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>

2 files changed, 4 insertions, 2 deletions

diff --git a/source/compiler-core/slang-downstream-compiler.h b/source/compiler-core/slang-downstream-compiler.h
index 5365b9839..c23a6eff0 100644
--- a/source/compiler-core/slang-downstream-compiler.h
+++ b/source/compiler-core/slang-downstream-compiler.h
@@ -260,6 +260,9 @@ struct DownstreamCompileOptions
     /// Profile name to use, only required for compiles that need to compile against a a specific
     /// profiles. Profile names are tied to compilers and targets.
     TerminatedCharSlice profileName;
+    // According to DirectX Raytracing Specification, PAQs are supported in Shader Model 6.7 and
+    // above
+    bool enablePAQ = false;
 
     /// The stage being compiled for
     SlangStage stage = SLANG_STAGE_NONE;
diff --git a/source/compiler-core/slang-dxc-compiler.cpp b/source/compiler-core/slang-dxc-compiler.cpp
index 065ee4145..0d4bc0a59 100644
--- a/source/compiler-core/slang-dxc-compiler.cpp
+++ b/source/compiler-core/slang-dxc-compiler.cpp
@@ -479,8 +479,7 @@ SlangResult DXCDownstreamCompiler::compile(const CompileOptions& inOptions, IArt
         args.add(compilerSpecific[i]);
     }
 
-    // This can be re-enabled when we add PAQs: https://github.com/shader-slang/slang/issues/3448
-    const bool enablePAQs = false;
+    bool enablePAQs = options.enablePAQ;
     if (!enablePAQs)
         args.add(L"-disable-payload-qualifiers");
     else