compiler, runtime: copy slice code from Go 1.7 runtime

[official-gcc.git] / libgo / go / runtime / stubs.go

// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package runtime

import (
        "runtime/internal/atomic"
        "runtime/internal/sys"
        "unsafe"
)

// Should be a built-in for unsafe.Pointer?
//go:nosplit
func add(p unsafe.Pointer, x uintptr) unsafe.Pointer {
        return unsafe.Pointer(uintptr(p) + x)
}

// getg returns the pointer to the current g.
// The compiler rewrites calls to this function into instructions
// that fetch the g directly (from TLS or from the dedicated register).
func getg() *g

// mcall switches from the g to the g0 stack and invokes fn(g),
// where g is the goroutine that made the call.
// mcall saves g's current PC/SP in g->sched so that it can be restored later.
// It is up to fn to arrange for that later execution, typically by recording
// g in a data structure, causing something to call ready(g) later.
// mcall returns to the original goroutine g later, when g has been rescheduled.
// fn must not return at all; typically it ends by calling schedule, to let the m
// run other goroutines.
//
// mcall can only be called from g stacks (not g0, not gsignal).
//
// This must NOT be go:noescape: if fn is a stack-allocated closure,
// fn puts g on a run queue, and g executes before fn returns, the
// closure will be invalidated while it is still executing.
func mcall(fn func(*g))

// systemstack runs fn on a system stack.
//
// 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:
//
//      ... set up y ...
//      systemstack(func() {
//              x = bigcall(y)
//      })
//      ... use x ...
//
// For the gc toolchain this permits running a function that requires
// additional stack space in a context where the stack can not be
// split.  For gccgo, however, stack splitting is not managed by the
// Go runtime. In effect, all stacks are system stacks. So this gccgo
// version just runs the function.
func systemstack(fn func()) {
        fn()
}

func badsystemstack() {
        throw("systemstack called from unexpected goroutine")
}

// memclr clears n bytes starting at ptr.
// in memclr_*.s
//go:noescape
func memclr(ptr unsafe.Pointer, n uintptr)

//go:linkname reflect_memclr reflect.memclr
func reflect_memclr(ptr unsafe.Pointer, n uintptr) {
        memclr(ptr, n)
}

// memmove copies n bytes from "from" to "to".
//go:noescape
func memmove(to, from unsafe.Pointer, n uintptr)

//go:linkname reflect_memmove reflect.memmove
func reflect_memmove(to, from unsafe.Pointer, n uintptr) {
        memmove(to, from, n)
}

//go:noescape
//extern __builtin_memcmp
func memcmp(a, b unsafe.Pointer, size uintptr) int32

// exported value for testing
var hashLoad = loadFactor

// in asm_*.s
func fastrand1() uint32

// in asm_*.s
//go:noescape
func memequal(a, b unsafe.Pointer, size uintptr) bool

// noescape hides a pointer from escape analysis.  noescape is
// the identity function but escape analysis doesn't think the
// output depends on the input.  noescape is inlined and currently
// compiles down to a single xor instruction.
// USE CAREFULLY!
//go:nosplit
func noescape(p unsafe.Pointer) unsafe.Pointer {
        x := uintptr(p)
        return unsafe.Pointer(x ^ 0)
}

func mincore(addr unsafe.Pointer, n uintptr, dst *byte) int32

//go:noescape
func jmpdefer(fv *funcval, argp uintptr)
func exit1(code int32)
func asminit()
func setg(gg *g)
func breakpoint()

