gcc/gdbhooks.py

   1 # Python hooks for gdb for debugging GCC
   2 # Copyright (C) 2013-2019 Free Software Foundation, Inc.
   3
   4 # Contributed by David Malcolm <dmalcolm@redhat.com>
   5
   6 # This file is part of GCC.
   7
   8 # GCC is free software; you can redistribute it and/or modify it under
   9 # the terms of the GNU General Public License as published by the Free
  10 # Software Foundation; either version 3, or (at your option) any later
  11 # version.
  12
  13 # GCC is distributed in the hope that it will be useful, but WITHOUT
  14 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 # for more details.
  17
  18 # You should have received a copy of the GNU General Public License
  19 # along with GCC; see the file COPYING3.  If not see
  20 # <http://www.gnu.org/licenses/>.
  21
  22 """
  23 Enabling the debugging hooks
  24 ----------------------------
  25 gcc/configure (from configure.ac) generates a .gdbinit within the "gcc"
  26 subdirectory of the build directory, and when run by gdb, this imports
  27 gcc/gdbhooks.py from the source directory, injecting useful Python code
  28 into gdb.
  29
  30 You may see a message from gdb of the form:
  31   "path-to-build/gcc/.gdbinit" auto-loading has been declined by your `auto-load safe-path'
  32 as a protection against untrustworthy python scripts.  See
  33   http://sourceware.org/gdb/onlinedocs/gdb/Auto_002dloading-safe-path.html
  34
  35 The fix is to mark the paths of the build/gcc directory as trustworthy.
  36 An easy way to do so is by adding the following to your ~/.gdbinit script:
  37   add-auto-load-safe-path /absolute/path/to/build/gcc
  38 for the build directories for your various checkouts of gcc.
  39
  40 If it's working, you should see the message:
  41   Successfully loaded GDB hooks for GCC
  42 as gdb starts up.
  43
  44 During development, I've been manually invoking the code in this way, as a
  45 precanned way of printing a variety of different kinds of value:
  46
  47   gdb \
  48     -ex "break expand_gimple_stmt" \
  49     -ex "run" \
  50     -ex "bt" \
  51     --args \
  52       ./cc1 foo.c -O3
  53
  54 Examples of output using the pretty-printers
  55 --------------------------------------------
  56 Pointer values are generally shown in the form:
  57   <type address extra_info>
  58
  59 For example, an opt_pass* might appear as:
  60   (gdb) p pass
  61   $2 = <opt_pass* 0x188b600 "expand"(170)>
  62
  63 The name of the pass is given ("expand"), together with the
  64 static_pass_number.
  65
  66 Note that you can dereference the pointer in the normal way:
  67   (gdb) p *pass
  68   $4 = {type = RTL_PASS, name = 0x120a312 "expand",
  69   [etc, ...snipped...]
  70
  71 and you can suppress pretty-printers using /r (for "raw"):
  72   (gdb) p /r pass
  73   $3 = (opt_pass *) 0x188b600
  74
  75 Basic blocks are shown with their index in parentheses, apart from the
  76 CFG's entry and exit blocks, which are given as "ENTRY" and "EXIT":
  77   (gdb) p bb
  78   $9 = <basic_block 0x7ffff041f1a0 (2)>
  79   (gdb) p cfun->cfg->x_entry_block_ptr
  80   $10 = <basic_block 0x7ffff041f0d0 (ENTRY)>
  81   (gdb) p cfun->cfg->x_exit_block_ptr
  82   $11 = <basic_block 0x7ffff041f138 (EXIT)>
  83
  84 CFG edges are shown with the src and dest blocks given in parentheses:
  85   (gdb) p e
  86   $1 = <edge 0x7ffff043f118 (ENTRY -> 6)>
  87
  88 Tree nodes are printed using Python code that emulates print_node_brief,
  89 running in gdb, rather than in the inferior:
  90   (gdb) p cfun->decl
  91   $1 = <function_decl 0x7ffff0420b00 foo>
  92 For usability, the type is printed first (e.g. "function_decl"), rather
  93 than just "tree".
  94
  95 RTL expressions use a kludge: they are pretty-printed by injecting
  96 calls into print-rtl.c into the inferior:
  97   Value returned is $1 = (note 9 8 10 [bb 3] NOTE_INSN_BASIC_BLOCK)
  98   (gdb) p $1
  99   $2 = (note 9 8 10 [bb 3] NOTE_INSN_BASIC_BLOCK)
 100   (gdb) p /r $1
 101   $3 = (rtx_def *) 0x7ffff043e140
 102 This won't work for coredumps, and probably in other circumstances, but
 103 it's a quick way of getting lots of debuggability quickly.
