================
@@ -48,6 +49,63 @@ Example
$ clang -fsanitize=address -fsanitize-ignorelist=ignorelist.txt foo.c ;
./a.out
# No error report here.
+Usage with UndefinedBehaviorSanitizer
+=====================================
+
+The arithmetic overflow sanitizers ``unsigned-integer-overflow`` and
+``signed-integer-overflow`` as well as the implicit integer truncation
+sanitizers ``implicit-signed-integer-truncation`` and
+``implicit-unsigned-integer-truncation`` support the ability to adjust
+instrumentation based on type.
+
+.. code-block:: bash
+
+ $ cat foo.c
+ void foo() {
+ int a = 2147483647; // INT_MAX
+ ++a; // Normally, an overflow with
-fsanitize=signed-integer-overflow
+ }
+ $ cat ignorelist.txt
+ [signed-integer-overflow]
+ type:int
+ $ clang -fsanitize=signed-integer-overflow
-fsanitize-ignorelist=ignorelist.txt foo.c ; ./a.out
+ # no signed-integer-overflow error
+
+Supplying ``ignorelist.txt`` with ``-fsanitize-ignorelist=ignorelist.txt``
+disables overflow sanitizer instrumentation for arithmetic operations
+containing values of type ``int``, for example. Custom types may be used.
+
+The following SCL categories are supported: ``=allow``, ``=skip`` and
+``=forbid``. The ``allow`` category is the default for any entry and specifies
+that the query, if matched, will have its sanitizer instrumentation ignored.
+Conversely, both ``skip`` and ``forbid`` cause their queries, if matched, to be
+left out of the ignorelist -- essentially ensuring sanitizer instrumentation
+remains for those types. This is useful for whitelisting specific types.
+
+With this, one may disable instrumentation for all types and specifically allow
+instrumentation for one or many types.
+
+.. code-block:: bash
+
+ $ cat ignorelist.txt
+ [implicit-signed-integer-truncation]
+ type:*=allow
+ type:T=skip
+ $ cat foo.c
+ typedef char T;
+ typedef char U;
+ void foo(int toobig) {
+ T a = toobig; // instrumented
+ U b = toobig; // not instrumented
+ char c = toobig; // also not instrumented
+ }
+
+Note that ``skip`` and ``forbid`` operate exactly the same in this context and
----------------
vitalybuka wrote:
maybe `allow` -> `no_sanitize`
https://github.com/llvm/llvm-project/pull/107332
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