Hi all,
I've been looking at implementing the complex multiply patterns for the
amdgcn port, but I'm not getting the code I was hoping for. When I try
to use the patterns on x86_64 or AArch64 they don't seem to work there
either, so is there something wrong with the middle-end? I've tried both
current HEAD and GCC 11.
The example shown in the internals manual is a simple loop multiplying
two arrays of complex numbers, and writing the results to a third. I had
expected that it would use the largest vectorization factor available,
with the real/imaginary numbers in even/odd lanes as described, but the
vectorization factor is only 2 (so, a single complex number), and I have
to set -fvect-cost-model=unlimited to get even that.
I tried another example with SLP and that too uses the cmul patterns
only for a single real/imaginary pair.
Did proper vectorization of cmul ever really work? There is a case in
the testsuite for the pattern match, but it isn't in a loop.
Thanks
Andrew
P.S. I attached my testcase, in case I'm doing something stupid.
P.P.S. The manual says the pattern is "cmulm4", etc., but it's actually
"cmulm3" in the implementation.typedef _Complex double complexT;
#define arraysize 256
void f(
complexT a[restrict arraysize],
complexT b[restrict arraysize],
complexT c[restrict arraysize]
)
{
#if defined(LOOP)
for (int i = 0; i < arraysize; i++)
c[i] = a[i] * b[i];
#else
c[0] = a[0] * b[0];
c[1] = a[1] * b[1];
c[2] = a[2] * b[2];
c[3] = a[3] * b[3];
c[4] = a[4] * b[4];
c[5] = a[5] * b[5];
c[6] = a[6] * b[6];
c[7] = a[7] * b[7];
c[8] = a[8] * b[8];
c[9] = a[9] * b[9];
c[10] = a[10] * b[10];
c[11] = a[11] * b[11];
c[12] = a[12] * b[12];
c[13] = a[13] * b[13];
c[14] = a[14] * b[14];
c[15] = a[15] * b[15];
c[16] = a[16] * b[16];
c[17] = a[17] * b[17];
c[18] = a[18] * b[18];
c[19] = a[19] * b[19];
c[20] = a[20] * b[20];
c[21] = a[21] * b[21];
c[22] = a[22] * b[22];
c[23] = a[23] * b[23];
c[24] = a[24] * b[24];
c[25] = a[25] * b[25];
c[26] = a[26] * b[26];
c[27] = a[27] * b[27];
c[28] = a[28] * b[28];
c[29] = a[29] * b[29];
c[30] = a[30] * b[30];
c[31] = a[31] * b[31];
c[32] = a[32] * b[32];
#endif
}
