Support PerVertexKHR decorated input and SV_Barycentric (microsoft#5649)

1. Replace extension AMD_shader_explicit_vertex_parameter with
KHR_fragment_shading_barycentric as they define same semantic.

2. Support new usage of SV_BaryCentrics and PerVertexKHR decorated
input.

3. For per-vertex inputs, they will be used as an array if a shader call
new intrinsic GetAttributeAtVertex explicitly.

4. Support mixed deprecate usage of `nointerpolation` qualifier. When
use non-interpolated inputs outside new intrinsic, it will be treated as
accessing to first provoking vertex : data[0]. But it will still be
treated as an array if used as a function call's argument.

5. As now we allow mixed usage of this kind of inputs, add spirv
instruction operand replacement in DXC. A new visitor will replace
normal access to those inputs with a new AccessChain instruction targets
its first element.

6. For bool and bool vector type, we reconstruct a new bool/boolVec type
array in entry function wrapper.

Author: ShchchowAMD

docs/SPIR-V.rst

@@ -297,10 +297,10 @@ Supported extensions
 * SPV_EXT_mesh_shader
 * SPV_EXT_shader_stencil_support
 * SPV_AMD_shader_early_and_late_fragment_tests
-* SPV_AMD_shader_explicit_vertex_parameter
 * SPV_GOOGLE_hlsl_functionality1
 * SPV_GOOGLE_user_type
 * SPV_NV_mesh_shader
+* SPV_KHR_fragment_shading_barycentric
 
 Vulkan specific attributes
 --------------------------
@@ -1583,7 +1583,7 @@ some system-value (SV) semantic strings will be translated into SPIR-V
 +---------------------------+-------------+----------------------------------------+-----------------------+-----------------------------+
 | SV_StencilRef             | PSOut       | ``FragStencilRefEXT``                  | N/A                   | ``StencilExportEXT``        |
 +---------------------------+-------------+----------------------------------------+-----------------------+-----------------------------+
-| SV_Barycentrics           | PSIn        | ``BaryCoord*AMD``                      | N/A                   | ``Shader``                  |
+| SV_Barycentrics           | PSIn        | ``BaryCoord*KHR``                      | N/A                   | ``FragmentBarycentricKHR``  |
 +---------------------------+-------------+----------------------------------------+-----------------------+-----------------------------+
 |                           | GSOut       | ``Layer``                              | N/A                   | ``Geometry``                |
 |                           +-------------+----------------------------------------+-----------------------+-----------------------------+

tools/clang/include/clang/SPIRV/FeatureManager.h

@@ -49,7 +49,6 @@ enum class Extension {
   EXT_shader_viewport_index_layer,
   AMD_gpu_shader_half_float,
   AMD_shader_early_and_late_fragment_tests,
-  AMD_shader_explicit_vertex_parameter,
   GOOGLE_hlsl_functionality1,
   GOOGLE_user_type,
   NV_ray_tracing,
@@ -59,6 +58,7 @@ enum class Extension {
   KHR_physical_storage_buffer,
   KHR_vulkan_memory_model,
   NV_compute_shader_derivatives,
+  KHR_fragment_shader_barycentric,
   Unknown,
 };
 

tools/clang/include/clang/SPIRV/SpirvBuilder.h

@@ -86,7 +86,8 @@ class SpirvBuilder {
   /// \brief Creates and registers a function parameter of the given pointer
   /// type in the current function and returns its pointer.
   SpirvFunctionParameter *addFnParam(QualType ptrType, bool isPrecise,
-                                     SourceLocation, llvm::StringRef name = "");
+                                     bool isNointerp, SourceLocation,
+                                     llvm::StringRef name = "");
 
   /// \brief Creates a local variable of the given type in the current
   /// function and returns it.
@@ -95,6 +96,7 @@ class SpirvBuilder {
   /// this method for the variable itself.
   SpirvVariable *addFnVar(QualType valueType, SourceLocation,
                           llvm::StringRef name = "", bool isPrecise = false,
+                          bool isNointerp = false,
                           SpirvInstruction *init = nullptr);
 
   /// \brief Ends building of the current function. All basic blocks constructed
@@ -628,7 +630,7 @@ class SpirvBuilder {
   /// constructed in this method.
   SpirvVariable *addStageIOVar(QualType type, spv::StorageClass storageClass,
                                llvm::StringRef name, bool isPrecise,
-                               SourceLocation loc);
+                               bool isNointerp, SourceLocation loc);
 
