[Announcement][HW4] segmentation fault when instrumenting json parser

[KihongHeo]

There is a problem when your sanitizer instruments the json parser.
Please do the followings:

• Change is_debug to

 match Llvm.instr_opcode instr with
 | Llvm.Opcode.Call ->
     let callee_expr = Llvm.operand instr (Llvm.num_operands instr - 1) in
     let r1 = Str.regexp "llvm\\.dbg\\..+" in
     Str.string_match r1 (Llvm.value_name callee_expr) 0
 | _ -> false

• Change your sanitizer not to instrument PHI node.

If you checkout after my fix, you will get the fixed is_debug code. For other students who have already checked out the code, please change the above by yourself.

[BaurTokenov]

I am not instrumenting PHI nodes, but I am still getting this error: "PHI nodes not grouped at top of the basic block!". The only Opcode I'm looking at is SDiv. Does anyone know what could be the reason?

[gunsodo]

@BaurTokenov This issue also occurs with me. In my case, I have to specifically ignore PHI nodes as what we have done with debug in the previous assignment. You may want to use some function in utils.ml that might help.