[clang] [clang][CodeGen] Fix assertion failure for new T[SIZE_MAX] with array cookie (PR #232570)

[via cfe-commits]

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@@ -1789,8 +1789,10 @@ llvm::Value *CodeGenFunction::EmitCXXNewExpr(const CXXNewExpr *E) {
     cleanupDominator = Builder.CreateUnreachable();
   }
 
-  assert((allocSize == allocSizeWithoutCookie) ==
-         CalculateCookiePadding(*this, E).isZero());
+  // Without a cookie the two sizes must match. With a cookie they usually
+  // differ, but on overflow both can be all-ones, so don't assert the converse.
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henrimarconni wrote:

Good idea, done, keeping the original iff. with an escape hatch just for the edge case where allocSize == all ones value.

https://github.com/llvm/llvm-project/pull/232570