Fix some MicroBenchmark failed at profile generation run

[taolq]

Summary

When -DTEST_SUITE_PROFILE_GENERATE=ON is set, some MicroBenchmark failed
because of the combination of env and cd command, shown at test.log

env LLVM_PROFILE_FILE=/home/taoliq/test-suite-build/O3-MicroBench/LoopInterchange/Output/LoopInterchange.test.profraw cd /home/taoliq/test-suite-build/O3-MicroBench/LoopInterchange && /home/taoliq/test-suite-build/O3-MicroBench/LoopInterchange/LoopInterchange --benchmark_format=json > /home/taoliq/test-suite-build/O3-MicroBench/LoopInterchange/Output/LoopInterchange.test.bench.json

env: 'cd': No such file or directory

Reproduce step

1. cmake -DCMAKE_C_COMPILER=$HOME/llvm-project/build/bin/clang -DTEST_SUITE_PROFILE_GENERATE=ON \
-DTEST_SUITE_RUN_TYPE=train -C../test-suite/cmake/caches/O3.cmake \
../test-suite

2. make -j32

3. llvm-lit MicroBenchmarks

The result

********************
Failed Tests (8):
  test-suite :: MicroBenchmarks/ImageProcessing/AnisotropicDiffusion/AnisotropicDiffusion.test
  test-suite :: MicroBenchmarks/ImageProcessing/BilateralFiltering/BilateralFilter.test
  test-suite :: MicroBenchmarks/ImageProcessing/Blur/blur.test
  test-suite :: MicroBenchmarks/ImageProcessing/Dilate/Dilate.test
  test-suite :: MicroBenchmarks/ImageProcessing/Dither/Dither.test
  test-suite :: MicroBenchmarks/ImageProcessing/Interpolation/Interpolation.test
  test-suite :: MicroBenchmarks/LoopInterchange/LoopInterchange.test
  test-suite :: MicroBenchmarks/harris/harris.test


Testing Time: 154.29s
  Passed: 12
  Failed:  8

[taolq]

update patch with arc

[MatzeB]

Thanks for the report and fix, could you test if this works for you too, and accept if so: D121225 ? Using shellcommand centralizes some of the tricky bits of understanding and modifying shell command lines...

litsupport/modules/profilegen.py

 """Test module that runs llvm-profdata merge after executing the benchmark."""
 from litsupport import shellcommand
 from litsupport import testplan
 
 
 def _mutateCommandline(context, commandline):
     """Adjust runscript to set a different value to the LLVM_PROFILE_FILE
     environment variable for each execution."""
     profilefile = context.tmpBase + ".profraw"
-    prefix = "env LLVM_PROFILE_FILE=%s " % profilefile
+    prefix = "export LLVM_PROFILE_FILE=%s" % profilefile
+    postfix = "unset LLVM_PROFILE_FILE"
     context.profilefiles.append(profilefile)
-    return prefix + commandline
+    return "; ".join([prefix, commandline, postfix])
 
 
 def _mutateScript(context, script):
     return testplan.mutateScript(context, script, _mutateCommandline)
 
 
 def mutatePlan(context, plan):
     context.profilefiles = []