[llvm] [DirectX] Infrastructure to collect shader flags for each function (PR #112967)

[S. Bharadwaj Yadavalli via llvm-commits]

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@@ -60,21 +61,47 @@ struct ComputedShaderFlags {
     return FeatureFlags;
   }
 
-  static ComputedShaderFlags computeFlags(Module &M);
+  uint64_t getModuleFlags() const {
+    uint64_t ModuleFlags = 0;
+#define DXIL_MODULE_FLAG(DxilModuleBit, FlagName, Str)                         \
+  ModuleFlags |= FlagName ? getMask(DxilModuleBit) : 0ull;
+#include "llvm/BinaryFormat/DXContainerConstants.def"
+    return ModuleFlags;
+  }
+
   void print(raw_ostream &OS = dbgs()) const;
   LLVM_DUMP_METHOD void dump() const { print(); }
 };
 
+struct DXILModuleShaderFlagsInfo {
+  Expected<const ComputedShaderFlags &>
+  getShaderFlagsMask(const Function *Func) const;
+  bool hasShaderFlagsMask(const Function *Func) const;
+  const ComputedShaderFlags &getModuleFlags() const;
+  const SmallVector<std::pair<Function const *, ComputedShaderFlags>> &
+  getFunctionFlags() const;
+  void insertInorderFunctionFlags(const Function *, ComputedShaderFlags);
+
+private:
+  // Shader Flag mask representing module-level properties. These are
+  // represented using the macro DXIL_MODULE_FLAG
+  ComputedShaderFlags ModuleFlags;
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bharadwajy wrote:

> Can you point me to where `ModuleFlags` gets set?

[Individual flags](https://github.com/llvm/llvm-project/blob/f548d39c3c751446d124c08769080214680d53ba/llvm/include/llvm/BinaryFormat/DXContainerConstants.def#L57) constituting `ModuleFlags` are expected to be set in `computeFlags()` (which is changed to `DXILModuleShaderFlagsInfo::initialize(const Module &M)` in the latest change) as part of [support planned](https://github.com/llvm/llvm-project/issues/112044) to be added for those module level flags before walking the various functions of the module. 

https://github.com/llvm/llvm-project/pull/112967