summaryrefslogtreecommitdiff
path: root/libgo/runtime/malloc.goc
blob: dfab683950a867cbef074e43769aaece93a4a808 (plain)
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
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
// 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"
#include "race.h"

MHeap *runtime_mheap;

int32	runtime_checking;

extern MStats mstats;	// defined in zruntime_def_$GOOS_$GOARCH.go

extern volatile intgo runtime_MemProfileRate
  __asm__ (GOSYM_PREFIX "runtime.MemProfileRate");

// 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 flag, int32 dogc, int32 zeroed)
{
	M *m;
	G *g;
	int32 sizeclass;
	intgo rate;
	MCache *c;
	uintptr npages;
	MSpan *s;
	void *v;

	m = runtime_m();
	g = runtime_g();
	if(g->status == Gsyscall)
		dogc = 0;
	if(runtime_gcwaiting && g != m->g0 && m->locks == 0 && dogc) {
		runtime_gosched();
		m = runtime_m();
	}
	if(m->mallocing)
		runtime_throw("malloc/free - deadlock");
	m->mallocing = 1;
	if(size == 0)
		size = 1;

	if(DebugTypeAtBlockEnd)
		size += sizeof(uintptr);

	c = m->mcache;
	c->local_nmalloc++;
	if(size <= MaxSmallSize) {
		// Allocate from mcache free lists.
		sizeclass = runtime_SizeToClass(size);
		size = runtime_class_to_size[sizeclass];
		v = runtime_MCache_Alloc(c, sizeclass, size, zeroed);
		if(v == nil)
			runtime_throw("out of memory");
		c->local_alloc += size;
		c->local_total_alloc += size;
		c->local_by_size[sizeclass].nmalloc++;
	} 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, zeroed);
		if(s == nil)
			runtime_throw("out of memory");
		size = npages<<PageShift;
		c->local_alloc += size;
		c->local_total_alloc += size;
		v = (void*)(s->start << PageShift);

		// setup for mark sweep
		runtime_markspan(v, 0, 0, true);
	}

	if (sizeof(void*) == 4 && c->local_total_alloc >= (1<<30)) {
		// purge cache stats to prevent overflow
		runtime_lock(runtime_mheap);
		runtime_purgecachedstats(c);
		runtime_unlock(runtime_mheap);
	}

	if(!(flag & FlagNoGC))
		runtime_markallocated(v, size, (flag&FlagNoPointers) != 0);

	if(DebugTypeAtBlockEnd)
		*(uintptr*)((uintptr)v+size-sizeof(uintptr)) = 0;

	m->mallocing = 0;

	if(!(flag & FlagNoProfiling) && (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 you change this, also change allocmcache.
			if(rate > 0x3fffffff)	// make 2*rate not overflow
				rate = 0x3fffffff;
			m->mcache->next_sample = runtime_fastrand1() % (2*rate);
		profile:
			runtime_setblockspecial(v, true);
			runtime_MProf_Malloc(v, size);
		}
	}

	if(dogc && mstats.heap_alloc >= mstats.next_gc)
		runtime_gc(0);

	if(raceenabled) {
		runtime_racemalloc(v, size, m->racepc);
		m->racepc = nil;
	}
	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)
{
	M *m;
	int32 sizeclass;
	MSpan *s;
	MCache *c;
	uint32 prof;
	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");
	}
	prof = runtime_blockspecial(v);

	if(raceenabled)
		runtime_racefree(v);

	// Find size class for v.
	sizeclass = s->sizeclass;
	c = m->mcache;
	if(sizeclass == 0) {
		// Large object.
		size = s->npages<<PageShift;
		*(uintptr*)(s->start<<PageShift) = (uintptr)0xfeedfeedfeedfeedll;	// mark as "needs to be zeroed"
		// 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, size);
		runtime_unmarkspan(v, 1<<PageShift);
		runtime_MHeap_Free(runtime_mheap, s, 1);
	} else {
		// Small object.
		size = runtime_class_to_size[sizeclass];
		if(size > sizeof(uintptr))
			((uintptr*)v)[1] = (uintptr)0xfeedfeedfeedfeedll;	// mark as "needs to be zeroed"
		// Must mark v freed before calling MCache_Free:
		// it might coalesce v and other blocks into a bigger span
		// and change the bitmap further.
		runtime_markfreed(v, size);
		c->local_by_size[sizeclass].nfree++;
		runtime_MCache_Free(c, v, sizeclass, size);
	}
	c->local_nfree++;
	c->local_alloc -= size;
	if(prof)
		runtime_MProf_Free(v, 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;
	}