 104
 105 Callgraph nodes are printed with the name of the function decl, if
 106 available:
 107   (gdb) frame 5
 108   #5  0x00000000006c288a in expand_function (node=<cgraph_node* 0x7ffff0312720 "foo"/12345>) at ../../src/gcc/cgraphunit.c:1594
 109   1594    execute_pass_list (g->get_passes ()->all_passes);
 110   (gdb) p node
 111   $1 = <cgraph_node* 0x7ffff0312720 "foo"/12345>
 112
 113 Similarly for symtab_node and varpool_node classes.
 114
 115 Cgraph edges are printed with the name of caller and callee:
 116     (gdb) p this->callees
 117     $4 = <cgraph_edge* 0x7fffe25aa000 (<cgraph_node * 0x7fffe62b22e0 "_GLOBAL__sub_I__ZN5Pooma5pinfoE"/19660> -> <cgraph_node * 0x7fffe620f730 "__static_initialization_and_destruction_1"/19575>)>
 118
 119 IPA reference follow very similar format:
 120     (gdb) Value returned is $5 = <ipa_ref* 0x7fffefcb80c8 (<symtab_node * 0x7ffff562f000 "__dt_base "/875> -> <symtab_node * 0x7fffe795f000 "_ZTVN6Smarts8RunnableE"/16056>:IPA_REF_ADDR)>
 121
 122 vec<> pointers are printed as the address followed by the elements in
 123 braces.  Here's a length 2 vec:
 124   (gdb) p bb->preds
 125   $18 = 0x7ffff0428b68 = {<edge 0x7ffff044d380 (3 -> 5)>, <edge 0x7ffff044d3b8 (4 -> 5)>}
 126
 127 and here's a length 1 vec:
 128   (gdb) p bb->succs
 129   $19 = 0x7ffff0428bb8 = {<edge 0x7ffff044d3f0 (5 -> EXIT)>}
 130
 131 You cannot yet use array notation [] to access the elements within the
 132 vector: attempting to do so instead gives you the vec itself (for vec[0]),
 133 or a (probably) invalid cast to vec<> for the memory after the vec (for
 134 vec[1] onwards).
 135
 136 Instead (for now) you must access m_vecdata:
 137   (gdb) p bb->preds->m_vecdata[0]
 138   $20 = <edge 0x7ffff044d380 (3 -> 5)>
 139   (gdb) p bb->preds->m_vecdata[1]
 140   $21 = <edge 0x7ffff044d3b8 (4 -> 5)>
 141 """
 142 import os.path
 143 import re
 144 import sys
 145 import tempfile
 146
 147 import gdb
 148 import gdb.printing
 149 import gdb.types
 150
 151 # Convert "enum tree_code" (tree.def and tree.h) to a dict:
 152 tree_code_dict = gdb.types.make_enum_dict(gdb.lookup_type('enum tree_code'))
 153
 154 # ...and look up specific values for use later:
 155 IDENTIFIER_NODE = tree_code_dict['IDENTIFIER_NODE']
 156 TYPE_DECL = tree_code_dict['TYPE_DECL']
 157
 158 # Similarly for "enum tree_code_class" (tree.h):
 159 tree_code_class_dict = gdb.types.make_enum_dict(gdb.lookup_type('enum tree_code_class'))
 160 tcc_type = tree_code_class_dict['tcc_type']
 161 tcc_declaration = tree_code_class_dict['tcc_declaration']
 162
 163 # Python3 has int() with arbitrary precision (bignum).  Python2 int() is 32-bit
 164 # on 32-bit hosts but remote targets may have 64-bit pointers there; Python2
 165 # long() is always 64-bit but Python3 no longer has anything named long.
