runtime: find a home for orphaned comments

These comments were left behind after runtime.h was converted
from C to Go. I examined the original code and tried to move these
to the places that the most sense.

Change-Id: I8769d60234c0113d682f9de3bd8d6c34c450c188
Reviewed-on: https://go-review.googlesource.com/21969
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/runtime/lfstack.go

@@ -3,6 +3,9 @@
 // license that can be found in the LICENSE file.
 
 // Lock-free stack.
+// Initialize head to 0, compare with 0 to test for emptiness.
+// The stack does not keep pointers to nodes,
+// so they can be garbage collected if there are no other pointers to nodes.
 // The following code runs only on g0 stack.
 
 package runtime

src/runtime/lock_futex.go

@@ -13,13 +13,13 @@ import (
 
 // This implementation depends on OS-specific implementations of
 //
-//	runtime·futexsleep(uint32 *addr, uint32 val, int64 ns)
+//	futexsleep(addr *uint32, val uint32, ns int64)
 //		Atomically,
-//			if(*addr == val) sleep
+//			if *addr == val { sleep }
 //		Might be woken up spuriously; that's allowed.
 //		Don't sleep longer than ns; ns < 0 means forever.
 //
-//	runtime·futexwakeup(uint32 *addr, uint32 cnt)
+//	futexwakeup(addr *uint32, cnt uint32)
 //		If any procs are sleeping on addr, wake up at most cnt.
 
 const (

src/runtime/mmap.go

@@ -13,4 +13,7 @@ package runtime
 import "unsafe"
 
 // mmap calls the mmap system call. It is implemented in assembly.
+// We only pass the lower 32 bits of file offset to the
+// assembly routine; the higher bits (if required), should be provided
+// by the assembly routine as 0.
 func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer

src/runtime/runtime2.go

@@ -10,9 +10,7 @@ import (
 	"unsafe"
 )
 
-/*
+// defined constants
- * defined constants
- */
 const (
 	// G status
 	//
@@ -99,6 +97,10 @@ const (
 	_Pdead
 )
 
+// Mutual exclusion locks.  In the uncontended case,
+// as fast as spin locks (just a few user-level instructions),
+// but on the contention path they sleep in the kernel.
+// A zeroed Mutex is unlocked (no need to initialize each lock).
 type mutex struct {
 	// Futex-based impl treats it as uint32 key,
 	// while sema-based impl as M* waitm.
@@ -106,6 +108,26 @@ type mutex struct {
 	key uintptr
 }
 
+// sleep and wakeup on one-time events.
+// before any calls to notesleep or notewakeup,
+// must call noteclear to initialize the Note.
+// then, exactly one thread can call notesleep
+// and exactly one thread can call notewakeup (once).
+// once notewakeup has been called, the notesleep
+// will return.  future notesleep will return immediately.
+// subsequent noteclear must be called only after
+// previous notesleep has returned, e.g. it's disallowed
+// to call noteclear straight after notewakeup.
+//
+// notetsleep is like notesleep but wakes up after
+// a given number of nanoseconds even if the event
+// has not yet happened.  if a goroutine uses notetsleep to
+// wake up early, it must wait to call noteclear until it
+// can be sure that no other goroutine is calling
+// notewakeup.
+//
+// notesleep/notetsleep are generally called on g0,
+// notetsleepg is similar to notetsleep but is called on user g.
 type note struct {
 	// Futex-based impl treats it as uint32 key,
 	// while sema-based impl as M* waitm.
@@ -397,8 +419,8 @@ type m struct {
 	waittraceskip int
 	startingtrace bool
 	syscalltick   uint32
-	//#ifdef GOOS_windows
+	thread        uintptr // thread handle
-	thread uintptr // thread handle
+
 	// these are here because they are too large to be on the stack
 	// of low-level NOSPLIT functions.
 	libcall   libcall
@@ -406,7 +428,7 @@ type m struct {
 	libcallsp uintptr
 	libcallg  guintptr
 	syscall   libcall // stores syscall parameters on windows
-	//#endif
+
 	mOS
 }
 
@@ -530,10 +552,10 @@ type schedt struct {
 	totaltime      int64 // ∫gomaxprocs dt up to procresizetime
 }
 
