[DFSan] Add efficient fast16labels instrumentation mode.
Adds the -fast-16-labels flag, which enables efficient instrumentation
for DFSan when the user needs <=16 labels. The instrumentation
eliminates most branches and most calls to __dfsan_union or
__dfsan_union_load.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D84371
GitOrigin-RevId: e2d0b44a7cd261218c9e527d23eb5d13425afe8b
diff --git a/FuzzerDataFlowTrace.cpp b/FuzzerDataFlowTrace.cpp
index 48df8e6..0e9cdf7 100644
--- a/FuzzerDataFlowTrace.cpp
+++ b/FuzzerDataFlowTrace.cpp
@@ -253,7 +253,7 @@
return 1;
}
- static char DFSanEnv[] = "DFSAN_OPTIONS=fast16labels=1:warn_unimplemented=0";
+ static char DFSanEnv[] = "DFSAN_OPTIONS=warn_unimplemented=0";
putenv(DFSanEnv);
MkDir(DirPath);
for (auto &F : CorporaFiles) {
diff --git a/dataflow/DataFlow.cpp b/dataflow/DataFlow.cpp
index 8bf4e25..78b3f9a 100644
--- a/dataflow/DataFlow.cpp
+++ b/dataflow/DataFlow.cpp
@@ -17,9 +17,11 @@
// and also provides basic-block coverage for every input.
//
// Build:
-// 1. Compile this file (DataFlow.cpp) with -fsanitize=dataflow and -O2.
+// 1. Compile this file (DataFlow.cpp) with -fsanitize=dataflow -mllvm
+// -dfsan-fast-16-labels and -O2.
// 2. Compile DataFlowCallbacks.cpp with -O2 -fPIC.
// 3. Build the fuzz target with -g -fsanitize=dataflow
+// -mllvm -dfsan-fast-16-labels
// -fsanitize-coverage=trace-pc-guard,pc-table,bb,trace-cmp
// 4. Link those together with -fsanitize=dataflow
//
@@ -36,7 +38,7 @@
// Run:
// # Collect data flow and coverage for INPUT_FILE
// # write to OUTPUT_FILE (default: stdout)
-// export DFSAN_OPTIONS=fast16labels=1:warn_unimplemented=0
+// export DFSAN_OPTIONS=warn_unimplemented=0
// ./a.out INPUT_FILE [OUTPUT_FILE]
//
// # Print all instrumented functions. llvm-symbolizer must be present in PATH
