gcc/libgo/runtime/malloc.goc

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// Copyright 2009 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.
// See malloc.h for overview.
//
// TODO(rsc): double-check stats.
package runtime
#include <stddef.h>
#include <errno.h>
#include <stdlib.h>
#include "go-alloc.h"
#include "runtime.h"
#include "malloc.h"
#include "go-string.h"
#include "interface.h"
#include "go-type.h"
typedef struct __go_empty_interface Eface;
typedef struct __go_type_descriptor Type;
typedef struct __go_func_type FuncType;
MHeap runtime_mheap;
extern MStats mstats; // defined in extern.go
extern volatile int32 runtime_MemProfileRate
__asm__ ("libgo_runtime.runtime.MemProfileRate");
// Same algorithm from chan.c, but a different
// instance of the static uint32 x.
// Not protected by a lock - let the threads use
// the same random number if they like.
static uint32
fastrand1(void)
{
static uint32 x = 0x49f6428aUL;
x += x;
if(x & 0x80000000L)
x ^= 0x88888eefUL;
return x;
}
// Allocate an object of at least size bytes.
// Small objects are allocated from the per-thread cache's free lists.
// Large objects (> 32 kB) are allocated straight from the heap.
void*
runtime_mallocgc(uintptr size, uint32 refflag, int32 dogc, int32 zeroed)
{
int32 sizeclass, rate;
MCache *c;
uintptr npages;
MSpan *s;
void *v;
uint32 *ref;
if(!__sync_bool_compare_and_swap(&m->mallocing, 0, 1))
runtime_throw("malloc/free - deadlock");
if(size == 0)
size = 1;
mstats.nmalloc++;
if(size <= MaxSmallSize) {
// Allocate from mcache free lists.
sizeclass = runtime_SizeToClass(size);
size = runtime_class_to_size[sizeclass];
c = m->mcache;
v = runtime_MCache_Alloc(c, sizeclass, size, zeroed);
if(v == nil)
runtime_throw("out of memory");
mstats.alloc += size;
mstats.total_alloc += size;
mstats.by_size[sizeclass].nmalloc++;
if(!runtime_mlookup(v, nil, nil, nil, &ref)) {
// runtime_printf("malloc %D; runtime_mlookup failed\n", (uint64)size);
runtime_throw("malloc runtime_mlookup");
}
*ref = RefNone | refflag;
} else {
// TODO(rsc): Report tracebacks for very large allocations.
// Allocate directly from heap.
npages = size >> PageShift;
if((size & PageMask) != 0)
npages++;
s = runtime_MHeap_Alloc(&runtime_mheap, npages, 0, 1);
if(s == nil)
runtime_throw("out of memory");
size = npages<<PageShift;
mstats.alloc += size;
mstats.total_alloc += size;
v = (void*)(s->start << PageShift);
// setup for mark sweep
s->gcref0 = RefNone | refflag;
ref = &s->gcref0;
}
__sync_bool_compare_and_swap(&m->mallocing, 1, 0);
if(__sync_bool_compare_and_swap(&m->gcing, 1, 0)) {
if(!(refflag & RefNoProfiling))
__go_run_goroutine_gc(0);
else {
// We are being called from the profiler. Tell it
// to invoke the garbage collector when it is
// done. No need to use a sync function here.
m->gcing_for_prof = 1;
}
}
if(!(refflag & RefNoProfiling) && (rate = runtime_MemProfileRate) > 0) {
if(size >= (uint32) rate)
goto profile;
if((uint32) m->mcache->next_sample > size)
m->mcache->next_sample -= size;
else {
// pick next profile time
if(rate > 0x3fffffff) // make 2*rate not overflow
rate = 0x3fffffff;
m->mcache->next_sample = fastrand1() % (2*rate);
profile:
*ref |= RefProfiled;
runtime_MProf_Malloc(v, size);
}
}
if(dogc && mstats.heap_alloc >= mstats.next_gc)
runtime_gc(0);
return v;
}
void*
__go_alloc(uintptr size)
{
return runtime_mallocgc(size, 0, 0, 1);
}
// Free the object whose base pointer is v.
void
__go_free(void *v)
{
int32 sizeclass, size;
MSpan *s;
MCache *c;
uint32 prof, *ref;
if(v == nil)
return;
if(!__sync_bool_compare_and_swap(&m->mallocing, 0, 1))
runtime_throw("malloc/free - deadlock");
if(!runtime_mlookup(v, nil, nil, &s, &ref)) {
// runtime_printf("free %p: not an allocated block\n", v);
runtime_throw("free runtime_mlookup");
}
prof = *ref & RefProfiled;
*ref = RefFree;
// Find size class for v.
sizeclass = s->sizeclass;
if(sizeclass == 0) {
// Large object.
if(prof)
runtime_MProf_Free(v, s->npages<<PageShift);
mstats.alloc -= s->npages<<PageShift;
runtime_memclr(v, s->npages<<PageShift);
runtime_MHeap_Free(&runtime_mheap, s, 1);
} else {
// Small object.
