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runtime: malloc fixes
* throw away dead code * add mlookup counter * add malloc counter * set up for blocks with no pointers Fixes #367. R=r https://golang.org/cl/165050
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@ -17,6 +17,8 @@ type Stats struct {
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Stacks uint64;
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InusePages uint64;
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NextGC uint64;
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Lookups uint64;
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Mallocs uint64;
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EnableGC bool;
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}
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@ -590,12 +590,12 @@ unsafe·Reflect(Eface e, Eface rettype, void *retaddr)
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// but then build pointer to x so that Reflect
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// always returns pointer to data.
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p = mallocgc(sizeof(uintptr));
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p = mal(sizeof(uintptr));
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*p = x;
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} else {
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// Already a pointer, but still make a copy,
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// to preserve value semantics for interface data.
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p = mallocgc(e.type->size);
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p = mal(e.type->size);
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algarray[e.type->alg].copy(e.type->size, p, e.data);
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}
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retaddr = p;
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@ -5,7 +5,6 @@
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// See malloc.h for overview.
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//
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// TODO(rsc): double-check stats.
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// TODO(rsc): solve "stack overflow during malloc" problem.
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package malloc
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#include "runtime.h"
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@ -19,7 +18,7 @@ MStats mstats;
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// Small objects are allocated from the per-thread cache's free lists.
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// Large objects (> 32 kB) are allocated straight from the heap.
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void*
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malloc(uintptr size)
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mallocgc(uintptr size, uint32 refflag, int32 dogc)
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{
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int32 sizeclass;
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MCache *c;
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@ -35,6 +34,7 @@ malloc(uintptr size)
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if(size == 0)
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size = 1;
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mstats.nmalloc++;
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if(size <= MaxSmallSize) {
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// Allocate from mcache free lists.
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sizeclass = SizeToClass(size);
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@ -63,21 +63,19 @@ malloc(uintptr size)
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printf("malloc %D; mlookup failed\n", (uint64)size);
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throw("malloc mlookup");
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}
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*ref = RefNone;
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*ref = RefNone | refflag;
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m->mallocing = 0;
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if(dogc && mstats.inuse_pages > mstats.next_gc)
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gc(0);
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return v;
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}
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void*
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mallocgc(uintptr size)
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malloc(uintptr size)
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{
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void *v;
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v = malloc(size);
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if(mstats.inuse_pages > mstats.next_gc)
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gc(0);
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return v;
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return mallocgc(size, 0, 0);
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}
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// Free the object whose base pointer is v.
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@ -138,6 +136,7 @@ mlookup(void *v, byte **base, uintptr *size, uint32 **ref)
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byte *p;
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MSpan *s;
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mstats.nlookup++;
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s = MHeap_LookupMaybe(&mheap, (uintptr)v>>PageShift);
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if(s == nil) {
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if(base)
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@ -209,6 +208,7 @@ void*
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SysAlloc(uintptr n)
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{
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void *p;
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mstats.sys += n;
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p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
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if(p < (void*)4096) {
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@ -241,30 +241,10 @@ SysFree(void *v, uintptr n)
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// Runtime stubs.
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extern void *oldmal(uint32);
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void*
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mal(uint32 n)
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{
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//return oldmal(n);
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void *v;
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v = mallocgc(n);
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if(0) {
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byte *p;
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uint32 i;
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p = v;
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for(i=0; i<n; i++) {
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if(p[i] != 0) {
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printf("mal %d => %p: byte %d is non-zero\n", n, v, i);
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throw("mal");
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}
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}
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}
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//printf("mal %d %p\n", n, v); // |checkmal to check for overlapping returns.
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return v;
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return mallocgc(n, 0, 1);
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}
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// Stack allocator uses malloc/free most of the time,
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@ -285,7 +265,6 @@ stackalloc(uint32 n)
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void *v;
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uint32 *ref;
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//return oldmal(n);
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if(m->mallocing || m->gcing) {
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lock(&stacks);
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if(stacks.size == 0)
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@ -308,8 +287,6 @@ stackalloc(uint32 n)
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void
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stackfree(void *v)
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{
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//return;
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if(m->mallocing || m->gcing) {
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lock(&stacks);
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FixAlloc_Free(&stacks, v);
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@ -163,6 +163,8 @@ struct MStats
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uint64 stacks;
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uint64 inuse_pages; // protected by mheap.Lock
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uint64 next_gc; // protected by mheap.Lock
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uint64 nlookup; // unprotected (approximate)
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uint64 nmalloc; // unprotected (approximate)
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bool enablegc;
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};
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extern MStats mstats;
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@ -271,6 +273,10 @@ struct MHeap
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// span lookup
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MHeapMap map;
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MHeapMapCache mapcache;
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// range of addresses we might see in the heap
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byte *min;
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byte *max;
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// central free lists for small size classes.
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// the union makes sure that the MCentrals are
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@ -292,6 +298,7 @@ void MHeap_Free(MHeap *h, MSpan *s);
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MSpan* MHeap_Lookup(MHeap *h, PageID p);
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MSpan* MHeap_LookupMaybe(MHeap *h, PageID p);
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void* mallocgc(uintptr size, uint32 flag, int32 dogc);
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int32 mlookup(void *v, byte **base, uintptr *size, uint32 **ref);
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void gc(int32 force);
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@ -300,9 +307,9 @@ enum
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RefcountOverhead = 4, // one uint32 per object
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RefFree = 0, // must be zero
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RefManual, // manual allocation - don't free
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RefStack, // stack segment - don't free and don't scan for pointers
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RefNone, // no references
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RefSome, // some references
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RefNoPointers = 0x80000000U, // flag - no pointers here
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};
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@ -13,67 +13,6 @@ enum
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NHUNK = 20<<20,
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};
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// Convenient wrapper around mmap.
