Disables Thumb 2 branch instructions in the legacy ARM lifter

lib/arm/arm_insn.ml

@@ -9,8 +9,11 @@ let is_thumb2 = String.is_prefix ~prefix:"t2"
 let recode_as_arm = String.chop_prefix_exn ~prefix:"t2"
 
 let of_name name =
-  let name = if is_thumb2 name then recode_as_arm name else name in
-  sexpable_of_string t_of_sexp name
+  let is_t2 = is_thumb2 name in
+  let name = if is_t2 then recode_as_arm name else name in
+  match sexpable_of_string t_of_sexp name with
+  | Some #Arm_types.branch_insn when is_t2 -> None
+  | t -> t
 
 let of_basic insn = of_name (Disasm_expert.Basic.Insn.name insn)
 let create insn = of_name (Insn.name insn)

plugins/arm/semantics/thumb.lisp

@@ -94,6 +94,23 @@
   (when (condition-holds pre)
     (exec-addr (+ (t2pc) off))))
 
+(defun t2Bcc (off pre _)
+  "bcc.w imm"
+  (when (condition-holds pre)
+    (exec-addr (+ (t2pc) off))))
+
+(defun t2TBB (rn rm _ _)
+  "tbb [rn, rm]"
+  (let ((addr (+ (t2reg rn) (t2reg rm)))
+        (halfwords (cast-unsigned 32 (load-bits 8 addr))))
+    (exec-addr (+ (t2pc) (* halfwords 2)))))
+
+(defun t2TBH (rn rm _ _)
+  "tbh [rn, rm, lsl #1]"
+  (let ((addr (+ (t2reg rn) (lshift rm 1)))
+        (halfwords (cast-unsigned 32 (load-hword addr))))
+    (exec-addr (+ (t2pc) (* halfwords 2)))))
+
 (defun t2LDRs (rt rn rm imm pre _)
   (when (condition-holds pre)
     (t2set rt (load-word (+ rn (lshift rm imm))))))