[Bug inline-asm/37188] There is no way to specify double precision floating point registers in inline asm arguments (VFP)

[siarhei dot siamashka at gmail dot com]

------- Comment #1 from siarhei dot siamashka at gmail dot com  2008-09-02 15:50 -------
Well, looks like it is not a missing feature, but just incompleteness of
documentation :)

It is possible to use double precision floating point registers and NEON
128-bit registers in the following way:

----------------------------------------------------------

#include <arm_neon.h>

int16x8_t test_neon(int16x8_t b, int16x8_t c)
{
    int16x8_t a;
    asm (
        "vadd.i32 %q0, %q1, %q2 \n\t"
        : "=w" (a)
        : "w" (b), "w" (c)
    );
    return a;
}

double test_double(double b, double c)
{
    double a;
    asm (
        "faddd %P0, %P1, %P2 \n\t"
        : "=w" (a)
        : "w" (b), "w" (c)
    );
    return a;
}

----------------------------------------------------------

Disassembly of section .text:

00000000 <test_quad>:
   0:   e52db004        push    {fp}            ; (str fp, [sp, #-4]!)
   4:   e28db000        add     fp, sp, #0      ; 0x0
   8:   ec410b12        vmov    d2, r0, r1
   c:   ec432b13        vmov    d3, r2, r3
  10:   ed9b6b01        vldr    d6, [fp, #4]
  14:   ed9b7b03        vldr    d7, [fp, #12]
  18:   f2224846        vadd.i32        q2, q1, q3
  1c:   ec510b14        vmov    r0, r1, d4
  20:   ec532b15        vmov    r2, r3, d5
  24:   e28bd000        add     sp, fp, #0      ; 0x0
  28:   e8bd0800        pop     {fp}
  2c:   e12fff1e        bx      lr

00000030 <test_double>:
  30:   ec410b15        vmov    d5, r0, r1
  34:   e52db004        push    {fp}            ; (str fp, [sp, #-4]!)
  38:   ec432b16        vmov    d6, r2, r3
  3c:   e28db000        add     fp, sp, #0      ; 0x0
  40:   ee357b06        faddd   d7, d5, d6
  44:   ec510b17        vmov    r0, r1, d7
  48:   e28bd000        add     sp, fp, #0      ; 0x0
  4c:   e8bd0800        pop     {fp}
  50:   e12fff1e        bx      lr


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37188