whereis asm_nodes? how to migrate it for GCC v6.x?

[Leslie Zhai]

Hi GCC developers,

There was
extern GTY(()) struct asm_node *asm_nodes;

for GCC v4.x, but how to migrate it for v6.x? there is no asm_nodes 
deprecated log in ChangeLog-201X nor git log cgraph.h... please give me 
some hint, thanks a lot!

--
Regards,
Leslie Zhai https://reviews.llvm.org/p/xiangzhai/