[Lldb-commits] [clang] [lldb] [Clang] Introduce OverflowBehaviorType for fine-grained overflow control (PR #148914)

[Justin Stitt via lldb-commits]

================
@@ -112,6 +112,25 @@ class LangOptionsBase {
     SOB_Trapping
   };
 
+  // Used by __attribute__((overflow_behavior())) to describe overflow behavior
+  // on a per-type basis.
+  enum OverflowBehaviorKind {
+    // Default C standard behavior (type dependent).
+    OB_Unset,
+
+    // __attribute__((overflow_behavior("wrap")))
+    OB_Wrap,
+
+    // __attribute__((overflow_behavior("no_wrap")))
+    OB_NoWrap,
+
+    // Signed types defined as wrapping via -fwrapv can still be instrumented
+    // by sanitizers (PR82432). This field is needed to disambiguate canonical
+    // wrapping type behaviors from -fwrapv behaviors.
+    // -fwrapv
+    OB_FWrapv
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JustinStitt wrote:

I am using `getOverflowBehaviorConsideringType()` which considers the `SignedOverflowBehavior` as well as any overflow behavior types. As I am combining both into a common interface, I need to disambiguate between unmodified signed arithmetic and `-fwrapv` arithmetic.

I think perhaps renaming this field to `OB_SignedAndDefined` would better represent its meaning.

https://github.com/llvm/llvm-project/pull/148914