runtime: define and use call16 everywhere

Currently, runtime.call16 is defined and used only on 32-bit
architectures, while 64-bit architectures all start at call32 and go
up from there. This led to unnecessary complexity because call16's
prototype needed to be in a different file, separate from all of the
other call* prototypes, which in turn led to it getting out of sync
with the other call* prototypes. This CL adds call16 on 64-bit
architectures, bringing them all into sync, and moves the call16
prototype to live with the others.

Prior to CL 31655 (in 2016), call16 couldn't be implemented on 64-bit
architectures because it needed at least four words of argument space
to invoke "callwritebarrier" after copying back the results. CL 31655
changed the way call* invoked the write barrier in preparation for the
hybrid barrier; since the hybrid barrier had to be invoked prior to
copying back results, it needed a different solution that didn't reuse
call*'s stack space. At this point, call16 was no longer a problem on
64-bit, but we never added it. Until now.

Change-Id: Id10ade0e4f75c6ea76afa6229ddaee2b994c27dd
Reviewed-on: https://go-review.googlesource.com/c/go/+/259339
Trust: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index b891a12fdd..bd2514e862 100644
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -271,6 +271,7 @@ func return0()
 
 // in asm_*.s
 // not called directly; definitions here supply type information for traceback.
+func call16(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
 func call32(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
 func call64(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
 func call128(typ, fn, arg unsafe.Pointer, n, retoffset uint32)