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static void*
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brk(uint32 n)
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{
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byte *v;
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v = runtime_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, 0, 0);
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if(v < (void *)4096) {
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printf("mmap: errno=%p\n", v);
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exit(2);
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}
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m->mem.nmmap += n;
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return v;
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}
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// Allocate n bytes of memory. Note that this gets used
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// to allocate new stack segments, so at each call to a function
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// you have to ask yourself "would it be okay to call mal recursively
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// right here?" The answer is yes unless we're in the middle of
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// editing the malloc state in m->mem.
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void*
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oldmal(uint32 n)
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{
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byte* v;
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// round to keep everything 64-bit aligned
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n = rnd(n, 8);
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// be careful. calling any function might invoke
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// mal to allocate more stack.
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if(n > NHUNK) {
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v = brk(n);
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} else {
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// allocate a new hunk if this one is too small
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if(n > m->mem.nhunk) {
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// here we're in the middle of editing m->mem
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// (we're about to overwrite m->mem.hunk),
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// so we can't call brk - it might call mal to grow the
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// stack, and the recursive call would allocate a new
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// hunk, and then once brk returned we'd immediately
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// overwrite that hunk with our own.
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// (the net result would be a memory leak, not a crash.)
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// so we have to call runtime_mmap directly - it is written
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// in assembly and tagged not to grow the stack.
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m->mem.hunk =
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runtime_mmap(nil, NHUNK, PROT_READ|PROT_WRITE|PROT_EXEC,
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MAP_ANON|MAP_PRIVATE, 0, 0);
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if(m->mem.hunk < (void*)4096) {
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*(uint32*)0xf1 = 0;
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}
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m->mem.nhunk = NHUNK;
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m->mem.nmmap += NHUNK;
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}
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v = m->mem.hunk;
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m->mem.hunk += n;
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m->mem.nhunk -= n;
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}
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m->mem.nmal += n;
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return v;
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}
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void
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runtime·mal(uint32 n, uint8 *ret)
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{
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vp = (void**)b;
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n /= PtrSize;
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for(i=0; i<n; i++) {
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if(mlookup(vp[i], &obj, &size, &ref)) {
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obj = vp[i];
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if(obj == nil || (byte*)obj < mheap.min || (byte*)obj >= mheap.max)
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continue;
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if(mlookup(obj, &obj, &size, &ref)) {
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if(*ref == RefFree || *ref == RefStack)
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continue;
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if(*ref == (RefNone|RefNoPointers)) {
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*ref = RefSome|RefNoPointers;
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continue;
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}
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if(*ref == RefNone) {
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if(Debug)
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printf("%d found at %p: ", depth, &vp[i]);
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@ -125,15 +132,16 @@ sweepspan(MSpan *s)
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default:
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throw("bad 'ref count'");
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case RefFree:
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case RefManual:
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case RefStack:
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break;
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case RefNone:
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case RefNone|RefNoPointers:
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if(Debug)
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printf("free %D at %p\n", (uint64)s->npages<<PageShift, p);
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free(p);
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break;
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case RefSome:
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case RefSome|RefNoPointers:
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//printf("gc-mem 1 %D\n", (uint64)s->npages<<PageShift);
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s->gcref0 = RefNone; // set up for next mark phase
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break;
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@ -151,15 +159,16 @@ sweepspan(MSpan *s)
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default:
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throw("bad 'ref count'");
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case RefFree:
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case RefManual:
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case RefStack:
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break;
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case RefNone:
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case RefNone|RefNoPointers:
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if(Debug)
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printf("free %d at %p\n", size, p+i*size);
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free(p + i*size);
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break;
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case RefSome:
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case RefSome|RefNoPointers:
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s->gcref[i] = RefNone; // set up for next mark phase
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break;
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}
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return false;
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}
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if((byte*)v < h->min || h->min == nil)
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h->min = v;
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if((byte*)v+ask > h->max)
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h->max = (byte*)v+ask;
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// NOTE(rsc): In tcmalloc, if we've accumulated enough
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// system allocations, the heap map gets entirely allocated
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// in 32-bit mode. (In 64-bit mode that's not practical.)
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void (*cgofn)(void*); // for cgo/ffi
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void *cgoarg;
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};
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struct Mem
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{
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uint8* hunk;
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uint32 nhunk;
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uint64 nmmap;
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uint64 nmal;
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};
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struct M
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{
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// The offsets of these fields are known to (hard-coded in) libmach.
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@ -208,7 +201,6 @@ struct M
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G* nextg;
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M* alllink; // on allm
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M* schedlink;
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Mem mem;
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uint32 machport; // Return address for Mach IPC (OS X)
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MCache *mcache;
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G* lockedg;
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@ -375,7 +367,6 @@ uintptr efacehash(Eface);
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uintptr nohash(uint32, void*);
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uint32 noequal(uint32, void*, void*);
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void* malloc(uintptr size);
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void* mallocgc(uintptr size);
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void free(void *v);
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void exit(int32);
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void breakpoint(void);
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