Incorrect order of operands for inline assembly MULX.

The following code produces different output between ICC16.2 and GCC5.3.

#include <stdint.h>
#include <stdlib.h>
#include <iostream>
using namespace std;

int main(){
    uint64_t a = 123456789123456789;
    uint64_t b = 987654321987654321;
    uint64_t L, H;

    __asm__(
        "mulx   %[a], %[L], %[H];"
        : [L] "=r" (L), [H] "=r" (H)
        : [a] "r" (a), [b] "d" (b)
    );

    cout << "low  = "<< L << endl;
    cout << "high = "<< H << endl;

    system("pause");
}

On Windows/ICC16, it outputs:

low  = 6609981190679600
high = 14369616054794401669

On Linux/GCC5.3, it outputs:

low  = 14369616054794401669
high = 6609981190679600

The order of the output operands on the MULX instruction are swapped. I believe GCC is correct since the inline assembly maps 1-to-1 to the AT&T GCC syntax, whereas ICC converts it to Intel syntax and in the process switches the order of the operands.