cmd/compile: fix bug of conditional instructions on arm64
CL 302231 added some optimization rules with instructions CSETM, CSINC,
CSINV, and CSNEG, but did not deal with the situation where flag is
constant, resulting in some cases that could be more optimized cannot
be optimized, and the FlagConstant value is passed to codegen pass. This
CL adds these missing rules.
Fixes #45359
Change-Id: I700608cfb9a6a768a18d1fd5d374d7e92aa6f838
Reviewed-on: https://go-review.googlesource.com/c/go/+/307650
Reviewed-by: eric fang <eric.fang@arm.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>
Run-TryBot: eric fang <eric.fang@arm.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: eric fang <eric.fang@arm.com>
Trust: Alberto Donizetti <alb.donizetti@gmail.com>