remove doc reference for SKIPSINGLEBLOCK
MODIFY
docs/env_variables.md
docs/env_variables.md
@@ -83,17 +83,12 @@ tools make fairly broad use of environmental variables:
The native instrumentation helpers (llvm_mode and gcc_plugin) accept a subset
of the settings discussed in section #1, with the exception of:
- - Setting AFL_LLVM_SKIPSINGLEBLOCK=1 will skip instrumenting
- functions with a single basic block. This is useful for most C and
- some C++ targets. This works for all instrumentation modes.
-
- AFL_AS, since this toolchain does not directly invoke GNU as.
- TMPDIR and AFL_KEEP_ASSEMBLY, since no temporary assembly files are
created.
- - AFL_INST_RATIO, as we switched for instrim instrumentation which
- is more effective but makes not much sense together with this option.
+ - AFL_INST_RATIO, as we by default collision free instrumentation is used.
Then there are a few specific features that are only available in llvm_mode:
@@ -121,7 +116,8 @@ Then there are a few specific features that are only available in llvm_mode:
built if LLVM 11 or newer is used.
- AFL_LLVM_INSTRUMENT=CFG will use Control Flow Graph instrumentation.
- (not recommended!)
+ (not recommended for afl-clang-fast, default for afl-clang-lto as there
+ it is a different and better kind of instrumentation.)
None of the following options are necessary to be used and are rather for
manual use (which only ever the author of this LTO implementation will use).

MODIFY
llvm_mode/README.instrim.md
llvm_mode/README.instrim.md
@@ -19,15 +19,6 @@ 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]

remove doc reference for SKIPSINGLEBLOCK