cmd/compile: convert branch with zero to more optimal branch zero on loong64
This reduces 7500+ instructions from the go toolchain binary on loong64.
file before after Δ %
asm 555066 554406 -660 -0.1189%
cgo 481480 480764 -716 -0.1487%
compile
2475836 2474776 -1060 -0.0428%
cover 516536 515788 -748 -0.1448%
link 702220 701216 -1004 -0.1430%
preprofile 238626 238122 -504 -0.2112%
vet 792798 791894 -904 -0.1140%
go
1573108 1571676 -1432 -0.0910%
gofmt 320578 320042 -536 -0.1672%
total
7656248 7648684 -7564 -0.0988%
Change-Id: I51b70a1543bc258b7664caa8647e75eecbaf5eed
Reviewed-on: https://go-review.googlesource.com/c/go/+/693495
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>