[Bug target/79430] [7/8 Regression] action of statement incorrectly optimised away

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79430

--- Comment #79 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 41269
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41269&action=edit
gcc7-pr79430.patch

Untested patch meant for 7.x, which just modifies reg-stack.c and nothing else.
Unlike the above patch which seems to affect also scheduling a lot, this one
doesn't.