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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 "arch.h"
#include "malloc.h"
#include "interface.h"
#include "go-type.h"
// Map gccgo field names to gc field names.
// Eface aka __go_empty_interface.
#define type __type_descriptor
// Type aka __go_type_descriptor
#define kind __code
#define string __reflection
// GCCGO SPECIFIC CHANGE
//
// There is a long comment in runtime_mallocinit about where to put the heap
// on a 64-bit system. It makes assumptions that are not valid on linux/arm64
// -- it assumes user space can choose the lower 47 bits of a pointer, but on
// linux/arm64 we can only choose the lower 39 bits. This means the heap is
// roughly a quarter of the available address space and we cannot choose a bit
// pattern that all pointers will have -- luckily the GC is mostly precise
// these days so this doesn't matter all that much. The kernel (as of 3.13)
// will allocate address space starting either down from 0x7fffffffff or up
// from 0x2000000000, so we put the heap roughly in the middle of these two
// addresses to minimize the chance that a non-heap allocation will get in the
// way of the heap.
//
// This all means that there isn't much point in trying 256 different
// locations for the heap on such systems.
#ifdef __aarch64__
#define HeapBase(i) ((void*)(uintptr)(0x40ULL<<32))
#define HeapBaseOptions 1
#else
#define HeapBase(i) ((void*)(uintptr)(i<<40|0x00c0ULL<<32))
#define HeapBaseOptions 0x80
#endif
// END GCCGO SPECIFIC CHANGE
// Mark mheap as 'no pointers', it does not contain interesting pointers but occupies ~45K.
MHeap runtime_mheap;
int32 runtime_checking;
extern volatile intgo runtime_MemProfileRate
__asm__ (GOSYM_PREFIX "runtime.MemProfileRate");
static MSpan* largealloc(uint32, uintptr*);
static void runtime_profilealloc(void *v, uintptr size);
static void settype(MSpan *s, void *v, uintptr typ);
// 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.
// If the block will be freed with runtime_free(), typ must be 0.
void*
runtime_mallocgc(uintptr size, uintptr typ, uint32 flag)
{
M *m;
G *g;
int32 sizeclass;
uintptr tinysize, size1;
intgo rate;
MCache *c;
MSpan *s;
MLink *v, *next;
byte *tiny;
bool incallback;
MStats *pmstats;
if(size == 0) {
// All 0-length allocations use this pointer.
// The language does not require the allocations to
// have distinct values.
return &runtime_zerobase;
}
g = runtime_g();
m = g->m;
incallback = false;
if(m->mcache == nil && m->ncgo > 0) {
// For gccgo this case can occur when a cgo or SWIG function
// has an interface return type and the function
// returns a non-pointer, so memory allocation occurs
// after syscall.Cgocall but before syscall.CgocallDone.
// We treat it as a callback.
runtime_exitsyscall(0);
m = runtime_m();
incallback = true;
flag |= FlagNoInvokeGC;
}
if(runtime_gcwaiting() && g != m->g0 && m->locks == 0 && !(flag & FlagNoInvokeGC) && m->preemptoff.len == 0) {
runtime_gosched();
m = runtime_m();
}
if(m->mallocing)
runtime_throw("malloc/free - deadlock");
// Disable preemption during settype.
// We can not use m->mallocing for this, because settype calls mallocgc.
m->locks++;
m->mallocing = 1;
if(DebugTypeAtBlockEnd)
size += sizeof(uintptr);
c = m->mcache;
if(!runtime_debug.efence && size <= MaxSmallSize) {
if((flag&(FlagNoScan|FlagNoGC)) == FlagNoScan && size < TinySize) {
// Tiny allocator.
//
// Tiny allocator combines several tiny allocation requests
// into a single memory block. The resulting memory block
// is freed when all subobjects are unreachable. The subobjects
// must be FlagNoScan (don't have pointers), this ensures that
// the amount of potentially wasted memory is bounded.
//
// Size of the memory block used for combining (TinySize) is tunable.
// Current setting is 16 bytes, which relates to 2x worst case memory
// wastage (when all but one subobjects are unreachable).
// 8 bytes would result in no wastage at all, but provides less
// opportunities for combining.
