diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/runtime/malloc.go | 3 | ||||
| -rw-r--r-- | src/runtime/mbitmap_allocheaders.go | 14 | ||||
| -rw-r--r-- | src/runtime/mfinal.go | 8 |
3 files changed, 17 insertions, 8 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go index 398eaf5d52..c7ab928fe6 100644 --- a/src/runtime/malloc.go +++ b/src/runtime/malloc.go @@ -1153,7 +1153,8 @@ func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer { memclrNoHeapPointers(x, size) } if goexperiment.AllocHeaders && hasHeader { - header = (**_type)(unsafe.Pointer(uintptr(v) + size - mallocHeaderSize)) + header = (**_type)(x) + x = add(x, mallocHeaderSize) size -= mallocHeaderSize } } diff --git a/src/runtime/mbitmap_allocheaders.go b/src/runtime/mbitmap_allocheaders.go index 03cec5ffcc..33535a515a 100644 --- a/src/runtime/mbitmap_allocheaders.go +++ b/src/runtime/mbitmap_allocheaders.go @@ -48,9 +48,9 @@ // is zeroed, so the GC just observes nil pointers. // Note that this "tiled" bitmap isn't stored anywhere; it is generated on-the-fly. // -// For objects without their own span, the type metadata is stored in the last -// word of the allocation slot. For objects with their own span, the type metadata -// is stored in the mspan. +// For objects without their own span, the type metadata is stored in the first +// word before the object at the beginning of the allocation slot. For objects +// with their own span, the type metadata is stored in the mspan. // // The bitmap for small unallocated objects in scannable spans is not maintained // (can be junk). @@ -167,7 +167,8 @@ func (span *mspan) typePointersOf(addr, size uintptr) typePointers { } // typePointersOfUnchecked is like typePointersOf, but assumes addr is the base -// pointer of an object in span. It returns an iterator that generates all pointers +// of an allocation slot in a span (the start of the object if no header, the +// header otherwise). It returns an iterator that generates all pointers // in the range [addr, addr+span.elemsize). // // nosplit because it is used during write barriers and must not be preempted. @@ -192,8 +193,9 @@ func (span *mspan) typePointersOfUnchecked(addr uintptr) typePointers { // All of these objects have a header. var typ *_type if spc.sizeclass() != 0 { - // Pull the allocation header from the last word of the object. - typ = *(**_type)(unsafe.Pointer(addr + span.elemsize - mallocHeaderSize)) + // Pull the allocation header from the first word of the object. + typ = *(**_type)(unsafe.Pointer(addr)) + addr += mallocHeaderSize } else { typ = span.largeType } diff --git a/src/runtime/mfinal.go b/src/runtime/mfinal.go index 18cd93e77e..be501e6fca 100644 --- a/src/runtime/mfinal.go +++ b/src/runtime/mfinal.go @@ -9,6 +9,7 @@ package runtime import ( "internal/abi" "internal/goarch" + "internal/goexperiment" "runtime/internal/atomic" "runtime/internal/sys" "unsafe" @@ -410,7 +411,7 @@ func SetFinalizer(obj any, finalizer any) { } // find the containing object - base, _, _ := findObject(uintptr(e.data), 0, 0) + base, span, _ := findObject(uintptr(e.data), 0, 0) if base == 0 { if isGoPointerWithoutSpan(e.data) { @@ -419,6 +420,11 @@ func SetFinalizer(obj any, finalizer any) { throw("runtime.SetFinalizer: pointer not in allocated block") } + // Move base forward if we've got an allocation header. + if goexperiment.AllocHeaders && !span.spanclass.noscan() && !heapBitsInSpan(span.elemsize) && span.spanclass.sizeclass() != 0 { + base += mallocHeaderSize + } + if uintptr(e.data) != 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). |