[Bug c/28568] compiler generates incorrect ARM instructions when using long bitfields

[pluto at agmk dot net]

------- Comment #2 from pluto at agmk dot net  2006-08-02 10:58 -------
(In reply to comment #0)
> #define __REG32 volatile unsigend long
> 
> typedef struct
> {
>   __REG32 Bit0 :1;
>   __REG32 Bit1 :1;
>   ...etc...
>   __REG32 Bit31 :1;
> }__Bitfield;
> 
> #define ADDRESS <address of my register>
> 
> #define REG (*( __REG32 *)(ADDRESS))
> #define REG_bit (*(__Bitfield *)&REG)
> 
> When I access the register using the bitfield I get the code like the 
> following
> 
> LCD_bit.Backlight=1;            //??
>      358:       e3a0320e        mov     r3, #-536870912 ; 0xe0000000
>      35c:       e283390a        add     r3, r3, #163840 ; 0x28000
>      360:       e5d32001        ldrb    r2, [r3, #1]
>      364:       e3822004        orr     r2, r2, #4      ; 0x4
>      368:       e5c32001        strb    r2, [r3, #1]
> 

this code isn't wrong. gcc doesn't know that is a register
mapped into arm address space which requires full-word access.
imo this is a dup of PR23623.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28568