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diff --git a/llvm_mode/README.instrim.md b/llvm_mode/README.instrim.md deleted file mode 100644 index 53a518a9..00000000 --- a/llvm_mode/README.instrim.md +++ /dev/null @@ -1,34 +0,0 @@ -# InsTrim - -InsTrim: Lightweight Instrumentation for Coverage-guided Fuzzing - -## Introduction - -InsTrim uses CFG and markers to instrument just what is necessary in the -binary in llvm_mode. It is about 10-15% faster without disadvantages. -It requires at least llvm version 3.8.0. - -## Usage - -Set the environment variable `AFL_LLVM_INSTRUMENT=CFG` or `AFL_LLVM_INSTRIM=1` -during compilation of the target. - -There is also an advanced mode which instruments loops in a way so that -afl-fuzz can see which loop path has been selected but not being able to -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] -(https://www.ndss-symposium.org/wp-content/uploads/2018/07/bar2018_14_Hsu_paper.pdf) |