[llvm-branch-commits] [clang] [llvm] [HLSL][RootSignature] Implement validation of resource ranges for `RootDescriptors` (PR #140962)

[Deric C. via llvm-branch-commits]

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@@ -951,6 +952,108 @@ void SemaHLSL::emitLogicalOperatorFixIt(Expr *LHS, Expr *RHS,
       << NewFnName << FixItHint::CreateReplacement(FullRange, OS.str());
 }
 
+namespace {
+
+// A resource range overlaps with another resource range if they have:
+// - equivalent ResourceClass (SRV, UAV, CBuffer, Sampler)
+// - equivalent resource space
+// - overlapping visbility
+class ResourceRanges {
+public:
+  // KeyT: 32-lsb denotes resource space, and 32-msb denotes resource type enum
+  using KeyT = uint64_t;
+
+  static const unsigned NumVisEnums =
+      (unsigned)llvm::hlsl::rootsig::ShaderVisibility::NumEnums;
+
+private:
+  llvm::hlsl::rootsig::ResourceRange::IMap::Allocator Allocator;
+
+  // Denotes a mapping of a unique combination of ResourceClass and register
+  // space to a ResourceRange
+  using MapT = llvm::SmallDenseMap<KeyT, llvm::hlsl::rootsig::ResourceRange>;
+
+  // Denotes a mapping for each unique visibility
+  MapT RangeMaps[NumVisEnums];
+
+  constexpr static KeyT getKey(const llvm::hlsl::rootsig::RangeInfo &Info) {
+    uint64_t SpacePacked = (uint64_t)Info.Space;
+    uint64_t ClassPacked = (uint64_t)llvm::to_underlying(Info.Class);
+    return (ClassPacked << 32) | SpacePacked;
+  }
+
+public:
+  // Returns std::nullopt if there was no collision. Otherwise, it will
+  // return the RangeInfo of the collision
+  std::optional<const llvm::hlsl::rootsig::RangeInfo *>
+  addRange(const llvm::hlsl::rootsig::RangeInfo &Info) {
+    MapT &VisRangeMap = RangeMaps[llvm::to_underlying(Info.Vis)];
+    auto [It, _] = VisRangeMap.insert(
+        {getKey(Info), llvm::hlsl::rootsig::ResourceRange(Allocator)});
+    auto Res = It->second.insert(Info);
+    if (Res.has_value())
+      return Res;
+
+    MutableArrayRef<MapT> Maps =
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Icohedron wrote:

Perhaps a comment here would be helpful to explain more clearly what this and the following loop are doing.

https://github.com/llvm/llvm-project/pull/140962