Allow requiring glsl language extensions on structs (#6173)

* Allow requiring glsl language extensions on structs

* format code

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
Co-authored-by: Yong He <yonghe@outlook.com>

source/slang/slang-emit-c-like.cpp

@@ -3722,10 +3722,6 @@ void CLikeSourceEmitter::emitSimpleFuncImpl(IRFunc* func)
         emitEntryPointAttributes(func, entryPointDecor);
     }
 
-    // Deal with required features/capabilities of the function
-    //
-    handleRequiredCapabilitiesImpl(func);
-
     emitFunctionPreambleImpl(func);
 
     emitFuncDecorations(func);
@@ -4885,6 +4881,10 @@ void CLikeSourceEmitter::emitGlobalInstImpl(IRInst* inst)
 {
     m_writer->advanceToSourceLocation(inst->sourceLoc);
 
+    // Deal with required features/capabilities of the global inst
+    //
+    handleRequiredCapabilitiesImpl(inst);
+
     switch (inst->getOp())
     {
     case kIROp_GlobalHashedStringLiterals:

source/slang/slang-lower-to-ir.cpp

@@ -9101,6 +9101,7 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
                 subBuilder->addAutoDiffBuiltinDecoration(irAggType);
         }
 
+        addTargetRequirementDecorations(irAggType, decl);
 
         return LoweredValInfo::simple(finalFinishedVal);
     }
@@ -9774,6 +9775,36 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
         }
     }
 
+    void addTargetRequirementDecorations(IRInst* inst, Decl* decl)
+    {
+        // If this declaration requires certain GLSL extension (or a particular GLSL version)
+        // for it to be usable, then declare that here. Similarly for SPIR-V or CUDA
+        //
+        // TODO: We should wrap this an `SpecializedForTargetModifier` together into a single
+        // case for enumerating the "capabilities" that a declaration requires.
+        //
+        for (auto extensionMod : decl->getModifiersOfType<RequiredGLSLExtensionModifier>())
+        {
+            getBuilder()->addRequireGLSLExtensionDecoration(
+                inst,
+                extensionMod->extensionNameToken.getContent());
+        }
+        for (auto versionMod : decl->getModifiersOfType<RequiredGLSLVersionModifier>())
+        {
+            getBuilder()->addRequireGLSLVersionDecoration(
+                inst,
+                Int(getIntegerLiteralValue(versionMod->versionNumberToken)));
+        }
+        for (auto versionMod : decl->getModifiersOfType<RequiredSPIRVVersionModifier>())
+        {
+            getBuilder()->addRequireSPIRVVersionDecoration(inst, versionMod->version);
+        }
+        for (auto versionMod : decl->getModifiersOfType<RequiredCUDASMVersionModifier>())
+        {
+            getBuilder()->addRequireCUDASMVersionDecoration(inst, versionMod->version);
+        }
+    }
+
     void addBitFieldAccessorDecorations(IRInst* irFunc, Decl* decl)
     {
         // If this is an accessor and the parent is describing some bitfield,
@@ -10340,6 +10371,8 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
 
         addCatchAllIntrinsicDecorationIfNeeded(irFunc, decl);
 
+        addTargetRequirementDecorations(irFunc, decl);
+
         bool isInline = false;
 
         addBitFieldAccessorDecorations(irFunc, decl);

tests/language-feature/glsl-extension.slang

@@ -0,0 +1,27 @@
+//TEST:SIMPLE(filecheck=CHECK): -target glsl -entry main -stage compute
+
+RWStructuredBuffer<float> outputBuffer;
+
+// Check that extensions on types work
+__glsl_extension(GL_BAR_bar)
+// CHECK-DAG: #extension GL_BAR_bar : require
+struct S
+{
+    float a;
+}
+
+// Check that extensions on functions work
+__glsl_extension(GL_FOO_foo)
+// CHECK-DAG: #extension GL_FOO_foo : require
+float foo(S s)
+{
+    return s.a;
+}
+
+[numthreads(4, 1, 1)]
+void main(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    S s;
+    s.a = 0;
+    outputBuffer[dispatchThreadID.x] = foo(s);
+}