[release-branch.go1.8] cmd/compile: check both syms when folding address into load/store on ARM64
The rules for folding addresses into load/stores checks sym1 is
not on stack (because the stack offset is not known at that point).
But sym1 could be nil, which invalidates the check. Check merged
sym instead.
Fixes #19137.
Change-Id: I8574da22ced1216bb5850403d8f08ec60a8d1005
Reviewed-on: https://go-review.googlesource.com/37145
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
(cherry picked from commit
3557d546090c7fedd69562c88d20767397de835d)
Reviewed-on: https://go-review.googlesource.com/37214