// 32 bytes provides more opportunities for combining,
// but can lead to 4x worst case wastage.
// The best case winning is 8x regardless of block size.
//
// Objects obtained from tiny allocator must not be freed explicitly.
// So when an object will be freed explicitly, we ensure that
// its size >= TinySize.
//
// SetFinalizer has a special case for objects potentially coming
// from tiny allocator, it such case it allows to set finalizers
// for an inner byte of a memory block.
//
// The main targets of tiny allocator are small strings and
// standalone escaping variables. On a json benchmark
// the allocator reduces number of allocations by ~12% and
// reduces heap size by ~20%.
tinysize = c->tinysize;
if(size <= tinysize) {
tiny = c->tiny;
// Align tiny pointer for required (conservative) alignment.
if((size&7) == 0)
tiny = (byte*)ROUND((uintptr)tiny, 8);
else if((size&3) == 0)
tiny = (byte*)ROUND((uintptr)tiny, 4);
else if((size&1) == 0)
tiny = (byte*)ROUND((uintptr)tiny, 2);
size1 = size + (tiny - (byte*)c->tiny);
if(size1 <= tinysize) {
// The object fits into existing tiny block.
v = (MLink*)tiny;
c->tiny = (byte*)c->tiny + size1;
c->tinysize -= size1;
m->mallocing = 0;
m->locks--;
if(incallback)
runtime_entersyscall(0);
return v;
}
}
// Allocate a new TinySize block.
s = c->alloc[TinySizeClass];
if(s->freelist == nil)
s = runtime_MCache_Refill(c, TinySizeClass);
v = s->freelist;
next = v->next;
s->freelist = next;
s->ref++;
if(next != nil) // prefetching nil leads to a DTLB miss
PREFETCH(next);
((uint64*)v)[0] = 0;
((uint64*)v)[1] = 0;
// See if we need to replace the existing tiny block with the new one
// based on amount of remaining free space.
if(TinySize-size > tinysize) {
c->tiny = (byte*)v + size;
c->tinysize = TinySize - size;
}
size = TinySize;
goto done;
}
// Allocate from mcache free lists.
// Inlined version of SizeToClass().
if(size <= 1024-8)
sizeclass = runtime_size_to_class8[(size+7)>>3];
else
sizeclass = runtime_size_to_class128[(size-1024+127) >> 7];
size = runtime_class_to_size[sizeclass];
s = c->alloc[sizeclass];
if(s->freelist == nil)
s = runtime_MCache_Refill(c, sizeclass);
v = s->freelist;
next = v->next;
s->freelist = next;
s->ref++;
if(next != nil) // prefetching nil leads to a DTLB miss
PREFETCH(next);
if(!(flag & FlagNoZero)) {
v->next = nil;
// block is zeroed iff second word is zero ...
if(size > 2*sizeof(uintptr) && ((uintptr*)v)[1] != 0)
runtime_memclr((byte*)v, size);
}
done:
c->local_cachealloc += size;
} else {
// Allocate directly from heap.
s = largealloc(flag, &size);
v = (void*)(s->start << PageShift);
}
if(flag & FlagNoGC)
runtime_marknogc(v);
else if(!(flag & FlagNoScan))
runtime_markscan(v);
if(DebugTypeAtBlockEnd)
*(uintptr*)((uintptr)v+size-sizeof(uintptr)) = typ;
m->mallocing = 0;
// TODO: save type even if FlagNoScan? Potentially expensive but might help
// heap profiling/tracing.
if(UseSpanType && !(flag & FlagNoScan) && typ != 0)
settype(s, v, typ);
if(runtime_debug.allocfreetrace)
runtime_tracealloc(v, size, typ);
if(!(flag & FlagNoProfiling) && (rate = runtime_MemProfileRate) > 0) {
if(size < (uintptr)rate && size < (uintptr)(uint32)c->next_sample)
c->next_sample -= size;
else
runtime_profilealloc(v, size);
}
m->locks--;
pmstats = mstats();
if(!(flag & FlagNoInvokeGC) && pmstats->heap_alloc >= pmstats->next_gc)
runtime_gc(0);
if(incallback)
runtime_entersyscall(0);
return v;
}
static MSpan*
largealloc(uint32 flag, uintptr *sizep)
{
uintptr npages, size;
MSpan *s;
void *v;
// Allocate directly from heap.
