GCC std :: sin矢量化bug？

Question

下一个代码（使用-O3 -ffast-math）：

#include <cmath>

float a[4];

void sin1() {
    for(unsigned i = 0; i < 4; i++) a[i] = sinf(a[i]);
}

编译sinf的矢量化版本（_ZGVbN4v_sinf）：

sin1():
        sub     rsp, 8
        movaps  xmm0, XMMWORD PTR a[rip]
        call    _ZGVbN4v_sinf
        movaps  XMMWORD PTR a[rip], xmm0
        add     rsp, 8
        ret

但是当我使用c ++版本的sinf（std :: sin）时，没有矢量化发生：

void sin2() {
    for(unsigned i = 0; i < 4; i++) a[i] = std::sin(a[i]);
}

sin2():
        sub     rsp, 8
        movss   xmm0, DWORD PTR a[rip]
        call    sinf
        movss   DWORD PTR a[rip], xmm0
        movss   xmm0, DWORD PTR a[rip+4]
        call    sinf
        movss   DWORD PTR a[rip+4], xmm0
        movss   xmm0, DWORD PTR a[rip+8]
        call    sinf
        movss   DWORD PTR a[rip+8], xmm0
        movss   xmm0, DWORD PTR a[rip+12]
        call    sinf
        movss   DWORD PTR a[rip+12], xmm0
        add     rsp, 8
        ret

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