AArch64: Implement widen_[us]sum using 2-way [US]UDOT for SVE2p1 [PR122069]HEADtrunkmaster

SVE2p1 adds 2-way dotproduct which we can use when we have to do a single step
widening addition.  This is useful for instance when the value to be widened
does not come from a load.  For example for

int foo2_int(unsigned short *x, unsigned short * restrict y) {
  int sum = 0;
  for (int i = 0; i < 8000; i++)
    {
      x[i] = x[i] + y[i];
      sum += x[i];
    }
  return sum;
}

we used to generate

.L12:
        ld1h    z30.h, p7/z, [x0, x2, lsl 1]
        ld1h    z29.h, p7/z, [x1, x2, lsl 1]
        add     z30.h, z30.h, z29.h
        uaddwb  z31.s, z31.s, z30.h
        uaddwt  z31.s, z31.s, z30.h
        st1h    z30.h, p7, [x0, x2, lsl 1]
        mov     x3, x2
        inch    x2
        cmp     w2, w4
        bls     .L12
        inch    x3
        uaddv   d31, p7, z31.s

but with +sve2p1

.L12:
        ld1h    z31.h, p7/z, [x0, x2, lsl 1]
        ld1h    z29.h, p7/z, [x1, x2, lsl 1]
        add     z31.h, z31.h, z29.h
        udot    z30.s, z31.h, z28.h
        st1h    z31.h, p7, [x0, x2, lsl 1]
        mov     x3, x2
        inch    x2
        cmp     w2, w4
        bls     .L12
        inch    x3
        uaddv   d30, p7, z30.s

gcc/ChangeLog:

	PR middle-end/122069
	* config/aarch64/aarch64-sve2.md
	(widen_ssum<mode><Vnarrow>3): Update.
	(widen_usum<mode><Vnarrow>3): Update.

gcc/testsuite/ChangeLog:

	PR middle-end/122069
	* gcc.target/aarch64/sve2/pr122069_3.c: New test.
	* gcc.target/aarch64/sve2/pr122069_4.c: New test.

0 files changed, 0 insertions, 0 deletions