size = *sizep;
if(size + PageSize < size)
runtime_throw("out of memory");
npages = size >> PageShift;
if((size & PageMask) != 0)
npages++;
s = runtime_MHeap_Alloc(&runtime_mheap, npages, 0, 1, !(flag & FlagNoZero));
if(s == nil)
runtime_throw("out of memory");
s->limit = (uintptr)((byte*)(s->start<<PageShift) + size);
*sizep = npages<<PageShift;
v = (void*)(s->start << PageShift);
// setup for mark sweep
runtime_markspan(v, 0, 0, true);
return s;
}
static void
runtime_profilealloc(void *v, uintptr size)
{
uintptr rate;
int32 next;
MCache *c;
c = runtime_m()->mcache;
rate = runtime_MemProfileRate;
if(size < rate) {
// pick next profile time
// If you change this, also change allocmcache.
if(rate > 0x3fffffff) // make 2*rate not overflow
rate = 0x3fffffff;
next = runtime_fastrand1() % (2*rate);
// Subtract the "remainder" of the current allocation.
// Otherwise objects that are close in size to sampling rate
// will be under-sampled, because we consistently discard this remainder.
next -= (size - c->next_sample);
if(next < 0)
next = 0;
c->next_sample = next;
}
runtime_MProf_Malloc(v, size);
}
void*
__go_alloc(uintptr size)
{
return runtime_mallocgc(size, 0, FlagNoInvokeGC);
}
// Free the object whose base pointer is v.
void
__go_free(void *v)
{
M *m;
int32 sizeclass;
MSpan *s;
MCache *c;
uintptr size;
if(v == nil)
return;
// If you change this also change mgc0.c:/^sweep,
// which has a copy of the guts of free.
m = runtime_m();
if(m->mallocing)
runtime_throw("malloc/free - deadlock");
m->mallocing = 1;
if(!runtime_mlookup(v, nil, nil, &s)) {
runtime_printf("free %p: not an allocated block\n", v);
runtime_throw("free runtime_mlookup");
}
size = s->elemsize;
sizeclass = s->sizeclass;
// Objects that are smaller than TinySize can be allocated using tiny alloc,
// if then such object is combined with an object with finalizer, we will crash.
if(size < TinySize)
runtime_throw("freeing too small block");
if(runtime_debug.allocfreetrace)
runtime_tracefree(v, size);
// Ensure that the span is swept.
// If we free into an unswept span, we will corrupt GC bitmaps.
runtime_MSpan_EnsureSwept(s);
if(s->specials != nil)
runtime_freeallspecials(s, v, size);
c = m->mcache;
if(sizeclass == 0) {
// Large object.
s->needzero = 1;
// Must mark v freed before calling unmarkspan and MHeap_Free:
// they might coalesce v into other spans and change the bitmap further.
runtime_markfreed(v);
runtime_unmarkspan(v, 1<<PageShift);
// NOTE(rsc,dvyukov): The original implementation of efence
// in CL 22060046 used SysFree instead of SysFault, so that
// the operating system would eventually give the memory
// back to us again, so that an efence program could run
// longer without running out of memory. Unfortunately,
// calling SysFree here without any kind of adjustment of the
// heap data structures means that when the memory does
// come back to us, we have the wrong metadata for it, either in
// the MSpan structures or in the garbage collection bitmap.
// Using SysFault here means that the program will run out of
// memory fairly quickly in efence mode, but at least it won't
// have mysterious crashes due to confused memory reuse.
