[llvm-branch-commits] [libc] Use UMAXV.4S to reduce bcmp result. (PR #99260)

[Schrodinger ZHU Yifan via llvm-branch-commits]

SchrodingerZhu wrote:

Hi, 

Thank you for the patch. Unfortunately, I think the proposed change is causing failures in tests:

```
Ran 5 tests.  PASS: 5  FAIL: 0
[4171/5229] Running unit test libc.test.src.stdio.snprintf_test.__unit__
FAILED: libc/test/src/stdio/CMakeFiles/libc.test.src.stdio.snprintf_test.__unit__ /home/schrodinger/development/llvm-project/build/libc/test/src/stdio/CMakeFiles/libc.test.src.stdio.snprintf_test.__unit__ 
cd /home/schrodinger/development/llvm-project/build/libc/test/src/stdio && /home/schrodinger/development/llvm-project/build/libc/test/src/stdio/libc.test.src.stdio.snprintf_test.__unit__.__build__
[==========] Running 2 tests from 1 test suite.
[ RUN      ] LlvmLibcSNPrintfTest.CutOff
/home/schrodinger/development/llvm-project/libc/test/src/stdio/snprintf_test.cpp:23: FAILURE
      Expected: buff
      Which is: 
To be equal to: "A simple string"
      Which is: A simple string
[  FAILED  ] LlvmLibcSNPrintfTest.CutOff
[ RUN      ] LlvmLibcSNPrintfTest.NoCutOff
/home/schrodinger/development/llvm-project/libc/test/src/stdio/snprintf_test.cpp:53: FAILURE
      Expected: buff
      Which is: 
To be equal to: "A simple string with no conversions."
      Which is: A simple string with no conversions.
[  FAILED  ] LlvmLibcSNPrintfTest.NoCutOff
Ran 2 tests.  PASS: 0  FAIL: 2
[4172/5229] Running unit test libc.test.src.stdio.vsnprintf_test.__unit__
FAILED: libc/test/src/stdio/CMakeFiles/libc.test.src.stdio.vsnprintf_test.__unit__ /home/schrodinger/development/llvm-project/build/libc/test/src/stdio/CMakeFiles/libc.test.src.stdio.vsnprintf_test.__unit__ 
cd /home/schrodinger/development/llvm-project/build/libc/test/src/stdio && /home/schrodinger/development/llvm-project/build/libc/test/src/stdio/libc.test.src.stdio.vsnprintf_test.__unit__.__build__
[==========] Running 2 tests from 1 test suite.
[ RUN      ] LlvmLibcVSNPrintfTest.CutOff
/home/schrodinger/development/llvm-project/libc/test/src/stdio/vsnprintf_test.cpp:35: FAILURE
      Expected: buff
      Which is: 
To be equal to: "A simple string"
      Which is: A simple string
[  FAILED  ] LlvmLibcVSNPrintfTest.CutOff
[ RUN      ] LlvmLibcVSNPrintfTest.NoCutOff
/home/schrodinger/development/llvm-project/libc/test/src/stdio/vsnprintf_test.cpp:64: FAILURE
      Expected: buff
      Which is: 
To be equal to: "A simple string with no conversions."
      Which is: A simple string with no conversions.
[  FAILED  ] LlvmLibcVSNPrintfTest.NoCutOff
Ran 2 tests.  PASS: 0  FAIL: 2
[4173/5229] Running unit test libc.test.src.stdio.fprintf_test.__unit__
FAILED: libc/test/src/stdio/CMakeFiles/libc.test.src.stdio.fprintf_test.__unit__ /home/schrodinger/development/llvm-project/build/libc/test/src/stdio/CMakeFiles/libc.test.src.stdio.fprintf_test.__unit__ 
cd /home/schrodinger/development/llvm-project/build/libc/test/src/stdio && /home/schrodinger/development/llvm-project/build/libc/test/src/stdio/libc.test.src.stdio.fprintf_test.__unit__.__build__
[==========] Running 1 test from 1 test suite.
[ RUN      ] LlvmLibcFPrintfTest.WriteToFile
/home/schrodinger/development/llvm-project/libc/test/src/stdio/fprintf_test.cpp:65: FAILURE
      Expected: printf_test::fread(data, 1, sizeof(simple) - 1, file)
      Which is: 0
To be equal to: sizeof(simple) - 1
      Which is: 37
[  FAILED  ] LlvmLibcFPrintfTest.WriteToFile
Ran 1 tests.  PASS: 0  FAIL: 1
[4184/5229] Linking CXX executable libc/test/src/stdio/libc.test.src.stdio.remove_test.__hermetic__.__build__
ninja: build stopped: subcommand failed.
```

https://github.com/llvm/llvm-project/pull/99260