// reflectcall calls fn with a copy of the n argument bytes pointed at by arg.
// After fn returns, reflectcall copies n-retoffset result bytes
// back into arg+retoffset before returning. If copying result bytes back,
// the caller should pass the argument frame type as argtype, so that
// call can execute appropriate write barriers during the copy.
// Package reflect passes a frame type. In package runtime, there is only
// one call that copies results back, in cgocallbackg1, and it does NOT pass a
// frame type, meaning there are no write barriers invoked. See that call
// site for justification.
func reflectcall(argtype *_type, fn, arg unsafe.Pointer, argsize uint32, retoffset uint32)

func procyield(cycles uint32)

type neverCallThisFunction struct{}

// goexit is the return stub at the top of every goroutine call stack.
// Each goroutine stack is constructed as if goexit called the
// goroutine's entry point function, so that when the entry point
// function returns, it will return to goexit, which will call goexit1
// to perform the actual exit.
//
// This function must never be called directly. Call goexit1 instead.
// gentraceback assumes that goexit terminates the stack. A direct
// call on the stack will cause gentraceback to stop walking the stack
// prematurely and if there are leftover stack barriers it may panic.
func goexit(neverCallThisFunction)

// publicationBarrier performs a store/store barrier (a "publication"
// or "export" barrier). Some form of synchronization is required
// between initializing an object and making that object accessible to
// another processor. Without synchronization, the initialization
// writes and the "publication" write may be reordered, allowing the
// other processor to follow the pointer and observe an uninitialized
// object. In general, higher-level synchronization should be used,
// such as locking or an atomic pointer write. publicationBarrier is
// for when those aren't an option, such as in the implementation of
// the memory manager.
//
// There's no corresponding barrier for the read side because the read
// side naturally has a data dependency order. All architectures that
// Go supports or seems likely to ever support automatically enforce
// data dependency ordering.
func publicationBarrier()

//go:noescape
func setcallerpc(argp unsafe.Pointer, pc uintptr)

// getcallerpc returns the program counter (PC) of its caller's caller.
// getcallersp returns the stack pointer (SP) of its caller's caller.
// For both, the argp must be a pointer to the caller's first function argument.
// The implementation may or may not use argp, depending on
// the architecture.
//
// For example:
//
//      func f(arg1, arg2, arg3 int) {
//              pc := getcallerpc(unsafe.Pointer(&arg1))
//              sp := getcallersp(unsafe.Pointer(&arg1))
//      }
//
// These two lines find the PC and SP immediately following
// the call to f (where f will return).
//
// The call to getcallerpc and getcallersp must be done in the
// frame being asked about. It would not be correct for f to pass &arg1
// to another function g and let g call getcallerpc/getcallersp.
// The call inside g might return information about g's caller or
// information about f's caller or complete garbage.
//
// The result of getcallersp is correct at the time of the return,
// but it may be invalidated by any subsequent call to a function
// that might relocate the stack in order to grow or shrink it.
// A general rule is that the result of getcallersp should be used
// immediately and can only be passed to nosplit functions.

//go:noescape
func getcallerpc(argp unsafe.Pointer) uintptr

//go:noescape
func getcallersp(argp unsafe.Pointer) uintptr

// argp used in Defer structs when there is no argp.
const _NoArgs = ^uintptr(0)

//go:linkname time_now time.now
func time_now() (sec int64, nsec int32)

// For gccgo, expose this for C callers.
//go:linkname unixnanotime runtime.unixnanotime
func unixnanotime() int64 {
        sec, nsec := time_now()
        return sec*1e9 + int64(nsec)
}

// round n up to a multiple of a.  a must be a power of 2.
func round(n, a uintptr) uintptr {
        return (n + a - 1) &^ (a - 1)
}

// checkASM returns whether assembly runtime checks have passed.
func checkASM() bool {
        return true
}

// For gccgo this is in the C code.
func osyield()

// For gccgo this can be called directly.
//extern syscall
func syscall(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) uintptr

// throw crashes the program.
// For gccgo unless and until we port panic.go.
func throw(string)

// newobject allocates a new object.
// For gccgo unless and until we port malloc.go.
func newobject(*_type) unsafe.Pointer

// newarray allocates a new array of objects.
// For gccgo unless and until we port malloc.go.
func newarray(*_type, int) unsafe.Pointer

