我在Making Code 64-Bit Clean中看到了这个主题
╔═════════════════════╤══════════════════════════════════════════════════════╗
║ Register name │ Description ║
╠═════════════════════╪══════════════════════════════════════════════════════╣
║ R8 │ A 64-bit register. ║
╟─────────────────────┼──────────────────────────────────────────────────────╢
║ R8d │ A 32-bit register containing the bottom half of R8. ║
╟─────────────────────┼──────────────────────────────────────────────────────╢
║ R8w │ A 16-bit register containing the bottom half of R8d. ║
╟─────────────────────┼──────────────────────────────────────────────────────╢
║ R8l (Lowercase “l”) │ An 8-bit register containing the bottom half of R8w. ║
╚═════════════════════╧══════════════════════════════════════════════════════╝
有了l后缀，我首先想到的是它是一个long寄存器，就像GAS语法中的那样。
为什么 Apple 使用与其他公司不同的名称？
最佳答案
从 Ross Ridge 的评论来看，这是因为 AMD 和 Intel 的寄存器命名约定不同
来自AMD64架构程序员手册，Volume 1: Application Programming
3.1.2 64-Bit-Mode Registers
In 64-bit mode, eight new GPRs are added to the eight legacy GPRs, all 16 GPRs are 64 bits wide, and the low bytes of all registers are accessible. Figure 3-3 on page 27 shows the GPRs, flags register, and instruction-pointer register available in 64-bit mode. The GPRs include:
- Sixteen 8-bit low-byte registers (AL, BL, CL, DL, SIL, DIL, BPL, SPL, R8B, R9B, R10B, R11B, R12B, R13B, R14B, R15B).
- Four 8-bit high-byte registers (AH, BH, CH, DH), addressable only when no REX prefix is used.
- Sixteen 16-bit registers (AX, BX, CX, DX, DI, SI, BP, SP, R8W, R9W, R10W, R11W, R12W, R13W, R14W, R15W).
- Sixteen 32-bit registers (EAX, EBX, ECX, EDX, EDI, ESI, EBP, ESP, R8D, R9D, R10D, R11D, R12D, R13D, R14D, R15D).
- Sixteen 64-bit registers (RAX, RBX, RCX, RDX, RDI, RSI, RBP, RSP, R8, R9, R10, R11, R12, R13, R14, R15).
与英特尔® 64 和 IA-32 架构相比 - 软件开发人员手册 Volume 1: Basic Architecture
3.7.2.1 Register Operands in 64-Bit Mode
Register operands in 64-bit mode can be any of the following:
- 64-bit general-purpose registers (RAX, RBX, RCX, RDX, RSI, RDI, RSP, RBP, or R8-R15)
- 32-bit general-purpose registers (EAX, EBX, ECX, EDX, ESI, EDI, ESP, EBP, or R8D-R15D)
- 16-bit general-purpose registers (AX, BX, CX, DX, SI, DI, SP, BP, or R8W-R15W)
- 8-bit general-purpose registers: AL, BL, CL, DL, SIL, DIL, SPL, BPL, and R8L-R15L are available using REX prefixes; AL, BL, CL, DL, AH, BH, CH, DH are available without using REX prefixes.
关于macos - 为什么 Apple 使用 R8l 作为字节寄存器而不是 R8b？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43991779/