[clang] [llvm] [RegAlloc] [X86] Enable callee saved register optimization for x86 (PR #220090)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ml-opt-devrel-x86-64` running on `ml-opt-devrel-x86-64-b2` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/175/builds/3996

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/MLRegAlloc/dev-mode-logging.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 6
/b/ml-opt-devrel-x86-64-b1/build/bin/llc -o /dev/null -mtriple=x86_64-linux-unknown -regalloc=greedy    -regalloc-enable-advisor=development -regalloc-training-log=/b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1 < /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/MLRegAlloc/Inputs/input.ll
# executed command: /b/ml-opt-devrel-x86-64-b1/build/bin/llc -o /dev/null -mtriple=x86_64-linux-unknown -regalloc=greedy -regalloc-enable-advisor=development -regalloc-training-log=/b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1
# RUN: at line 8
"/usr/bin/python3" /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/MLRegAlloc/../../../lib/Analysis/models/log_reader.py /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1 > /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1.readable
# executed command: /usr/bin/python3 /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/MLRegAlloc/../../../lib/Analysis/models/log_reader.py /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1
# RUN: at line 9
/b/ml-opt-devrel-x86-64-b1/build/bin/FileCheck --input-file /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1.readable /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/MLRegAlloc/dev-mode-logging.ll --check-prefixes=CHECK,NOML
# executed command: /b/ml-opt-devrel-x86-64-b1/build/bin/FileCheck --input-file /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1.readable /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/MLRegAlloc/dev-mode-logging.ll --check-prefixes=CHECK,NOML
# .---command stderr------------
# | /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/MLRegAlloc/dev-mode-logging.ll:31:15: error: CHECK-NEXT: is not on the line after the previous match
# | ; CHECK-NEXT: observation: 1
# |               ^
# | /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1.readable:242:1: note: 'next' match was here
# | observation: 10
# | ^
# | /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1.readable:49:10: note: previous match ended here
# | reward: 0.0
# |          ^
# | /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1.readable:50:1: note: non-matching line after previous match is here
# | observation: 2
# | ^
# | 
# | Input file: /b/ml-opt-devrel-x86-64-b1/build/test/CodeGen/MLRegAlloc/Output/dev-mode-logging.ll.tmp1.readable
# | Check file: /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/test/CodeGen/MLRegAlloc/dev-mode-logging.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            .
# |            .
# |            .
# |           44: use_def_density: 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.05077143386006355,1.0,0.014165595173835754,0.014222974888980389,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.019454877823591232 
# |           45: max_stage: 0,0,0,0,0,0,0,0,0,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4 
# |           46: min_stage: 0,0,0,0,0,0,0,0,0,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4 
# |           47: progress: 0.8888888955116272 
# |           48: index_to_evict: 11 
# |           49: reward: 0.0 
# | next:31'0             {     search range start (exclusive)
# |           50: observation: 2 
# |           51: mask: 0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 
# |           52: is_free: 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 
# |           53: nr_urgent: 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0 
# |           54: nr_broken_hints: 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0 
...

```

</details>

https://github.com/llvm/llvm-project/pull/220090