analyzer: Fix ICE on MD builtin [PR101721]

analyzer: Fix ICE on MD builtin [PR101721]

The following testcase ICEs because DECL_FUNCTION_CODE asserts the builtin
is BUILT_IN_NORMAL, but it sees a backend (MD) builtin instead.
The FE, normal and MD builtin numbers overlap, so one should always
check what kind of builtin it is before looking at specific codes.

On the other side, region-model.cc has:
      if (fndecl_built_in_p (callee_fndecl, BUILT_IN_NORMAL)
          && gimple_builtin_call_types_compatible_p (call, callee_fndecl))
        switch (DECL_UNCHECKED_FUNCTION_CODE (callee_fndecl))
which IMO should use DECL_FUNCTION_CODE instead, it checked first it is
a normal builtin...

2021-08-03  Jakub Jelinek  <jakub@redhat.com>

	PR analyzer/101721
	* sm-malloc.cc (known_allocator_p): Only check DECL_FUNCTION_CODE on
	BUILT_IN_NORMAL builtins.

	* gcc.dg/analyzer/pr101721.c: New test.