	if((byte*)v >= (byte*)s->limit) {
		// pointers past the last block do not count as pointers.
		return 0;
	}

	n = s->elemsize;
	if(base) {
		i = ((byte*)v - p)/n;
		*base = p + i*n;
	}
	if(size)
		*size = n;

	return 1;
}

MCache*
runtime_allocmcache(void)
{
	intgo rate;
	MCache *c;

	runtime_lock(runtime_mheap);
	c = runtime_FixAlloc_Alloc(&runtime_mheap->cachealloc);
	mstats.mcache_inuse = runtime_mheap->cachealloc.inuse;
	mstats.mcache_sys = runtime_mheap->cachealloc.sys;
	runtime_unlock(runtime_mheap);
	runtime_memclr((byte*)c, sizeof(*c));

	// Set first allocation sample size.
	rate = runtime_MemProfileRate;
	if(rate > 0x3fffffff)	// make 2*rate not overflow
		rate = 0x3fffffff;
	if(rate != 0)
		c->next_sample = runtime_fastrand1() % (2*rate);

	return c;
}

void
runtime_freemcache(MCache *c)
{
	runtime_MCache_ReleaseAll(c);
	runtime_lock(runtime_mheap);
	runtime_purgecachedstats(c);
	runtime_FixAlloc_Free(&runtime_mheap->cachealloc, c);
	runtime_unlock(runtime_mheap);
}

void
runtime_purgecachedstats(MCache *c)
{
	// Protected by either heap or GC lock.
	mstats.heap_alloc += c->local_cachealloc;
	c->local_cachealloc = 0;
	mstats.heap_objects += c->local_objects;
	c->local_objects = 0;
	mstats.nmalloc += c->local_nmalloc;
	c->local_nmalloc = 0;
	mstats.nfree += c->local_nfree;
	c->local_nfree = 0;
	mstats.nlookup += c->local_nlookup;
	c->local_nlookup = 0;
	mstats.alloc += c->local_alloc;
	c->local_alloc= 0;
	mstats.total_alloc += c->local_total_alloc;
	c->local_total_alloc= 0;
}

extern uintptr runtime_sizeof_C_MStats
  __asm__ (GOSYM_PREFIX "runtime.Sizeof_C_MStats");

#define MaxArena32 (2U<<30)

void
runtime_mallocinit(void)
{
	byte *p;
	uintptr arena_size, bitmap_size;
	extern byte end[];
	byte *want;
	uintptr limit;

	runtime_sizeof_C_MStats = sizeof(MStats);

	p = nil;
	arena_size = 0;
	bitmap_size = 0;
	
	// for 64-bit build
	USED(p);
	USED(arena_size);
	USED(bitmap_size);

	if((runtime_mheap = runtime_SysAlloc(sizeof(*runtime_mheap))) == nil)
		runtime_throw("runtime: cannot allocate heap metadata");

	runtime_InitSizes();

	// 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 0x000000c000000000 if possible.
		// 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, ..., 0x0x00df.
		// 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. An earlier attempt to use 0x11f8 
		// caused out of memory errors on OS X during thread allocations.
		// 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);
		p = runtime_SysReserve((void*)(0x00c0ULL<<32), bitmap_size + arena_size);
	}
	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;
		if(limit > 0 && arena_size+bitmap_size > limit) {
			bitmap_size = (limit / 9) & ~((1<<PageShift) - 1);
			arena_size = bitmap_size * 8;
		}
		
		// 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.
		want = (byte*)(((uintptr)end + (1<<18) + (1<<20) - 1)&~((1<<20)-1));
		if(0xffffffff - (uintptr)want <= bitmap_size + arena_size)
		  want = 0;
		p = runtime_SysReserve(want, bitmap_size + arena_size);
		if(p == nil)
			runtime_throw("runtime: cannot reserve arena virtual address space");
		if((uintptr)p & (((uintptr)1<<PageShift)-1))
			runtime_printf("runtime: SysReserve returned unaligned address %p; asked for %p", p, bitmap_size+arena_size);
	}
	if((uintptr)p & (((uintptr)1<<PageShift)-1))
		runtime_throw("runtime: SysReserve returned unaligned address");

	runtime_mheap->bitmap = p;
	runtime_mheap->arena_start = p + bitmap_size;
	runtime_mheap->arena_used = runtime_mheap->arena_start;
	runtime_mheap->arena_end = runtime_mheap->arena_start + arena_size;