 166 def intptr(gdbval):
 167     return long(gdbval) if sys.version_info.major == 2 else int(gdbval)
 168
 169 class Tree:
 170     """
 171     Wrapper around a gdb.Value for a tree, with various methods
 172     corresponding to macros in gcc/tree.h
 173     """
 174     def __init__(self, gdbval):
 175         self.gdbval = gdbval
 176
 177     def is_nonnull(self):
 178         return intptr(self.gdbval)
 179
 180     def TREE_CODE(self):
 181         """
 182         Get gdb.Value corresponding to TREE_CODE (self)
 183         as per:
 184           #define TREE_CODE(NODE) ((enum tree_code) (NODE)->base.code)
 185         """
 186         return self.gdbval['base']['code']
 187
 188     def DECL_NAME(self):
 189         """
 190         Get Tree instance corresponding to DECL_NAME (self)
 191         """
 192         return Tree(self.gdbval['decl_minimal']['name'])
 193
 194     def TYPE_NAME(self):
 195         """
 196         Get Tree instance corresponding to result of TYPE_NAME (self)
 197         """
 198         return Tree(self.gdbval['type_common']['name'])
 199
 200     def IDENTIFIER_POINTER(self):
 201         """
 202         Get str correspoinding to result of IDENTIFIER_NODE (self)
 203         """
 204         return self.gdbval['identifier']['id']['str'].string()
 205
 206 class TreePrinter:
 207     "Prints a tree"
 208
 209     def __init__ (self, gdbval):
 210         self.gdbval = gdbval
 211         self.node = Tree(gdbval)
 212
 213     def to_string (self):
 214         # like gcc/print-tree.c:print_node_brief
 215         # #define TREE_CODE(NODE) ((enum tree_code) (NODE)->base.code)
 216         # tree_code_name[(int) TREE_CODE (node)])
 217         if intptr(self.gdbval) == 0:
 218             return '<tree 0x0>'
 219
 220         val_TREE_CODE = self.node.TREE_CODE()
 221
 222         # extern const enum tree_code_class tree_code_type[];
 223         # #define TREE_CODE_CLASS(CODE) tree_code_type[(int) (CODE)]
 224
 225         val_tree_code_type = gdb.parse_and_eval('tree_code_type')
 226         val_tclass = val_tree_code_type[val_TREE_CODE]
 227
 228         val_tree_code_name = gdb.parse_and_eval('tree_code_name')
 229         val_code_name = val_tree_code_name[intptr(val_TREE_CODE)]
 230         #print(val_code_name.string())
 231
 232         result = '<%s 0x%x' % (val_code_name.string(), intptr(self.gdbval))
 233         if intptr(val_tclass) == tcc_declaration:
 234             tree_DECL_NAME = self.node.DECL_NAME()
 235             if tree_DECL_NAME.is_nonnull():
 236                  result += ' %s' % tree_DECL_NAME.IDENTIFIER_POINTER()
 237             else:
 238                 pass # TODO: labels etc
 239         elif intptr(val_tclass) == tcc_type:
 240             tree_TYPE_NAME = Tree(self.gdbval['type_common']['name'])
 241             if tree_TYPE_NAME.is_nonnull():
 242                 if tree_TYPE_NAME.TREE_CODE() == IDENTIFIER_NODE:
 243                     result += ' %s' % tree_TYPE_NAME.IDENTIFIER_POINTER()
 244                 elif tree_TYPE_NAME.TREE_CODE() == TYPE_DECL:
 245                     if tree_TYPE_NAME.DECL_NAME().is_nonnull():
 246                         result += ' %s' % tree_TYPE_NAME.DECL_NAME().IDENTIFIER_POINTER()
 247         if self.node.TREE_CODE() == IDENTIFIER_NODE:
 248             result += ' %s' % self.node.IDENTIFIER_POINTER()
 249         # etc
 250         result += '>'
 251         return result
 252
 253 ######################################################################
 254 # Callgraph pretty-printers
 255 ######################################################################
 256
 257 class SymtabNodePrinter:
 258     def __init__(self, gdbval):
 259         self.gdbval = gdbval
 260
 261     def to_string (self):
 262         t = str(self.gdbval.type)
 263         result = '<%s 0x%x' % (t, intptr(self.gdbval))
 264         if intptr(self.gdbval):
 265             # symtab_node::name calls lang_hooks.decl_printable_name
 266             # default implementation (lhd_decl_printable_name) is:
 267             #    return IDENTIFIER_POINTER (DECL_NAME (decl));
 268             tree_decl = Tree(self.gdbval['decl'])
 269             result += ' "%s"/%d' % (tree_decl.DECL_NAME().IDENTIFIER_POINTER(), self.gdbval['order'])
 270         result += '>'
 271         return result
 272
 273 class CgraphEdgePrinter:
 274     def __init__(self, gdbval):
 275         self.gdbval = gdbval
 276
 277     def to_string (self):
 278         result = '<cgraph_edge* 0x%x' % intptr(self.gdbval)
 279         if intptr(self.gdbval):
