0     ~~~
# |           10: <unknown>:0: error: Epilogue in func3 not correctly terminated 
# | check:6'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | check:6'1                  ?                                                  possible intended match
# |           11: <unknown>:0: error: Epilogue in func4 not correctly terminated 
# | check:6'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/172895