normal aaa = normal (0,0,1),
bbb = normal (1,0,0);
float buba =  abs(aaa . bbb ); // in this case all fine
buba =  abs(normal(0,0,1) . normal(1,0,0) ); // <- problem here

sdrc can't parse last line and says:
error : Function abs not found
error : Unable to cast a float