Perhaps useful for footprint work...
The enclosed perl script generates a gdb command script from ptype output that shows the byte offset, length in bytes and cumulative fill byte count for each field of the class or structure. Where class/structure ordering isn't imposed, the output could be used to argue for an ordering that pushes alignment fill to the end or brings frequently referenced fields together for `better' cache usage. Any scripting support added to gdb should be able to do something like this directly. 501 /devel/spanopen/700 % gdb libff/librds.so GNU gdb 19990928 Copyright 1998 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i686-pc-linux-gnu"... (gdb) ptype sql_proccolinfo_t type = class sql_proccolinfo_t { private: dh_i16_t dtor_flag; hm_hdl_t *hm_curhdl; public: slink sl; dh_u16_t pci_proccolid; procid_t pci_procid; tpe_rssid_t pci_rssid; char pci_col[36]; char pci_datatype[36]; typeid_t pci_typeid; sql_proccoltype_t pci_coltype; dh_i32_t pci_width; dh_i32_t pci_scale; dh_boolean pci_nonull; sql_dflt_t pci_dflttp; dh_char_t *pci_default; sql_proccolinfo_t & operator=(sql_proccolinfo_t const &); sql_proccolinfo_t(sql_proccolinfo_t const &); static void * operator new(unsigned int); static void * operator new(unsigned int, hm_hdl_t *); static void operator delete(void *); sql_proccolinfo_t(alloctype_t); sql_proccolinfo_t(hm_hdl_t *, alloctype_t); ~sql_proccolinfo_t(void); } (gdb) shell # xterm cut & paste 501 /devel/spanopen/700 % perl gdboff.pl > gdb.proccolinfo_t <<EOF > type = class sql_proccolinfo_t { > private: > dh_i16_t dtor_flag; > hm_hdl_t *hm_curhdl; > public: > slink sl; > dh_u16_t pci_proccolid; > procid_t pci_procid; > tpe_rssid_t pci_rssid; > char pci_col[36]; > char pci_datatype[36]; > typeid_t pci_typeid; > sql_proccoltype_t pci_coltype; > dh_i32_t pci_width; > dh_i32_t pci_scale; > dh_boolean pci_nonull; > sql_dflt_t pci_dflttp; > dh_char_t *pci_default; > > sql_proccolinfo_t & operator=(sql_proccolinfo_t const &); > sql_proccolinfo_t(sql_proccolinfo_t const &); > static void * operator new(unsigned int); > static void * operator new(unsigned int, hm_hdl_t *); > static void operator delete(void *); > sql_proccolinfo_t(alloctype_t); > sql_proccolinfo_t(hm_hdl_t *, alloctype_t); > ~sql_proccolinfo_t(void); > } > EOF 502 /devel/spanopen/700 % exit # Leading `>'-s from bash. exit (gdb) source gdb.proccolinfo_t sizeof(sql_proccolinfo_t) 128 sql_proccolinfo_t.dtor_flag 0 2 0 sql_proccolinfo_t.hm_curhdl 4 4 2 sql_proccolinfo_t.sl 8 8 2 sql_proccolinfo_t.pci_proccolid 16 2 2 sql_proccolinfo_t.pci_procid 20 4 4 sql_proccolinfo_t.pci_rssid 24 4 4 sql_proccolinfo_t.pci_col 28 36 4 sql_proccolinfo_t.pci_datatype 64 36 4 sql_proccolinfo_t.pci_typeid 100 4 4 sql_proccolinfo_t.pci_coltype 104 4 4 sql_proccolinfo_t.pci_width 108 4 4 sql_proccolinfo_t.pci_scale 112 4 4 sql_proccolinfo_t.pci_nonull 116 1 4 sql_proccolinfo_t.pci_dflttp 120 4 7 sql_proccolinfo_t.pci_default 124 4 7 (gdb) q 502 /devel/spanopen/700 % exit # Generate a gdb script to display offset, length and cumulative fill bytes # for each field of a class or struct, # from the gdb ptype output of the class or struct. # eg #sizeof(xyz) 128 #xyz.dtor_flag 0 2 0 #xyz.hm_curhdl 4 4 2 # ... while (<>) { if (/^type = (?:class|struct) (\w+) {\s*$/) { $the_type = $1; printf "printf \"sizeof(%s)\\t%%d\\n\", sizeof(%s)\n", $the_type, $the_type; printf "set variable \$cumlen = 0\n"; } if (defined($the_type)) { if (/^}\s*$/) { undef $the_type; } elsif (/^(?:| p(?:rivate|public):)\s*$/) { } elsif (/ \**(\w+)(?:|\[\d+\]);\s*$/) { my($the_field) = $1; printf "set variable \$offset = (int)(&(((%s *)0)->%s))\nset variable \$fieldlen = sizeof(((%s *)0)->%s)\nprintf \"%s.%s\\t%%d\\t%%d\\t%%d\\n\", \$offset, \$fieldlen, \$offset - \$cumlen\nset variable \$cumlen += \$fieldlen\n", $the_type, $the_field, $the_type, $the_field, $the_type, $the_field; } elsif (/(?:[^; ]|\);)\s*$/) { } } }
