[llvm] [ARM][Thumb1] Improve EstimateFunctionSizeInBytes accuracy (PR #203318)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 135659 tests passed
* 3423 tests skipped
* 1 test failed

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

### LLVM
<details>
<summary>LLVM.CodeGen/ARM/estimate-size-copy.mir</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 3
c:\_work\llvm-project\llvm-project\build\bin\llc.exe -mtriple=thumbv6m -start-before=machine-cp -debug -o - C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir 2>C:\_work\llvm-project\llvm-project\build\test\CodeGen\ARM\Output\estimate-size-copy.mir.tmp |      c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir --check-prefix=OUTPUT
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\llc.exe' -mtriple=thumbv6m -start-before=machine-cp -debug -o - 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir'
# note: command had no output on stdout or stderr
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe' 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir' --check-prefix=OUTPUT
# note: command had no output on stdout or stderr
# RUN: at line 5
c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir --check-prefix=DEBUG < C:\_work\llvm-project\llvm-project\build\test\CodeGen\ARM\Output\estimate-size-copy.mir.tmp
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe' 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir' --check-prefix=DEBUG
# .---command stderr------------
# | C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir:7:10: error: DEBUG: expected string not found in input
# | # DEBUG: Estimated function size for f = 4 bytes
# |          ^
# | <stdin>:1:1: note: scanning from here
# | Args: c:\_work\llvm-project\llvm-project\build\bin\llc.exe -mtriple=thumbv6m -start-before=machine-cp -debug -o - C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir 
# | ^
# | <stdin>:1:172: note: possible intended match here
# | Args: c:\_work\llvm-project\llvm-project\build\bin\llc.exe -mtriple=thumbv6m -start-before=machine-cp -debug -o - C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir 
# |                                                                                                                                                                            ^
# | 
# | Input file: <stdin>
# | Check file: C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1: Args: c:\_work\llvm-project\llvm-project\build\bin\llc.exe -mtriple=thumbv6m -start-before=machine-cp -debug -o - C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\ARM\estimate-size-copy.mir  
# | check:7'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
# | check:7'1                                                                                                                                                                                ?                        possible intended match
# |            2:  
# | check:7'0     ~
# |            3: Features:+armv6-m,+thumb-mode,+v4t 
# | check:7'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |            4: CPU:generic 
# | check:7'0     ~~~~~~~~~~~~
# |            5: TuneCPU:generic 
# | check:7'0     ~~~~~~~~~~~~~~~~
# |            6:  
# | check:7'0     ~
# |            .
# |            .
# |            .
# | >>>>>>
# `-----------------------------
# 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/203318