List all source files in debug source file list (#7203)

* List all source files in debug source file list

The source file which does not participate in the line table is
missing from the debug source file list. Always copy IRDebugSource
instruction in linkIR() to fix the issue.

* Update the code to address review

* Add [[fallthrough]]

1 files changed, 23 insertions, 15 deletions

diff --git a/source/slang/slang-ir-link.cpp b/source/slang/slang-ir-link.cpp
index a84390f14..29a42b73c 100644
--- a/source/slang/slang-ir-link.cpp
+++ b/source/slang/slang-ir-link.cpp
@@ -2146,26 +2146,34 @@ LinkedIR linkIR(CodeGenContext* codeGenContext)
         }
     }
 
-    // Bindings for global generic parameters are currently represented
-    // as stand-alone global-scope instructions in the IR module for
-    // `SpecializedComponentType`s. These instructions are required for
-    // correct codegen, and so we must make sure to copy them all over,
-    // even though they are not directly referenced.
-    //
-    // TODO: We should change these to decorations, akin to how
-    // `[bindExistentialSlots(...)]` works, so that they can be attached
-    // 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.
-    //
-
+    // Clone additional insts that should be included in the linked IR module
+    // even if they are not being directly referenced.
     for (IRModule* irModule : userModules)
     {
         for (auto inst : irModule->getGlobalInsts())
         {
-            if (auto bindInst = as<IRBindGlobalGenericParam>(inst))
+            switch (inst->getOp())
             {
-                cloneValue(context, bindInst);
+            default:
+                break;
+            case kIROp_BindGlobalGenericParam:
+                // Bindings for global generic parameters are currently represented
+                // as stand-alone global-scope instructions in the IR module for
+                // `SpecializedComponentType`s. These instructions are required for
+                // correct codegen, and so we must make sure to copy them all over,
+                // even though they are not directly referenced.
+                //
+                // TODO: We should change these to decorations, akin to how
+                // `[bindExistentialSlots(...)]` works, so that they can be attached
+                // 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;
             }
         }
     }