easily print VASMs of current code emission

hhvm.gdb

# auxiliary of print_vasms
define pvector
  set $i = 0
  while($i < $arg0.size())
    printf "\t"
    p $arg0[$i].$arg1

    set $i = $i + 1
  end
end

# this function is to be called on this scope:
# HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>
define print_vasms
  printf "To be used on HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>\n"
  printf "==========================================================================\n\n"
  set $j = 0
  while($j < unit.blocks.size())
    printf "unit.blocks[%d]:\n", $j
    pvector unit.blocks[$j].code op

    set $j = $j + 1
  end
end

usage example

$ cat ~/.gdbinit
# auxiliary of print_vasms
define pvector
  set $i = 0
  while($i < $arg0.size())
    printf "\t"
    p $arg0[$i].$arg1

    set $i = $i + 1
  end
end

# this function is to be called on this scope:
# HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>
define print_vasms
  printf "To be used on HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>\n"
  printf "==========================================================================\n\n"
  set $j = 0
  while($j < unit.blocks.size())
    printf "unit.blocks[%d]:\n", $j
    pvector unit.blocks[$j].code op

    set $j = $j + 1
  end
end

$ cat blank.php
<?php ?>
$ gdb hphp/hhvm/hhvm
GNU gdb (GDB) 7.10
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "powerpc64le-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
(gdb) b HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>
Breakpoint 1 at 0x141fdb6c: HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>. (3 locations)
(gdb) r blank.php
Starting program: /home/hhvm/hphp/hhvm/hhvm blank.php
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/powerpc64le-linux-gnu/libthread_db.so.1".

Breakpoint 1, HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen> (unit=..., text=..., asm_info=0x0) at /home/hhvm/hphp/runtime/vm/jit/vasm-internal-inl.h:124
124       Venv env { unit, text };
(gdb) print_vasms
To be used on HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>
==========================================================================

unit.blocks[0]:
        $1 = HPHP::jit::Vinstr::copy
        $2 = HPHP::jit::Vinstr::copy
        $3 = HPHP::jit::Vinstr::call
        $4 = HPHP::jit::Vinstr::jmpr
unit.blocks[1]:
        $5 = HPHP::jit::Vinstr::fallthru
(gdb) c
Continuing.

Breakpoint 1, HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen> (unit=..., text=..., asm_info=0x0) at /home/hhvm/hphp/runtime/vm/jit/vasm-internal-inl.h:124
124       Venv env { unit, text };
(gdb) print_vasms
To be used on HPHP::jit::vasm_emit<HPHP::jit::(anonymous namespace)::Vgen>
==========================================================================

unit.blocks[0]:
        $6 = HPHP::jit::Vinstr::copy
        $7 = HPHP::jit::Vinstr::load
        $8 = HPHP::jit::Vinstr::cmplim
        $9 = HPHP::jit::Vinstr::jcc
unit.blocks[1]:
        $10 = HPHP::jit::Vinstr::fallthru
unit.blocks[2]:
        $11 = HPHP::jit::Vinstr::copy
        $12 = HPHP::jit::Vinstr::jcc
unit.blocks[3]:
        $13 = HPHP::jit::Vinstr::copy
        $14 = HPHP::jit::Vinstr::ret
unit.blocks[4]:
        $15 = HPHP::jit::Vinstr::copy
        $16 = HPHP::jit::Vinstr::declm
        $17 = HPHP::jit::Vinstr::ret
unit.blocks[5]:
        $18 = HPHP::jit::Vinstr::copy
        $19 = HPHP::jit::Vinstr::push
        $20 = HPHP::jit::Vinstr::push
        $21 = HPHP::jit::Vinstr::shrli
        $22 = HPHP::jit::Vinstr::callm
        $23 = HPHP::jit::Vinstr::syncpoint
        $24 = HPHP::jit::Vinstr::pop
        $25 = HPHP::jit::Vinstr::pop
        $26 = HPHP::jit::Vinstr::jmp
unit.blocks[6]:
        $27 = HPHP::jit::Vinstr::copy
        $28 = HPHP::jit::Vinstr::jmp