[clang] [Clang] Add wraps attribute (for granular integer overflow handling) (PR #86618)

[Justin Stitt via cfe-commits]

================
@@ -4093,6 +4109,11 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
       op.RHS->getType()->isPointerTy())
     return emitPointerArithmetic(CGF, op, CodeGenFunction::NotSubtraction);
 
+  if ((op.Ty->isSignedIntegerOrEnumerationType() ||
----------------
JustinStitt wrote:

It can't just be flat out removed, if that's what you're asking. An alternative would be a few additions to existing if-statements resulting in about the same level of readability.

Specifically a diff like this should perform the same:

```diff
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 70b3849240cd..3f6bac748506 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -4109,12 +4109,7 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
       op.RHS->getType()->isPointerTy())
     return emitPointerArithmetic(CGF, op, CodeGenFunction::NotSubtraction);
 
-  if ((op.Ty->isSignedIntegerOrEnumerationType() ||
-       op.Ty->isUnsignedIntegerType()) &&
-      op.hasWrappingOperand())
-    return Builder.CreateAdd(op.LHS, op.RHS, "add");
-
-  if (op.Ty->isSignedIntegerOrEnumerationType()) {
+  if (op.Ty->isSignedIntegerOrEnumerationType() && !op.hasWrappingOperand()) {
     switch (CGF.getLangOpts().getSignedOverflowBehavior()) {
     case LangOptions::SOB_Defined:
       if (!CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow))
@@ -4147,7 +4142,7 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
 
   if (op.Ty->isUnsignedIntegerType() &&
       CGF.SanOpts.has(SanitizerKind::UnsignedIntegerOverflow) &&
-      !CanElideOverflowCheck(CGF.getContext(), op))
+      !CanElideOverflowCheck(CGF.getContext(), op) && !op.hasWrappingOperand())
     return EmitOverflowCheckedBinOp(op);
 
   if (op.LHS->getType()->isFPOrFPVectorTy()) {

```


https://github.com/llvm/llvm-project/pull/86618