[Bug inline-asm/87984] [7/8/9 Regression] wrong code for local reg var input to asm

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87984

--- Comment #14 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
With -fno-tree-fre it's still broken.

How long will GCC play this sort of whack-a-mole with ad-hoc restrictions to
gimple optimizations (PR 29877, PR 42491, PR 61572)?

And this:

> for fixed registers there is no need to specify them in clobbers, but users might still use those fixed registers in asm) as possibly modifying content of local or global register vars.

is not true, we do require inline asm to properly inform the compiler about
accessing global register variables by mentioning them in constraints.