mirror of git://gcc.gnu.org/git/gcc.git
77 lines
1.8 KiB
Go
77 lines
1.8 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import (
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"runtime/internal/atomic"
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"unsafe"
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)
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type mOS struct {
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waitsemacount uint32
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}
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//go:noescape
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//extern thrsleep
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func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32
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//go:noescape
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//extern thrwakeup
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func thrwakeup(ident uintptr, n int32) int32
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//go:nosplit
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func semacreate(mp *m) {
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}
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//go:nosplit
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func semasleep(ns int64) int32 {
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_g_ := getg()
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// Compute sleep deadline.
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var tsp *timespec
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if ns >= 0 {
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var ts timespec
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var nsec int32
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ns += nanotime()
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ts.set_sec(int64(timediv(ns, 1000000000, &nsec)))
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ts.set_nsec(nsec)
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tsp = &ts
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}
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for {
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v := atomic.Load(&_g_.m.mos.waitsemacount)
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if v > 0 {
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if atomic.Cas(&_g_.m.mos.waitsemacount, v, v-1) {
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return 0 // semaphore acquired
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}
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continue
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}
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// Sleep until woken by semawakeup or timeout; or abort if waitsemacount != 0.
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//
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// From OpenBSD's __thrsleep(2) manual:
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// "The abort argument, if not NULL, points to an int that will
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// be examined [...] immediately before blocking. If that int
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// is non-zero then __thrsleep() will immediately return EINTR
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// without blocking."
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ret := thrsleep(uintptr(unsafe.Pointer(&_g_.m.mos.waitsemacount)), _CLOCK_MONOTONIC, tsp, 0, &_g_.m.mos.waitsemacount)
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if ret == _EWOULDBLOCK {
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return -1
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}
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}
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}
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//go:nosplit
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func semawakeup(mp *m) {
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atomic.Xadd(&mp.mos.waitsemacount, 1)
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ret := thrwakeup(uintptr(unsafe.Pointer(&mp.mos.waitsemacount)), 1)
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if ret != 0 && ret != _ESRCH {
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// semawakeup can be called on signal stack.
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systemstack(func() {
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print("thrwakeup addr=", &mp.mos.waitsemacount, " sem=", mp.mos.waitsemacount, " ret=", ret, "\n")
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})
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}
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}
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