cmd/compile: extend all the cmov into math generic rules with their contrary

If the bool comes from a local operation this is foldable into the comparison.
  if a == b {
  } else {
    x++
  }
becomes:
  x += !(a == b)
becomes:
  x += a != b

If the bool is passed in or loaded rather than being locally computed
this adds an extra XOR ^1 to invert it.

But at worst it should make the math equal to the compute + CMP + CMOV
which is a tie on modern CPUs which can execute CMOV on all int ALUs
and a win on the cheaper or older ones which can't.

Change-Id: Idd2566c7a3826ec432ebfbba7b3898aa0db4b812
Reviewed-on: https://go-review.googlesource.com/c/go/+/760922
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Jorropo <jorropo.pgm@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Junyang Shao <shaojunyang@google.com>

0 files changed, 0 insertions, 0 deletions