[Bug rtl-optimization/55757] Suboptimal interrupt prologue/epilogue for ARMv7-M (Cortex-M3)

[joey.ye at arm dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55757



--- Comment #5 from Joey Ye <joey.ye at arm dot com> 2012-12-21 03:32:21 UTC ---

However, there is room to improve both performance and stack consumption in

case of Os:



extern void bar(int *);



void foo()

{

    int a;

    bar(&a);

}



Built with -mcpu=cortex-m3 -Os:

    push    {r0, r1, r2, lr}

    add    r0, sp, #4

    bl    bar

    pop    {r1, r2, r3, pc}



Apparently it should be optimized to save 8 bytes of stack consumption and two

stores:

    push    {r0, lr}

    mov    r0, sp

    bl    bar

    pop    {r1, pc}