1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
//go:build gc.leaking
// +build gc.leaking
package runtime
// This GC implementation is the simplest useful memory allocator possible: it
// only allocates memory and never frees it. For some constrained systems, it
// may be the only memory allocator possible.
import (
"unsafe"
)
const gcAsserts = false // perform sanity checks
// Ever-incrementing pointer: no memory is freed.
var heapptr = heapStart
// Total amount allocated for runtime.MemStats
var gcTotalAlloc uint64
// Total number of calls to alloc()
var gcMallocs uint64
// Total number of objected freed; for leaking collector this stays 0
const gcFrees = 0
// Inlining alloc() speeds things up slightly but bloats the executable by 50%,
// see https://github.com/tinygo-org/tinygo/issues/2674. So don't.
//
//go:noinline
func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
// TODO: this can be optimized by not casting between pointers and ints so
// much. And by using platform-native data types (e.g. *uint8 for 8-bit
// systems).
size = align(size)
addr := heapptr
gcTotalAlloc += uint64(size)
gcMallocs++
heapptr += size
for heapptr >= heapEnd {
// Try to increase the heap and check again.
if growHeap() {
continue
}
// Failed to make the heap bigger, so we must really be out of memory.
runtimePanic("out of memory")
}
pointer := unsafe.Pointer(addr)
memzero(pointer, size)
return pointer
}
func realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
newAlloc := alloc(size, nil)
if ptr == nil {
return newAlloc
}
// according to POSIX everything beyond the previous pointer's
// size will have indeterminate values so we can just copy garbage
memcpy(newAlloc, ptr, size)
return newAlloc
}
func free(ptr unsafe.Pointer) {
// Memory is never freed.
}
func GC() {
// No-op.
}
func KeepAlive(x interface{}) {
// Unimplemented. Only required with SetFinalizer().
}
func SetFinalizer(obj interface{}, finalizer interface{}) {
// Unimplemented.
}
func initHeap() {
// preinit() may have moved heapStart; reset heapptr
heapptr = heapStart
}
// setHeapEnd sets a new (larger) heapEnd pointer.
func setHeapEnd(newHeapEnd uintptr) {
// This "heap" is so simple that simply assigning a new value is good
// enough.
heapEnd = newHeapEnd
}
func markRoots(start, end uintptr) {
// dummy, so that markGlobals will compile
}
|
