[PATCH] D144541: [X86] Save/restore base pointer register when it is clobbered

Mon Feb 27 18:40:21 PST 2023

LuoYuanke added a comment.

In D144541#4155710 <https://reviews.llvm.org/D144541#4155710>, @efriedma wrote:

>> Why it would mess unwinding?
>
> I meant fp-based unwinding for profiling etc., not DWARF unwind.
>
>> That register (other register) may also be clobbered in another inline asm
>
> We don't have to use the same register for each inline asm.

The base pointer register is reserved by compiler, we can't reserve too much register?

>> Don't know what ech cif_escape means
>
> llvm-readobj --unwind can decode the DWARF for you.
>
> The important thing is that it allocates a variable amount of space between the arguments and the frame pointer, and saves the incoming value of esp on the stack.

It seems this option is the best one. What do you think?

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https://reviews.llvm.org/D144541