From 395302d2404e3429f3cdfa406e89fa76bc0d444b Mon Sep 17 00:00:00 2001
From: Darren Wihandi <65404740+fairywreath@users.noreply.github.com>
Date: Thu, 13 Mar 2025 06:28:03 -0400
Subject: Add mesh shader output topology checks (#6592)

* initial wip

* more wip

* add test

* add unexpected for invalid target

* fixups and improve error message

* fixups and improve error message

* remove incorrect comment

---------

Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>
---
 source/slang/slang-ir-entry-point-decorations.cpp | 140 ++++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 source/slang/slang-ir-entry-point-decorations.cpp

(limited to 'source/slang/slang-ir-entry-point-decorations.cpp')

diff --git a/source/slang/slang-ir-entry-point-decorations.cpp b/source/slang/slang-ir-entry-point-decorations.cpp
new file mode 100644
index 000000000..eceb94e16
--- /dev/null
+++ b/source/slang/slang-ir-entry-point-decorations.cpp
@@ -0,0 +1,140 @@
+#include "slang-ir-entry-point-decorations.h"
+
+#include "compiler-core/slang-diagnostic-sink.h"
+#include "core/slang-signal.h"
+#include "core/slang-string.h"
+#include "core/slang-type-text-util.h"
+#include "slang-compiler.h"
+#include "slang-ir-insts.h"
+#include "slang-ir.h"
+#include "slang-options.h"
+
+namespace Slang
+{
+
+class CheckEntryPointDecorationsContext
+{
+public:
+    CheckEntryPointDecorationsContext(IRModule* module, CodeGenTarget target, DiagnosticSink* sink)
+        : m_module(module), m_target(target), m_sink(sink)
+    {
+    }
+
+    void check()
+    {
+        for (auto inst : m_module->getGlobalInsts())
+        {
+            const auto func = as<IRFunc>(inst);
+            if (!func)
+                continue;
+            const auto entryPointDecoration = func->findDecoration<IREntryPointDecoration>();
+            if (!entryPointDecoration)
+                continue;
+
+            checkEntryPoint(func, entryPointDecoration->getProfile().getStage());
+        }
+    }
+
+private:
+    void checkEntryPoint(IRFunc* entryPoint, Stage stage)
+    {
+        for (auto decoration : entryPoint->getDecorations())
+        {
+            if (auto outputTopologyDecoration = as<IROutputTopologyDecoration>(decoration))
+            {
+                checkOutputTopologyDecoration(outputTopologyDecoration, stage);
+            }
+        }
+    }
+
+    void checkOutputTopologyDecoration(IROutputTopologyDecoration* decoration, Stage stage)
+    {
+        if (stage == Stage::Mesh)
+        {
+            const auto outputTopologyType = OutputTopologyType(decoration->getTopologyType());
+            if (isTargetGLSL() || isTargetSPIRV() || isTargetMetal())
+            {
+                if (outputTopologyType != OutputTopologyType::Point &&
+                    outputTopologyType != OutputTopologyType::Line &&
+                    outputTopologyType != OutputTopologyType::Triangle)
+                {
+                    diagnoseInvalidMeshStageOutputTopology(
+                        decoration,
+                        "'point', 'line', 'triangle'");
+                }
+            }
+            else if (isTargetHLSL())
+            {
+                if (outputTopologyType != OutputTopologyType::Line &&
+                    outputTopologyType != OutputTopologyType::Triangle)
+                {
+                    diagnoseInvalidMeshStageOutputTopology(decoration, "'line', 'triangle'");
+                }
+            }
+            else
+            {
+                SLANG_UNEXPECTED("Invalid compilation target for mesh stage");
+            }
+        }
+    }
+
+    void diagnoseInvalidMeshStageOutputTopology(
+        IROutputTopologyDecoration* decoration,
+        String validTopologies)
+    {
+        m_sink->diagnose(
+            decoration,
+            Diagnostics::invalidMeshStageOutputTopology,
+            decoration->getTopology()->getStringSlice(),
+            TypeTextUtil::getCompileTargetName(SlangCompileTarget(m_target)),
+            validTopologies);
+    }
+
+    bool isTargetHLSL() const { return m_target == CodeGenTarget::HLSL; }
+
+    bool isTargetGLSL() const { return m_target == CodeGenTarget::GLSL; }
+
+    bool isTargetSPIRV() const
+    {
+        return m_target == CodeGenTarget::SPIRV || m_target == CodeGenTarget::SPIRVAssembly;
+    }
+
+    bool isTargetMetal() const
+    {
+        return m_target == CodeGenTarget::Metal || m_target == CodeGenTarget::MetalLib ||
+               m_target == CodeGenTarget::MetalLibAssembly;
+    }
+
+    IRModule* m_module;
+    const CodeGenTarget m_target;
+    DiagnosticSink* m_sink;
+};
+
+void checkEntryPointDecorations(IRModule* module, CodeGenTarget target, DiagnosticSink* sink)
+{
+    CheckEntryPointDecorationsContext(module, target, sink).check();
+}
+
+OutputTopologyType convertOutputTopologyStringToEnum(String rawOutputTopology)
+{
+    auto name = rawOutputTopology.toLower();
+
+    OutputTopologyType outputTopologyType = OutputTopologyType::Unknown;
+
+#define CASE(ID, NAME)                               \
+    if (name == String(#NAME).toLower())             \
+    {                                                \
+        outputTopologyType = OutputTopologyType::ID; \
+    }                                                \
+    else
+
+    OUTPUT_TOPOLOGY_TYPES(CASE)
+#undef CASE
+    {
+        outputTopologyType = OutputTopologyType::Unknown;
+        // no match
+    }
+    return outputTopologyType;
+}
+
+} // namespace Slang
-- 
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