Fix DebugGlobalVariable source file assignment for included/imported files

source/slang/slang-emit-spirv.cpp

@@ -1642,6 +1642,9 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
     }
 
     IRInst* m_defaultDebugSource = nullptr;
+    IRInst* m_entryPointDebugSource = nullptr;
+
+    void setEntryPointDebugSource(IRInst* source) { m_entryPointDebugSource = source; }
 
     Dictionary<UnownedStringSlice, SpvInst*> m_extensionInsts;
     SpvInst* ensureExtensionDeclaration(UnownedStringSlice name)
@@ -2356,10 +2359,18 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
                 }
 
                 auto moduleInst = inst->getModule()->getModuleInst();
-                if (!m_defaultDebugSource)
-                    m_defaultDebugSource = debugSource;
                 // Only create DebugCompilationUnit for non-included files
-                auto isIncludedFile = as<IRBoolLit>(debugSource->getIsIncludedFile())->getValue();
+                auto isIncludedFileLit = as<IRBoolLit>(debugSource->getIsIncludedFile());
+                bool isIncludedFile = isIncludedFileLit ? isIncludedFileLit->getValue() : false;
+                // Prefer the entry point's debug source as the default.
+                // Otherwise, only set default debug source to non-included files.
+                if (!m_defaultDebugSource)
+                {
+                    if (m_entryPointDebugSource && debugSource == m_entryPointDebugSource)
+                        m_defaultDebugSource = debugSource;
+                    else if (!m_entryPointDebugSource && !isIncludedFile)
+                        m_defaultDebugSource = debugSource;
+                }
                 if (!m_mapIRInstToSpvDebugInst.containsKey(moduleInst) && !isIncludedFile)
                 {
                     IRBuilder builder(inst);
@@ -9831,6 +9842,24 @@ SlangResult emitSPIRVFromIR(
         CompilerOptionName::PreserveParameters);
     auto generateWholeProgram = codeGenContext->getTargetProgram()->getOptionSet().getBoolOption(
         CompilerOptionName::GenerateWholeProgram);
+
+    // Pre-identify the entry point's debug source to use as the default debug source.
+    // This ensures that global variables without explicit debug locations use the
+    // correct source file (the main shader file where the entry point is defined,
+    // not imported module files).
+    for (auto entryPoint : irEntryPoints)
+    {
+        if (auto debugLoc = entryPoint->findDecoration<IRDebugLocationDecoration>())
+        {
+            auto entryPointDebugSource = as<IRDebugSource>(debugLoc->getSource());
+            if (entryPointDebugSource)
+            {
+                context.setEntryPointDebugSource(entryPointDebugSource);
+                break;
+            }
+        }
+    }
+
     for (auto inst : irModule->getGlobalInsts())
     {
         if (as<IRDebugSource>(inst))

source/slang/slang-ir-link.cpp

@@ -2155,6 +2155,7 @@ LinkedIR linkIR(CodeGenContext* codeGenContext)
 
     // Clone additional insts that should be included in the linked IR module
     // even if they are not being directly referenced.
+    bool isFirstUserModule = true;
     for (IRModule* irModule : userModules)
     {
         for (auto inst : irModule->getGlobalInsts())
@@ -2175,19 +2176,53 @@ LinkedIR linkIR(CodeGenContext* codeGenContext)
                 // to the relevant parameters and cloned via `cloneExtraDecorations`.
                 // In the long run we do not want to *ever* iterate over all the
                 // instructions in all the input modules.
-                [[fallthrough]];
-            case kIROp_DebugSource:
-                // Need to list all source files in the debug source file list,
-                // regardless if the source files participate in the line table or not.
                 cloneValue(context, inst);
                 break;
+            case kIROp_DebugSource:
+                {
+                    // Need to list all source files in the debug source file list,
+                    // regardless if the source files participate in the line table or not.
+                    // For DebugSource from imported modules (not the first/main module),
+                    // we need to mark them as included files so they don't become the
+                    // default debug source for global variables.
+                    auto debugSource = as<IRDebugSource>(inst);
+                    auto isIncludedFileLit = as<IRBoolLit>(debugSource->getIsIncludedFile());
+
+                    // If this is from an imported module and not already marked as included,
+                    // create a new DebugSource with isIncludedFile=true
+                    if (!isFirstUserModule && isIncludedFileLit && !isIncludedFileLit->getValue())
+                    {
+                        auto fileName = as<IRStringLit>(debugSource->getFileName());
+                        auto source = as<IRStringLit>(debugSource->getSource());
+                        if (fileName && source)
+                        {
+                            auto newDebugSource = context->builder->emitDebugSource(
+                                fileName->getStringSlice(),
+                                source->getStringSlice(),
+                                true);
+                            // Register this as the clone of the original so that references
+                            // to the original will use the new one with isIncludedFile=true
+                            registerClonedValue(context, newDebugSource, inst);
+                        }
+                        else
+                        {
+                            cloneValue(context, inst);
+                        }
+                    }
+                    else
+                    {
+                        cloneValue(context, inst);
+                    }
+                }
+                break;
             case kIROp_DebugBuildIdentifier:
                 // The debug build identifier won't be referenced by anything,
                 // but we still need to keep it around if it is in the IR.
                 cloneValue(context, inst);
                 break;
             }
         }
+        isFirstUserModule = false;
     }
 
