The ifcvt dead code elimination code was not built to deal with inline
assembly, as loops with such would never be if-converted in the past since
we can't do data-reference analysis on them and vectorization would 
eventually fail.
For this reason we now also do not lower bitfields if the data-reference 
analysis
fails, as we would not end up vectorizing it.  As a consequence this 
also fixes
this PR as the dead code elimination will not run for such cases and 
wrongfully
eliminate inline assembly statements.

Bootstrapped and regression tested on aarch64-none-linux-gnu and 
x86_64-pc-linux-gnu.

gcc/ChangeLog:

     PR tree-optimization/107275
     * tree-if-conv.cc (if_convertible_loop_p_1): Move
     find_data_references_in_loop call from here...
     (if_convertible_loop_p): And move data-reference vector initialization
     from here...
     (tree_if_conversion):... to here.

gcc/testsuite/ChangeLog:

     * gcc.dg/vect/pr107275.c: New test.