c = m->mcache;
size = runtime_class_to_size[sizeclass];
if(size > (int32)sizeof(uintptr))
((uintptr*)v)[1] = 1; // mark as "needs to be zeroed"
if(prof)
runtime_MProf_Free(v, size);
mstats.alloc -= size;
mstats.by_size[sizeclass].nfree++;
runtime_MCache_Free(c, v, sizeclass, size);
}
__sync_bool_compare_and_swap(&m->mallocing, 1, 0);
if(__sync_bool_compare_and_swap(&m->gcing, 1, 0))
__go_run_goroutine_gc(1);
}
int32
runtime_mlookup(void *v, byte **base, uintptr *size, MSpan **sp, uint32 **ref)
{
uintptr n, nobj, i;
byte *p;
MSpan *s;
mstats.nlookup++;
s = runtime_MHeap_LookupMaybe(&runtime_mheap, (uintptr)v>>PageShift);
if(sp)
*sp = s;
if(s == nil) {
if(base)
*base = nil;
if(size)
*size = 0;
if(ref)
*ref = 0;
return 0;
}
p = (byte*)((uintptr)s->start<<PageShift);
if(s->sizeclass == 0) {
// Large object.
if(base)
*base = p;
if(size)
*size = s->npages<<PageShift;
if(ref)
*ref = &s->gcref0;
return 1;
}
if((byte*)v >= (byte*)s->gcref) {
// pointers into the gc ref counts
// do not count as pointers.
return 0;
}
n = runtime_class_to_size[s->sizeclass];
i = ((byte*)v - p)/n;
if(base)
*base = p + i*n;
if(size)
*size = n;
// good for error checking, but expensive
if(0) {
nobj = (s->npages << PageShift) / (n + RefcountOverhead);
if((byte*)s->gcref < p || (byte*)(s->gcref+nobj) > p+(s->npages<<PageShift)) {
// runtime_printf("odd span state=%d span=%p base=%p sizeclass=%d n=%D size=%D npages=%D\n",
// s->state, s, p, s->sizeclass, (uint64)nobj, (uint64)n, (uint64)s->npages);
// runtime_printf("s->base sizeclass %d v=%p base=%p gcref=%p blocksize=%D nobj=%D size=%D end=%p end=%p\n",
// s->sizeclass, v, p, s->gcref, (uint64)s->npages<<PageShift,
// (uint64)nobj, (uint64)n, s->gcref + nobj, p+(s->npages<<PageShift));
runtime_throw("bad gcref");
}
}
if(ref)
*ref = &s->gcref[i];
return 1;
}
MCache*
runtime_allocmcache(void)
{
MCache *c;
runtime_lock(&runtime_mheap);
c = runtime_FixAlloc_Alloc(&runtime_mheap.cachealloc);
// Clear the free list used by FixAlloc; assume the rest is zeroed.
c->list[0].list = nil;
mstats.mcache_inuse = runtime_mheap.cachealloc.inuse;
mstats.mcache_sys = runtime_mheap.cachealloc.sys;
runtime_unlock(&runtime_mheap);
return c;
}
void
runtime_mallocinit(void)
{
runtime_initfintab();
runtime_Mprof_Init();
runtime_SysMemInit();
runtime_InitSizes();
runtime_MHeap_Init(&runtime_mheap, runtime_SysAlloc);
m->mcache = runtime_allocmcache();
// See if it works.
runtime_free(runtime_malloc(1));
}
// Runtime stubs.
void*
runtime_mal(uintptr n)
{
return runtime_mallocgc(n, 0, 1, 1);
}
func Alloc(n uintptr) (p *byte) {
p = runtime_malloc(n);
}
func Free(p *byte) {
runtime_free(p);
}
func Lookup(p *byte) (base *byte, size uintptr) {
runtime_mlookup(p, &base, &size, nil, nil);
}
func GC() {
runtime_gc(1);
}
func SetFinalizer(obj Eface, finalizer Eface) {
byte *base;
uintptr size;
const FuncType *ft;
if(obj.__type_descriptor == nil) {
// runtime_printf("runtime.SetFinalizer: first argument is nil interface\n");
throw:
runtime_throw("runtime.SetFinalizer");
}
if(obj.__type_descriptor->__code != GO_PTR) {
// runtime_printf("runtime.SetFinalizer: first argument is %S, not pointer\n", *obj.type->string);
goto throw;
}
if(!runtime_mlookup(obj.__object, &base, &size, nil, nil) || obj.__object != base) {
// runtime_printf("runtime.SetFinalizer: pointer not at beginning of allocated block\n");
goto throw;
}
ft = nil;
if(finalizer.__type_descriptor != nil) {
if(finalizer.__type_descriptor->__code != GO_FUNC) {
badfunc:
// runtime_printf("runtime.SetFinalizer: second argument is %S, not func(%S)\n", *finalizer.type->string, *obj.type->string);
goto throw;
}
ft = (const FuncType*)finalizer.__type_descriptor;
if(ft->__dotdotdot || ft->__in.__count != 1 || !__go_type_descriptors_equal(*(Type**)ft->__in.__values, obj.__type_descriptor))
goto badfunc;
if(runtime_getfinalizer(obj.__object, 0)) {
// runtime_printf("runtime.SetFinalizer: finalizer already set");
goto throw;
}
}
runtime_addfinalizer(obj.__object, finalizer.__type_descriptor != nil ? *(void**)finalizer.__object : nil, ft);
}