[SPIRV] Fix DebugLine generated from source with #line directive. (#3678)

3 files changed, 59 insertions, 12 deletions

diff --git a/source/slang/slang-emit-spirv-ops-debug-info-ext.h b/source/slang/slang-emit-spirv-ops-debug-info-ext.h
index cd4f274f8..a48a9eb04 100644
--- a/source/slang/slang-emit-spirv-ops-debug-info-ext.h
+++ b/source/slang/slang-emit-spirv-ops-debug-info-ext.h
@@ -10,10 +10,13 @@ SpvInst* emitOpDebugCompilationUnit(SpvInstParent* parent, IRInst* inst, const T
 
 // https://github.com/KhronosGroup/SPIRV-Registry/blob/main/nonsemantic/NonSemantic.Shader.DebugInfo.100.asciidoc#DebugSource
 template<typename T>
-SpvInst* emitOpDebugSource(SpvInstParent* parent, IRInst* inst, const T& idResultType, SpvInst* set, IRInst* file, SpvInst* text)
+SpvInst* emitOpDebugSource(SpvInstParent* parent, IRInst* inst, const T& idResultType, SpvInst* set, IRInst* file, SpvInst* text = nullptr)
 {
     static_assert(isSingular<T>);
-    return emitInst(parent, inst, SpvOpExtInst, idResultType, kResultID, set, SpvWord(35), file, text);
+    if (text)
+        return emitInst(parent, inst, SpvOpExtInst, idResultType, kResultID, set, SpvWord(35), file, text);
+    else
+        return emitInst(parent, inst, SpvOpExtInst, idResultType, kResultID, set, SpvWord(35), file);
 }
 
 template<typename T>
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index dd417e38f..e37d09af7 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -1599,10 +1599,20 @@ struct SPIRVEmitContext
         case kIROp_DebugSource:
             {
                 ensureExtensionDeclaration(UnownedStringSlice("SPV_KHR_non_semantic_info"));
-                // SPIRV does not allow string lits longer than 65535, so we need to split the source string
-                // in OpDebugSourceContinued instructions.
                 auto debugSource = as<IRDebugSource>(inst);
                 auto sourceStr = as<IRStringLit>(debugSource->getSource())->getStringSlice();
+                // If source content is empty, skip the content operand.
+                if (sourceStr.getLength() == 0)
+                {
+                    return emitOpDebugSource(
+                        getSection(SpvLogicalSectionID::ConstantsAndTypes),
+                        inst,
+                        inst->getFullType(),
+                        getNonSemanticDebugInfoExtInst(),
+                        debugSource->getFileName());
+                }
+                // SPIRV does not allow string lits longer than 65535, so we need to split the source string
+                // in OpDebugSourceContinued instructions.
                 auto sourceStrHead = sourceStr.getLength() > 65535 ? sourceStr.head(65535) : sourceStr;
                 auto spvStrHead = emitInst(
                     getSection(SpvLogicalSectionID::DebugStringsAndSource),
diff --git a/source/slang/slang-lower-to-ir.cpp b/source/slang/slang-lower-to-ir.cpp
index 638a9c577..753b21589 100644
--- a/source/slang/slang-lower-to-ir.cpp
+++ b/source/slang/slang-lower-to-ir.cpp
@@ -498,6 +498,7 @@ struct SharedIRGenContext
     Dictionary<Stmt*, IRBlock*> continueLabels;
 
     Dictionary<SourceFile*, IRInst*> mapSourceFileToDebugSourceInst;
+    Dictionary<String, IRInst*> mapSourcePathToDebugSourceInst;
 
     void setGlobalValue(Decl* decl, LoweredValInfo value)
     {
@@ -6366,26 +6367,59 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor>
     }
 };
 
+IRInst* getOrEmitDebugSource(IRGenContext* context, PathInfo path)
+{
+    if (auto result = context->shared->mapSourcePathToDebugSourceInst.tryGetValue(path.foundPath))
+        return *result;
+
+    ComPtr<ISlangBlob> outBlob;
+    if (path.hasFileFoundPath())
+    {
+        context->getLinkage()->getFileSystemExt()->loadFile(path.foundPath.getBuffer(), outBlob.writeRef());
+    }
+    UnownedStringSlice content;
+    if (outBlob)
+        content = UnownedStringSlice((char*)outBlob->getBufferPointer(), outBlob->getBufferSize());
+    IRBuilder builder(*context->irBuilder);
+    builder.setInsertInto(context->irBuilder->getModule());
+    auto debugSrcInst = builder.emitDebugSource(path.foundPath.getUnownedSlice(), content);
+    context->shared->mapSourcePathToDebugSourceInst[path.foundPath] = debugSrcInst;
+    return debugSrcInst;
+}
+
 void maybeEmitDebugLine(IRGenContext* context, StmtLoweringVisitor& visitor, Stmt* stmt)
 {
     if (!context->includeDebugInfo)
         return;
     if (as<EmptyStmt>(stmt))
         return;
+    auto sourceManager = context->getLinkage()->getSourceManager();
     auto sourceView = context->getLinkage()->getSourceManager()->findSourceView(stmt->loc);
     if (!sourceView)
         return;
-    auto source = sourceView->getSourceFile();
+
     IRInst* debugSourceInst = nullptr;
-    if (context->shared->mapSourceFileToDebugSourceInst.tryGetValue(source, debugSourceInst))
+    auto humaneLoc = context->getLinkage()->getSourceManager()->getHumaneLoc(stmt->loc, SourceLocType::Emit);
+
+    // Do a best-effort attempt to retrieve the nominal source file.
+    auto pathInfo = sourceView->getPathInfo(stmt->loc, SourceLocType::Emit);
+
+    // If the source file path correspond to an existing SourceFile in the source manager, use it.
+    auto source = sourceManager->findSourceFileByPathRecursively(pathInfo.foundPath);
+    if (!source)
+        source = sourceManager->findSourceFile(pathInfo.getMostUniqueIdentity());
+    if (source)
+    {
+        context->shared->mapSourceFileToDebugSourceInst.tryGetValue(source, debugSourceInst);
+    }
+    // If the source manager does not have an entry for the corresponding file name, make sure we still emit
+    // an source file entry in the spirv module.
+    if (!debugSourceInst)
     {
-        // When working with RenderDoc, we need to use actual source loc instead of the nominal one,
-        // since RenderDoc has the builtin support to split a source file into multiple files based on
-        // line directives in the file.
-        auto humaneLoc = context->getLinkage()->getSourceManager()->getHumaneLoc(stmt->loc, SourceLocType::Actual);
-        visitor.startBlockIfNeeded(stmt);
-        context->irBuilder->emitDebugLine(debugSourceInst, humaneLoc.line, humaneLoc.line, humaneLoc.column, humaneLoc.column + 1);
+        debugSourceInst = getOrEmitDebugSource(context, pathInfo);
     }
+    visitor.startBlockIfNeeded(stmt);
+    context->irBuilder->emitDebugLine(debugSourceInst, humaneLoc.line, humaneLoc.line, humaneLoc.column, humaneLoc.column + 1);
 }
 
 void maybeAddDebugLocationDecoration(IRGenContext* context, IRInst* inst)