On Tue, Jul 29, 2014 at 10:44 PM, David Malcolm <dmalc...@redhat.com> wrote: > A complaint I heard at Cauldron with the C++ification of GCC passes is > that it's become much more difficult to set breakpoints on the execute > hooks of a pass, now that the passes are classes within anonymous > namespaces. > > When this was first done, the execute methods were trivial > implementations that called into the existing named functions, which are > still easy to put a breakpoint on by name (assuming you know the name of > the function), but some of these have now been converted so that the > "execute" method is the body of the pass. > > I did some experimentation, on this box with > gdb-7.6.50.20130731-19.fc20.x86_64 and gcc trunk r212913 (the latter > from a week ago). > > You *can* set a breakpoint by name on such an execute method, but it's > tedious to type: > (gdb) break '(anonymous namespace)::pass_expand::execute' > Breakpoint 7 at 0x655220: file ../../src/gcc/cfgexpand.c, line > > ...since tab-completion doesn't work well: > > (gdb) break '(a<TAB> > does tab complete to: > (gdb) break '(anonymous namespace):: > > but typing anything else then hitting tab returns back to: > (gdb) break '(anonymous namespace):: > > Is anyone else seeing this?
Yes, I filed a gdb bug about this. > I had a go at implementing a workaround, for the lack of tab completion > (and the general verbosity) using gdbhooks.py. > > Attached is a patch to gdbhooks.py which adds a new command > "break-on-pass" to gdb; in particular, it locates and parses passes.def, > so that it can tab-complete on pass classnames: > > Example of use from the script: putting a breakpoint on "final", i.e. > classname "pass_final": > > (gdb) break-on-pass > Press <TAB>; it autocompletes to "pass_": > (gdb) break-on-pass pass_ > Press <TAB>: > Display all 219 possibilities? (y or n) > Press "n"; then type "f": > (gdb) break-on-pass pass_f > Press <TAB> to autocomplete to pass classnames beginning with "pass_f": > pass_fast_rtl_dce pass_fold_builtins > pass_feedback_split_functions pass_forwprop > pass_final pass_fre > pass_fixup_cfg pass_free_cfg > Type "in<TAB>" to complete to "pass_final": > (gdb) break-on-pass pass_final > ...and hit <RETURN>: > Breakpoint 6 at 0x8396ba: file ../../src/gcc/final.c, line 4526. > ...and we have a breakpoint set; continue execution: > (gdb) cont > Continuing. > Breakpoint 6, (anonymous namespace)::pass_final::execute (this=0x17fb990) > at ../../src/gcc/final.c:4526 > 4526 virtual unsigned int execute (function *) { return > rest_of_handle_final (); } > > This assumes you've suitably enabled gdbhooks.py, as documented at the > top of that file. > > Thoughts? Works for me though I'm not able to review python ;) Richard. > Dave > > gcc/ > * gdbhooks.py (find_gcc_source_dir): New helper function. > (class PassNames): New class, locating and parsing passes.def. > (class BreakOnPass): New command "break-on-pass". >