cmd/asm,cmd/compile: generate less instructions for most 32 bit constant adds on ppc64x
For GOPPC64 < 10 targets, most large 32 bit constants (those
exceeding int16 capacity) can be added using two instructions
instead of 3.
This cannot be done for values greater than 0x7FFF7FFF, so this
must be done during asm preprocessing as the optab matching
rules cannot differentiate this special case.
Likewise, constants 0x8000 <= x < 0x10000 are not converted. The
assembler currently generates 2 instructions sequences for these
constants.
Change-Id: I1ccc839c6c28fc32f15d286b2e52e2d22a2a06d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/568116 Reviewed-by: Cherry Mui <cherryyz@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Paul Murphy <murp@ibm.com> Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>