[PATCH] D130956: [X86][MC] Always emit `rep` prefix for `bsf`

[Florian Mayer via Phabricator via llvm-commits]

fmayer added a comment.

This seems related to an error we see on our sanitizer bots: https://lab.llvm.org/buildbot/#/builders/37/builds/15446/steps/33/logs/stdio

  FAIL: Builtins-i386-linux :: ffssi2_test.c (2860 of 8387)
  ******************** TEST 'Builtins-i386-linux :: ffssi2_test.c' FAILED ********************
  Script:
  --
  : 'RUN: at line 1';       /b/sanitizer-x86_64-linux/build/llvm_build64/bin/clang   -gline-tables-only  -m32 -DCOMPILER_RT_HAS_FLOAT16  -fno-builtin -I /b/sanitizer-x86_64-linux/build/llvm-project/compiler-rt/lib/builtins -nodefaultlibs /b/sanitizer-x86_64-linux/build/llvm-project/compiler-rt/test/builtins/Unit/ffssi2_test.c /b/sanitizer-x86_64-linux/build/compiler_rt_build/lib/linux/libclang_rt.builtins-i386.a -lc -lm -o /b/sanitizer-x86_64-linux/build/compiler_rt_build/test/builtins/Unit/I386LinuxConfig/Output/ffssi2_test.c.tmp &&  /b/sanitizer-x86_64-linux/build/compiler_rt_build/test/builtins/Unit/I386LinuxConfig/Output/ffssi2_test.c.tmp
  --
  Exit Code: 1
  Command Output (stdout):
  --
  error in __ffssi2(0x0) = 33, expected 0
  --
  ********************
  Testing:  0.. 10.. 20.. 30.
  FAIL: Builtins-x86_64-linux :: ffssi2_test.c (3084 of 8387)
  ******************** TEST 'Builtins-x86_64-linux :: ffssi2_test.c' FAILED ********************
  Script:
  --
  : 'RUN: at line 1';       /b/sanitizer-x86_64-linux/build/llvm_build64/bin/clang   -gline-tables-only  -m64 -DCOMPILER_RT_HAS_FLOAT16  -fno-builtin -I /b/sanitizer-x86_64-linux/build/llvm-project/compiler-rt/lib/builtins -nodefaultlibs /b/sanitizer-x86_64-linux/build/llvm-project/compiler-rt/test/builtins/Unit/ffssi2_test.c /b/sanitizer-x86_64-linux/build/compiler_rt_build/lib/linux/libclang_rt.builtins-x86_64.a -lc -lm -o /b/sanitizer-x86_64-linux/build/compiler_rt_build/test/builtins/Unit/X86_64LinuxConfig/Output/ffssi2_test.c.tmp &&  /b/sanitizer-x86_64-linux/build/compiler_rt_build/test/builtins/Unit/X86_64LinuxConfig/Output/ffssi2_test.c.tmp
  --
  Exit Code: 1
  Command Output (stdout):
  --
  error in __ffssi2(0x0) = 33, expected 0
  --
  ********************
  Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90..


Repository:
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