// funcPC returns the entry PC of the function f.
// It assumes that f is a func value. Otherwise the behavior is undefined.
// For gccgo here unless and until we port proc.go.
//go:nosplit
func funcPC(f interface{}) uintptr {
        return **(**uintptr)(add(unsafe.Pointer(&f), sys.PtrSize))
}

// typedmemmove copies a typed value.
// For gccgo for now.
//go:nosplit
func typedmemmove(typ *_type, dst, src unsafe.Pointer) {
        memmove(dst, src, typ.size)
}

// Temporary for gccgo until we port mbarrier.go.
//go:linkname typedslicecopy runtime.typedslicecopy
func typedslicecopy(typ *_type, dst, src slice) int {
        n := dst.len
        if n > src.len {
                n = src.len
        }
        if n == 0 {
                return 0
        }
        memmove(dst.array, src.array, uintptr(n)*typ.size)
        return n
}

// Here for gccgo until we port malloc.go.
const (
        _64bit              = 1 << (^uintptr(0) >> 63) / 2
        _MHeapMap_TotalBits = (_64bit*sys.GoosWindows)*35 + (_64bit*(1-sys.GoosWindows)*(1-sys.GoosDarwin*sys.GoarchArm64))*39 + sys.GoosDarwin*sys.GoarchArm64*31 + (1-_64bit)*32
        _MaxMem             = uintptr(1<<_MHeapMap_TotalBits - 1)
)

// Here for gccgo until we port malloc.go.
//extern runtime_mallocgc
func c_mallocgc(size uintptr, typ uintptr, flag uint32) unsafe.Pointer
func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
        flag := uint32(0)
        if !needzero {
                flag = 1 << 3
        }
        return c_mallocgc(size, uintptr(unsafe.Pointer(typ)), flag)
}

// Here for gccgo until we port mgc.go.
var writeBarrier struct {
        enabled bool   // compiler emits a check of this before calling write barrier
        needed  bool   // whether we need a write barrier for current GC phase
        cgo     bool   // whether we need a write barrier for a cgo check
        alignme uint64 // guarantee alignment so that compiler can use a 32 or 64-bit load
}

// Here for gccgo until we port atomic_pointer.go and mgc.go.
//go:nosplit
func casp(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
        if !atomic.Casp1((*unsafe.Pointer)(noescape(unsafe.Pointer(ptr))), noescape(old), new) {
                return false
        }
        return true
}

// Here for gccgo until we port lock_*.go.
func lock(l *mutex)
func unlock(l *mutex)

// Here for gccgo for netpoll and Solaris.
func errno() int

// Temporary for gccgo until we port proc.go.
func entersyscall(int32)
func entersyscallblock(int32)
func exitsyscall(int32)
func gopark(func(*g, unsafe.Pointer) bool, unsafe.Pointer, string, byte, int)
func goparkunlock(*mutex, string, byte, int)
func goready(*g, int)

// Temporary hack for gccgo until we port proc.go.
//go:nosplit
func acquireSudog() *sudog {
        mp := acquirem()
        pp := mp.p.ptr()
        if len(pp.sudogcache) == 0 {
                pp.sudogcache = append(pp.sudogcache, new(sudog))
        }
        n := len(pp.sudogcache)
        s := pp.sudogcache[n-1]
        pp.sudogcache[n-1] = nil
        pp.sudogcache = pp.sudogcache[:n-1]
        if s.elem != nil {
                throw("acquireSudog: found s.elem != nil in cache")
        }
        releasem(mp)
        return s
}

// Temporary hack for gccgo until we port proc.go.
//go:nosplit
func releaseSudog(s *sudog) {
        if s.elem != nil {
                throw("runtime: sudog with non-nil elem")
        }
        if s.selectdone != nil {
                throw("runtime: sudog with non-nil selectdone")
        }
        if s.next != nil {
                throw("runtime: sudog with non-nil next")
        }
        if s.prev != nil {
                throw("runtime: sudog with non-nil prev")
        }
        if s.waitlink != nil {
                throw("runtime: sudog with non-nil waitlink")
        }
        if s.c != nil {
                throw("runtime: sudog with non-nil c")
        }
        gp := getg()
        if gp.param != nil {
                throw("runtime: releaseSudog with non-nil gp.param")
        }
        mp := acquirem() // avoid rescheduling to another P
        pp := mp.p.ptr()
        pp.sudogcache = append(pp.sudogcache, s)
        releasem(mp)
}

