From ce87ab925d06a784eec194081e00a1b4c9b94d0c Mon Sep 17 00:00:00 2001
From: "Harsh Aggarwal (NVIDIA)" <haaggarwal@nvidia.com>
Date: Mon, 7 Apr 2025 13:26:11 +0530
Subject: Support for Payload Access Qualifiers (#3448) (#6595)

* Add support for Ray Payload Access Qualifiers (PAQs) (#3448)

- Added [raypayload] attribute for struct declarations
- Implemented field validation requiring read/write access qualifiers
- Added diagnostic error for missing qualifiers
- Enabled PAQs in DXC compiler and HLSL emission
- Added new test demonstrating PAQ syntax
- Implemented proper handling of ray payload attributes in IR generation

* format code

* Cleanup: Remove unused vars

* Add check to enablePAQ only for profile >= lib_6_7

* Review Fix - Add PAQ support for DX Raytracing

add enablePAQ flag to DownstreamCompileOpitons, improve PAQ handling
update raypayload-attribute-paq.slang to ensure hlsl and dxil is
validated

* Add diagnostic test for missing paq for lib_6_7

Compile using `-disable-payload-qualifiers` aka lib_6_6 profile
raypayload-attribute-no-struct.slang and
raypayload-attribute.slang

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>
---
 source/slang/slang-check-modifier.cpp | 42 +++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'source/slang/slang-check-modifier.cpp')

diff --git a/source/slang/slang-check-modifier.cpp b/source/slang/slang-check-modifier.cpp
index 741823a65..d94c77d6a 100644
--- a/source/slang/slang-check-modifier.cpp
+++ b/source/slang/slang-check-modifier.cpp
@@ -1413,9 +1413,20 @@ bool isModifierAllowedOnDecl(bool isGLSLInput, ASTNodeType modifierType, Decl* d
     case ASTNodeType::ConstRefModifier:
     case ASTNodeType::GLSLBufferModifier:
     case ASTNodeType::GLSLPatchModifier:
+        return (as<VarDeclBase>(decl) && isGlobalDecl(decl)) || as<ParamDecl>(decl) ||
+               as<GLSLInterfaceBlockDecl>(decl);
     case ASTNodeType::RayPayloadAccessSemantic:
     case ASTNodeType::RayPayloadReadSemantic:
     case ASTNodeType::RayPayloadWriteSemantic:
+        // Allow on struct fields if the parent struct has the [raypayload] attribute
+        if (auto varDecl = as<VarDeclBase>(decl))
+        {
+            if (auto structDecl = as<StructDecl>(varDecl->parentDecl))
+            {
+                if (structDecl->findModifier<RayPayloadAttribute>())
+                    return true;
+            }
+        }
         return (as<VarDeclBase>(decl) && isGlobalDecl(decl)) || as<ParamDecl>(decl) ||
                as<GLSLInterfaceBlockDecl>(decl);
 
@@ -2179,5 +2190,36 @@ void SemanticsVisitor::checkModifiers(ModifiableSyntaxNode* syntaxNode)
     postProcessingOnModifiers(syntaxNode->modifiers);
 }
 
+void SemanticsVisitor::checkRayPayloadStructFields(StructDecl* structDecl)
+{
+    // Only check structs with the [raypayload] attribute
+    if (!structDecl->findModifier<RayPayloadAttribute>())
+    {
+        return;
+    }
+
+    // Check each field in the struct
+    for (auto member : structDecl->members)
+    {
+        auto fieldVarDecl = as<VarDeclBase>(member);
+        if (!fieldVarDecl)
+        {
+            continue;
+        }
+
+        bool hasReadModifier = fieldVarDecl->findModifier<RayPayloadReadSemantic>() != nullptr;
+        bool hasWriteModifier = fieldVarDecl->findModifier<RayPayloadWriteSemantic>() != nullptr;
+
+        if (!hasReadModifier && !hasWriteModifier)
+        {
+            // Emit the diagnostic error
+            getSink()->diagnose(
+                fieldVarDecl,
+                Diagnostics::rayPayloadFieldMissingAccessQualifiers,
+                fieldVarDecl->getName());
+        }
+    }
+}
+
 
 } // namespace Slang
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