code: func ForArch(arch string) *Sizes {
  	wordSize := int64(8)
  	maxAlign := int64(8)
  	switch build.Default.GOARCH {
  	case "386", "arm":
  		wordSize, maxAlign = 4, 4
  	case "amd64p32":
  		wordSize = 4
  	}
  	return &Sizes{WordSize: wordSize, MaxAlign: maxAlign}
  }
docs: // ForArch returns a correct Sizes for the given architecture.