ARMv7: Add support for register-shifted registers

Author: negasora

arch/armv7/il.cpp

@@ -167,13 +167,73 @@ static ExprId GetShiftedOffset(LowLevelILFunction& il, InstructionOperand& op)
 }
 
 
+static ExprId GetRegisterShiftedRegister(LowLevelILFunction& il, Register reg, Register shiftReg, Shift shiftType)
+{
+	if (shiftType == SHIFT_NONE)
+		return il.Register(get_register_size(reg), reg);
+
+	uint32_t regSize = get_register_size(reg);
+	uint32_t shiftRegSize = get_register_size(shiftReg);
+	switch (shiftType)
+	{
+		case SHIFT_ASR:
+			return il.ArithShiftRight(
+				regSize,
+				il.Register(regSize, reg),
+				il.And(
+					shiftRegSize,
+					il.Register(shiftRegSize, shiftReg),
+					il.Const(shiftRegSize, 0xff)
+				));
+		case SHIFT_LSL:
+			return il.ShiftLeft(
+				regSize,
+				il.Register(regSize, reg),
+				il.And(
+					shiftRegSize,
+					il.Register(shiftRegSize, shiftReg),
+					il.Const(shiftRegSize, 0xff)
+				));
+		case SHIFT_LSR:
+			return il.LogicalShiftRight(
+				regSize,
+				il.Register(regSize, reg),
+				il.And(
+					shiftRegSize,
+					il.Register(shiftRegSize, shiftReg),
+					il.Const(shiftRegSize, 0xff)
+				));
+		case SHIFT_ROR:
+			return il.RotateRight(
+				regSize,
+				il.Register(regSize, reg),
+				il.And(
+					shiftRegSize,
+					il.Register(shiftRegSize, shiftReg),
+					il.Const(shiftRegSize, 0xff)
+				));
+		case SHIFT_RRX:
+			//RRX can only shift 1 at a time
+			return il.RotateRightCarry(
+				regSize,
+				il.Register(regSize, reg),
+				il.Const(1, 1),
+				il.Flag(IL_FLAG_C)
+			);
+		default:
+			return 0;
+	}
+}
+
+
 static ExprId GetShiftedRegister(LowLevelILFunction& il, InstructionOperand& op)
 {
+	if (op.flags.offsetRegUsed == 1)
+		return GetRegisterShiftedRegister(il, op.reg, op.offset, op.shift);
 	return GetShifted(il, op.reg, op.imm, op.shift);
 }
 
 
-
 static ExprId ReadAddress(LowLevelILFunction& il, InstructionOperand& op, size_t addr)
 {
 	//This should only be called by with cls or MEM_* or label