RE: [avr-gcc-list] wrong code from avr-gcc 4.1.2?

[John Regehr]

> Can you post the output using?: -O1 -dP

See below (but this isn't likely to be useful-- the function returns the 
correct result at -O1).  Code is wrong at -Os, -O2, and -O3.  Even further 
below is the compiler output for -Os -dP.

Thanks,

John



address@hidden tmp14]$ avr-gcc -O1 -dP -mmcu=atmega128 -fwrapv -S foo.c -o 
-
        .file   "foo.c"
        .arch atmega128
__SREG__ = 0x3f
__SP_H__ = 0x3e
__SP_L__ = 0x3d
__tmp_reg__ = 0
__zero_reg__ = 1
        .global __do_copy_data
        .global __do_clear_bss
        .text
.global func_1
        .type   func_1, @function
func_1:
/* prologue: frame size=0 */
/* prologue end (size=0) */
 ; (insn 16 9 22 (set (reg/i:HI 24 r24 [ <result> ])
 ;         (const_int 0 [0x0])) 12 {*movhi} (nil)
 ;     (nil))
        ldi r24,lo8(0)   ;  16  *movhi/4        [length = 2]
        ldi r25,hi8(0)
/* epilogue: frame size=0 */
        ret
/* epilogue end (size=1) */
/* function func_1 size 3 (2) */
        .size   func_1, .-func_1
        .comm g_66,4,1
        .comm g_73,4,1
/* File "foo.c": code    3 = 0x0003 (   2), prologues   0, epilogues   1 
*/






address@hidden tmp14]$ avr-gcc -Os -dP -mmcu=atmega128 -fwrapv -S foo.c -o 
-
        .file   "foo.c"
        .arch atmega128
__SREG__ = 0x3f
__SP_H__ = 0x3e
__SP_L__ = 0x3d
__tmp_reg__ = 0
__zero_reg__ = 1
        .global __do_copy_data
        .global __do_clear_bss
        .text
.global func_1
        .type   func_1, @function
func_1:
/* prologue: frame size=0 */
/* prologue end (size=0) */
 ; (insn 16 9 22 (set (reg/i:HI 24 r24 [ <result> ])
 ;         (const_int 1 [0x1])) 12 {*movhi} (nil)
 ;     (nil))
        ldi r24,lo8(1)   ;  16  *movhi/4        [length = 2]
        ldi r25,hi8(1)
/* epilogue: frame size=0 */
        ret
/* epilogue end (size=1) */
/* function func_1 size 3 (2) */
        .size   func_1, .-func_1
        .comm g_66,4,1
        .comm g_73,4,1
/* File "foo.c": code    3 = 0x0003 (   2), prologues   0, epilogues   1 
*/