Hi all I wrote a function "DataFlowOutput" to get the use-def and def-use statistics of the registers. static void DataFlowOutput(void) { struct df *df; df = df_init (); df_analyse (df, 0, DF_ALL); df_dump (df, DF_ALL, stderr); df_finish (df); } This function is invoked before the final pass i.e before the RTL gets converted to assembly.. but the function is not printing the statistics.. It outputs the following Dataflow summary: n_regs = 66, n_defs = 0, n_uses = 0, n_bbs = 17 Reaching defs: bb 0 in bb 0 gen bb 0 kill bb 0 out bb 1 in bb 1 gen Use-def chains: Reaching uses: bb 0 in bb 0 gen bb 0 kill bb 0 out bb 1 in bb 1 gen bb 1 kill bb 1 out Def-use chains: Live regs: bb 0 in bb 0 use bb 0 def bb 0 out bb 1 in bb 1 use bb 1 def bb 1 out Iam trying to get the definition and use of each register in the program and their instrn id(INSN_UID).. I would appreciate any kind of help. regards kripa __________________________________ Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard. http://promotions.yahoo.com/new_mail