Fix entrypoint auto discovery logic. (shader-slang#5885)

* Fix entrypoint auto discovery logic.

* format code

---------

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

Author: csyonghe

source/slang/slang.cpp

@@ -5171,22 +5171,24 @@ IArtifact* ComponentType::getTargetArtifact(Int targetIndex, slang::IBlob** outD
                 entryPointsDiscovered = true;
             }
         }
-        // If no entry points were discovered, then we should return nullptr.
-        if (!entryPointsDiscovered)
-        {
-            return nullptr;
-        }
 
-        RefPtr<CompositeComponentType> composite = new CompositeComponentType(linkage, components);
-        ComPtr<IComponentType> linkedComponentType;
-        SLANG_RETURN_NULL_ON_FAIL(composite->link(linkedComponentType.writeRef(), outDiagnostics));
-        auto targetArtifact = static_cast<ComponentType*>(linkedComponentType.get())
-                                  ->getTargetArtifact(targetIndex, outDiagnostics);
-        if (targetArtifact)
+        // If any entry points were discovered, then we should emit the program with entrypoints
+        // linked.
+        if (entryPointsDiscovered)
         {
-            m_targetArtifacts[targetIndex] = targetArtifact;
+            RefPtr<CompositeComponentType> composite =
+                new CompositeComponentType(linkage, components);
+            ComPtr<IComponentType> linkedComponentType;
+            SLANG_RETURN_NULL_ON_FAIL(
+                composite->link(linkedComponentType.writeRef(), outDiagnostics));
+            auto targetArtifact = static_cast<ComponentType*>(linkedComponentType.get())
+                                      ->getTargetArtifact(targetIndex, outDiagnostics);
+            if (targetArtifact)
+            {
+                m_targetArtifacts[targetIndex] = targetArtifact;
+            }
+            return targetArtifact;
         }
-        return targetArtifact;
     }
 
     auto target = linkage->targets[targetIndex];

tools/slang-unit-test/unit-test-cuda-compile.cpp

@@ -0,0 +1,56 @@
+// unit-test-cuda-compile.cpp
+
+#include "../../source/core/slang-io.h"
+#include "../../source/core/slang-process.h"
+#include "slang-com-ptr.h"
+#include "slang.h"
+#include "unit-test/slang-unit-test.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+using namespace Slang;
+
+// Test that the compilation API can be used to produce CUDA source.
+
+SLANG_UNIT_TEST(CudaCompile)
+{
+    // Source for a module that contains an undecorated entrypoint.
+    const char* userSourceBody = R"(
+        [CudaDeviceExport]
+        float testExportedFunc(float3 particleRayOrigin)
+        {
+            return dot(particleRayOrigin,particleRayOrigin); 
+        };
+        )";
+
+    auto moduleName = "moduleG" + String(Process::getId());
+    ComPtr<slang::IGlobalSession> globalSession;
+    SLANG_CHECK(slang_createGlobalSession(SLANG_API_VERSION, globalSession.writeRef()) == SLANG_OK);
+    slang::TargetDesc targetDesc = {};
+    targetDesc.format = SLANG_CUDA_SOURCE;
+    slang::SessionDesc sessionDesc = {};
+    sessionDesc.targetCount = 1;
+    sessionDesc.targets = &targetDesc;
+    ComPtr<slang::ISession> session;
+    SLANG_CHECK(globalSession->createSession(sessionDesc, session.writeRef()) == SLANG_OK);
+
+    ComPtr<slang::IBlob> diagnosticBlob;
+    auto module = session->loadModuleFromSourceString(
+        "m",
+        "m.slang",
+        userSourceBody,
+        diagnosticBlob.writeRef());
+    SLANG_CHECK(module != nullptr);
+
+    ComPtr<slang::IComponentType> linkedProgram;
+    module->link(linkedProgram.writeRef(), diagnosticBlob.writeRef());
+    SLANG_CHECK(linkedProgram != nullptr);
+
+    ComPtr<slang::IBlob> code;
+    linkedProgram->getTargetCode(0, code.writeRef(), diagnosticBlob.writeRef());
+    SLANG_CHECK(code != nullptr);
+    SLANG_CHECK(code->getBufferSize() != 0);
+    String text = String((char*)code->getBufferPointer());
+    SLANG_CHECK(text.indexOf("testExportedFunc") > 0);
+}