all: merge dev.cc (81884b89bd88) into default

With this change, default now contains Go 1.5 work.
Any future bug fixes for Go 1.4 in the compilers or
the runtime will have to be made directly to the
release branch.

1 files changed, 36 insertions, 119 deletions

diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 1282397ad..aa7577cf9 100644
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -23,12 +23,7 @@ func roundup(p unsafe.Pointer, n uintptr) unsafe.Pointer {
 	return unsafe.Pointer(uintptr(p) + delta)
 }
 
-// in runtime.c
 func getg() *g
-func acquirem() *m
-func releasem(mp *m)
-func gomcache() *mcache
-func readgstatus(*g) uint32 // proc.c
 
 // mcall switches from the g to the g0 stack and invokes fn(g),
 // where g is the goroutine that made the call.
@@ -43,85 +38,30 @@ func readgstatus(*g) uint32 // proc.c
 //go:noescape
 func mcall(fn func(*g))
 
-// onM switches from the g to the g0 stack and invokes fn().
-// When fn returns, onM switches back to the g and returns,
-// continuing execution on the g stack.
-// If arguments must be passed to fn, they can be written to
-// g->m->ptrarg (pointers) and g->m->scalararg (non-pointers)
-// before the call and then consulted during fn.
-// Similarly, fn can pass return values back in those locations.
-// If fn is written in Go, it can be a closure, which avoids the need for
-// ptrarg and scalararg entirely.
-// After reading values out of ptrarg and scalararg it is conventional
-// to zero them to avoid (memory or information) leaks.
+// systemstack runs fn on a system stack.
+// If systemstack is called from the per-OS-thread (g0) stack, or
+// if systemstack is called from the signal handling (gsignal) stack,
+// systemstack calls fn directly and returns.
+// Otherwise, systemstack is being called from the limited stack
+// of an ordinary goroutine. In this case, systemstack switches
+// to the per-OS-thread stack, calls fn, and switches back.
+// It is common to use a func literal as the argument, in order
+// to share inputs and outputs with the code around the call
+// to system stack:
 //
-// If onM is called from a g0 stack, it invokes fn and returns,
-// without any stack switches.
-//
-// If onM is called from a gsignal stack, it crashes the program.
-// The implication is that functions used in signal handlers must
-// not use onM.
-//
-// NOTE(rsc): We could introduce a separate onMsignal that is
-// like onM but if called from a gsignal stack would just run fn on
-// that stack. The caller of onMsignal would be required to save the
-// old values of ptrarg/scalararg and restore them when the call
-// was finished, in case the signal interrupted an onM sequence
-// in progress on the g or g0 stacks. Until there is a clear need for this,
-// we just reject onM in signal handling contexts entirely.
-//
-//go:noescape
-func onM(fn func())
-
-// onMsignal is like onM but is allowed to be used in code that
-// might run on the gsignal stack. Code running on a signal stack
-// may be interrupting an onM sequence on the main stack, so
-// if the onMsignal calling sequence writes to ptrarg/scalararg,
-// it must first save the old values and then restore them when
-// finished. As an exception to the rule, it is fine not to save and
-// restore the values if the program is trying to crash rather than
-// return from the signal handler.
-// Once all the runtime is written in Go, there will be no ptrarg/scalararg
-// and the distinction between onM and onMsignal (and perhaps mcall)
-// can go away.
-//
-// If onMsignal is called from a gsignal stack, it invokes fn directly,
-// without a stack switch. Otherwise onMsignal behaves like onM.
+//	... set up y ...
+//	systemstack(func() {
+//		x = bigcall(y)
+//	})
+//	... use x ...
 //
 //go:noescape
-func onM_signalok(fn func())
+func systemstack(fn func())
 
-func badonm() {
-	gothrow("onM called from signal goroutine")
+func badsystemstack() {
+	gothrow("systemstack called from unexpected goroutine")
 }
 