-// The m->locked word holds two pieces of state counting active calls to LockOSThread/lockOSThread.
+// The m.locked word holds two pieces of state counting active calls to LockOSThread/lockOSThread.
 // The low bit (LockExternal) is a boolean reporting whether any LockOSThread call is active.
 // External locks are not recursive; a second lock is silently ignored.
-// The upper bits of m->locked record the nesting depth of calls to lockOSThread
+// The upper bits of m.locked record the nesting depth of calls to lockOSThread
 // (counting up by LockInternal), popped by unlockOSThread (counting down by LockInternal).
 // Internal locks can be recursive. For instance, a lock for cgo can occur while the main
 // goroutine is holding the lock during the initialization phase.
@@ -603,13 +625,6 @@ type forcegcstate struct {
 	idle uint32
 }
 
-/*
- * known to compiler
- */
-const (
-	_Structrnd = sys.RegSize
-)
-
 // startup_random_data holds random bytes initialized at startup. These come from
 // the ELF AT_RANDOM auxiliary vector (vdso_linux_amd64.go or os_linux_386.go).
 var startupRandomData []byte
@@ -635,9 +650,7 @@ func extendRandom(r []byte, n int) {
 	}
 }
 
-/*
+// deferred subroutine calls
- * deferred subroutine calls
- */
 type _defer struct {
 	siz     int32
 	started bool
@@ -648,9 +661,7 @@ type _defer struct {
 	link    *_defer
 }
 
-/*
+// panics
- * panics
- */
 type _panic struct {
 	argp      unsafe.Pointer // pointer to arguments of deferred call run during panic; cannot move - known to liblink
 	arg       interface{}    // argument to panic
@@ -659,10 +670,7 @@ type _panic struct {
 	aborted   bool           // the panic was aborted
 }
 
-/*
+// stack traces
- * stack traces
- */
-
 type stkframe struct {
 	fn       *_func     // function being run
 	pc       uintptr    // program counter within fn
@@ -682,10 +690,8 @@ const (
 	_TraceJumpStack                 // if traceback is on a systemstack, resume trace at g that called into it
 )
 
-const (
+// The maximum number of frames we print for a traceback
-	// The maximum number of frames we print for a traceback
+const _TracebackMaxFrames = 100
-	_TracebackMaxFrames = 100
-)
 
 var (
 	emptystring string
@@ -716,46 +722,3 @@ var (
 	islibrary bool // -buildmode=c-shared
 	isarchive bool // -buildmode=c-archive
 )
-
-/*
- * mutual exclusion locks.  in the uncontended case,
- * as fast as spin locks (just a few user-level instructions),
- * but on the contention path they sleep in the kernel.
- * a zeroed Mutex is unlocked (no need to initialize each lock).
- */
-
-/*
- * sleep and wakeup on one-time events.
- * before any calls to notesleep or notewakeup,
- * must call noteclear to initialize the Note.
- * then, exactly one thread can call notesleep
- * and exactly one thread can call notewakeup (once).
- * once notewakeup has been called, the notesleep
- * will return.  future notesleep will return immediately.
- * subsequent noteclear must be called only after
- * previous notesleep has returned, e.g. it's disallowed
- * to call noteclear straight after notewakeup.
- *
- * notetsleep is like notesleep but wakes up after
- * a given number of nanoseconds even if the event
- * has not yet happened.  if a goroutine uses notetsleep to
- * wake up early, it must wait to call noteclear until it
- * can be sure that no other goroutine is calling
- * notewakeup.
- *
- * notesleep/notetsleep are generally called on g0,
- * notetsleepg is similar to notetsleep but is called on user g.
- */
-// bool	runtime·notetsleep(Note*, int64);  // false - timeout
-// bool	runtime·notetsleepg(Note*, int64);  // false - timeout
-
-/*
- * Lock-free stack.
- * Initialize uint64 head to 0, compare with 0 to test for emptiness.
- * The stack does not keep pointers to nodes,
- * so they can be garbage collected if there are no other pointers to nodes.
- */
-
-// for mmap, we only pass the lower 32 bits of file offset to the
-// assembly routine; the higher bits (if required), should be provided
-// by the assembly routine as 0.