// It should be possible to switch back to SysFree if we also
// implement and then call some kind of MHeap_DeleteSpan.
if(runtime_debug.efence)
runtime_SysFault((void*)(s->start<<PageShift), size);
else
runtime_MHeap_Free(&runtime_mheap, s, 1);
c->local_nlargefree++;
c->local_largefree += size;
} else {
// Small object.
if(size > 2*sizeof(uintptr))
((uintptr*)v)[1] = (uintptr)0xfeedfeedfeedfeedll; // mark as "needs to be zeroed"
else if(size > sizeof(uintptr))
((uintptr*)v)[1] = 0;
// Must mark v freed before calling MCache_Free:
// it might coalesce v and other blocks into a bigger span
// and change the bitmap further.
c->local_nsmallfree[sizeclass]++;
c->local_cachealloc -= size;
if(c->alloc[sizeclass] == s) {
// We own the span, so we can just add v to the freelist
runtime_markfreed(v);
((MLink*)v)->next = s->freelist;
s->freelist = v;
s->ref--;
} else {
// Someone else owns this span. Add to free queue.
runtime_MCache_Free(c, v, sizeclass, size);
}
}
m->mallocing = 0;
}
int32
runtime_mlookup(void *v, byte **base, uintptr *size, MSpan **sp)
{
M *m;
uintptr n, i;
byte *p;
MSpan *s;
m = runtime_m();
m->mcache->local_nlookup++;
if (sizeof(void*) == 4 && m->mcache->local_nlookup >= (1<<30)) {
// purge cache stats to prevent overflow
runtime_lock(&runtime_mheap);
runtime_purgecachedstats(m->mcache);
runtime_unlock(&runtime_mheap);
}
s = runtime_MHeap_LookupMaybe(&runtime_mheap, v);
if(sp)
*sp = s;
if(s == nil) {
runtime_checkfreed(v, 1);
if(base)
*base = nil;
if(size)
*size = 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;
return 1;
}
n = s->elemsize;
if(base) {
i = ((byte*)v - p)/n;
*base = p + i*n;
}
if(size)
*size = n;
return 1;
}
void
runtime_purgecachedstats(MCache *c)
{
MHeap *h;
int32 i;
// Protected by either heap or GC lock.
h = &runtime_mheap;
mstats()->heap_alloc += (intptr)c->local_cachealloc;
c->local_cachealloc = 0;
mstats()->nlookup += c->local_nlookup;
c->local_nlookup = 0;
h->largefree += c->local_largefree;
c->local_largefree = 0;
h->nlargefree += c->local_nlargefree;
c->local_nlargefree = 0;
for(i=0; i<(int32)nelem(c->local_nsmallfree); i++) {
h->nsmallfree[i] += c->local_nsmallfree[i];
c->local_nsmallfree[i] = 0;
}
}
// Initialized in mallocinit because it's defined in go/runtime/mem.go.
#define MaxArena32 (2U<<30)
void
runtime_mallocinit(void)
{
byte *p, *p1;
uintptr arena_size, bitmap_size, spans_size, p_size;
uintptr *pend;
uintptr end;
uintptr limit;
uint64 i;
bool reserved;
p = nil;
p_size = 0;
arena_size = 0;
bitmap_size = 0;
spans_size = 0;
reserved = false;
// for 64-bit build
USED(p);
USED(p_size);
USED(arena_size);
USED(bitmap_size);
USED(spans_size);
runtime_InitSizes();
if(runtime_class_to_size[TinySizeClass] != TinySize)
runtime_throw("bad TinySizeClass");
// limit = runtime_memlimit();
// See https://code.google.com/p/go/issues/detail?id=5049
// TODO(rsc): Fix after 1.1.
limit = 0;
// Set up the allocation arena, a contiguous area of memory where
// allocated data will be found. The arena begins with a bitmap large
// enough to hold 4 bits per allocated word.
if(sizeof(void*) == 8 && (limit == 0 || limit > (1<<30))) {
// On a 64-bit machine, allocate from a single contiguous reservation.
// 128 GB (MaxMem) should be big enough for now.
//
// The code will work with the reservation at any address, but ask
// SysReserve to use 0x0000XXc000000000 if possible (XX=00...7f).
// Allocating a 128 GB region takes away 37 bits, and the amd64
// doesn't let us choose the top 17 bits, so that leaves the 11 bits
// in the middle of 0x00c0 for us to choose. Choosing 0x00c0 means
// that the valid memory addresses will begin 0x00c0, 0x00c1, ..., 0x00df.