 280             src = SymtabNodePrinter(self.gdbval['caller']).to_string()
 281             dest = SymtabNodePrinter(self.gdbval['callee']).to_string()
 282             result += ' (%s -> %s)' % (src, dest)
 283         result += '>'
 284         return result
 285
 286 class IpaReferencePrinter:
 287     def __init__(self, gdbval):
 288         self.gdbval = gdbval
 289
 290     def to_string (self):
 291         result = '<ipa_ref* 0x%x' % intptr(self.gdbval)
 292         if intptr(self.gdbval):
 293             src = SymtabNodePrinter(self.gdbval['referring']).to_string()
 294             dest = SymtabNodePrinter(self.gdbval['referred']).to_string()
 295             result += ' (%s -> %s:%s)' % (src, dest, str(self.gdbval['use']))
 296         result += '>'
 297         return result
 298
 299 ######################################################################
 300 # Dwarf DIE pretty-printers
 301 ######################################################################
 302
 303 class DWDieRefPrinter:
 304     def __init__(self, gdbval):
 305         self.gdbval = gdbval
 306
 307     def to_string (self):
 308         if intptr(self.gdbval) == 0:
 309             return '<dw_die_ref 0x0>'
 310         result = '<dw_die_ref 0x%x' % intptr(self.gdbval)
 311         result += ' %s' % self.gdbval['die_tag']
 312         if intptr(self.gdbval['die_parent']) != 0:
 313             result += ' <parent=0x%x %s>' % (intptr(self.gdbval['die_parent']),
 314                                              self.gdbval['die_parent']['die_tag'])
 315
 316         result += '>'
 317         return result
 318
 319 ######################################################################
 320
 321 class GimplePrinter:
 322     def __init__(self, gdbval):
 323         self.gdbval = gdbval
 324
 325     def to_string (self):
 326         if intptr(self.gdbval) == 0:
 327             return '<gimple 0x0>'
 328         val_gimple_code = self.gdbval['code']
 329         val_gimple_code_name = gdb.parse_and_eval('gimple_code_name')
 330         val_code_name = val_gimple_code_name[intptr(val_gimple_code)]
 331         result = '<%s 0x%x' % (val_code_name.string(),
 332                                intptr(self.gdbval))
 333         result += '>'
 334         return result
 335
 336 ######################################################################
 337 # CFG pretty-printers
 338 ######################################################################
 339
 340 def bb_index_to_str(index):
 341     if index == 0:
 342         return 'ENTRY'
 343     elif index == 1:
 344         return 'EXIT'
 345     else:
 346         return '%i' % index
 347
 348 class BasicBlockPrinter:
 349     def __init__(self, gdbval):
 350         self.gdbval = gdbval
 351
 352     def to_string (self):
 353         result = '<basic_block 0x%x' % intptr(self.gdbval)
 354         if intptr(self.gdbval):
 355             result += ' (%s)' % bb_index_to_str(intptr(self.gdbval['index']))
 356         result += '>'
 357         return result
 358
 359 class CfgEdgePrinter:
 360     def __init__(self, gdbval):
 361         self.gdbval = gdbval
 362
 363     def to_string (self):
 364         result = '<edge 0x%x' % intptr(self.gdbval)
 365         if intptr(self.gdbval):
 366             src = bb_index_to_str(intptr(self.gdbval['src']['index']))
 367             dest = bb_index_to_str(intptr(self.gdbval['dest']['index']))
 368             result += ' (%s -> %s)' % (src, dest)
 369         result += '>'
 370         return result
 371
 372 ######################################################################
 373
 374 class Rtx:
 375     def __init__(self, gdbval):
 376         self.gdbval = gdbval
 377
 378     def GET_CODE(self):
 379         return self.gdbval['code']
 380
 381 def GET_RTX_LENGTH(code):
 382     val_rtx_length = gdb.parse_and_eval('rtx_length')
 383     return intptr(val_rtx_length[code])
 384
 385 def GET_RTX_NAME(code):
 386     val_rtx_name = gdb.parse_and_eval('rtx_name')
 387     return val_rtx_name[code].string()
 388
 389 def GET_RTX_FORMAT(code):
 390     val_rtx_format = gdb.parse_and_eval('rtx_format')
 391     return val_rtx_format[code].string()
 392
 393 class RtxPrinter:
 394     def __init__(self, gdbval):
 395         self.gdbval = gdbval
 396         self.rtx = Rtx(gdbval)
 397
 398     def to_string (self):
 399         """
 400         For now, a cheap kludge: invoke the inferior's print
 401         function to get a string to use the user, and return an empty
 402         string for gdb
 403         """
