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https://github.com/golang/go
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runtime: remove outdated comment and related indentation
R=golang-dev, iant CC=golang-dev https://golang.org/cl/39810043
This commit is contained in:
Carl Shapiro
parent
ddbad5ef20
commit
c69402d82b
@ -409,131 +409,125 @@ flushptrbuf(Scanbuf *sbuf)
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runtime·throw("ptrbuf has to be smaller than WorkBuf");
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}
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// TODO(atom): This block is a branch of an if-then-else statement.
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// The single-threaded branch may be added in a next CL.
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{
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// Multi-threaded version.
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while(ptrbuf < ptrbuf_end) {
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obj = ptrbuf->p;
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ti = ptrbuf->ti;
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ptrbuf++;
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while(ptrbuf < ptrbuf_end) {
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obj = ptrbuf->p;
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ti = ptrbuf->ti;
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ptrbuf++;
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// obj belongs to interval [mheap.arena_start, mheap.arena_used).
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if(Debug > 1) {
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if(obj < runtime·mheap.arena_start || obj >= runtime·mheap.arena_used)
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runtime·throw("object is outside of mheap");
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}
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// obj belongs to interval [mheap.arena_start, mheap.arena_used).
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if(Debug > 1) {
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if(obj < runtime·mheap.arena_start || obj >= runtime·mheap.arena_used)
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runtime·throw("object is outside of mheap");
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}
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// obj may be a pointer to a live object.
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// Try to find the beginning of the object.
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// obj may be a pointer to a live object.
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// Try to find the beginning of the object.
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// Round down to word boundary.
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if(((uintptr)obj & ((uintptr)PtrSize-1)) != 0) {
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obj = (void*)((uintptr)obj & ~((uintptr)PtrSize-1));
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ti = 0;
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}
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// Round down to word boundary.
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if(((uintptr)obj & ((uintptr)PtrSize-1)) != 0) {
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obj = (void*)((uintptr)obj & ~((uintptr)PtrSize-1));
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ti = 0;
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}
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// Find bits for this word.
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off = (uintptr*)obj - (uintptr*)arena_start;
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bitp = (uintptr*)arena_start - off/wordsPerBitmapWord - 1;
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shift = off % wordsPerBitmapWord;
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xbits = *bitp;
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bits = xbits >> shift;
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// Find bits for this word.
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off = (uintptr*)obj - (uintptr*)arena_start;
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bitp = (uintptr*)arena_start - off/wordsPerBitmapWord - 1;
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shift = off % wordsPerBitmapWord;
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xbits = *bitp;
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bits = xbits >> shift;
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// Pointing at the beginning of a block?
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if((bits & (bitAllocated|bitBlockBoundary)) != 0) {
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if(CollectStats)
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runtime·xadd64(&gcstats.flushptrbuf.foundbit, 1);
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goto found;
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}
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// Pointing at the beginning of a block?
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if((bits & (bitAllocated|bitBlockBoundary)) != 0) {
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ti = 0;
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// Pointing just past the beginning?
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// Scan backward a little to find a block boundary.
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for(j=shift; j-->0; ) {
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if(((xbits>>j) & (bitAllocated|bitBlockBoundary)) != 0) {
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obj = (byte*)obj - (shift-j)*PtrSize;
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shift = j;
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bits = xbits>>shift;
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if(CollectStats)
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runtime·xadd64(&gcstats.flushptrbuf.foundbit, 1);
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runtime·xadd64(&gcstats.flushptrbuf.foundword, 1);
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goto found;
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}
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ti = 0;
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// Pointing just past the beginning?
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// Scan backward a little to find a block boundary.
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for(j=shift; j-->0; ) {
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if(((xbits>>j) & (bitAllocated|bitBlockBoundary)) != 0) {
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obj = (byte*)obj - (shift-j)*PtrSize;
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shift = j;
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bits = xbits>>shift;
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if(CollectStats)
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runtime·xadd64(&gcstats.flushptrbuf.foundword, 1);
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goto found;
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}
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}
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// Otherwise consult span table to find beginning.
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// (Manually inlined copy of MHeap_LookupMaybe.)
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k = (uintptr)obj>>PageShift;
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x = k;
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if(sizeof(void*) == 8)
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x -= (uintptr)arena_start>>PageShift;
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s = runtime·mheap.spans[x];
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if(s == nil || k < s->start || obj >= s->limit || s->state != MSpanInUse)
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continue;
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p = (byte*)((uintptr)s->start<<PageShift);
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if(s->sizeclass == 0) {
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obj = p;
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} else {
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size = s->elemsize;
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int32 i = ((byte*)obj - p)/size;
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obj = p+i*size;
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}
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// Now that we know the object header, reload bits.
