CMD:CFG: add option to show nodes with NOPS

Author: sipma

chb/app/Instruction.py

@@ -206,6 +206,10 @@ def is_store_instruction(self) -> bool:
     def is_return_instruction(self) -> bool:
         ...
 
+    @property
+    def is_nop_instruction(self) -> bool:
+        return False
+
     @property
     @abstractmethod
     def call_target(self) -> CallTarget:

chb/arm/ARMInstruction.py

@@ -171,6 +171,10 @@ def is_store_instruction(self) -> bool:
     def is_return_instruction(self) -> bool:
         return self.opcode.is_return_instruction(self.xdata)
 
+    @property
+    def is_nop_instruction(self) -> bool:
+        return self.opcode.is_nop_instruction(self.xdata)
+
     def return_value(self) -> Optional[XXpr]:
         if self.is_return_instruction:
             return self.opcode.return_value(self.xdata)

chb/arm/ARMOpcode.py

@@ -408,6 +408,9 @@ def is_load_instruction(self, xdata: InstrXData) -> bool:
     def is_store_instruction(self, xdata: InstrXData) -> bool:
         return False
 
+    def is_nop_instruction(self, xdata: InstrXData) -> bool:
+        return False
+
     def simulate(self, iaddr: str, simstate: "SimulationState") -> str:
         raise SU.CHBSimError(
             simstate,

chb/arm/opcodes/ARMMove.py

@@ -98,6 +98,9 @@ def opargs(self) -> List[ARMOperand]:
     def operandstring(self) -> str:
         return ", ".join(str(op) for op in self.operands)
 
+    def is_nop_instruction(self, xdata: InstrXData) -> bool:
+        return xdata.is_nop
+
     def annotation(self, xdata: InstrXData) -> str:
         if xdata.is_nop:
             return "NOP"

chb/cmdline/chkx

@@ -759,6 +759,10 @@ def parse() -> argparse.Namespace:
         '--calls',
         action="store_true",
         help="add calls to nodes")
+    showcfg.add_argument(
+        "--nops",
+        action="store_true",
+        help="show node in yellow if first instruction is a no-op")
     showcfg.add_argument(
         "--instr_opcodes",
         action="store_true",

chb/cmdline/commandutil.py

@@ -1764,6 +1764,7 @@ def showcfg(args: argparse.Namespace) -> NoReturn:
     xview: bool = args.view
     xpredicates: bool = args.predicates
     xcalls: bool = args.calls
+    xnops: bool = args.nops
     xstores: bool = args.stores
     xinstr_opcodes: bool = args.instr_opcodes
     xinstr_text: bool = args.instr_text
@@ -1811,6 +1812,10 @@ def showcfg(args: argparse.Namespace) -> NoReturn:
                 if any(k.is_unreachable for k in invariants[b]):
                     nodecolors[b] = "grey"
 
+            if xnops:
+                if f.instruction(b).is_nop_instruction:
+                    nodecolors[b] = "yellow"
+
         if xjson:
             fresult = JU.function_cfg_to_json_result(f)
             if fresult.is_ok: