Fix type legalization pass. (shader-slang#2768)

Author: csyonghe

source/slang/slang-ir-legalize-types.cpp

@@ -3541,32 +3541,42 @@ struct IRTypeLegalizationPass
         // In order to process an entire module, we start by adding the
         // root module insturction to our work list, and then we will
         // proceed to process instructions until the work list goes dry.
+        // The entire process is repeated until no more changes can be
+        // made to the module.
         //
-        addToWorkList(module->getModuleInst());
-        while( workList.getCount() != 0 )
-        {
-            // The order of items in the work list is signficiant;
-            // later entries could depend on earlier ones. As such, we
-            // cannot just do something like the `fastRemoveAt(...)`
-            // operation that could potentially lead to instructions
-            // being processed in a different order than they were added.
-            //
-            // Instead, we will make a copy of the current work list
-            // at each step, and swap in an empty work list to be added
-            // to with any new instructions.
-            //
-            List<IRInst*> workListCopy;
-            Swap(workListCopy, workList);
-            addedToWorkListSet.Clear();
-
-            // Now we simply process each instruction on the copy of
-            // the work list, knowing that `processInst` may add additional
-            // instructions to the original work list.
-            //
-            for( auto inst : workListCopy )
+        for (;;)
+        {
+            auto lastReplacedInstCount = context->replacedInstructions.Count();
+            addToWorkList(module->getModuleInst());
+            while( workList.getCount() != 0 )
             {
-                processInst(inst);
+                // The order of items in the work list is signficiant;
+                // later entries could depend on earlier ones. As such, we
+                // cannot just do something like the `fastRemoveAt(...)`
+                // operation that could potentially lead to instructions
+                // being processed in a different order than they were added.
+                //
+                // Instead, we will make a copy of the current work list
+                // at each step, and swap in an empty work list to be added
+                // to with any new instructions.
+                //
+                List<IRInst*> workListCopy;
+                Swap(workListCopy, workList);
+                addedToWorkListSet.Clear();
+
+                // Now we simply process each instruction on the copy of
+                // the work list, knowing that `processInst` may add additional
+                // instructions to the original work list.
+                //
+                for( auto inst : workListCopy )
+                {
+                    processInst(inst);
+                }
             }
+            
+            // Any changes made? Run the process again.
+            if (lastReplacedInstCount == context->replacedInstructions.Count())
+                break;
         }
 
         // After we are done, there might be various instructions that