     bool shouldCopyGlobalParams =

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

@@ -8019,7 +8019,7 @@ IRInst* getOrEmitDebugSource(IRGenContext* context, PathInfo path)
         content = UnownedStringSlice((char*)outBlob->getBufferPointer(), outBlob->getBufferSize());
     IRBuilder builder(*context->irBuilder);
     builder.setInsertInto(context->irBuilder->getModule());
-    auto debugSrcInst = builder.emitDebugSource(path.foundPath.getUnownedSlice(), content, false);
+    auto debugSrcInst = builder.emitDebugSource(path.foundPath.getUnownedSlice(), content, true);
     context->shared->mapSourcePathToDebugSourceInst[path.foundPath] = debugSrcInst;
     return debugSrcInst;
 }

tests/spirv/debug-global-variable-source-import.slang

@@ -0,0 +1,35 @@
+//TEST:SIMPLE(filecheck=CHECK):-target spirv -entry main -stage fragment -g2 -emit-spirv-directly
+
+// Test that DebugGlobalVariable references the correct source file (this main file)
+// when using import syntax instead of #include.
+
+import shader_utils_module;
+
+struct VertexOutput
+{
+    float4 position : SV_Position;
+    float2 texCoord : TEXCOORD0;
+}
+
+[shader("fragment")]
+float4 main(VertexOutput input) : SV_Target
+{
+    float2 uv = input.texCoord;
+    float distanceFromCenter = calculateDistanceFromCenterModule(uv);
+    float radialFade = createRadialFadeModule(uv, 0.7);
+    float4 color = float4(
+        uv.x * (1.0 - distanceFromCenter * 0.5),
+        uv.y * radialFade,
+        uv.x * uv.y,
+        1.0
+    );
+    return color;
+}
+
+// Verify that DebugSource for the main file is defined
+// CHECK-DAG: [[MAIN_FILE:%[0-9]+]] = OpString "{{.*}}debug-global-variable-source-import.slang"
+// CHECK-DAG: [[SOURCE_MAIN:%[0-9]+]] = OpExtInst %void %{{[0-9]+}} DebugSource [[MAIN_FILE]] %{{[0-9]+}}
+
+// Verify that DebugGlobalVariable for entry point parameters references the main file source
+// The key fix: DebugGlobalVariable should reference the main file source, not the imported file source
+// CHECK-DAG: OpExtInst %void %{{[0-9]+}} DebugGlobalVariable {{%[0-9]+}} {{%[0-9]+}} [[SOURCE_MAIN]] %uint_0 %uint_0

tests/spirv/debug-global-variable-source.slang

@@ -0,0 +1,35 @@
+//TEST:SIMPLE(filecheck=CHECK):-target spirv -entry main -stage fragment -g2 -emit-spirv-directly
+
+// Test that DebugGlobalVariable references the correct source file (this main file)
+// rather than an included header file.
+
+#include "shader-utils.slang"
+
+struct VertexOutput
+{
+    float4 position : SV_Position;
+    float2 texCoord : TEXCOORD0;
+}
+
+[shader("fragment")]
+float4 main(VertexOutput input) : SV_Target
+{
+    float2 uv = input.texCoord;
+    float distanceFromCenter = calculateDistanceFromCenter(uv);
+    float radialFade = createRadialFade(uv, 0.7);
+    float4 color = float4(
+        uv.x * (1.0 - distanceFromCenter * 0.5),
+        uv.y * radialFade,
+        uv.x * uv.y,
+        1.0
+    );
+    return color;
+}
+
+// Verify that DebugSource for the main file is defined
+// CHECK-DAG: [[MAIN_FILE:%[0-9]+]] = OpString "{{.*}}debug-global-variable-source.slang"
+// CHECK-DAG: [[SOURCE_MAIN:%[0-9]+]] = OpExtInst %void %{{[0-9]+}} DebugSource [[MAIN_FILE]] %{{[0-9]+}}
+
+// Verify that DebugGlobalVariable for entry point parameters references the main file source
+// The key fix: DebugGlobalVariable should reference the main file source, not the included file source
+// CHECK-DAG: OpExtInst %void %{{[0-9]+}} DebugGlobalVariable {{%[0-9]+}} {{%[0-9]+}} [[SOURCE_MAIN]] %uint_0 %uint_0

tests/spirv/shader-utils-module.slang

@@ -0,0 +1,16 @@
+// Module containing utility functions for debug tests
+module shader_utils_module;
+
+// Helper function to calculate distance from center
+public float calculateDistanceFromCenterModule(float2 uv)
+{
+    float2 center = float2(0.5, 0.5);
+    return length(uv - center);
+}
+
+// Additional utility function - simple smoothstep fade
+public float createRadialFadeModule(float2 uv, float radius)
+{
+    float dist = calculateDistanceFromCenterModule(uv);
+    return smoothstep(radius, 0.0, dist);
+}