From 8f6c6e333c06ae1c3b9f00396563c14a2ae09b4d Mon Sep 17 00:00:00 2001
From: Darren Wihandi <65404740+fairywreath@users.noreply.github.com>
Date: Sun, 27 Apr 2025 14:31:34 -0600
Subject: Emit SPIRV NonReadable decoration for WTexture* (#6922)

---
 source/slang/slang-emit-glsl.cpp  | 10 ++++++++--
 source/slang/slang-emit-spirv.cpp | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

(limited to 'source')

diff --git a/source/slang/slang-emit-glsl.cpp b/source/slang/slang-emit-glsl.cpp
index 848d9c08d..5e9fa7f70 100644
--- a/source/slang/slang-emit-glsl.cpp
+++ b/source/slang/slang-emit-glsl.cpp
@@ -1837,8 +1837,9 @@ bool GLSLSourceEmitter::tryEmitGlobalParamImpl(IRGlobalParam* varDecl, IRType* v
 
 void GLSLSourceEmitter::emitImageFormatModifierImpl(IRInst* varDecl, IRType* varType)
 {
-    // As a special case, if we are emitting a GLSL declaration
-    // for an HLSL `RWTexture*` then we need to emit a `format` layout qualifier.
+    // Special cases when emitting a GLSL declaration for HLSL/Slang `RWTexture* and `WTexture*`:
+    // - Emit a `format` layout qualifier.
+    // - Emit `writeonly` memory qualifier for `WTexture*`.
 
     if (auto resourceType = as<IRTextureType>(unwrapArray(varType)))
     {
@@ -1855,6 +1856,11 @@ void GLSLSourceEmitter::emitImageFormatModifierImpl(IRInst* varDecl, IRType* var
         default:
             break;
         }
+
+        if (resourceType->getAccess() == SLANG_RESOURCE_ACCESS_WRITE)
+        {
+            m_writer->emit("writeonly\n");
+        }
     }
 }
 
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index d07d587e5..e4b5c2f4d 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -2767,6 +2767,7 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
             param->getDataType(),
             storageClass);
         maybeEmitPointerDecoration(varInst, param);
+        maybeEmitWriteOnlyImageDecoration(varInst, param);
         if (layout)
             emitVarLayout(param, varInst, layout);
         emitDecorations(param, getID(varInst));
@@ -5686,6 +5687,25 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         maybeEmitPointerDecoration(varInst, inst->getDataType(), as<IRVar>(inst), inst->getOp());
     }
 
+    void maybeEmitWriteOnlyImageDecoration(SpvInst* varInst, IRInst* inst)
+    {
+        auto ptrType = as<IRPtrTypeBase>(inst->getDataType());
+        if (!ptrType)
+            return;
+        auto textureType = as<IRTextureType>(ptrType->getValueType());
+        if (!textureType)
+            return;
+
+        if (textureType->getAccess() == SLANG_RESOURCE_ACCESS_WRITE)
+        {
+            emitOpDecorate(
+                getSection(SpvLogicalSectionID::Annotations),
+                nullptr,
+                getID(varInst),
+                SpvDecorationNonReadable);
+        }
+    }
+
     SpvInst* emitParam(SpvInstParent* parent, IRInst* inst)
     {
         auto paramSpvInst = emitOpFunctionParameter(parent, inst, inst->getFullType());
-- 
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