 404         # We use print_inline_rtx to avoid a trailing newline
 405         gdb.execute('call print_inline_rtx (stderr, (const_rtx) %s, 0)'
 406                     % intptr(self.gdbval))
 407         return ''
 408
 409         # or by hand; based on gcc/print-rtl.c:print_rtx
 410         result = ('<rtx_def 0x%x'
 411                   % (intptr(self.gdbval)))
 412         code = self.rtx.GET_CODE()
 413         result += ' (%s' % GET_RTX_NAME(code)
 414         format_ = GET_RTX_FORMAT(code)
 415         for i in range(GET_RTX_LENGTH(code)):
 416             print(format_[i])
 417         result += ')>'
 418         return result
 419
 420 ######################################################################
 421
 422 class PassPrinter:
 423     def __init__(self, gdbval):
 424         self.gdbval = gdbval
 425
 426     def to_string (self):
 427         result = '<opt_pass* 0x%x' % intptr(self.gdbval)
 428         if intptr(self.gdbval):
 429             result += (' "%s"(%i)'
 430                        % (self.gdbval['name'].string(),
 431                           intptr(self.gdbval['static_pass_number'])))
 432         result += '>'
 433         return result
 434
 435 ######################################################################
 436
 437 class VecPrinter:
 438     #    -ex "up" -ex "p bb->preds"
 439     def __init__(self, gdbval):
 440         self.gdbval = gdbval
 441
 442     def display_hint (self):
 443         return 'array'
 444
 445     def to_string (self):
 446         # A trivial implementation; prettyprinting the contents is done
 447         # by gdb calling the "children" method below.
 448         return '0x%x' % intptr(self.gdbval)
 449
 450     def children (self):
 451         if intptr(self.gdbval) == 0:
 452             return
 453         m_vecpfx = self.gdbval['m_vecpfx']
 454         m_num = m_vecpfx['m_num']
 455         m_vecdata = self.gdbval['m_vecdata']
 456         for i in range(m_num):
 457             yield ('[%d]' % i, m_vecdata[i])
 458
 459 ######################################################################
 460
 461 class MachineModePrinter:
 462     def __init__(self, gdbval):
 463         self.gdbval = gdbval
 464
 465     def to_string (self):
 466         name = str(self.gdbval['m_mode'])
 467         return name[2:] if name.startswith('E_') else name
 468
 469 ######################################################################
 470
 471 class OptMachineModePrinter:
 472     def __init__(self, gdbval):
 473         self.gdbval = gdbval
 474
 475     def to_string (self):
 476         name = str(self.gdbval['m_mode'])
 477         if name == 'E_VOIDmode':
 478             return '<None>'
 479         return name[2:] if name.startswith('E_') else name
 480
 481 ######################################################################
 482
 483 # TODO:
 484 #   * hashtab
 485 #   * location_t
 486
 487 class GdbSubprinter(gdb.printing.SubPrettyPrinter):
 488     def __init__(self, name, class_):
 489         super(GdbSubprinter, self).__init__(name)
 490         self.class_ = class_
 491
 492     def handles_type(self, str_type):
 493         raise NotImplementedError
 494
 495 class GdbSubprinterTypeList(GdbSubprinter):
 496     """
 497     A GdbSubprinter that handles a specific set of types
 498     """
 499     def __init__(self, str_types, name, class_):
 500         super(GdbSubprinterTypeList, self).__init__(name, class_)
 501         self.str_types = frozenset(str_types)
 502
 503     def handles_type(self, str_type):
 504         return str_type in self.str_types
 505
 506 class GdbSubprinterRegex(GdbSubprinter):
 507     """
 508     A GdbSubprinter that handles types that match a regex
 509     """
 510     def __init__(self, regex, name, class_):
 511         super(GdbSubprinterRegex, self).__init__(name, class_)
 512         self.regex = re.compile(regex)
 513
 514     def handles_type(self, str_type):
 515         return self.regex.match(str_type)
 516
 517 class GdbPrettyPrinters(gdb.printing.PrettyPrinter):
 518     def __init__(self, name):
 519         super(GdbPrettyPrinters, self).__init__(name, [])
 520
 521     def add_printer_for_types(self, name, class_, types):
 522         self.subprinters.append(GdbSubprinterTypeList(name, class_, types))
 523
 524     def add_printer_for_regex(self, name, class_, regex):
 525         self.subprinters.append(GdbSubprinterRegex(name, class_, regex))
 526
 527     def __call__(self, gdbval):
 528         type_ = gdbval.type.unqualified()
 529         str_type = str(type_)
