[PATCH] D102615: [LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration

Mon May 31 00:47:49 PDT 2021

uweigand added a comment.

In D102615#2788912 <https://reviews.llvm.org/D102615#2788912>, @mkazantsev wrote:

> The last failure also looks like a timeout, I don't see any indication of miscompile:
>
>   FAIL: test-suite :: MultiSource/Benchmarks/MallocBench/gs/gs.test (73 of 2021)
>   ******************** TEST 'test-suite :: MultiSource/Benchmarks/MallocBench/gs/gs.test' FAILED ********************
>   
>   /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/tools/timeit-target --limit-core 0 --limit-cpu 7200 --timeout 7200 --limit-file-size 104857600 --limit-rss-size 838860800 --append-exitstatus --redirect-output /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/MultiSource/Benchmarks/MallocBench/gs/Output/gs.test.out --redirect-input /dev/null --chdir /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/MultiSource/Benchmarks/MallocBench/gs --summary /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/MultiSource/Benchmarks/MallocBench/gs/Output/gs.test.time /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/MultiSource/Benchmarks/MallocBench/gs/gs -DNODISPLAY INPUT/large.ps
>   cd /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/MultiSource/Benchmarks/MallocBench/gs ; /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/tools/fpcmp-target /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/MultiSource/Benchmarks/MallocBench/gs/Output/gs.test.out gs.reference_output
>   
>   /home/uweigand/sandbox/buildbot/clang-s390x-linux-lnt/test/sandbox/build/tools/fpcmp-target: FP Comparison failed, not a numeric difference between '
>   ' and 'g'
>
> @uweigand could you please confirm that the output like this could have been a result of timeout?

No, there is no timeout - execution of the test binary fails with an internal error:

  Reading ghost.ps... 
  Interp returns -16
  ostack:
  0x103e848: 0x02 dict -ewr------ 0x0000 0x01045b58
  estack:
  0x103de38: 0x09 oper x--------- 0x0000 0x010069c0
  0x103de48: 0x03 file xe-r------ 0x0003 0x0105f708
  exit 1

In the "good" case (with the patch reverted) we instead get the expected output:

  Reading ghost.ps... ghost.ps read.
  exit 0

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https://reviews.llvm.org/D102615