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off = (uintptr*)obj - (uintptr*)arena_start;
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bitp = (uintptr*)arena_start - off/wordsPerBitmapWord - 1;
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shift = off % wordsPerBitmapWord;
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xbits = *bitp;
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bits = xbits >> shift;
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if(CollectStats)
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runtime·xadd64(&gcstats.flushptrbuf.foundspan, 1);
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found:
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// Now we have bits, bitp, and shift correct for
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// obj pointing at the base of the object.
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// Only care about allocated and not marked.
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if((bits & (bitAllocated|bitMarked)) != bitAllocated)
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continue;
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if(work.nproc == 1)
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*bitp |= bitMarked<<shift;
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else {
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for(;;) {
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x = *bitp;
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if(x & (bitMarked<<shift))
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goto continue_obj;
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if(runtime·casp((void**)bitp, (void*)x, (void*)(x|(bitMarked<<shift))))
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break;
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}
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}
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// If object has no pointers, don't need to scan further.
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if((bits & bitNoScan) != 0)
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continue;
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// Ask span about size class.
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// (Manually inlined copy of MHeap_Lookup.)
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x = (uintptr)obj >> PageShift;
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if(sizeof(void*) == 8)
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x -= (uintptr)arena_start>>PageShift;
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s = runtime·mheap.spans[x];
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PREFETCH(obj);
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*wp = (Obj){obj, s->elemsize, ti};
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wp++;
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nobj++;
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continue_obj:;
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}
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// If another proc wants a pointer, give it some.
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if(work.nwait > 0 && nobj > handoffThreshold && work.full == 0) {
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wbuf->nobj = nobj;
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wbuf = handoff(wbuf);
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nobj = wbuf->nobj;
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wp = wbuf->obj + nobj;
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// Otherwise consult span table to find beginning.
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// (Manually inlined copy of MHeap_LookupMaybe.)
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k = (uintptr)obj>>PageShift;
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x = k;
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if(sizeof(void*) == 8)
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x -= (uintptr)arena_start>>PageShift;
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s = runtime·mheap.spans[x];
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if(s == nil || k < s->start || obj >= s->limit || s->state != MSpanInUse)
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continue;
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p = (byte*)((uintptr)s->start<<PageShift);
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if(s->sizeclass == 0) {
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obj = p;
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} else {
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size = s->elemsize;
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int32 i = ((byte*)obj - p)/size;
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obj = p+i*size;
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}
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// Now that we know the object header, reload bits.
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off = (uintptr*)obj - (uintptr*)arena_start;
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bitp = (uintptr*)arena_start - off/wordsPerBitmapWord - 1;
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shift = off % wordsPerBitmapWord;
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xbits = *bitp;
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bits = xbits >> shift;
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if(CollectStats)
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runtime·xadd64(&gcstats.flushptrbuf.foundspan, 1);
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found:
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// Now we have bits, bitp, and shift correct for
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// obj pointing at the base of the object.
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// Only care about allocated and not marked.
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if((bits & (bitAllocated|bitMarked)) != bitAllocated)
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continue;
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if(work.nproc == 1)
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*bitp |= bitMarked<<shift;
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else {
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for(;;) {
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x = *bitp;
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if(x & (bitMarked<<shift))
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goto continue_obj;
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if(runtime·casp((void**)bitp, (void*)x, (void*)(x|(bitMarked<<shift))))
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break;
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}
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}
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// If object has no pointers, don't need to scan further.
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if((bits & bitNoScan) != 0)
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continue;
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// Ask span about size class.
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// (Manually inlined copy of MHeap_Lookup.)
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x = (uintptr)obj >> PageShift;
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if(sizeof(void*) == 8)
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x -= (uintptr)arena_start>>PageShift;
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s = runtime·mheap.spans[x];
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PREFETCH(obj);
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*wp = (Obj){obj, s->elemsize, ti};
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wp++;
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nobj++;
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continue_obj:;
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}
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// If another proc wants a pointer, give it some.
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if(work.nwait > 0 && nobj > handoffThreshold && work.full == 0) {
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wbuf->nobj = nobj;
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wbuf = handoff(wbuf);
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nobj = wbuf->nobj;
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wp = wbuf->obj + nobj;
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}
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sbuf->wp = wp;
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