// Temporary hack for gccgo until we port the garbage collector.
func typeBitsBulkBarrier(typ *_type, p, size uintptr) {}

// Here for gccgo until we port msize.go.
func roundupsize(uintptr) uintptr

// Here for gccgo until we port mgc.go.
func GC()

// Here for gccgo until we port proc.go.
var worldsema uint32 = 1

func stopTheWorldWithSema()
func startTheWorldWithSema()

// For gccgo to call from C code.
//go:linkname acquireWorldsema runtime.acquireWorldsema
func acquireWorldsema() {
        semacquire(&worldsema, false)
}

// For gccgo to call from C code.
//go:linkname releaseWorldsema runtime.releaseWorldsema
func releaseWorldsema() {
        semrelease(&worldsema)
}

// Here for gccgo until we port proc.go.
func stopTheWorld(reason string) {
        semacquire(&worldsema, false)
        getg().m.preemptoff = reason
        getg().m.gcing = 1
        systemstack(stopTheWorldWithSema)
}

// Here for gccgo until we port proc.go.
func startTheWorld() {
        getg().m.gcing = 0
        getg().m.locks++
        systemstack(startTheWorldWithSema)
        // worldsema must be held over startTheWorldWithSema to ensure
        // gomaxprocs cannot change while worldsema is held.
        semrelease(&worldsema)
        getg().m.preemptoff = ""
        getg().m.locks--
}

// For gccgo to call from C code, so that the C code and the Go code
// can share the memstats variable for now.
//go:linkname getMstats runtime.getMstats
func getMstats() *mstats {
        return &memstats
}

// Temporary for gccgo until we port proc.go.
func setcpuprofilerate_m(hz int32)

// Temporary for gccgo until we port mem_GOOS.go.
func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer

// Temporary for gccgo until we port proc.go, so that the C signal
// handler can call into cpuprof.
//go:linkname cpuprofAdd runtime.cpuprofAdd
func cpuprofAdd(stk []uintptr) {
        cpuprof.add(stk)
}

// For gccgo until we port proc.go.
func Breakpoint()
func LockOSThread()
func UnlockOSThread()
func allm() *m
func allgs() []*g

//go:nosplit
func readgstatus(gp *g) uint32 {
        return atomic.Load(&gp.atomicstatus)
}

// Temporary for gccgo until we port malloc.go
func persistentalloc(size, align uintptr, sysStat *uint64) unsafe.Pointer

// Temporary for gccgo until we port mheap.go
func setprofilebucket(p unsafe.Pointer, b *bucket)

// Currently in proc.c.
func tracebackothers(*g)

// Temporary for gccgo until we port mgc.go.
func setgcpercent(int32) int32

//go:linkname setGCPercent runtime_debug.setGCPercent
func setGCPercent(in int32) (out int32) {
        return setgcpercent(in)
}

// Temporary for gccgo until we port proc.go.
func setmaxthreads(int) int

//go:linkname setMaxThreads runtime_debug.setMaxThreads
func setMaxThreads(in int) (out int) {
        return setmaxthreads(in)
}

// Temporary for gccgo until we port atomic_pointer.go.
//go:nosplit
func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
        atomic.StorepNoWB(noescape(ptr), new)
}

// Temporary for gccgo until we port mbarrier.go
func writebarrierptr(dst *uintptr, src uintptr) {
        *dst = src
}

// Temporary for gccgo until we port malloc.go
var zerobase uintptr

//go:linkname getZerobase runtime.getZerobase
func getZerobase() *uintptr {
        return &zerobase
}