[clang] [Clang] Re-land Overflow Pattern Exclusions (PR #104889)

[Justin Stitt via cfe-commits]

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@@ -293,6 +293,48 @@ To silence reports from unsigned integer overflow, you can set
 ``-fsanitize-recover=unsigned-integer-overflow``, is particularly useful for
 providing fuzzing signal without blowing up logs.
 
+Disabling instrumentation for common overflow patterns
+------------------------------------------------------
+
+There are certain overflow-dependent or overflow-prone code patterns which
+produce a lot of noise for integer overflow/truncation sanitizers. Negated
+unsigned constants, post-decrements in a while loop condition and simple
+overflow checks are accepted and pervasive code patterns. However, the signal
+received from sanitizers instrumenting these code patterns may be too noisy for
+some projects. To disable instrumentation for these common patterns one should
+use ``-fsanitize-undefined-ignore-overflow-pattern=``.
+
+Currently, this option supports three overflow-dependent code idioms:
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JustinStitt wrote:

Yes, good idea. 

https://github.com/llvm/llvm-project/pull/104889