cmd/link: establish dependable package initialization order

(This is a retry of CL 462035 which was reverted at 474976.
The only change from that CL is the aix fix SRODATA->SNOPTRDATA
at inittask.go:141)

As described here:

https://github.com/golang/go/issues/31636#issuecomment-493271830

"Find the lexically earliest package that is not initialized yet,
but has had all its dependencies initialized, initialize that package,
 and repeat."

Simplify the runtime a bit, by just computing the ordering required
in the linker and giving a list to the runtime.

Update #31636
Fixes #57411

RELNOTE=yes

Change-Id: I28c09451d6aa677d7394c179d23c2c02c503fc56
Reviewed-on: https://go-review.googlesource.com/c/go/+/478916
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

1 files changed, 9 insertions, 11 deletions

diff --git a/src/plugin/plugin_dlopen.go b/src/plugin/plugin_dlopen.go
index b4c4e4061c..f6ae219d95 100644
--- a/src/plugin/plugin_dlopen.go
+++ b/src/plugin/plugin_dlopen.go
@@ -74,7 +74,7 @@ func open(name string) (*Plugin, error) {
 	if plugins == nil {
 		plugins = make(map[string]*Plugin)
 	}
-	pluginpath, syms, errstr := lastmoduleinit()
+	pluginpath, syms, initTasks, errstr := lastmoduleinit()
 	if errstr != "" {
 		plugins[filepath] = &Plugin{
 			pluginpath: pluginpath,
@@ -92,14 +92,7 @@ func open(name string) (*Plugin, error) {
 	plugins[filepath] = p
 	pluginsMu.Unlock()
 
-	initStr := make([]byte, len(pluginpath)+len("..inittask")+1) // +1 for terminating NUL
-	copy(initStr, pluginpath)
-	copy(initStr[len(pluginpath):], "..inittask")
-
-	initTask := C.pluginLookup(h, (*C.char)(unsafe.Pointer(&initStr[0])), &cErr)
-	if initTask != nil {
-		doInit(initTask)
-	}
+	doInit(initTasks)
 
 	// Fill out the value of each plugin symbol.
 	updatedSyms := map[string]any{}
@@ -147,9 +140,14 @@ var (
 )
 
 // lastmoduleinit is defined in package runtime.
-func lastmoduleinit() (pluginpath string, syms map[string]any, errstr string)
+func lastmoduleinit() (pluginpath string, syms map[string]any, inittasks []*initTask, errstr string)
 
 // doInit is defined in package runtime.
 //
 //go:linkname doInit runtime.doInit
-func doInit(t unsafe.Pointer) // t should be a *runtime.initTask
+func doInit(t []*initTask)
+
+type initTask struct {
+	// fields defined in runtime.initTask. We only handle pointers to an initTask
+	// in this package, so the contents are irrelevant.
+}