	// Initialize the rest of the allocator.	
	runtime_MHeap_Init(runtime_mheap, runtime_SysAlloc);
	runtime_m()->mcache = runtime_allocmcache();

	// See if it works.
	runtime_free(runtime_malloc(1));
}

void*
runtime_MHeap_SysAlloc(MHeap *h, uintptr n)
{
	byte *p;


	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;
		uintptr needed;

		needed = (uintptr)h->arena_used + n - (uintptr)h->arena_end;
		// Round wanted arena size to a multiple of 256MB.
		needed = (needed + (256<<20) - 1) & ~((256<<20)-1);
		new_end = h->arena_end + needed;
		if(new_end <= h->arena_start + MaxArena32) {
			p = runtime_SysReserve(h->arena_end, new_end - h->arena_end);
			if(p == h->arena_end)
				h->arena_end = new_end;
		}
	}
	if(n <= (uintptr)(h->arena_end - h->arena_used)) {
		// Keep taking from our reservation.
		p = h->arena_used;
		runtime_SysMap(p, n);
		h->arena_used += n;
		runtime_MHeap_MapBits(h);
		if(raceenabled)
			runtime_racemapshadow(p, n);
		return p;
	}
	
	// If using 64-bit, our reservation is all we have.
	if(sizeof(void*) == 8 && (uintptr)h->bitmap >= 0xffffffffU)
		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 = runtime_SysAlloc(n);
	if(p == nil)
		return nil;

	if(p < h->arena_start || (uintptr)(p+n - 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, n);
		return nil;
	}

	if(p+n > h->arena_used) {
		h->arena_used = p+n;
		if(h->arena_used > h->arena_end)
			h->arena_end = h->arena_used;
		runtime_MHeap_MapBits(h);
		if(raceenabled)
			runtime_racemapshadow(p, n);
	}
	
	return p;
}

static Lock settype_lock;

void
runtime_settype_flush(M *mp, bool sysalloc)
{
	uintptr *buf, *endbuf;
	uintptr size, ofs, j, t;
	uintptr ntypes, nbytes2, nbytes3;
	uintptr *data2;
	byte *data3;
	bool sysalloc3;
	void *v;
	uintptr typ, p;
	MSpan *s;

	buf = mp->settype_buf;
	endbuf = buf + mp->settype_bufsize;

	runtime_lock(&settype_lock);
	while(buf < endbuf) {
		v = (void*)*buf;
		*buf = 0;
		buf++;
		typ = *buf;
		buf++;

		// (Manually inlined copy of runtime_MHeap_Lookup)
		p = (uintptr)v>>PageShift;
		if(sizeof(void*) == 8)
			p -= (uintptr)runtime_mheap->arena_start >> PageShift;
		s = runtime_mheap->map[p];

		if(s->sizeclass == 0) {
			s->types.compression = MTypes_Single;
			s->types.data = typ;
			continue;
		}

		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;

			if(!sysalloc) {
				data3 = runtime_mallocgc(nbytes3, FlagNoProfiling|FlagNoPointers, 0, 1);
			} else {
				data3 = runtime_SysAlloc(nbytes3);
				if(data3 == nil)
					runtime_throw("runtime: cannot allocate memory");
				if(0) runtime_printf("settype(0->3): SysAlloc(%x) --> %p\n", (uint32)nbytes3, data3);
			}

			s->types.compression = MTypes_Bytes;
			s->types.sysalloc = sysalloc;
			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);

				if(!sysalloc) {
					data2 = runtime_mallocgc(nbytes2, FlagNoProfiling|FlagNoPointers, 0, 1);
				} else {
					data2 = runtime_SysAlloc(nbytes2);
					if(data2 == nil)
						runtime_throw("runtime: cannot allocate memory");
					if(0) runtime_printf("settype.(3->2): SysAlloc(%x) --> %p\n", (uint32)nbytes2, data2);
				}

				sysalloc3 = s->types.sysalloc;

				s->types.compression = MTypes_Words;
				s->types.sysalloc = sysalloc;
				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;
				}
				if(sysalloc3) {
					nbytes3 = 8*sizeof(uintptr) + 1*ntypes;
					if(0) runtime_printf("settype.(3->2): SysFree(%p,%x)\n", data3, (uint32)nbytes3);
					runtime_SysFree(data3, nbytes3);
				}

				data2[ofs] = typ;
			}
			break;
		}
	}
	runtime_unlock(&settype_lock);

