malloc in runtime (not used by default)

R=r
DELTA=1551  (1550 added, 0 deleted, 1 changed)
OCL=21404
CL=21538

src/runtime/malloc.c

@@ -0,0 +1,169 @@
+// 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.
+// TODO(rsc): solve "stack overflow during malloc" problem.
+
+#include "runtime.h"
+#include "malloc.h"
+
+MHeap mheap;
+MStats mstats;
+
+// 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*
+malloc(uintptr size)
+{
+	int32 sizeclass;
+	MCache *c;
+	uintptr npages;
+	MSpan *s;
+	void *v;
+
+	if(size == 0)
+		size = 1;
+
+	if(size <= MaxSmallSize) {
+		// Allocate from mcache free lists.
+		sizeclass = SizeToClass(size);
+		size = class_to_size[sizeclass];
+		c = m->mcache;
+		v = MCache_Alloc(c, sizeclass, size);
+		if(v == nil)
+			return nil;
+		mstats.alloc += size;
+		return v;
+	}
+
+	// TODO(rsc): Report tracebacks for very large allocations.
+
+	// Allocate directly from heap.
+	npages = size >> PageShift;
+	if((size & PageMask) != 0)
+		npages++;
+	s = MHeap_Alloc(&mheap, npages, 0);
+	if(s == nil)
+		return nil;
+	mstats.alloc += npages<<PageShift;
+	return (void*)(s->start << PageShift);
+}
+
+// Free the object whose base pointer is v.
+void
+free(void *v)
+{
+	int32 sizeclass, size;
+	uintptr page, tmp;
+	MSpan *s;
+	MCache *c;
+
+	// Find size class for v.
+	page = (uintptr)v >> PageShift;
+	sizeclass = MHeapMapCache_GET(&mheap.mapcache, page, tmp);
+	if(sizeclass == 0) {
+		// Missed in cache.
+		s = MHeap_Lookup(&mheap, page);
+		if(s == nil)
+			throw("free - invalid pointer");
+		sizeclass = s->sizeclass;
+		if(sizeclass == 0) {
+			// Large object.
+			mstats.alloc -= s->npages<<PageShift;
+			sys·memclr(v, s->npages<<PageShift);
+			MHeap_Free(&mheap, s);
+			return;
+		}
+		MHeapMapCache_SET(&mheap.mapcache, page, sizeclass);
+	}
+
+	// Small object.
+	c = m->mcache;
+	size = class_to_size[sizeclass];
+	sys·memclr(v, size);
+	mstats.alloc -= size;
+	MCache_Free(c, v, sizeclass, size);
+}
+
+MCache*
+allocmcache(void)
+{
+	return FixAlloc_Alloc(&mheap.cachealloc);
+}
+
+void
+mallocinit(void)
+{
+	InitSizes();
+	MHeap_Init(&mheap, SysAlloc);
+	m->mcache = allocmcache();
+
+	// See if it works.
+	free(malloc(1));
+}
+
+// TODO(rsc): Move elsewhere.
+enum
+{
+	NHUNK		= 20<<20,
+
+	PROT_NONE	= 0x00,
+	PROT_READ	= 0x01,
+	PROT_WRITE	= 0x02,
+	PROT_EXEC	= 0x04,
+
+	MAP_FILE	= 0x0000,
+	MAP_SHARED	= 0x0001,
+	MAP_PRIVATE	= 0x0002,
+	MAP_FIXED	= 0x0010,
+	MAP_ANON	= 0x1000,	// not on Linux - TODO(rsc)
+};
+
+void*
+SysAlloc(uintptr n)
+{
+	mstats.sys += n;
+	return sys·mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0);
+}
+
+void
+SysUnused(void *v, uintptr n)
+{
+	// TODO(rsc): call madvise MADV_DONTNEED
+}
+
+void
+SysFree(void *v, uintptr n)
+{
+	USED(v);
+	USED(n);
+	// TODO(rsc): call munmap
+}
+
+
+// Go function stubs.
+
+void
+malloc·Alloc(uintptr n, byte *p)
+{
+	p = malloc(n);
+	FLUSH(&p);
+}
+
+void
+malloc·Free(byte *p)
+{
+	free(p);
+}
+
+void
+malloc·GetStats(MStats *s)
+{
+	s = &mstats;
+	FLUSH(&s);
+}
+