-// C functions that run on the M stack.
-// Call using mcall.
-func gosched_m(*g)
-func park_m(*g)
-func recovery_m(*g)
-
-// More C functions that run on the M stack.
-// Call using onM.
-func mcacheRefill_m()
-func largeAlloc_m()
-func gc_m()
-func scavenge_m()
-func setFinalizer_m()
-func removeFinalizer_m()
-func markallocated_m()
-func unrollgcprog_m()
-func unrollgcproginplace_m()
-func setgcpercent_m()
-func setmaxthreads_m()
-func ready_m()
-func deferproc_m()
-func goexit_m()
-func startpanic_m()
-func dopanic_m()
-func readmemstats_m()
-func writeheapdump_m()
-
 // memclr clears n bytes starting at ptr.
 // in memclr_*.s
 //go:noescape
@@ -132,12 +72,6 @@ func memclr(ptr unsafe.Pointer, n uintptr)
 //go:noescape
 func memmove(to unsafe.Pointer, from unsafe.Pointer, n uintptr)
 
-func starttheworld()
-func stoptheworld()
-func newextram()
-func lockOSThread()
-func unlockOSThread()
-
 // exported value for testing
 var hashLoad = loadFactor
 
@@ -159,16 +93,9 @@ func noescape(p unsafe.Pointer) unsafe.Pointer {
 	return unsafe.Pointer(x ^ 0)
 }
 
-func entersyscall()
-func reentersyscall(pc uintptr, sp unsafe.Pointer)
-func entersyscallblock()
-func exitsyscall()
-
 func cgocallback(fn, frame unsafe.Pointer, framesize uintptr)
 func gogo(buf *gobuf)
 func gosave(buf *gobuf)
-func read(fd int32, p unsafe.Pointer, n int32) int32
-func close(fd int32) int32
 func mincore(addr unsafe.Pointer, n uintptr, dst *byte) int32
 
 //go:noescape
@@ -176,35 +103,31 @@ func jmpdefer(fv *funcval, argp uintptr)
 func exit1(code int32)
 func asminit()
 func setg(gg *g)
-func exit(code int32)
 func breakpoint()
-func nanotime() int64
-func usleep(usec uint32)
-
-// careful: cputicks is not guaranteed to be monotonic!  In particular, we have
-// noticed drift between cpus on certain os/arch combinations.  See issue 8976.
-func cputicks() int64
 
-func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer
-func munmap(addr unsafe.Pointer, n uintptr)
-func madvise(addr unsafe.Pointer, n uintptr, flags int32)
 func reflectcall(fn, arg unsafe.Pointer, n uint32, retoffset uint32)
-func osyield()
 func procyield(cycles uint32)
 func cgocallback_gofunc(fv *funcval, frame unsafe.Pointer, framesize uintptr)
-func readgogc() int32
-func purgecachedstats(c *mcache)
-func gostringnocopy(b *byte) string
 func goexit()
 
 //go:noescape
-func write(fd uintptr, p unsafe.Pointer, n int32) int32
-
-//go:noescape
 func cas(ptr *uint32, old, new uint32) bool
 
-//go:noescape
-func casp(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool
+// casp cannot have a go:noescape annotation, because
+// while ptr and old do not escape, new does. If new is marked as
+// not escaping, the compiler will make incorrect escape analysis
+// decisions about the value being xchg'ed.
+// Instead, make casp a wrapper around the actual atomic.
+// When calling the wrapper we mark ptr as noescape explicitly.
+
+//go:nosplit
+func casp(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
+	return casp1((*unsafe.Pointer)(noescape(unsafe.Pointer(ptr))), noescape(old), new)
+}
+
+func casp1(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool
+
+func nop() // call to prevent inlining of function body
 
 //go:noescape
 func casuintptr(ptr *uintptr, old, new uintptr) bool
@@ -261,18 +184,10 @@ func asmcgocall(fn, arg unsafe.Pointer)
 //go:noescape
 func asmcgocall_errno(fn, arg unsafe.Pointer) int32
 
-//go:noescape
-func open(name *byte, mode, perm int32) int32
-
-//go:noescape
-func gotraceback(*bool) int32
-
+// argp used in Defer structs when there is no argp.
 const _NoArgs = ^uintptr(0)
 
-func newstack()
-func newproc()
 func morestack()
-func mstart()
 func rt0_go()
 
 // return0 is a stub used to return 0 from deferproc.
@@ -314,3 +229,5 @@ func call134217728(fn, arg unsafe.Pointer, n, retoffset uint32)
 func call268435456(fn, arg unsafe.Pointer, n, retoffset uint32)
 func call536870912(fn, arg unsafe.Pointer, n, retoffset uint32)
 func call1073741824(fn, arg unsafe.Pointer, n, retoffset uint32)
+
+func systemstack_switch()