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The SROA tests can be found here: https://github.com/llvm/llvm-project/tree/main/llvm/test/Transforms/SROA You can either create a new file or try to find an existing one for this code path -- the easiest way to do that is to add an assert and see which tests fail :)

It's worth noting that we have another copy of the memset splat generation code here, using a different implementation:

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

git-clang-format --diff HEAD~1 HEAD --extensions cpp -- llvm/lib/Transforms/Scalar/SROA.cpp

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 028bcde5a..403baed93 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -3222,14 +3222,14 @@ private:
 
     Type *SplatIntTy = Type::getIntNTy(VTy->getContext(), Size * 8);
     if (isa<UndefValue>(V)) {
-        V = UndefValue::get(VTy);
+      V = UndefValue::get(VTy);
     } else {
-        V = IRB.CreateMul(
-            IRB.CreateZExt(V, SplatIntTy, "zext"),
-            IRB.CreateUDiv(Constant::getAllOnesValue(SplatIntTy),
-                           IRB.CreateZExt(Constant::getAllOnesValue(V->getType()),
-                                          SplatIntTy)),
-            "isplat");
+      V = IRB.CreateMul(
+          IRB.CreateZExt(V, SplatIntTy, "zext"),
+          IRB.CreateUDiv(Constant::getAllOnesValue(SplatIntTy),
+                         IRB.CreateZExt(Constant::getAllOnesValue(V->getType()),
+                                        SplatIntTy)),
+          "isplat");
     }
     return V;
   }

⚠️ undef deprecator found issues in your code. ⚠️

git diff -U0 --pickaxe-regex -S '([^a-zA-Z0-9#_-]undef[^a-zA-Z0-9_-]|UndefValue::get)' 'HEAD~1' HEAD llvm/lib/Transforms/Scalar/SROA.cpp

The following files introduce new uses of undef:

• llvm/lib/Transforms/Scalar/SROA.cpp

Undef is now deprecated and should only be used in the rare cases where no replacement is possible. For example, a load of uninitialized memory yields undef. You should use poison values for placeholders instead.

In tests, avoid using undef and having tests that trigger undefined behavior. If you need an operand with some unimportant value, you can add a new argument to the function and use that instead.

For example, this is considered a bad practice:

define void @fn() {
  ...
  br i1 undef, ...
}

Please use the following instead:

define void @fn(i1 %cond) {
  ...
  br i1 %cond, ...
}

Please refer to the Undefined Behavior Manual for more information.