// In little-endian, that's c0 00, c1 00, ..., df 00. None of those are valid
// UTF-8 sequences, and they are otherwise as far away from
// ff (likely a common byte) as possible. If that fails, we try other 0xXXc0
// addresses. An earlier attempt to use 0x11f8 caused out of memory errors
// on OS X during thread allocations. 0x00c0 causes conflicts with
// AddressSanitizer which reserves all memory up to 0x0100.
// These choices are both for debuggability and to reduce the
// odds of the conservative garbage collector not collecting memory
// because some non-pointer block of memory had a bit pattern
// that matched a memory address.
//
// Actually we reserve 136 GB (because the bitmap ends up being 8 GB)
// but it hardly matters: e0 00 is not valid UTF-8 either.
//
// If this fails we fall back to the 32 bit memory mechanism
arena_size = MaxMem;
bitmap_size = arena_size / (sizeof(void*)*8/4);
spans_size = arena_size / PageSize * sizeof(runtime_mheap.spans[0]);
spans_size = ROUND(spans_size, PageSize);
for(i = 0; i < HeapBaseOptions; i++) {
p = HeapBase(i);
p_size = bitmap_size + spans_size + arena_size + PageSize;
p = runtime_SysReserve(p, p_size, &reserved);
if(p != nil)
break;
}
}
if (p == nil) {
// On a 32-bit machine, we can't typically get away
// with a giant virtual address space reservation.
// Instead we map the memory information bitmap
// immediately after the data segment, large enough
// to handle another 2GB of mappings (256 MB),
// along with a reservation for another 512 MB of memory.
// When that gets used up, we'll start asking the kernel
// for any memory anywhere and hope it's in the 2GB
// following the bitmap (presumably the executable begins
// near the bottom of memory, so we'll have to use up
// most of memory before the kernel resorts to giving out
// memory before the beginning of the text segment).
//
// Alternatively we could reserve 512 MB bitmap, enough
// for 4GB of mappings, and then accept any memory the
// kernel threw at us, but normally that's a waste of 512 MB
// of address space, which is probably too much in a 32-bit world.
bitmap_size = MaxArena32 / (sizeof(void*)*8/4);
arena_size = 512<<20;
spans_size = MaxArena32 / PageSize * sizeof(runtime_mheap.spans[0]);
if(limit > 0 && arena_size+bitmap_size+spans_size > limit) {
bitmap_size = (limit / 9) & ~((1<<PageShift) - 1);
arena_size = bitmap_size * 8;
spans_size = arena_size / PageSize * sizeof(runtime_mheap.spans[0]);
}
spans_size = ROUND(spans_size, PageSize);
// SysReserve treats the address we ask for, end, as a hint,
// not as an absolute requirement. If we ask for the end
// of the data segment but the operating system requires
// a little more space before we can start allocating, it will
// give out a slightly higher pointer. Except QEMU, which
// is buggy, as usual: it won't adjust the pointer upward.
// So adjust it upward a little bit ourselves: 1/4 MB to get
// away from the running binary image and then round up
// to a MB boundary.
end = 0;
pend = &__go_end;
if(pend != nil)
end = *pend;
p = (byte*)ROUND(end + (1<<18), 1<<20);
p_size = bitmap_size + spans_size + arena_size + PageSize;
p = runtime_SysReserve(p, p_size, &reserved);
if(p == nil)
runtime_throw("runtime: cannot reserve arena virtual address space");
}
// PageSize can be larger than OS definition of page size,
// so SysReserve can give us a PageSize-unaligned pointer.
// To overcome this we ask for PageSize more and round up the pointer.
p1 = (byte*)ROUND((uintptr)p, PageSize);
runtime_mheap.spans = (MSpan**)p1;
runtime_mheap.bitmap = p1 + spans_size;
runtime_mheap.arena_start = p1 + spans_size + bitmap_size;
runtime_mheap.arena_used = runtime_mheap.arena_start;
runtime_mheap.arena_end = p + p_size;
runtime_mheap.arena_reserved = reserved;
if(((uintptr)runtime_mheap.arena_start & (PageSize-1)) != 0)
runtime_throw("misrounded allocation in mallocinit");
// Initialize the rest of the allocator.
runtime_MHeap_Init(&runtime_mheap);
runtime_m()->mcache = runtime_allocmcache();
// See if it works.
runtime_free(runtime_malloc(TinySize));
}
void*
runtime_MHeap_SysAlloc(MHeap *h, uintptr n)
{
byte *p, *p_end;
uintptr p_size;
bool reserved;
if(n > (uintptr)(h->arena_end - h->arena_used)) {
// We are in 32-bit mode, maybe we didn't use all possible address space yet.
