cmd/compile: optimize unsigned comparisons to 0/1 on amd64
Plus a bonus optimization I noticed while working on this.
There are no functions (besides the rewrite rules) whose text size
increases as a result of this change.
Updates #21439
The following per-package text size stats were generated by parsing the
output of compiling with -S and summing the function size reported on the
STEXT line. This gives a far more accurate picture of the impact
on generated code than merely looking at the object file size changes
or the resulting binary size changes. The latter are below, for reference.
file before after Δ %
runtime.s 477257 476417 -840 -0.176%
math.s 35985 35976 -9 -0.025%
vendor/golang.org/x/net/dns/dnsmessage.s 87314 87232 -82 -0.094%
debug/dwarf.s 108444 108432 -12 -0.011%
regexp.s 64535 64467 -68 -0.105%
internal/xcoff.s 23175 22945 -230 -0.992%
cmd/vendor/golang.org/x/arch/arm/armasm.s 45263 45260 -3 -0.007%
cmd/vendor/golang.org/x/arch/arm64/arm64asm.s 118140 118135 -5 -0.004%
cmd/internal/obj/arm64.s 151502 151498 -4 -0.003%
cmd/compile/internal/ssa.s
6061483 6063120 +1637 +0.027%
total
9321728 9322112 +384 +0.004%
file before after Δ %
go
15188916 15184820 -4096 -0.027%
addr2line
4315984 4311888 -4096 -0.095%
cgo
4836088 4831992 -4096 -0.085%
compile
24506008 24493720 -12288 -0.050%
doc
4680952 4676856 -4096 -0.088%
link
6605336 6601240 -4096 -0.062%
pprof
14776756 14772660 -4096 -0.028%
total
135250956 135214092 -36864 -0.027%
Change-Id: I1243a098a08db452f7d1eb0998e241c9b199e2b4
Reviewed-on: https://go-review.googlesource.com/c/go/+/213058
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>