// and never escape. The escape analysis doesn't know, as it is a
			// function pointer call.
			return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&zeroVal[0]))
		}
		if typ.TFlag&abi.TFlagRegularMemory != 0 {
			// For some types where the zero value is a value where all bits of this type are 0
			// optimize it.
			return isZero(unsafe.Slice(((*byte)(v.ptr)), typ.Size()))
		}

			gctyp = (*_type)(unsafe.Pointer(progSpan.base()))
			gctyp.Size_ = typ.Size_
			gctyp.PtrBytes = typ.PtrBytes
			gctyp.GCData = (*byte)(add(unsafe.Pointer(progSpan.base()), heapBitsOff))
			gctyp.TFlag = abi.TFlagUnrolledBitmap

			// Expand the GC program into space reserved at the end of the new span.
			runGCProg(addb(typ.GCData, 4), gctyp.GCData)
		}

		// Write out the header.
		*header = gctyp