[Bug rtl-optimization/114688] repeat load argument of an inline function

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114688

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-04-11
           Keywords|                            |missed-optimization, ra
     Ever confirmed|0                           |1
             Target|                            |x86_64-*-*
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
char g;
int v;

static inline __attribute__((always_inline)) void foo(char p_17);
void func_1() { foo(g); }

static inline void foo(char c) { 
    v = (char)(2 - c) & c; 
}

shows that with -Os we get

func_1:
.LFB0:
        .cfi_startproc
        movb    g(%rip), %dl
        movb    $2, %al
        subl    %edx, %eax
        andl    %edx, %eax
        movsbl  %al, %eax
        movl    %eax, v(%rip)
        ret

I think we have duplicate bugs that show we're too happy replicating
memory operands to multiple instructions.  That might be a target cost
thing in the end.