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问题 伪寄存器在函数调用前后是如何恢复现场的 #47

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zhaozy93 opened this issue May 9, 2021 · 2 comments
Open

问题 伪寄存器在函数调用前后是如何恢复现场的 #47

zhaozy93 opened this issue May 9, 2021 · 2 comments
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@zhaozy93
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zhaozy93 commented May 9, 2021

C系语言中，调用函数把硬件寄存器BP值写入栈中，被调用函数ret后，读取当前bp加固定位移得到调用函数的硬件寄存器BP值，即可恢复现场，看plan9的文章对4个伪寄存器并没有进行类似操作。
请问 伪寄存器在函数调用前后是如何恢复现场的？
@zhaozy93
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zhaozy93 commented May 9, 2021

或者说 不需要恢复现场 伪SP和伪BP可以通过硬件寄存器的BP计算出来？

@cch123
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cch123 commented May 10, 2021 •
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BP 在 callee 的 framesize 大小 > 0 的时候也是会在栈上存的
ret 的流程和其他语言应该是一样的

另外，伪寄存器编译后都会转成真实的物理寄存器，不会在最终生成的汇编代码中有任何伪寄存器的

@cch123 cch123 added the question Further information is requested label May 10, 2021
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