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Diffstat (limited to 'docs/env_variables.txt')
| -rw-r--r-- | docs/env_variables.txt | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/docs/env_variables.txt b/docs/env_variables.txt index 2a824766..d854ea8d 100644 --- a/docs/env_variables.txt +++ b/docs/env_variables.txt @@ -106,6 +106,14 @@ Then there are a few specific features that are only available in llvm_mode: See llvm_mode/README.whitelist for more information. + OTHER + ===== + - Setting export AFL_LLVM_NOT_ZERO=1 during compilation will use counters + that skip zero on overflow. This is the default for llvm >= 9, + however for llvm versions below that this will increase an unnecessary + slowdown due a performance issue that is only fixed in llvm 9+. + This feature increases path discovery by a little bit. + Note that AFL_INST_RATIO will behave a bit differently than for afl-gcc, because functions are *not* instrumented unconditionally - so low values will have a more striking effect. For this tool, 0 is not a valid choice. |