 530         for printer in self.subprinters:
 531             if printer.enabled and printer.handles_type(str_type):
 532                 return printer.class_(gdbval)
 533
 534         # Couldn't find a pretty printer (or it was disabled):
 535         return None
 536
 537
 538 def build_pretty_printer():
 539     pp = GdbPrettyPrinters('gcc')
 540     pp.add_printer_for_types(['tree'],
 541                              'tree', TreePrinter)
 542     pp.add_printer_for_types(['cgraph_node *', 'varpool_node *', 'symtab_node *'],
 543                              'symtab_node', SymtabNodePrinter)
 544     pp.add_printer_for_types(['cgraph_edge *'],
 545                              'cgraph_edge', CgraphEdgePrinter)
 546     pp.add_printer_for_types(['ipa_ref *'],
 547                              'ipa_ref', IpaReferencePrinter)
 548     pp.add_printer_for_types(['dw_die_ref'],
 549                              'dw_die_ref', DWDieRefPrinter)
 550     pp.add_printer_for_types(['gimple', 'gimple *',
 551
 552                               # Keep this in the same order as gimple.def:
 553                               'gimple_cond', 'const_gimple_cond',
 554                               'gimple_statement_cond *',
 555                               'gimple_debug', 'const_gimple_debug',
 556                               'gimple_statement_debug *',
 557                               'gimple_label', 'const_gimple_label',
 558                               'gimple_statement_label *',
 559                               'gimple_switch', 'const_gimple_switch',
 560                               'gimple_statement_switch *',
 561                               'gimple_assign', 'const_gimple_assign',
 562                               'gimple_statement_assign *',
 563                               'gimple_bind', 'const_gimple_bind',
 564                               'gimple_statement_bind *',
 565                               'gimple_phi', 'const_gimple_phi',
 566                               'gimple_statement_phi *'],
 567
 568                              'gimple',
 569                              GimplePrinter)
 570     pp.add_printer_for_types(['basic_block', 'basic_block_def *'],
 571                              'basic_block',
 572                              BasicBlockPrinter)
 573     pp.add_printer_for_types(['edge', 'edge_def *'],
 574                              'edge',
 575                              CfgEdgePrinter)
 576     pp.add_printer_for_types(['rtx_def *'], 'rtx_def', RtxPrinter)
 577     pp.add_printer_for_types(['opt_pass *'], 'opt_pass', PassPrinter)
 578
 579     pp.add_printer_for_regex(r'vec<(\S+), (\S+), (\S+)> \*',
 580                              'vec',
 581                              VecPrinter)
 582
 583     pp.add_printer_for_regex(r'opt_mode<(\S+)>',
 584                              'opt_mode', OptMachineModePrinter)
 585     pp.add_printer_for_types(['opt_scalar_int_mode',
 586                               'opt_scalar_float_mode',
 587                               'opt_scalar_mode'],
 588                              'opt_mode', OptMachineModePrinter)
 589     pp.add_printer_for_regex(r'pod_mode<(\S+)>',
 590                              'pod_mode', MachineModePrinter)
 591     pp.add_printer_for_types(['scalar_int_mode_pod',
 592                               'scalar_mode_pod'],
 593                              'pod_mode', MachineModePrinter)
 594     for mode in ('scalar_mode', 'scalar_int_mode', 'scalar_float_mode',
 595                  'complex_mode'):
 596         pp.add_printer_for_types([mode], mode, MachineModePrinter)
 597
 598     return pp
 599
 600 gdb.printing.register_pretty_printer(
 601     gdb.current_objfile(),
 602     build_pretty_printer())
 603
 604 def find_gcc_source_dir():
 605     # Use location of global "g" to locate the source tree
 606     sym_g = gdb.lookup_global_symbol('g')
 607     path = sym_g.symtab.filename # e.g. '../../src/gcc/context.h'
 608     srcdir = os.path.split(path)[0] # e.g. '../../src/gcc'
 609     return srcdir
 610
 611 class PassNames:
 612     """Parse passes.def, gathering a list of pass class names"""
 613     def __init__(self):
 614         srcdir = find_gcc_source_dir()
 615         self.names = []
 616         with open(os.path.join(srcdir, 'passes.def')) as f:
 617             for line in f:
 618                 m = re.match('\s*NEXT_PASS \(([^,]+).*\);', line)
 619                 if m:
 620                     self.names.append(m.group(1))
 621
 622 class BreakOnPass(gdb.Command):
 623     """
