[Bug middle-end/116003] [15 Regression] ICE: in register_initial_def, at value-relation.cc:610 with -O2 -fnon-call-exceptions -fprofile-arcs -finstrument-functions -fno-tree-copy-prop and _BitInt()

[amacleod at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116003

--- Comment #1 from Andrew Macleod <amacleod at redhat dot com> ---
When registering an equivalence, the oracle creates an initial equivalence for
an SSA_NAME with itself in the def block.   This  prevents dominator queries
from searching past the definition block.

In this case the definition stmt has no gimple_bb set yet, so it is ice-ing

If the definition stmt for the SSA_NAME has not been placed in the CFG yet, we
should defer creating this record until it has.    The next time an equivalence
is registered, if the SSA_NAME is in the IL then this record will be created.

Patch in testing