[llvm] [DirectX] Add support for heap resources to `DXILResourceMap` (PR #216454)

[Justin Bogner via llvm-commits]

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@@ -415,16 +416,39 @@ class ResourceInfo {
   ResourceInfo(uint32_t Space, uint32_t LowerBound, uint32_t Size,
                TargetExtType *HandleTy, StringRef Name = "",
                GlobalVariable *Symbol = nullptr)
-      : Binding{0, Space, LowerBound, Size}, HandleTy(HandleTy), Name(Name),
-        Symbol(Symbol) {}
+      : BindingOrHeapID{ResourceBinding{0, Space, LowerBound, Size}},
+        HandleTy(HandleTy), Name(Name), Symbol(Symbol) {}
 
-  void setBindingID(unsigned ID) { Binding.BindingID = ID; }
+  ResourceInfo(uint32_t HeapResourceID, TargetExtType *HandleTy)
+      : BindingOrHeapID{HeapResourceID}, HandleTy(HandleTy), Name(""),
+        Symbol(nullptr) {}
+
+  bool hasBinding() const {
+    return std::holds_alternative<ResourceBinding>(BindingOrHeapID);
+  }
+  void setBindingID(unsigned ID) {
+    assert(hasBinding() && "Resource does not have a binding");
+    std::get<ResourceBinding>(BindingOrHeapID).BindingID = ID;
+  }
 
   bool hasCounter() const {
     return CounterDirection != ResourceCounterDirection::Unknown;
   }
 
-  const ResourceBinding &getBinding() const { return Binding; }
+  const ResourceBinding &getBinding() const {
+    assert(hasBinding() && "Resource does not have a binding");
+    return std::get<ResourceBinding>(BindingOrHeapID);
+  }
+
+  uint32_t getSize() const {
+    return hasBinding() ? std::get<ResourceBinding>(BindingOrHeapID).Size : 1;
+  }
+
+  uint32_t getHeapID() const {
+    assert(!hasBinding() && "Resource does not have a heap ID");
+    return std::get<uint32_t>(BindingOrHeapID);
+  }
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bogner wrote:

The ordering feels weird here - can we put the two variant accessors next to each other and `getSize` after them?

https://github.com/llvm/llvm-project/pull/216454