diff --git a/dev-clean/src/main/scala/sai/ccbse/Engine.scala b/dev-clean/src/main/scala/sai/ccbse/Engine.scala
index 65aca82b..5ed7c1a1 100644
--- a/dev-clean/src/main/scala/sai/ccbse/Engine.scala
+++ b/dev-clean/src/main/scala/sai/ccbse/Engine.scala
@@ -25,6 +25,8 @@ import scala.collection.immutable.{List => StaticList, Map => StaticMap}
 import scala.collection.mutable.{Map => StaticMutMap, Queue => StaticQueue, Set => StaticSet}
 import sai.lmsx.smt.SMTBool
 
+// Note (ST): possible optimization - track path information to branch level
+
 @virtualize
 trait CCBSEEngine extends SAIOps with StagedNondet with SymExeDefs {
   object CompileTimeRuntime {
diff --git a/dev-clean/src/main/scala/sai/ccbse/possible_optimization b/dev-clean/src/main/scala/sai/ccbse/possible_optimization
deleted file mode 100644
index 46ef8ebe..00000000
--- a/dev-clean/src/main/scala/sai/ccbse/possible_optimization
+++ /dev/null
@@ -1 +0,0 @@
-track path information to branch level
diff --git a/dev-clean/src/main/scala/sai/lang/LLVMInstructions.md b/doc/LLVMInstructions.md
similarity index 92%
rename from dev-clean/src/main/scala/sai/lang/LLVMInstructions.md
rename to doc/LLVMInstructions.md
index f0d6aa60..19ad1a61 100644
--- a/dev-clean/src/main/scala/sai/lang/LLVMInstructions.md
+++ b/doc/LLVMInstructions.md
@@ -1,7 +1,11 @@
-##### Note: bold instructions appear in `coreutils`
+LLVM instructions supported by `llsc/engines/Engine.scala`.
 
->count: 
->>umimplemented: 25\
+THIS IS OUTDATED, NEED UPDATE.
+
+** Note: bold instructions appear in `coreutils` **
+
+>count:
+>>unimplemented: 25\
 >>implemented: 17
 
 >types missing: float, struct
@@ -83,4 +87,4 @@
     7. va_arg Instruction
     8. landingpad Instruction
     9. catchpad Instruction
-    10. cleanuppad Instruction
\ No newline at end of file
+    10. cleanuppad Instruction