// Reserve some more space.
byte *new_end;
p_size = ROUND(n + PageSize, 256<<20);
new_end = h->arena_end + p_size;
if(new_end <= h->arena_start + MaxArena32) {
// TODO: It would be bad if part of the arena
// is reserved and part is not.
p = runtime_SysReserve(h->arena_end, p_size, &reserved);
if(p == h->arena_end) {
h->arena_end = new_end;
h->arena_reserved = reserved;
}
else if(p+p_size <= h->arena_start + MaxArena32) {
// Keep everything page-aligned.
// Our pages are bigger than hardware pages.
h->arena_end = p+p_size;
h->arena_used = p + (-(uintptr)p&(PageSize-1));
h->arena_reserved = reserved;
} else {
uint64 stat;
stat = 0;
runtime_SysFree(p, p_size, &stat);
}
}
}
if(n <= (uintptr)(h->arena_end - h->arena_used)) {
// Keep taking from our reservation.
p = h->arena_used;
runtime_SysMap(p, n, h->arena_reserved, &mstats()->heap_sys);
h->arena_used += n;
runtime_MHeap_MapBits(h);
runtime_MHeap_MapSpans(h);
if(((uintptr)p & (PageSize-1)) != 0)
runtime_throw("misrounded allocation in MHeap_SysAlloc");
return p;
}
// If using 64-bit, our reservation is all we have.
if((uintptr)(h->arena_end - h->arena_start) >= MaxArena32)
return nil;
// On 32-bit, once the reservation is gone we can
// try to get memory at a location chosen by the OS
// and hope that it is in the range we allocated bitmap for.
p_size = ROUND(n, PageSize) + PageSize;
p = runtime_SysAlloc(p_size, &mstats()->heap_sys);
if(p == nil)
return nil;
if(p < h->arena_start || (uintptr)(p+p_size - h->arena_start) >= MaxArena32) {
runtime_printf("runtime: memory allocated by OS (%p) not in usable range [%p,%p)\n",
p, h->arena_start, h->arena_start+MaxArena32);
runtime_SysFree(p, p_size, &mstats()->heap_sys);
return nil;
}
p_end = p + p_size;
p += -(uintptr)p & (PageSize-1);
if(p+n > h->arena_used) {
h->arena_used = p+n;
if(p_end > h->arena_end)
h->arena_end = p_end;
runtime_MHeap_MapBits(h);
runtime_MHeap_MapSpans(h);
}
if(((uintptr)p & (PageSize-1)) != 0)
runtime_throw("misrounded allocation in MHeap_SysAlloc");
return p;
}
static struct
{
Lock;
byte* pos;
byte* end;
} persistent;
enum
{
PersistentAllocChunk = 256<<10,
PersistentAllocMaxBlock = 64<<10, // VM reservation granularity is 64K on windows
};
// Wrapper around SysAlloc that can allocate small chunks.
// There is no associated free operation.
// Intended for things like function/type/debug-related persistent data.
// If align is 0, uses default align (currently 8).
