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| author | van Hauser <vh@thc.org> | 2020-03-10 07:14:42 +0100 |
|---|---|---|
| committer | van Hauser <vh@thc.org> | 2020-03-10 07:14:42 +0100 |
| commit | 1148a2d0d1ce43ab89e14eefb70bc410726838c4 (patch) | |
| tree | 4c2a69940d07cb2fadd8b8a5cbbfdb7f902c8d36 /llvm_mode/README.instrim.md | |
| parent | 38d9aedb26d6c4530763a29fe7695155a21ffbbc (diff) | |
| download | afl++-1148a2d0d1ce43ab89e14eefb70bc410726838c4.tar.gz | |
document new environment variables and code format
Diffstat (limited to 'llvm_mode/README.instrim.md')
| -rw-r--r-- | llvm_mode/README.instrim.md | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/llvm_mode/README.instrim.md b/llvm_mode/README.instrim.md index b40dbb18..5c3f32c8 100644 --- a/llvm_mode/README.instrim.md +++ b/llvm_mode/README.instrim.md @@ -19,6 +19,15 @@ see how often the loop has been rerun. This again is a tradeoff for speed for less path information. To enable this mode set `AFL_LLVM_INSTRIM_LOOPHEAD=1`. +There is an additional optimization option that skips single block +functions. In 95% of the C targets and (guess) 50% of the C++ targets +it is good to enable this, as otherwise pointless instrumentation occurs. +The corner case where we want this instrumentation is when vtable/call table +is used and the index to that vtable/call table is not set in specific +basic blocks. +To enable skipping these (most of the time) unnecessary instrumentations set +`AFL_LLVM_INSTRIM_SKIPSINGLEBLOCK=1` + ## Background The paper: [InsTrim: Lightweight Instrumentation for Coverage-guided Fuzzing] |