re PR ipa/82801 (Internal compiler error with Eigen and __attribute__((always_inline, flatten)))
PR ipa/82801
PR ipa/83346
* ipa-inline.c (flatten_remove_node_hook): New function.
(ipa_inline): Keep only nodes with flatten attribute at the end of
the array in the order from ipa_reverse_postorder, only walk that
portion of array for flattening, if there is more than one such
node, temporarily register a removal hook and ignore removed nodes.