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b46c89892f
This patch modifies the x86_64 XRay trampolines to fix the CFI information generated by the assembler. One of the main issues in correcting the CFI directives is the `ALIGNED_CALL_RAX` macro, which makes the CFA dependent on the alignment of the stack. However, this macro is not really necessary because some additional assumptions can be made on the alignment of the stack when the trampolines are called. The code has been written as if the stack is guaranteed to be 8-bytes aligned; however, it is instead guaranteed to be misaligned by 8 bytes with respect to a 16-bytes alignment. For this reason, always moving the stack pointer by 8 bytes is sufficient to restore the appropriate alignment. Trampolines that are called from within a function as a result of the builtins `__xray_typedevent` and `__xray_customevent` are necessarely called with the stack properly aligned so, in this case too, `ALIGNED_CALL_RAX` can be eliminated. Fixes https://bugs.llvm.org/show_bug.cgi?id=49060 Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D96785