From 6492906ebe59b573f6243e7c44476944b9dd5592 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Thu, 7 Mar 2024 14:04:30 -0800
Subject: Fix SPIRV emit logic of `PrimitiveId` in fragment shader. (#3705)

---
 source/slang/slang-emit-spirv.cpp | 42 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'source')

diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index e37d09af7..098c2cc2b 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -3461,6 +3461,17 @@ struct SPIRVEmitContext
             varInst,
             builtinVal
         );
+        
+        if (storageClass == SpvStorageClassInput ||
+            storageClass == SpvStorageClassOutput)
+        {
+            switch (builtinVal)
+            {
+            case SpvBuiltInPrimitiveId:
+                _maybeEmitInterpolationModifierDecoration(IRInterpolationMode::NoInterpolation, varInst);
+                break;
+            }
+        }
         m_builtinGlobalVars[key] = varInst;
         return varInst;
     }
@@ -3565,6 +3576,37 @@ struct SPIRVEmitContext
                 }
                 else if (semanticName == "sv_primitiveid")
                 {
+                    auto entryPoints = m_referencingEntryPoints.tryGetValue(inst);
+                    // SPIRV requires `Geometry` capability being declared for a fragment
+                    // shader, if that shader uses sv_primitiveid.
+                    // We will check if this builtin is used by non-ray-tracing, non-geometry or
+                    // non-tessellation shader stages, and if so include a declaration of
+                    // Geometry capability.
+                    bool needGeometryCapability = true;
+                    if (entryPoints)
+                    {
+                        for (auto entryPoint : *entryPoints)
+                        {
+                            if (auto entryPointDecor = entryPoint->findDecoration<IREntryPointDecoration>())
+                            {
+                                switch (entryPointDecor->getProfile().getStage())
+                                {
+                                case Stage::Geometry:
+                                case Stage::Intersection:
+                                case Stage::Mesh:
+                                case Stage::Amplification:
+                                case Stage::AnyHit:
+                                case Stage::ClosestHit:
+                                case Stage::Hull:
+                                case Stage::Domain:
+                                    needGeometryCapability = false;
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                    if (needGeometryCapability)
+                        requireSPIRVCapability(SpvCapabilityGeometry);
                     return getBuiltinGlobalVar(inst->getFullType(), SpvBuiltInPrimitiveId);
                 }
                 else if (semanticName == "sv_rendertargetarrayindex")
-- 
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