[llvm] [DirectX] fix illegal behavior flag in module flags. (PR #96577)

[Damyan Pepper via llvm-commits]

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@@ -0,0 +1,17 @@
+; RUN: opt -S -dxil-prepare < %s | FileCheck %s
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damyanp wrote:

Seems overkill to me - and by this precedent we'd need to add new combinations of flags is new ones ever show up. But probably doesn't hurt.

https://github.com/llvm/llvm-project/pull/96577