void*
runtime_persistentalloc(uintptr size, uintptr align, uint64 *stat)
{
byte *p;
if(align != 0) {
if(align&(align-1))
runtime_throw("persistentalloc: align is not a power of 2");
if(align > PageSize)
runtime_throw("persistentalloc: align is too large");
} else
align = 8;
if(size >= PersistentAllocMaxBlock)
return runtime_SysAlloc(size, stat);
runtime_lock(&persistent);
persistent.pos = (byte*)ROUND((uintptr)persistent.pos, align);
if(persistent.pos + size > persistent.end) {
persistent.pos = runtime_SysAlloc(PersistentAllocChunk, &mstats()->other_sys);
if(persistent.pos == nil) {
runtime_unlock(&persistent);
runtime_throw("runtime: cannot allocate memory");
}
persistent.end = persistent.pos + PersistentAllocChunk;
}
p = persistent.pos;
persistent.pos += size;
runtime_unlock(&persistent);
if(stat != &mstats()->other_sys) {
// reaccount the allocation against provided stat
runtime_xadd64(stat, size);
runtime_xadd64(&mstats()->other_sys, -(uint64)size);
}
return p;
}
static void
settype(MSpan *s, void *v, uintptr typ)
{
uintptr size, ofs, j, t;
uintptr ntypes, nbytes2, nbytes3;
uintptr *data2;
byte *data3;
if(s->sizeclass == 0) {
s->types.compression = MTypes_Single;
s->types.data = typ;
return;
}
size = s->elemsize;
ofs = ((uintptr)v - (s->start<<PageShift)) / size;
switch(s->types.compression) {
case MTypes_Empty:
ntypes = (s->npages << PageShift) / size;
nbytes3 = 8*sizeof(uintptr) + 1*ntypes;
data3 = runtime_mallocgc(nbytes3, 0, FlagNoProfiling|FlagNoScan|FlagNoInvokeGC);
s->types.compression = MTypes_Bytes;
s->types.data = (uintptr)data3;
((uintptr*)data3)[1] = typ;
data3[8*sizeof(uintptr) + ofs] = 1;
break;
case MTypes_Words:
((uintptr*)s->types.data)[ofs] = typ;
break;
case MTypes_Bytes:
data3 = (byte*)s->types.data;
for(j=1; j<8; j++) {
if(((uintptr*)data3)[j] == typ) {
break;
}
if(((uintptr*)data3)[j] == 0) {
((uintptr*)data3)[j] = typ;
break;
}
}
if(j < 8) {
data3[8*sizeof(uintptr) + ofs] = j;
} else {
ntypes = (s->npages << PageShift) / size;
nbytes2 = ntypes * sizeof(uintptr);
data2 = runtime_mallocgc(nbytes2, 0, FlagNoProfiling|FlagNoScan|FlagNoInvokeGC);
s->types.compression = MTypes_Words;
s->types.data = (uintptr)data2;
// Move the contents of data3 to data2. Then deallocate data3.
for(j=0; j<ntypes; j++) {
t = data3[8*sizeof(uintptr) + j];
t = ((uintptr*)data3)[t];
data2[j] = t;
}
data2[ofs] = typ;
}
break;
}
}
uintptr
runtime_gettype(void *v)
{
MSpan *s;
uintptr t, ofs;
byte *data;
s = runtime_MHeap_LookupMaybe(&runtime_mheap, v);
if(s != nil) {
t = 0;
switch(s->types.compression) {
case MTypes_Empty:
break;
case MTypes_Single:
t = s->types.data;
break;
case MTypes_Words:
ofs = (uintptr)v - (s->start<<PageShift);
t = ((uintptr*)s->types.data)[ofs/s->elemsize];
break;
case MTypes_Bytes:
ofs = (uintptr)v - (s->start<<PageShift);
data = (byte*)s->types.data;
t = data[8*sizeof(uintptr) + ofs/s->elemsize];
t = ((uintptr*)data)[t];
break;
default:
runtime_throw("runtime_gettype: invalid compression kind");
}
if(0) {
runtime_printf("%p -> %d,%X\n", v, (int32)s->types.compression, (int64)t);
}
return t;
}
return 0;
}
// Runtime stubs.
