Compiler error

[Zaphirot]

Hi, I'm a noob, I try to compile the fw with 1.6.5 and give me error:

Arduino:1.6.5 (Windows XP), Scheda:"Arduino Mega or Mega 2560, ATmega2560 (Mega 2560)"

temperature.cpp: In function 'void manage_heater()':
temperature.cpp:665: error: unable to find a register to spill in class 'POINTER_REGS'
}
^
temperature.cpp:665: error: this is the insn:
(insn 98 97 100 4 (set (reg/v:SF 103 [ pid_input ])
(mem:SF (post_inc:HI (reg:HI 141 [ ivtmp.169 ])) [4 MEM[base: _101, offset: 0B]+0 S4 A8])) temperature.cpp:449 99 {*movsf}
(expr_list:REG_INC (reg:HI 141 [ ivtmp.169 ])
(nil)))
temperature.cpp:665: confused by earlier errors, bailing out
unable to find a register to spill in class 'POINTER_REGS'

Any clues? I would like to try the ditto feature. Thanks
Stefano