[llvm] [DXIL] Consume Metadata Analysis information in passes (PR #108034)

[Justin Bogner via llvm-commits]

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@@ -247,9 +247,10 @@ class DXILPrepareModule : public ModulePass {
 
   DXILPrepareModule() : ModulePass(ID) {}
   void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
     AU.addPreserved<ShaderFlagsAnalysisWrapper>();
     AU.addPreserved<DXILResourceMDWrapper>();
-    AU.addPreserved<DXILMetadataAnalysisWrapperPass>();
+    AU.addRequired<DXILMetadataAnalysisWrapperPass>();
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bogner wrote:

I'm not arguing that the `addRequired<DXILMetadataAnalysisWrapperPass>()` isn't necessary, it obviously is. I'm saying we shouldn't change the specific list of preserved passes to `setPreservesAll`. This pass does not preserve all analyses, since it modifies instructions. The code before your change looks correct to me:
```c++
    AU.addPreserved<ShaderFlagsAnalysisWrapper>();
    AU.addPreserved<DXILResourceMDWrapper>();
    AU.addPreserved<DXILMetadataAnalysisWrapperPass>();
    AU.addPreserved<DXILResourceWrapperPass>();
```

We can simply add `AU.addRequired<DXILMetadataAnalysisWrapperPass>();` after those calls instead of changing those calls to `setPreservesAll`, since that is incorrect.

https://github.com/llvm/llvm-project/pull/108034