 624     A custom command for putting breakpoints on the execute hook of passes.
 625     This is largely a workaround for issues with tab-completion in gdb when
 626     setting breakpoints on methods on classes within anonymous namespaces.
 627
 628     Example of use: putting a breakpoint on "final"
 629       (gdb) break-on-pass
 630     Press <TAB>; it autocompletes to "pass_":
 631       (gdb) break-on-pass pass_
 632     Press <TAB>:
 633       Display all 219 possibilities? (y or n)
 634     Press "n"; then type "f":
 635       (gdb) break-on-pass pass_f
 636     Press <TAB> to autocomplete to pass classnames beginning with "pass_f":
 637       pass_fast_rtl_dce              pass_fold_builtins
 638       pass_feedback_split_functions  pass_forwprop
 639       pass_final                     pass_fre
 640       pass_fixup_cfg                 pass_free_cfg
 641     Type "in<TAB>" to complete to "pass_final":
 642       (gdb) break-on-pass pass_final
 643     ...and hit <RETURN>:
 644       Breakpoint 6 at 0x8396ba: file ../../src/gcc/final.c, line 4526.
 645     ...and we have a breakpoint set; continue execution:
 646       (gdb) cont
 647       Continuing.
 648       Breakpoint 6, (anonymous namespace)::pass_final::execute (this=0x17fb990) at ../../src/gcc/final.c:4526
 649       4526        virtual unsigned int execute (function *) { return rest_of_handle_final (); }
 650     """
 651     def __init__(self):
 652         gdb.Command.__init__(self, 'break-on-pass', gdb.COMMAND_BREAKPOINTS)
 653         self.pass_names = None
 654
 655     def complete(self, text, word):
 656         # Lazily load pass names:
 657         if not self.pass_names:
 658             self.pass_names = PassNames()
 659
 660         return [name
 661                 for name in sorted(self.pass_names.names)
 662                 if name.startswith(text)]
 663
 664     def invoke(self, arg, from_tty):
 665         sym = '(anonymous namespace)::%s::execute' % arg
 666         breakpoint = gdb.Breakpoint(sym)
 667
 668 BreakOnPass()
 669
 670 class DumpFn(gdb.Command):
 671     """
 672     A custom command to dump a gimple/rtl function to file.  By default, it
 673     dumps the current function using 0 as dump_flags, but the function and flags
 674     can also be specified. If /f <file> are passed as the first two arguments,
 675     the dump is written to that file.  Otherwise, a temporary file is created
 676     and opened in the text editor specified in the EDITOR environment variable.
