[llvm-bugs] [Bug 48737] New: Run loop-idiom with -Oz

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=48737

            Bug ID: 48737
           Summary: Run loop-idiom with -Oz
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Loop Optimizer
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

void copy(float *__restrict__ d, float *__restrict__ s, __SIZE_TYPE__ sz) {
    __SIZE_TYPE__ i;
    for (i = 0; i < sz; i++) {
        *d++ = *s++;
    }
}

-Os
copy(float*, float*, unsigned long):                           # @copy(float*,
float*, unsigned long)
        test    rdx, rdx
        je      .LBB0_2
        push    rax
        shl     rdx, 2
        call    memcpy at PLT
        add     rsp, 8
.LBB0_2:
        ret

-Oz
copy(float*, float*, unsigned long):                           # @copy(float*,
float*, unsigned long)
        xor     eax, eax
.LBB0_1:                                # =>This Inner Loop Header: Depth=1
        cmp     rdx, rax
        je      .LBB0_3
        movss   xmm0, dword ptr [rsi + 4*rax]   # xmm0 = mem[0],zero,zero,zero
        movss   dword ptr [rdi + 4*rax], xmm0
        inc     rax
        jmp     .LBB0_1
.LBB0_3:
        ret


https://godbolt.org/z/61EnzG

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