[clang] [compiler-rt] [ASan] Document define to disable container overflow checks at compile time. (PR #163468)

[Paddy McDonald via cfe-commits]

================
@@ -242,6 +255,43 @@ AddressSanitizer also supports
 works similar to ``__attribute__((no_sanitize("address")))``, but it also
 prevents instrumentation performed by other sanitizers.
 
+Disabling container overflow checks
+-----------------------------------
+
+Runtime suppression
+^^^^^^^^^^^^^^^^^^^
+
+Container overflow checks can be disabled at runtime using
+``ASAN_OPTIONS=detect_container_overflow=0``
+
+Compile time suppression
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+``-D__ASAN_DISABLE_CONTAINER_OVERFLOW__`` can be used at compile time to
+disable container overflow checks if the container library has added support
+for this define.
----------------
padriff wrote:

The `__sanitizer_annotate_*` functions are controllable at runtime using `ASAN_OPTIONS=detect_container_overflow=0`.  

The issue we hit was where users were unable to recompile the entire set of dylibs / dlls to have uniformity of sanitized binaries and were unable to control the runtime environment to disable there.   

The request was to allow this instrumentation to be disabled at compile time for the template library code that is instantiated into their application code to simplify the workflows.



https://github.com/llvm/llvm-project/pull/163468