 677
 678     Examples of use:
 679       (gdb) dump-fn
 680       (gdb) dump-fn /f foo.1.txt
 681       (gdb) dump-fn cfun->decl
 682       (gdb) dump-fn /f foo.1.txt cfun->decl
 683       (gdb) dump-fn cfun->decl 0
 684       (gdb) dump-fn cfun->decl dump_flags
 685     """
 686
 687     def __init__(self):
 688         gdb.Command.__init__(self, 'dump-fn', gdb.COMMAND_USER)
 689
 690     def invoke(self, arg, from_tty):
 691         # Parse args, check number of args
 692         args = gdb.string_to_argv(arg)
 693         if len(args) >= 1 and args[0] == "/f":
 694             if len(args) == 1:
 695                 print ("Missing file argument")
 696                 return
 697             filename = args[1]
 698             editor_mode = False
 699             base_arg = 2
 700         else:
 701             editor = os.getenv("EDITOR", "")
 702             if editor == "":
 703                 print ("EDITOR environment variable not defined")
 704                 return
 705             editor_mode = True
 706             base_arg = 0
 707         if len(args) - base_arg > 2:
 708             print ("Too many arguments")
 709             return
 710
 711         # Set func
 712         if len(args) - base_arg >= 1:
 713             funcname = args[base_arg]
 714             printfuncname = "function %s" % funcname
 715         else:
 716             funcname = "cfun ? cfun->decl : current_function_decl"
 717             printfuncname = "current function"
 718         func = gdb.parse_and_eval(funcname)
 719         if func == 0:
 720             print ("Could not find %s" % printfuncname)
 721             return
 722         func = "(tree)%u" % func
 723
 724         # Set flags
 725         if len(args) - base_arg >= 2:
 726             flags = gdb.parse_and_eval(args[base_arg + 1])
 727         else:
 728             flags = 0
 729
 730         # Get tempory file, if necessary
 731         if editor_mode:
 732             f = tempfile.NamedTemporaryFile(delete=False, suffix=".txt")
 733             filename = f.name
 734             f.close()
 735
 736         # Open file
 737         fp = gdb.parse_and_eval("fopen (\"%s\", \"w\")" % filename)
 738         if fp == 0:
 739             print ("Could not open file: %s" % filename)
 740             return
 741         fp = "(FILE *)%u" % fp
 742
 743         # Dump function to file
 744         _ = gdb.parse_and_eval("dump_function_to_file (%s, %s, %u)" %
 745                                (func, fp, flags))
 746
 747         # Close file
 748         ret = gdb.parse_and_eval("fclose (%s)" % fp)
 749         if ret != 0:
 750             print ("Could not close file: %s" % filename)
 751             return
 752
 753         # Open file in editor, if necessary
 754         if editor_mode:
 755             os.system("( %s \"%s\"; rm \"%s\" ) &" %
 756                       (editor, filename, filename))
 757
 758 DumpFn()
 759
 760 class DotFn(gdb.Command):
 761     """
 762     A custom command to show a gimple/rtl function control flow graph.
 763     By default, it show the current function, but the function can also be
 764     specified.
 765
 766     Examples of use:
 767       (gdb) dot-fn
 768       (gdb) dot-fn cfun
 769       (gdb) dot-fn cfun 0
 770       (gdb) dot-fn cfun dump_flags
 771     """
 772     def __init__(self):
 773         gdb.Command.__init__(self, 'dot-fn', gdb.COMMAND_USER)
 774
 775     def invoke(self, arg, from_tty):
 776         # Parse args, check number of args
 777         args = gdb.string_to_argv(arg)
 778         if len(args) > 2:
 779             print("Too many arguments")
 780             return
 781
 782         # Set func
 783         if len(args) >= 1:
 784             funcname = args[0]
 785             printfuncname = "function %s" % funcname
 786         else:
 787             funcname = "cfun"
 788             printfuncname = "current function"
 789         func = gdb.parse_and_eval(funcname)
 790         if func == 0:
 791             print("Could not find %s" % printfuncname)
 792             return
 793         func = "(struct function *)%s" % func
 794
 795         # Set flags
 796         if len(args) >= 2:
 797             flags = gdb.parse_and_eval(args[1])
 798         else:
 799             flags = 0
 800
 801         # Get temp file
 802         f = tempfile.NamedTemporaryFile(delete=False)
 803         filename = f.name
 804
 805         # Close and reopen temp file to get C FILE*
 806         f.close()
 807         fp = gdb.parse_and_eval("fopen (\"%s\", \"w\")" % filename)
 808         if fp == 0:
 809             print("Cannot open temp file")
 810             return
 811         fp = "(FILE *)%u" % fp
 812
 813         # Write graph to temp file
 814         _ = gdb.parse_and_eval("start_graph_dump (%s, \"<debug>\")" % fp)
 815         _ = gdb.parse_and_eval("print_graph_cfg (%s, %s, %u)"
 816                                % (fp, func, flags))
 817         _ = gdb.parse_and_eval("end_graph_dump (%s)" % fp)
 818
 819         # Close temp file
 820         ret = gdb.parse_and_eval("fclose (%s)" % fp)
 821         if ret != 0:
 822             print("Could not close temp file: %s" % filename)
 823             return
 824
 825         # Show graph in temp file
 826         os.system("( dot -Tx11 \"%s\"; rm \"%s\" ) &" % (filename, filename))
 827
 828 DotFn()
 829
 830 print('Successfully loaded GDB hooks for GCC')