	mp->settype_bufsize = 0;
}

// It is forbidden to use this function if it is possible that
// explicit deallocation via calling runtime_free(v) may happen.
void
runtime_settype(void *v, uintptr t)
{
	M *mp;
	uintptr *buf;
	uintptr i;
	MSpan *s;

	if(t == 0)
		runtime_throw("settype: zero type");

	mp = runtime_m();
	buf = mp->settype_buf;
	i = mp->settype_bufsize;
	buf[i+0] = (uintptr)v;
	buf[i+1] = t;
	i += 2;
	mp->settype_bufsize = i;

	if(i == nelem(mp->settype_buf)) {
		runtime_settype_flush(mp, false);
	}

	if(DebugTypeAtBlockEnd) {
		s = runtime_MHeap_Lookup(runtime_mheap, v);
		*(uintptr*)((uintptr)v+s->elemsize-sizeof(uintptr)) = t;
	}
}

void
runtime_settype_sysfree(MSpan *s)
{
	uintptr ntypes, nbytes;

	if(!s->types.sysalloc)
		return;

	nbytes = (uintptr)-1;

	switch (s->types.compression) {
	case MTypes_Words:
		ntypes = (s->npages << PageShift) / s->elemsize;
		nbytes = ntypes * sizeof(uintptr);
		break;
	case MTypes_Bytes:
		ntypes = (s->npages << PageShift) / s->elemsize;
		nbytes = 8*sizeof(uintptr) + 1*ntypes;
		break;
	}

	if(nbytes != (uintptr)-1) {
		if(0) runtime_printf("settype: SysFree(%p,%x)\n", (void*)s->types.data, (uint32)nbytes);
		runtime_SysFree((void*)s->types.data, nbytes);
	}
}

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_lock(&settype_lock);
			runtime_printf("%p -> %d,%X\n", v, (int32)s->types.compression, (int64)t);
			runtime_unlock(&settype_lock);
		}
		return t;
	}
	return 0;
}

// Runtime stubs.

void*
runtime_mal(uintptr n)
{
	return runtime_mallocgc(n, 0, 1, 1);
}

void *
runtime_new(const Type *typ)
{
	void *ret;
	uint32 flag;

	if(raceenabled)
		runtime_m()->racepc = runtime_getcallerpc(&typ);

	if(typ->__size == 0) {
		// All 0-length allocations use this pointer.
		// The language does not require the allocations to
		// have distinct values.
		ret = (uint8*)&runtime_zerobase;
	} else {
		flag = typ->__code&GO_NO_POINTERS ? FlagNoPointers : 0;
		ret = runtime_mallocgc(typ->__size, flag, 1, 1);

		if(UseSpanType && !flag) {
			if(false)
				runtime_printf("new %S: %p\n", *typ->__reflection, ret);
			runtime_settype(ret, (uintptr)typ | TypeInfo_SingleObject);
		}
	}

	return ret;
}

static void*
cnew(const Type *typ, intgo n, int32 objtyp)
{
	uint32 flag;
	void *ret;

	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");
	if(typ->__size == 0 || n == 0) {
		// All 0-length allocations use this pointer.
		// The language does not require the allocations to
		// have distinct values.
		return &runtime_zerobase;
	}
	flag = typ->__code&GO_NO_POINTERS ? FlagNoPointers : 0;
	ret = runtime_mallocgc(typ->__size*n, flag, 1, 1);
	if(UseSpanType && !flag) {
		if(false)
			runtime_printf("cnew [%D]%S: %p\n", (int64)n, *typ->__reflection, ret);
		runtime_settype(ret, (uintptr)typ | TypeInfo_SingleObject);
	}
	return ret;
}

// 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(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");
		goto throw;
	}
	if(obj.__type_descriptor->__code != GO_PTR) {
		runtime_printf("runtime.SetFinalizer: first argument is %S, not pointer\n", *obj.__type_descriptor->__reflection);
		goto throw;
	}
	if(!runtime_mlookup(obj.__object, &base, &size, 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)
			goto badfunc;
		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_addfinalizer(obj.__object, finalizer.__type_descriptor != nil ? *(void**)finalizer.__object : nil, ft)) {
		runtime_printf("runtime.SetFinalizer: finalizer already set\n");
		goto throw;
	}
	return;

badfunc:
	runtime_printf("runtime.SetFinalizer: second argument is %S, not func(%S)\n", *finalizer.__type_descriptor->__reflection, *obj.__type_descriptor->__reflection);
throw:
	runtime_throw("runtime.SetFinalizer");
}