[llvm] [AMDGPU] Avoid repeated hash lookups (NFC) (PR #127573)

[Kazu Hirata via llvm-commits]

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@@ -384,13 +384,14 @@ class AMDGPUWaitSGPRHazards {
       }
     }
 
-    bool Changed = State != BlockState[&MBB].Out;
+    auto &BS = BlockState[&MBB];
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kazutakahirata wrote:

I've replaced `auto` with `BlockHazardState`.  Thanks!

https://github.com/llvm/llvm-project/pull/127573