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authorvan Hauser <vh@thc.org>2019-07-05 13:27:53 +0200
committerGitHub <noreply@github.com>2019-07-05 13:27:53 +0200
commit18e031d3464b1c93d426299d270fea62d481bb11 (patch)
tree8ef28842ef80063972b925faea1c3dd883d4eb3d /docs
parentb57b2073acf85e985f513a12d8aae725f8942689 (diff)
parentc0332ad98b84bad3798cbe23d36b07423f216479 (diff)
downloadafl++-18e031d3464b1c93d426299d270fea62d481bb11.tar.gz
Merge pull request #11 from vanhauser-thc/neverZero_counters
Never zero counters added
Diffstat (limited to 'docs')
-rw-r--r--docs/ChangeLog2
-rw-r--r--docs/env_variables.txt8
2 files changed, 10 insertions, 0 deletions
diff --git a/docs/ChangeLog b/docs/ChangeLog
index b758b211..b8d0d7ac 100644
--- a/docs/ChangeLog
+++ b/docs/ChangeLog
@@ -17,6 +17,8 @@ sending a mail to <afl-users+subscribe@googlegroups.com>.
Version ++2.52d (tbd):
-----------------------------
+ - added never zero counters for afl-gcc and optional (because of an
+ optimization issue in llvm < 9) for llvm_mode (AFL_LLVM_NEVER_ZERO=1)
- more cpu power for afl-system-config
- added forkserver patch to afl-tmin, makes it much faster (originally from
github.com/nccgroup/TriforceAFL)
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.