Add flag role for carry flag when subtraction is implemented with addition

4 files changed, 9 insertions, 17 deletions

diff --git a/arch/arm64/arch_arm64.cpp b/arch/arm64/arch_arm64.cpp
index 13198af9..9020b99b 100644
--- a/arch/arm64/arch_arm64.cpp
+++ b/arch/arm64/arch_arm64.cpp
@@ -1511,7 +1511,7 @@ class Arm64Architecture : public Architecture
 		case IL_FLAG_Z:
 			return ZeroFlagRole;
 		case IL_FLAG_C:
-			return CarryFlagRole;
+			return CarryFlagWithInvertedSubtractRole;
 		case IL_FLAG_V:
 			return OverflowFlagRole;
 		default:
diff --git a/arch/armv7/arch_armv7.cpp b/arch/armv7/arch_armv7.cpp
index d14641d8..57ed3057 100644
--- a/arch/armv7/arch_armv7.cpp
+++ b/arch/armv7/arch_armv7.cpp
@@ -1734,7 +1734,7 @@ BNFlagRole ArmCommonArchitecture::GetFlagRole(uint32_t flag, uint32_t)
 	case IL_FLAG_Z:
 		return ZeroFlagRole;
 	case IL_FLAG_C:
-		return CarryFlagRole;
+		return CarryFlagWithInvertedSubtractRole;
 	case IL_FLAG_V:
 		return OverflowFlagRole;
 	default:
diff --git a/binaryninjacore.h b/binaryninjacore.h
index 45ef79f2..5f631827 100644
--- a/binaryninjacore.h
+++ b/binaryninjacore.h
@@ -37,7 +37,7 @@
 // Current ABI version for linking to the core. This is incremented any time
 // there are changes to the API that affect linking, including new functions,
 // new types, or modifications to existing functions or types.
-#define BN_CURRENT_CORE_ABI_VERSION 72
+#define BN_CURRENT_CORE_ABI_VERSION 73
 
 // Minimum ABI version that is supported for loading of plugins. Plugins that
 // are linked to an ABI version less than this will not be able to load and
@@ -671,7 +671,8 @@ extern "C"
 		EvenParityFlagRole = 7,
 		OddParityFlagRole = 8,
 		OrderedFlagRole = 9,
-		UnorderedFlagRole = 10
+		UnorderedFlagRole = 10,
+		CarryFlagWithInvertedSubtractRole = 11,
 	} BNFlagRole;
 
 	typedef enum BNFunctionGraphType
diff --git a/python/examples/nes.py b/python/examples/nes.py
index 64a33d22..b12a616d 100644
--- a/python/examples/nes.py
+++ b/python/examples/nes.py
@@ -87,7 +87,7 @@ class M6502(Architecture):
 	flags = [c_flag, z_flag, i_flag, d_flag, b_flag, v_flag, s_flag]
 	flag_write_types = [FlagWriteTypeName("*"), FlagWriteTypeName("czs"), FlagWriteTypeName("zvs"),FlagWriteTypeName( "zs")]
 	flag_roles = {
-	  c_flag: FlagRole.SpecialFlagRole,  # Not a normal carry flag, subtract result is inverted
+	  c_flag: FlagRole.CarryFlagWithInvertedSubtractRole,
 	  z_flag: FlagRole.ZeroFlagRole, v_flag: FlagRole.OverflowFlagRole, s_flag: FlagRole.NegativeSignFlagRole
 	}
 	flags_required_for_flag_condition = {
@@ -104,8 +104,8 @@ class M6502(Architecture):
 		Mnemonic("asl"):lambda il, operand: il.store(1, operand, il.shift_left(1, il.load(1, operand), il.const(1, 1), flags=FlagName("czs"))),
 		Mnemonic("asl@"):lambda il, operand: il.set_reg(1, a_reg, il.shift_left(1, operand, il.const(1, 1), flags=FlagName("czs"))),
 		Mnemonic("and"):lambda il, operand: il.set_reg(1, a_reg, il.and_expr(1, il.reg(1, a_reg), operand, flags=FlagName("zs"))),
-		Mnemonic("bcc"):lambda il, operand: M6502.cond_branch(il, il.flag_condition(LowLevelILFlagCondition.LLFC_UGE), operand),
-		Mnemonic("bcs"):lambda il, operand: M6502.cond_branch(il, il.flag_condition(LowLevelILFlagCondition.LLFC_ULT), operand),
+		Mnemonic("bcc"):lambda il, operand: M6502.cond_branch(il, il.flag_condition(LowLevelILFlagCondition.LLFC_ULT), operand),
+		Mnemonic("bcs"):lambda il, operand: M6502.cond_branch(il, il.flag_condition(LowLevelILFlagCondition.LLFC_UGE), operand),
 		Mnemonic("beq"):lambda il, operand: M6502.cond_branch(il, il.flag_condition(LowLevelILFlagCondition.LLFC_E), operand),
 		Mnemonic("bit"):lambda il, operand: il.and_expr(1, il.reg(1, a_reg), operand, flags=FlagName("czs")),
 		Mnemonic("bmi"):lambda il, operand: M6502.cond_branch(il, il.flag_condition(LowLevelILFlagCondition.LLFC_NEG), operand),
@@ -528,15 +528,6 @@ class M6502(Architecture):
 			il.append(i)
 		return length
 
-	def get_flag_write_low_level_il(self, op: LowLevelILOperation, size: int, write_type: Optional[FlagWriteTypeName], flag: FlagType, operands: List[ILRegisterType], il: LowLevelILFunction) -> ExpressionIndex:
-		if flag == 'c':
-			if (op == LowLevelILOperation.LLIL_SUB) or (op == LowLevelILOperation.LLIL_SBB):
-				# Subtraction carry flag is inverted from the commom implementation
-				return il.not_expr(0, self.get_default_flag_write_low_level_il(op, size, FlagRole.CarryFlagRole, operands, il))
-			# Other operations use a normal carry flag
-			return self.get_default_flag_write_low_level_il(op, size, FlagRole.CarryFlagRole, operands, il)
-		return Architecture.get_flag_write_low_level_il(self, op, size, write_type, flag, operands, il)
-
 	def is_never_branch_patch_available(self, data:bytes, addr:int) -> bool:
 		if (data[0:1] == b"\x10") or (data[0:1] == b"\x30") or (data[0:1] == b"\x50") or (data[0:1] == b"\x70") or (
 		  data[0:1] == b"\x90"
@@ -708,7 +699,7 @@ class NESView(BinaryView):
 		return True
 
 	def perform_get_address_size(self) -> int:
-		return self.address_size
+		return 2
 
 	def perform_get_entry_point(self) -> int:
 		return struct.unpack("<H", self.read(0xfffc, 2))[0]