Attached you'll find the (preprocessed) source of the routine that
printed the Infinity's (of course, I cannot be completely certain that
it actually resulted in the wrong code, but at least it might be studied
to see if it helps to find the culprit).
No, this function is sane (the peephole *is* called a lot by this
function, but all is in due order). I looked at the dumps and assembly
for -O2, -O3 and -O3 -fno-schedule-insns (*), and all is as expected.
Interestingly enough, you *should* expect a speedup when this is resolved...
The next guess then is that the RHXU and RHYV arrays are wrong. From
these, ZHXY is computed, and ZHXY is multiplied into each of the
outputs. Can you send the routine that computes those, or is it too big?