Update the comments

Author: jkwak-work

source/slang/slang-ir-specialize.cpp

@@ -3123,13 +3123,18 @@ IRInst* specializeGenericImpl(
         //
         IRInstList<IRInst> ordinaryInsts = bb->getOrdinaryInsts();
 
-        // After IRWitnessTable became Hoistable, they are removed and insered back by
+        // After IRWitnessTable became Hoistable, they are removed and inserted back by
         // `addHoistableInst()`. But when they are re-inserted, the order it appears in the block is
-        // changed. When IRWitnessTable refers to IRSpecialize, as an example, IRSpecialize must be
+        // changed. We need to change the order in a way that the dependancy is resolved.
+        //
+        // The dependency cannot be resolve in `addHoistableInst()`, because IRWitnessTable doesn't
+        // have IRWitnessTableEntry yet while in the function.
+        //
+        // When IRWitnessTable refers to IRSpecialize, as an example, IRSpecialize must be
         // cloned before the cloning of IRWitnessTable. It is because the operands are assumed to be
         // cloned before the cloning of IRInst.
         //
-        // We need to resolve the dependency problem by changing the order of them.
+        // Similarly, there can be dependencies between an IRWitnessTable and another IRWitnessTable.
         //
         List<IRInst*> insts;
         int instCount = 0;

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

@@ -8016,12 +8016,9 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
                             irWitnessTableBaseType,
                             irWitnessTable->getConcreteType());
 
-                        // TODO: When WitnessTable became HOISTABLE, we needed a way to avoid
-                        // adding the same decorations and childrens redundantly.
-                        // There isn't an easy way to tell if the returned WitnessTable is a
-                        // brand new or a found one from the existing pool.
-                        // The code below assumes that when there are any decoration or child,
-                        // it is a pre-existed one.
+                        // Since IRWitnessTable is Hoistable, `createWitnessTable()` may return a
+                        // pre-existing one. We need to avoid adding the same decorations/children
+                        // when the IRWitnessTable already has them.
                         //
                         if (irSatisfyingWitnessTable->getFirstDecorationOrChild() == nullptr)
                         {
@@ -8167,12 +8164,9 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
         // Create the IR-level witness table
         auto irWitnessTable = subBuilder->createWitnessTable(irWitnessTableBaseType, irSubType);
 
-        // TODO: When WitnessTable became HOISTABLE, we needed a way to avoid
-        // adding the same decorations and childrens redundantly.
-        // There isn't an easy way to tell if the returned WitnessTable is a
-        // brand new or a found one from the existing pool.
-        // The code below assumes that when there are any decoration or child,
-        // it is a pre-existed one.
+        // Since IRWitnessTable is Hoistable, `createWitnessTable()` may return a
+        // pre-existing one. We need to avoid adding the same decorations/children
+        // when the IRWitnessTable already has them.
         //
         if (irWitnessTable->getFirstDecorationOrChild() == nullptr)
         {