<p style="text-indent: 21pt;" class="MsoNormal"><span style="font-family: 宋体;">使用该属性对</span><span lang="EN-US">struct</span><span style="font-family: 宋体;">或者</span><span lang="EN-US">union</span><span style="font-family: 宋体;">类型进行定义,设定其类型的每一个变量的内存约束。当用在</span><span lang="EN-US">enum</span><span style="font-family: 宋体;">类型定义时,暗示了应该使用最小完整的类型(</span><span lang="EN-US">it indicates that the smallest integral type should be used</span><span style="font-family: 宋体;">)。</span><span lang="EN-US"><o:p /></span></p>
Hint that the marked function is "cold" and should be optimized for size, predicted as unlikely for branch prediction, and/or placed near other "cold" functions (so other functions can have improved cache locality).
函数前面使用这个扩展,表示该函数比较冷门,这样在分支预测机制里就不会对该函数进行预取,或说是将它和其他同样冷门(cold)的函数放到一块,这样它就很可能不会被放到缓存中来,而让更热门的指令放到缓存中。