[GitHub] [arrow] westonpace commented on pull request #12928: ARROW-15678: [C++][CI] a crossbow job with MinRelSize enabled

[GitBox <gi...@apache.org>]

westonpace commented on PR #12928:
URL: https://github.com/apache/arrow/pull/12928#issuecomment-1105955726

   I played around with this a bit more.  I can reproduce it locally by building with SSE4_2:
   
   ```
   cmake .. -DARROW_PARQUET=ON -DARROW_SIMD_LEVEL=SSE4_2 -DARROW_RUNTIME_SIMD_LEVEL=MAX -DARROW_BUILD_TESTS=ON
   ```
   
   From there it's easiest to verify by just manually checking to see which version ends up in `libparquet.so`:
   
   ```
   objdump --disassemble=_ZN5arrow8internal21FirstTimeBitmapWriter10AppendWordEml -S ./minsizerel/libparquet.so.800.0.0
   ```
   If the output contains `shlx` then you've reproduced the bug.  If it only contains `shl` then it picked the correct default symbol.  If the method is entirely inlined you get no output.
   
   * The symbol is inlined with `-DCMAKE_BUILD_TYPE=Release`
   * The symbol is not inlined with `-DCMAKE_BUILD_TYPE=MinSizeRel`
     * However, on my system, in all cases, the `libparquet.so` file chooses the correct version unless...
     * I can get an invalid `.so` file if I switch the order the object files are passed to the linker: `/usr/bin/clang++-13 ... level_conversion_bmi2.cc.o ... level_conversion.cc.o ...`
   * The symbol is inlined, even with `MinSizeRel` is I try @kou's fix (`__attribute__((always_inline))`).
     * This seems like the easiest "spot fix" if we wanted to include something as part of 8.0.0
   
   If you really want to reproduce the issue, I found a tool [sde64](https://www.intel.com/content/www/us/en/developer/articles/tool/software-development-emulator.html) which will work if you have an Intel processor.  It allows you to simulate older Intel processors and so you can pretend to have an Ivy Bridge processor (which does not have AVX2/BMI2 support):
   
   ```
   sde64 -ivb -- ./minsizerel/parquet-arrow-test --gtest_filter=TestParquetIO/0.SingleNullableListNullableColumnReadWrite
   Running main() from ../googletest/src/gtest_main.cc
   Note: Google Test filter = TestParquetIO/0.SingleNullableListNullableColumnReadWrite
   [==========] Running 1 test from 1 test suite.
   [----------] Global test environment set-up.
   [----------] 1 test from TestParquetIO/0, where TypeParam = arrow::BooleanType
   [ RUN      ] TestParquetIO/0.SingleNullableListNullableColumnReadWrite
   TID 0 SDE-ERROR: Executed instruction not valid for specified chip (IVYBRIDGE): 0x7f80c95b96b3: shlx rax, rbx, rax
   Image: /home/pace/dev/arrow/cpp/sse4.2-min-build/minsizerel/libparquet.so.800+0x1666b3
   Function: _ZN5arrow8internal21FirstTimeBitmapWriter10AppendWordEml
   Instruction bytes are: c4 e2 f9 f7 c3 
   ```
   
   @pitrou has also posted a suggestion on the ML using pragmas.  I had to include the arch specifier so it generated `__attribute__((target("arch=haswell,avx2")))` and this appears to do what is expected.  The function is compiled with avx2 but the nested call is not.


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