ARM to C 调用约定，NEON 寄存器保存 [英] ARM to C calling convention, NEON registers to save

问题描述

有一个类似的帖子，涵盖了常规寄存器.NEON寄存器怎么样.据我所知，必须跨函数调用保留寄存器的上半部分或下半部分.我在任何地方都找不到该信息，有人可以澄清一下吗?

There is a similar post that covers regular registers. What about NEON registers. As far as I remember either top half or bottom half of registers have to be preserved across function calls. I can't find that info anywhere, can somebody clarify that?

谢谢

来自 AAPCS，§5.1.1 核心寄存器:

• r0-r3 是参数和暂存寄存器；r0-r1 也是结果寄存器
• r4-r8 是被调用者保存寄存器
• r9 可能是一个被调用者保存寄存器(在 AAPCS 的某些变体上它是一个特殊寄存器)
• r10-r11 是被调用者保存寄存器
• r12-r15 是特殊寄存器

• r0-r3 are the argument and scratch registers; r0-r1 are also the result registers
• r4-r8 are callee-save registers
• r9 might be a callee-save register or not (on some variants of AAPCS it is a special register)
• r10-r11 are callee-save registers
• r12-r15 are special registers

来自 AAPCS，§5.1.2.1 VFP 寄存器使用约定(VFP v2、v3 和高级 SIMD 扩展):

• s16–s31 (d8–d15, q4–q7) 必须保留
• s0–s15 (d0–d7, q0–q3) 和 d16–d31 (q8–q15) 不需要保留

• s16–s31 (d8–d15, q4–q7) must be preserved
• s0–s15 (d0–d7, q0–q3) and d16–d31 (q8–q15) do not need to be preserved

推荐答案

来自 AAPCS，§5.1.2.1:

• s16–s31 (d8–d15, q4–q7) 必须保留
• s0–s15 (d0–d7, q0–q3) 和 d16–d31 (q8–q15) 不需要保留

• s16–s31 (d8–d15, q4–q7) must be preserved
• s0–s15 (d0–d7, q0–q3) and d16–d31 (q8–q15) do not need to be preserved

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