mirror of https://go.googlesource.com/go
35 lines
1.3 KiB
Go
35 lines
1.3 KiB
Go
// 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.
|
|
|
|
// Malloc small size classes.
|
|
//
|
|
// See malloc.go for overview.
|
|
// See also mksizeclasses.go for how we decide what size classes to use.
|
|
|
|
package runtime
|
|
|
|
// Returns size of the memory block that mallocgc will allocate if you ask for the size,
|
|
// minus any inline space for metadata.
|
|
func roundupsize(size uintptr, noscan bool) (reqSize uintptr) {
|
|
reqSize = size
|
|
if reqSize <= maxSmallSize-mallocHeaderSize {
|
|
// Small object.
|
|
if !noscan && reqSize > minSizeForMallocHeader { // !noscan && !heapBitsInSpan(reqSize)
|
|
reqSize += mallocHeaderSize
|
|
}
|
|
// (reqSize - size) is either mallocHeaderSize or 0. We need to subtract mallocHeaderSize
|
|
// from the result if we have one, since mallocgc will add it back in.
|
|
if reqSize <= smallSizeMax-8 {
|
|
return uintptr(class_to_size[size_to_class8[divRoundUp(reqSize, smallSizeDiv)]]) - (reqSize - size)
|
|
}
|
|
return uintptr(class_to_size[size_to_class128[divRoundUp(reqSize-smallSizeMax, largeSizeDiv)]]) - (reqSize - size)
|
|
}
|
|
// Large object. Align reqSize up to the next page. Check for overflow.
|
|
reqSize += pageSize - 1
|
|
if reqSize < size {
|
|
return size
|
|
}
|
|
return reqSize &^ (pageSize - 1)
|
|
}
|