[Bug target/87548] Optimize fetch atomics with unused results

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87548

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
        .file   "example.cpp"
        .intel_syntax noprefix
        .text
        .p2align 4,,15
        .globl  f(int*)
        .type   f(int*), @function
f(int*):
.LFB0:
        .cfi_startproc
        lock and        DWORD PTR [rdi], 10
        ret
        .cfi_endproc
.LFE0:
        .size   f(int*), .-f(int*)
        .p2align 4,,15
        .globl  f1(int*)
        .type   f1(int*), @function
f1(int*):
.LFB1:
        .cfi_startproc
        lock and        DWORD PTR [rdi], 10
        ret
        .cfi_endproc
.LFE1:
        .size   f1(int*), .-f1(int*)
        .p2align 4,,15
        .globl  f2(int*)
        .type   f2(int*), @function
f2(int*):
.LFB2:
        .cfi_startproc
        lock xor        DWORD PTR [rdi], 10
        ret
        .cfi_endproc
.LFE2:
        .size   f2(int*), .-f2(int*)
        .p2align 4,,15
        .globl  f12(int*)
        .type   f12(int*), @function
f12(int*):
.LFB3:
        .cfi_startproc
        lock xor        DWORD PTR [rdi], 10
        ret
        .cfi_endproc
.LFE3:
        .size   f12(int*), .-f12(int*)
        .ident  "GCC: (GCC-Explorer-Build) 4.7.1"
        .section        .note.GNU-stack,"",@progbits