[clang] [Clang] Add missing __ob_trap check for sign change (PR #188340)

[Matheus Izvekov via cfe-commits]

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@@ -1663,6 +1667,20 @@ Value *ScalarExprEmitter::EmitScalarConversion(Value *Src, QualType SrcType,
 
   llvm::Type *DstTy = ConvertType(DstType);
 
+  // Determine whether an overflow behavior of 'trap' has been specified for
+  // either the destination or the source types. If so, we can elide sanitizer
+  // capability checks as this overflow behavior kind is also capable of
+  // emitting traps without runtime sanitizer support.
+  // Also skip instrumentation if either source or destination has 'wrap'
+  // behavior - the user has explicitly indicated they accept wrapping
+  // semantics. Use non-canonical types to preserve OBT annotations.
+  const auto *DstOBT = NoncanonicalDstType->getAs<OverflowBehaviorType>();
+  const auto *SrcOBT = NoncanonicalSrcType->getAs<OverflowBehaviorType>();
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mizvekov wrote:

I was thinking this could have been a left over from before obt was part of the canonical type.

Anyway, using the canonical type seems to be the right approach here.

https://github.com/llvm/llvm-project/pull/188340