[llvm] [X86] Emit ADD instead of SHL by 1 when shrinking TEST with a mask (PR #217508)

Wed Aug 26 05:59:43 PDT 2026

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-aarch64-darwin` running on `doug-worker-5` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/48609

<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 'Clang :: ClangScanDeps/modules-pch-common-submodule.c' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 11
rm -rf /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp && mkdir /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp
# executed command: rm -rf /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp
# note: command had no output on stdout or stderr
# executed command: mkdir /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp
# note: command had no output on stdout or stderr
# RUN: at line 12
cp /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/test/ClangScanDeps/Inputs/modules-pch-common-submodule/* /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp
# executed command: cp '/Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/test/ClangScanDeps/Inputs/modules-pch-common-submodule/*' /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp
# note: command had no output on stdout or stderr
# RUN: at line 16
sed "s|DIR|/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp|g" /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/test/ClangScanDeps/Inputs/modules-pch-common-submodule/cdb_pch.json > /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/cdb.json
# executed command: sed 's|DIR|/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp|g' /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/test/ClangScanDeps/Inputs/modules-pch-common-submodule/cdb_pch.json
# note: command had no output on stdout or stderr
# RUN: at line 17
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/clang-scan-deps -compilation-database /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/cdb.json -format experimental-full    -module-files-dir /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/build > /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/result_pch.json
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/clang-scan-deps -compilation-database /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/cdb.json -format experimental-full -module-files-dir /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/build
# note: command had no output on stdout or stderr
# RUN: at line 19
cat /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/result_pch.json | sed 's:\\\\\?:/:g'    | "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9" /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/utils/scan-deps-filter.py --fields=name,clang-module-deps,clang-modulemap-file,context-hash,file-deps,link-libraries,clang-context-hash,input-file    | /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/test/ClangScanDeps/modules-pch-common-submodule.c -DPREFIX=/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp -check-prefix=CHECK-PCH
# executed command: cat /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/result_pch.json
# note: command had no output on stdout or stderr
# executed command: sed 's:\\\\\?:/:g'
# note: command had no output on stdout or stderr
# executed command: /Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9 /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/utils/scan-deps-filter.py --fields=name,clang-module-deps,clang-modulemap-file,context-hash,file-deps,link-libraries,clang-context-hash,input-file
# note: command had no output on stdout or stderr
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/test/ClangScanDeps/modules-pch-common-submodule.c -DPREFIX=/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp -check-prefix=CHECK-PCH
# note: command had no output on stdout or stderr
# RUN: at line 55
"/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9" /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/utils/module-deps-to-rsp.py /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/result_pch.json --module-name=ModCommon > /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/mod_common.cc1.rsp
# executed command: /Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9 /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/utils/module-deps-to-rsp.py /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/result_pch.json --module-name=ModCommon
# note: command had no output on stdout or stderr
# RUN: at line 56
"/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9" /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/utils/module-deps-to-rsp.py /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/result_pch.json --tu-index=0 > /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/pch.rsp
# executed command: /Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9 /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/clang/utils/module-deps-to-rsp.py /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/result_pch.json --tu-index=0
# note: command had no output on stdout or stderr
# RUN: at line 58
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/clang @/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/mod_common.cc1.rsp
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/clang @/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/mod_common.cc1.rsp
# note: command had no output on stdout or stderr
# RUN: at line 59
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/clang @/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/pch.rsp
# executed command: /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/clang @/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/tools/clang/test/ClangScanDeps/Output/modules-pch-common-submodule.c.tmp/pch.rsp
# note: command had no output on stdout or stderr
# RUN: at line 63
...

```

</details>

https://github.com/llvm/llvm-project/pull/217508