Add SV_DrawIndex. (#5787)

Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>

5 files changed, 16 insertions, 0 deletions

diff --git a/source/slang/slang-emit-glsl.cpp b/source/slang/slang-emit-glsl.cpp
index 6c525d064..f22419147 100644
--- a/source/slang/slang-emit-glsl.cpp
+++ b/source/slang/slang-emit-glsl.cpp
@@ -1127,6 +1127,10 @@ void GLSLSourceEmitter::_maybeEmitGLSLBuiltin(IRGlobalParam* var, UnownedStringS
     {
         _requireGLSLExtension(toSlice("GL_EXT_fragment_shading_rate_primitive"));
     }
+    else if (name == "gl_DrawID")
+    {
+        _requireGLSLVersion(460);
+    }
 }
 
 void GLSLSourceEmitter::_requireBaseType(BaseType baseType)
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index 58f5e4f66..f4aa900db 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -5137,6 +5137,11 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
                     // float in hlsl & glsl
                     return getBuiltinGlobalVar(inst->getFullType(), SpvBuiltInPointSize, inst);
                 }
+                else if (semanticName == "sv_drawindex")
+                {
+                    requireSPIRVCapability(SpvCapabilityDrawParameters);
+                    return getBuiltinGlobalVar(inst->getFullType(), SpvBuiltInDrawIndex, inst);
+                }
                 else if (semanticName == "sv_primitiveid")
                 {
                     auto entryPoints = m_referencingEntryPoints.tryGetValue(inst);
diff --git a/source/slang/slang-ir-glsl-legalize.cpp b/source/slang/slang-ir-glsl-legalize.cpp
index 3f3f2dbe0..619682692 100644
--- a/source/slang/slang-ir-glsl-legalize.cpp
+++ b/source/slang/slang-ir-glsl-legalize.cpp
@@ -623,6 +623,11 @@ GLSLSystemValueInfo* getGLSLSystemValueInfo(
         name = "gl_PointSize";
         requiredType = builder->getBasicType(BaseType::Float);
     }
+    else if (semanticName == "sv_drawindex")
+    {
+        name = "gl_DrawID";
+        requiredType = builder->getBasicType(BaseType::Int);
+    }
     else if (semanticName == "sv_primitiveid")
     {
         // uint in hlsl, int in glsl
diff --git a/source/slang/slang-ir-legalize-varying-params.h b/source/slang/slang-ir-legalize-varying-params.h
index 3c97d739b..c8952f604 100644
--- a/source/slang/slang-ir-legalize-varying-params.h
+++ b/source/slang/slang-ir-legalize-varying-params.h
@@ -48,6 +48,7 @@ IRInst* emitCalcGroupIndex(IRBuilder& builder, IRInst* groupThreadID, IRInst* gr
     M(OutputControlPointID, SV_OutputControlPointID)     \
     M(PointSize, SV_PointSize)                           \
     M(PrimitiveID, SV_PrimitiveID)                       \
+    M(DrawIndex, SV_DrawIndex)                           \
     M(RenderTargetArrayIndex, SV_RenderTargetArrayIndex) \
     M(SampleIndex, SV_SampleIndex)                       \
     M(StencilRef, SV_StencilRef)                         \
diff --git a/source/slang/slang-language-server-completion.cpp b/source/slang/slang-language-server-completion.cpp
index 82b7286ea..03c6b88ed 100644
--- a/source/slang/slang-language-server-completion.cpp
+++ b/source/slang/slang-language-server-completion.cpp
@@ -116,6 +116,7 @@ static const char* hlslSemanticNames[] = {
     "SV_Position",
     "SV_PointSize",
     "SV_PrimitiveID",
+    "SV_DrawIndex",
     "SV_RenderTargetArrayIndex",
     "SV_SampleIndex",
     "SV_StencilRef",