github.com/zxy12/go_duplicate_112_new@v0.0.0-20200807091221-747231827200/src/runtime/mem_js.go (about) 1 // Copyright 2018 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // +build js,wasm 6 7 package runtime 8 9 import ( 10 "runtime/internal/sys" 11 "unsafe" 12 ) 13 14 // Don't split the stack as this function may be invoked without a valid G, 15 // which prevents us from allocating more stack. 16 //go:nosplit 17 func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer { 18 p := sysReserve(nil, n) 19 sysMap(p, n, sysStat) 20 return p 21 } 22 23 func sysUnused(v unsafe.Pointer, n uintptr) { 24 } 25 26 func sysUsed(v unsafe.Pointer, n uintptr) { 27 } 28 29 // Don't split the stack as this function may be invoked without a valid G, 30 // which prevents us from allocating more stack. 31 //go:nosplit 32 func sysFree(v unsafe.Pointer, n uintptr, sysStat *uint64) { 33 mSysStatDec(sysStat, n) 34 } 35 36 func sysFault(v unsafe.Pointer, n uintptr) { 37 } 38 39 var reserveEnd uintptr 40 41 func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer { 42 // TODO(neelance): maybe unify with mem_plan9.go, depending on how https://github.com/WebAssembly/design/blob/master/FutureFeatures.md#finer-grained-control-over-memory turns out 43 44 if reserveEnd < lastmoduledatap.end { 45 reserveEnd = lastmoduledatap.end 46 } 47 if uintptr(v) < reserveEnd { 48 v = unsafe.Pointer(reserveEnd) 49 } 50 reserveEnd = uintptr(v) + n 51 52 current := currentMemory() 53 needed := int32(reserveEnd/sys.DefaultPhysPageSize + 1) 54 if current < needed { 55 if growMemory(needed-current) == -1 { 56 return nil 57 } 58 } 59 60 return v 61 } 62 63 func currentMemory() int32 64 func growMemory(pages int32) int32 65 66 func sysMap(v unsafe.Pointer, n uintptr, sysStat *uint64) { 67 mSysStatInc(sysStat, n) 68 }