Distinguishing between 32-bit and 64-bit A64 instructions
Distinguishing between 32-bit and 64-bit A64 instructions
Most integer instructions in the A64 instruction set have two forms, which operate on either 32-bit or 64-bit values within the 64-bit general-purpose register file.
When looking at the register name that the instruction uses:
• If the register name starts with X, it is a 64-bit register.
• If the register name starts with W, it is a 32-bit register.
When a 32-bit register form is selected:
• Right shifts and rotates inject at bit 31, instead of bit 63.
• The condition flags, where set by the instruction, are computed from the lower 32 bits.
• Writes to the W register set bits [63:32] of the X register to zero.
This distinction applies even when the results of a 32-bit register form would be indistinguishable from the lower 32 bits computed by the equivalent 64-bit register form. For example, A64 includes separate 32-bit and 64-bit register forms of the ORR instructions. A 32-bit bitwise ORR could just as easily be performed using a 64-bit ORR and ignoring the top 32 bits of the result.
【推荐】编程新体验,更懂你的AI,立即体验豆包MarsCode编程助手
【推荐】凌霞软件回馈社区,博客园 & 1Panel & Halo 联合会员上线
【推荐】抖音旗下AI助手豆包,你的智能百科全书,全免费不限次数
【推荐】博客园社区专享云产品让利特惠,阿里云新客6.5折上折
【推荐】轻量又高性能的 SSH 工具 IShell:AI 加持,快人一步
· 浏览器原生「磁吸」效果!Anchor Positioning 锚点定位神器解析
· 没有源码,如何修改代码逻辑?
· 一个奇形怪状的面试题:Bean中的CHM要不要加volatile?
· [.NET]调用本地 Deepseek 模型
· 一个费力不讨好的项目,让我损失了近一半的绩效!
· 在鹅厂做java开发是什么体验
· 百万级群聊的设计实践
· WPF到Web的无缝过渡:英雄联盟客户端的OpenSilver迁移实战
· 永远不要相信用户的输入:从 SQL 注入攻防看输入验证的重要性
· 浏览器原生「磁吸」效果!Anchor Positioning 锚点定位神器解析