diff options
Diffstat (limited to 'llvm_mode/README.llvm')
| -rw-r--r-- | llvm_mode/README.llvm | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/llvm_mode/README.llvm b/llvm_mode/README.llvm index 77c406f8..779ff47c 100644 --- a/llvm_mode/README.llvm +++ b/llvm_mode/README.llvm @@ -88,13 +88,18 @@ which C/C++ files to actually intrument. See README.whitelist For splitting memcmp, strncmp, etc. please see README.laf-intel -As the original afl llvm_mode implementation has been replaced with -then much more effective instrim (https://github.com/csienslab/instrim/) -there is an option for optimizing loops. This optimization shows which -part of the loop has been selected, but not how many time a loop has been -called in a row (unless its a complex loop and a block inside was -instrumented). If you want to enable this set the environment variable -LOOPHEAD=1 +Then there is an optimized instrumentation strategy that uses CFGs and +markers to just instrument what is needed. This increases speed by 20-25% +however has a lower path discovery. +If you want to use this, set AFL_LLVM_INSTRIM=1 +See README.instrim + +Finally if your llvm version is 8 or lower, you can activate a mode that +prevents that a counter overflow result in a 0 value. This is good for +path discovery, but the llvm implementation for intel for this functionality +is not optimal and was only fixed in llvm 9. +You can set this with AFL_LLVM_NOT_ZERO=1 +See README.neverzero 4) Gotchas, feedback, bugs |