[Bug c/79027] [8 Regression] fold-const.c:11104:1: internal compiler error: Floating point exception

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79027

--- Comment #8 from John David Anglin <danglin at gcc dot gnu.org> ---
The error on the trunk is caused by the middle end trying to do a mode change
between SImode and BLKmode.  Tweaking pa_cannot_change_mode_class() to reject
changes to/modes with zero size appears to fix this bug.  Running a full build
and check.

The bug has been present for a long time but only recently exposed by a
gcc-8 change and/or selecting the right configure options.