void*
runtime_mal(uintptr n)
{
return runtime_mallocgc(n, 0, 0);
}
func new(typ *Type) (ret *uint8) {
ret = runtime_mallocgc(typ->__size, (uintptr)typ | TypeInfo_SingleObject, typ->kind&kindNoPointers ? FlagNoScan : 0);
}
static void*
cnew(const Type *typ, intgo n, int32 objtyp)
{
if((objtyp&(PtrSize-1)) != objtyp)
runtime_throw("runtime: invalid objtyp");
if(n < 0 || (typ->__size > 0 && (uintptr)n > (MaxMem/typ->__size)))
runtime_panicstring("runtime: allocation size out of range");
return runtime_mallocgc(typ->__size*n, (uintptr)typ | objtyp, typ->kind&kindNoPointers ? FlagNoScan : 0);
}
// same as runtime_new, but callable from C
void*
runtime_cnew(const Type *typ)
{
return cnew(typ, 1, TypeInfo_SingleObject);
}
void*
runtime_cnewarray(const Type *typ, intgo n)
{
return cnew(typ, n, TypeInfo_Array);
}
func GC() {
runtime_gc(2); // force GC and do eager sweep
}
func SetFinalizer(obj Eface, finalizer Eface) {
byte *base;
uintptr size;
const FuncType *ft;
const Type *fint;
const PtrType *ot;
if(obj.__type_descriptor == nil) {
runtime_printf("runtime.SetFinalizer: first argument is nil interface\n");
goto throw;
}
if((obj.__type_descriptor->kind&kindMask) != GO_PTR) {
runtime_printf("runtime.SetFinalizer: first argument is %S, not pointer\n", *obj.__type_descriptor->__reflection);
goto throw;
}
ot = (const PtrType*)obj.type;
// As an implementation detail we do not run finalizers for zero-sized objects,
// because we use &runtime_zerobase for all such allocations.
if(ot->__element_type != nil && ot->__element_type->__size == 0)
return;
// The following check is required for cases when a user passes a pointer to composite literal,
// but compiler makes it a pointer to global. For example:
// var Foo = &Object{}
// func main() {
// runtime.SetFinalizer(Foo, nil)
// }
// See issue 7656.
if((byte*)obj.__object < runtime_mheap.arena_start || runtime_mheap.arena_used <= (byte*)obj.__object)
return;
if(!runtime_mlookup(obj.__object, &base, &size, nil) || obj.__object != base) {
// As an implementation detail we allow to set finalizers for an inner byte
// of an object if it could come from tiny alloc (see mallocgc for details).
if(ot->__element_type == nil || (ot->__element_type->kind&kindNoPointers) == 0 || ot->__element_type->__size >= TinySize) {
runtime_printf("runtime.SetFinalizer: pointer not at beginning of allocated block (%p)\n", obj.__object);
goto throw;
}
}
if(finalizer.__type_descriptor != nil) {
runtime_createfing();
if((finalizer.__type_descriptor->kind&kindMask) != GO_FUNC)
goto badfunc;
ft = (const FuncType*)finalizer.__type_descriptor;
if(ft->__dotdotdot || ft->__in.__count != 1)
goto badfunc;
fint = *(Type**)ft->__in.__values;
if(__go_type_descriptors_equal(fint, obj.__type_descriptor)) {
// ok - same type
} else if((fint->kind&kindMask) == GO_PTR && (fint->__uncommon == nil || fint->__uncommon->__name == nil || obj.type->__uncommon == nil || obj.type->__uncommon->__name == nil) && __go_type_descriptors_equal(((const PtrType*)fint)->__element_type, ((const PtrType*)obj.type)->__element_type)) {
// ok - not same type, but both pointers,
// one or the other is unnamed, and same element type, so assignable.
} else if((fint->kind&kindMask) == GO_INTERFACE && ((const InterfaceType*)fint)->__methods.__count == 0) {
// ok - satisfies empty interface
} else if((fint->kind&kindMask) == GO_INTERFACE && __go_convert_interface_2(fint, obj.__type_descriptor, 1) != nil) {
// ok - satisfies non-empty interface
} else
goto badfunc;
ot = (const PtrType*)obj.__type_descriptor;
if(!runtime_addfinalizer(obj.__object, *(FuncVal**)finalizer.__object, ft, ot)) {
runtime_printf("runtime.SetFinalizer: finalizer already set\n");
goto throw;
}
} else {
// NOTE: asking to remove a finalizer when there currently isn't one set is OK.
runtime_removefinalizer(obj.__object);
}
return;
badfunc:
runtime_printf("runtime.SetFinalizer: cannot pass %S to finalizer %S\n", *obj.__type_descriptor->__reflection, *finalizer.__type_descriptor->__reflection);
throw:
runtime_throw("runtime.SetFinalizer");
}
func KeepAlive(x Eface) {
USED(x);
}
|