proc merge_phase { prefix } {
    set pattern $prefix
    append pattern "_*"
    set dumps [glob $pattern ]
    foreach f $dumps {
       lappend input -in $f
    }
    #layout filemerge $input -out dump_merged.oas -smartdiff -mode append
    eval "layout filemerge $input -out dump_merged_$prefix.oas -smartdiff -mode append"
}

merge_phase phase0
merge_phase phase1
merge_phase phase2
merge_phase phase3