cmd/compile: delay expansion of OpArg until expand_calls
As it says, delay expanpsion of OpArg to the expand_calls phase,
to enable (eventually) interprocedural SSA optimizations, and
(sooner) change to a register ABI.
Includes a round of cleanup to function names and comments,
largely to match the expanded scope of the functions.
This CL removes the per-function dependence on GOSSAHASH,
but the go116lateCallExpansion kill switch remains (and was
tested locally to ensure it worked).
Two functions in expand_calls.go that performed overlapping
things were combined into a single function that is called
twice.
Fixes #42236.
For #40724.
Change-Id: Icbb78947eaa39f17f2c1210d5c2caef20abd6571
Reviewed-on: https://go-review.googlesource.com/c/go/+/262117
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com> Reviewed-by: Cherry Zhang <cherryyz@google.com>