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[compiler-rt][Fuzzer] Relax reduce_inputs.test to account for non-determinism (#182495)

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I have seen that very occasionally this test is failing on a bot, with
only 3 files in the corpus. After running the test in a loop 4000+
times, I witnessed this same failure twice.

In both cases the first corpus member was some string not containing a
'F'; the second corpus member was 'F[' or 'FZ'; and the final corpus
member 'FUZ'.

In a normal run there is an intermediate corpus member 'FU.' - so this
test is failing in very rare cases where the fuzzer gets lucky and
matches 2 branch conditions in one mutation.

This patch allows the FileCheck condition to match 3 or 4 corpus files.
It may be possible for the fuzzer to reach the target in 2 files, but I
think that if that is possible, it will be exceptionally rare.

rdar://170440934
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Dan Blackwell 2026-02-25 10:55:41 -08:00 committed by GitHub
parent 81afd93a51
commit ed1a1eda0f
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1 changed files with 3 additions and 2 deletions
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compiler-rt/test/fuzzer/reduce_inputs.test
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@ -7,9 +7,10 @@ RUN: %cpp_compiler %S/ShrinkControlFlowTest.cpp -o %t-ShrinkControlFlowTest
RUN: %run %t-ShrinkControlFlowSimpleTest -exit_on_item=0eb8e4ed029b774d80f2b66408203801cb982a60 -runs=10000000 %t/C 2>&1 | FileCheck %s
CHECK: INFO: found item with checksum '0eb8e4ed029b774d80f2b66408203801cb982a60'
# Test that reduce_inputs deletes redundant files in the corpus.
# Test that reduce_inputs deletes redundant files in the corpus (note reduce_inputs=1 by default).
RUN: %run %t-ShrinkControlFlowSimpleTest -runs=0 %t/C 2>&1 | FileCheck %s --check-prefix=COUNT
COUNT: seed corpus: files: 4
# Allow 3 or 4 - sometimes the fuzzer gets lucky and gets straight from "F." to "FUZ", skipping "FU"
COUNT: seed corpus: files: {{3|4}}
# a bit longer test
RUN: %run %t-ShrinkControlFlowTest -exit_on_item=0eb8e4ed029b774d80f2b66408203801cb982a60 -seed=42 -runs=10000000 2>&1 | FileCheck %s