assembly - 应该在 PowerPC 中求和有效地址 'wrap' 吗？如果是这样，如何？

Question

例如，PowerPC book I 的第 3.3.2 节定义了 lbz指令为:

Let the effective address (EA) be the sum (RA|0)+ D. The byte in storage addressed by EA is loaded into RT_56:63. RT_0:55 are set to 0.

以下两种情况我该怎么办？

我应该在 (RA) + D > memory_capacity 时包裹或做些什么?

我应该在 (RA) + D > 4294967295 时包裹或做些什么?

换句话说，有效地址就是 (RA) + D的总和, 或者计算完成 mod memory_capacity或 mod 2^32-1 ?

相关实用资料:每一行设置 var EA在 this script .

Answer 1

来自 Power ISA 2.06 一书的第 1.9.3 节有效地址计算

In 32-bit mode, the low-order 32 bits of the 64-bit result, preceded by 32 0 bits, comprise the 64-bit effective address for the purpose of addressing storage. [...] As used to address storage, the effective address arithmetic appears to wrap around from the maximum address, 2³²-1, to address 0, except that if the current instruction is at effective address 2³²-4 the effective address of the next sequential instruction is undefined.