   /// \brief Adds a stage builtin variable whose value is of the given type.
   ///
@@ -646,12 +648,12 @@ class SpirvBuilder {
   /// constructed in this method.
   SpirvVariable *
   addModuleVar(QualType valueType, spv::StorageClass storageClass,
-               bool isPrecise, llvm::StringRef name = "",
+               bool isPrecise, bool isNointerp, llvm::StringRef name = "",
                llvm::Optional<SpirvInstruction *> init = llvm::None,
                SourceLocation loc = {});
   SpirvVariable *
   addModuleVar(const SpirvType *valueType, spv::StorageClass storageClass,
-               bool isPrecise, llvm::StringRef name = "",
+               bool isPrecise, bool isNointerp, llvm::StringRef name = "",
                llvm::Optional<SpirvInstruction *> init = llvm::None,
                SourceLocation loc = {});
 
@@ -711,6 +713,9 @@ class SpirvBuilder {
   void decoratePerTaskNV(SpirvInstruction *target, uint32_t offset,
                          SourceLocation);
 
+  /// \brief Decorates the given target with PerVertexKHR
+  void decoratePerVertexKHR(SpirvInstruction *argInst, SourceLocation);
+
   /// \brief Decorates the given target with Coherent
   void decorateCoherent(SpirvInstruction *target, SourceLocation);
 
@@ -758,6 +763,13 @@ class SpirvBuilder {
   const SpirvPointerType *
   getPhysicalStorageBufferType(const SpirvType *pointee);
 
+  void setPerVertexInterpMode(bool b);
+  bool isPerVertexInterpMode();
+
+  void addPerVertexStgInputFuncVarEntry(SpirvInstruction *k,
+                                        SpirvInstruction *v);
+  SpirvInstruction *getPerVertexStgInput(SpirvInstruction *k);
+
 public:
   std::vector<uint32_t> takeModule();
 
@@ -863,6 +875,10 @@ class SpirvBuilder {
   /// clone variables. We need it to avoid multiple clone variables for the same
   /// CTBuffer.
   llvm::DenseMap<SpirvVariable *, SpirvVariable *> fxcCTBufferToClone;
+
+  /// Mapping of a temporary stage parameter variable to real stage input
+  /// variables, only when the declaration has attribute `nointerpolation`
+  llvm::DenseMap<SpirvInstruction *, SpirvInstruction *> perVertexInputVarMap;
 };
 
 void SpirvBuilder::requireCapability(spv::Capability cap, SourceLocation loc) {

tools/clang/include/clang/SPIRV/SpirvFunction.h

@@ -59,6 +59,9 @@ class SpirvFunction {
     return parameters;
   }
 
+  // Gets the vector of variables.
+  std::vector<SpirvVariable *> getVariables() { return variables; }
+
   // Sets the SPIR-V type of the function
   void setFunctionType(SpirvType *type) { fnType = type; }
   // Returns the SPIR-V type of the function
@@ -98,6 +101,21 @@ class SpirvFunction {
     basicBlocks[0]->addFirstInstruction(inst);
   }
 
+  /// Adds instructions to a cache array.
+  void addToInstructionCache(SpirvInstruction *inst) {
+    instructionsCache.push_back(inst);
+  }
+
+  /// Adds cached instructions to the front of current function.
+  void addInstrCacheToFront() {
+    int cacheSize = instructionsCache.size();
+    for (int i = 0; i < cacheSize; i++) {
+      auto *inst = instructionsCache.back();
+      addFirstInstruction(inst);
+      instructionsCache.pop_back();
+    }
+    instructionsCache.clear();
+  }
   /// Legalization-specific code
   ///
   /// Note: the following methods are used for properly handling aliasing.
@@ -122,6 +140,15 @@ class SpirvFunction {
     return parameters[0]->getDebugName() == "param.this";
   }
 
+  /// Get or set a record for relationship between
+  /// a function parameter and variable within current function.
+  void addFuncParamVarEntry(SpirvInstruction *v, SpirvInstruction *p) {
+    funcVarParamMap[v] = p;
+  }
+  SpirvInstruction *getMappedFuncParam(SpirvInstruction *v) {
+    return funcVarParamMap.lookup(v);
+  }
+
 private:
   uint32_t functionId;         ///< This function's <result-id>
   QualType astReturnType;      ///< The return type
@@ -130,6 +157,9 @@ class SpirvFunction {
   bool relaxedPrecision; ///< Whether the return type is at relaxed precision
   bool precise;          ///< Whether the return value is 'precise'
   bool noInline;         ///< The function is marked as no inline
+  ///< An instructions cache vector. Would be used to help insert instructions
+  ///< at the beginning of a function.
+  std::vector<SpirvInstruction *> instructionsCache;
 
   /// Legalization-specific code
   ///
@@ -164,6 +194,9 @@ class SpirvFunction {
 
   /// DebugDeclare instructions for parameters to this function.
   llvm::SmallVector<SpirvDebugDeclare *, 8> debugDeclares;
+
+  /// Record relationship between a function parameter and its mapped variable.
+  llvm::DenseMap<SpirvInstruction *, SpirvInstruction *> funcVarParamMap;
 };
 
 } // end namespace spirv