[Bug analyzer/104434] Analyzer doesn't know about "pure" and "const" functions

[dmalcolm at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104434

--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Seen on
https://github.com/xianyi/OpenBLAS/blob/c5f280a7f0e875d83833d895b2b8b0e341efabf4/lapack-netlib/LAPACKE/src/lapacke_cgbbrd_work.c
where the code has:

   if( LAPACKE_lsame( vect, 'b' ) || LAPACKE_lsame( vect, 'p' ) ) {
            pt_t = (lapack_complex_float*)
                LAPACKE_malloc( sizeof(lapack_complex_float) *
                                ldpt_t * MAX(1,n) );
      ...snip...
   }

   [...snip lots of code...]

   if( LAPACKE_lsame( vect, 'b' ) || LAPACKE_lsame( vect, 'p' ) ) {
            LAPACKE_free( pt_t );
   }

where the analyzer considers the execution path where the conditions
guarding the malloc and the free are first true, and then false.

LAPACKE_lsame is a case-insensitive comparison, implemented in its own
source file.  I think if it were marked as "pure", the analyzer could
fix this without needing LTO.