gcc/gdbhooks.py

   1 # Python hooks for gdb for debugging GCC
   2 # Copyright (C) 2013-2020 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         if val_TREE_CODE == 0xa5a5:
 226             return '<ggc_freed 0x%x>' % intptr(self.gdbval)
 227
 228         val_tree_code_type = gdb.parse_and_eval('tree_code_type')
 229         val_tclass = val_tree_code_type[val_TREE_CODE]
 230
 231         val_tree_code_name = gdb.parse_and_eval('tree_code_name')
 232         val_code_name = val_tree_code_name[intptr(val_TREE_CODE)]
 233         #print(val_code_name.string())
 234
 235         try:
 236             result = '<%s 0x%x' % (val_code_name.string(), intptr(self.gdbval))
 237         except:
 238             return '<tree 0x%x>' % intptr(self.gdbval)
 239         if intptr(val_tclass) == tcc_declaration:
 240             tree_DECL_NAME = self.node.DECL_NAME()
 241             if tree_DECL_NAME.is_nonnull():
 242                  result += ' %s' % tree_DECL_NAME.IDENTIFIER_POINTER()
 243             else:
 244                 pass # TODO: labels etc
 245         elif intptr(val_tclass) == tcc_type:
 246             tree_TYPE_NAME = Tree(self.gdbval['type_common']['name'])
 247             if tree_TYPE_NAME.is_nonnull():
 248                 if tree_TYPE_NAME.TREE_CODE() == IDENTIFIER_NODE:
 249                     result += ' %s' % tree_TYPE_NAME.IDENTIFIER_POINTER()
 250                 elif tree_TYPE_NAME.TREE_CODE() == TYPE_DECL:
 251                     if tree_TYPE_NAME.DECL_NAME().is_nonnull():
 252                         result += ' %s' % tree_TYPE_NAME.DECL_NAME().IDENTIFIER_POINTER()
 253         if self.node.TREE_CODE() == IDENTIFIER_NODE:
 254             result += ' %s' % self.node.IDENTIFIER_POINTER()
 255         # etc
 256         result += '>'
 257         return result
 258
 259 ######################################################################
 260 # Callgraph pretty-printers
 261 ######################################################################
 262
 263 class SymtabNodePrinter:
 264     def __init__(self, gdbval):
 265         self.gdbval = gdbval
 266
 267     def to_string (self):
 268         t = str(self.gdbval.type)
 269         result = '<%s 0x%x' % (t, intptr(self.gdbval))
 270         if intptr(self.gdbval):
 271             # symtab_node::name calls lang_hooks.decl_printable_name
 272             # default implementation (lhd_decl_printable_name) is:
 273             #    return IDENTIFIER_POINTER (DECL_NAME (decl));
 274             tree_decl = Tree(self.gdbval['decl'])
 275             result += ' "%s"/%d' % (tree_decl.DECL_NAME().IDENTIFIER_POINTER(), self.gdbval['order'])
 276         result += '>'
 277         return result
 278
 279 class CgraphEdgePrinter:
 280     def __init__(self, gdbval):
 281         self.gdbval = gdbval
 282
 283     def to_string (self):
 284         result = '<cgraph_edge* 0x%x' % intptr(self.gdbval)
 285         if intptr(self.gdbval):
 286             src = SymtabNodePrinter(self.gdbval['caller']).to_string()
 287             dest = SymtabNodePrinter(self.gdbval['callee']).to_string()
 288             result += ' (%s -> %s)' % (src, dest)
 289         result += '>'
 290         return result
 291
 292 class IpaReferencePrinter:
 293     def __init__(self, gdbval):
 294         self.gdbval = gdbval
 295
 296     def to_string (self):
 297         result = '<ipa_ref* 0x%x' % intptr(self.gdbval)
 298         if intptr(self.gdbval):
 299             src = SymtabNodePrinter(self.gdbval['referring']).to_string()
 300             dest = SymtabNodePrinter(self.gdbval['referred']).to_string()
 301             result += ' (%s -> %s:%s)' % (src, dest, str(self.gdbval['use']))
 302         result += '>'
 303         return result
 304
 305 ######################################################################
 306 # Dwarf DIE pretty-printers
 307 ######################################################################
 308
 309 class DWDieRefPrinter:
 310     def __init__(self, gdbval):
 311         self.gdbval = gdbval
 312
 313     def to_string (self):
 314         if intptr(self.gdbval) == 0:
 315             return '<dw_die_ref 0x0>'
 316         result = '<dw_die_ref 0x%x' % intptr(self.gdbval)
 317         result += ' %s' % self.gdbval['die_tag']
 318         if intptr(self.gdbval['die_parent']) != 0:
 319             result += ' <parent=0x%x %s>' % (intptr(self.gdbval['die_parent']),
 320                                              self.gdbval['die_parent']['die_tag'])
 321
 322         result += '>'
 323         return result
 324
 325 ######################################################################
 326
 327 class GimplePrinter:
 328     def __init__(self, gdbval):
 329         self.gdbval = gdbval
 330
 331     def to_string (self):
 332         if intptr(self.gdbval) == 0:
 333             return '<gimple 0x0>'
 334         val_gimple_code = self.gdbval['code']
 335         val_gimple_code_name = gdb.parse_and_eval('gimple_code_name')
 336         val_code_name = val_gimple_code_name[intptr(val_gimple_code)]
 337         result = '<%s 0x%x' % (val_code_name.string(),
 338                                intptr(self.gdbval))
 339         result += '>'
 340         return result
 341
 342 ######################################################################
 343 # CFG pretty-printers
 344 ######################################################################
 345
 346 def bb_index_to_str(index):
 347     if index == 0:
 348         return 'ENTRY'
 349     elif index == 1:
 350         return 'EXIT'
 351     else:
 352         return '%i' % index
 353
 354 class BasicBlockPrinter:
 355     def __init__(self, gdbval):
 356         self.gdbval = gdbval
 357
 358     def to_string (self):
 359         result = '<basic_block 0x%x' % intptr(self.gdbval)
 360         if intptr(self.gdbval):
 361             result += ' (%s)' % bb_index_to_str(intptr(self.gdbval['index']))
 362         result += '>'
 363         return result
 364
 365 class CfgEdgePrinter:
 366     def __init__(self, gdbval):
 367         self.gdbval = gdbval
 368
 369     def to_string (self):
 370         result = '<edge 0x%x' % intptr(self.gdbval)
 371         if intptr(self.gdbval):
 372             src = bb_index_to_str(intptr(self.gdbval['src']['index']))
 373             dest = bb_index_to_str(intptr(self.gdbval['dest']['index']))
 374             result += ' (%s -> %s)' % (src, dest)
 375         result += '>'
 376         return result
 377
 378 ######################################################################
 379
 380 class Rtx:
 381     def __init__(self, gdbval):
 382         self.gdbval = gdbval
 383
 384     def GET_CODE(self):
 385         return self.gdbval['code']
 386
 387 def GET_RTX_LENGTH(code):
 388     val_rtx_length = gdb.parse_and_eval('rtx_length')
 389     return intptr(val_rtx_length[code])
 390
 391 def GET_RTX_NAME(code):
 392     val_rtx_name = gdb.parse_and_eval('rtx_name')
 393     return val_rtx_name[code].string()
 394
 395 def GET_RTX_FORMAT(code):
 396     val_rtx_format = gdb.parse_and_eval('rtx_format')
 397     return val_rtx_format[code].string()
 398
 399 class RtxPrinter:
 400     def __init__(self, gdbval):
 401         self.gdbval = gdbval
 402         self.rtx = Rtx(gdbval)
 403
 404     def to_string (self):
 405         """
 406         For now, a cheap kludge: invoke the inferior's print
 407         function to get a string to use the user, and return an empty
 408         string for gdb
 409         """
 410         # We use print_inline_rtx to avoid a trailing newline
 411         gdb.execute('call print_inline_rtx (stderr, (const_rtx) %s, 0)'
 412                     % intptr(self.gdbval))
 413         return ''
 414
 415         # or by hand; based on gcc/print-rtl.c:print_rtx
 416         result = ('<rtx_def 0x%x'
 417                   % (intptr(self.gdbval)))
 418         code = self.rtx.GET_CODE()
 419         result += ' (%s' % GET_RTX_NAME(code)
 420         format_ = GET_RTX_FORMAT(code)
 421         for i in range(GET_RTX_LENGTH(code)):
 422             print(format_[i])
 423         result += ')>'
 424         return result
 425
 426 ######################################################################
 427
 428 class PassPrinter:
 429     def __init__(self, gdbval):
 430         self.gdbval = gdbval
 431
 432     def to_string (self):
 433         result = '<opt_pass* 0x%x' % intptr(self.gdbval)
 434         if intptr(self.gdbval):
 435             result += (' "%s"(%i)'
 436                        % (self.gdbval['name'].string(),
 437                           intptr(self.gdbval['static_pass_number'])))
 438         result += '>'
 439         return result
 440
 441 ######################################################################
 442
 443 class VecPrinter:
 444     #    -ex "up" -ex "p bb->preds"
 445     def __init__(self, gdbval):
 446         self.gdbval = gdbval
 447
 448     def display_hint (self):
 449         return 'array'
 450
 451     def to_string (self):
 452         # A trivial implementation; prettyprinting the contents is done
 453         # by gdb calling the "children" method below.
 454         return '0x%x' % intptr(self.gdbval)
 455
 456     def children (self):
 457         if intptr(self.gdbval) == 0:
 458             return
 459         m_vecpfx = self.gdbval['m_vecpfx']
 460         m_num = m_vecpfx['m_num']
 461         m_vecdata = self.gdbval['m_vecdata']
 462         for i in range(m_num):
 463             yield ('[%d]' % i, m_vecdata[i])
 464
 465 ######################################################################
 466
 467 class MachineModePrinter:
 468     def __init__(self, gdbval):
 469         self.gdbval = gdbval
 470
 471     def to_string (self):
 472         name = str(self.gdbval['m_mode'])
 473         return name[2:] if name.startswith('E_') else name
 474
 475 ######################################################################
 476
 477 class OptMachineModePrinter:
 478     def __init__(self, gdbval):
 479         self.gdbval = gdbval
 480
 481     def to_string (self):
 482         name = str(self.gdbval['m_mode'])
 483         if name == 'E_VOIDmode':
 484             return '<None>'
 485         return name[2:] if name.startswith('E_') else name
 486
 487 ######################################################################
 488
 489 # TODO:
 490 #   * hashtab
 491 #   * location_t
 492
 493 class GdbSubprinter(gdb.printing.SubPrettyPrinter):
 494     def __init__(self, name, class_):
 495         super(GdbSubprinter, self).__init__(name)
 496         self.class_ = class_
 497
 498     def handles_type(self, str_type):
 499         raise NotImplementedError
 500
 501 class GdbSubprinterTypeList(GdbSubprinter):
 502     """
 503     A GdbSubprinter that handles a specific set of types
 504     """
 505     def __init__(self, str_types, name, class_):
 506         super(GdbSubprinterTypeList, self).__init__(name, class_)
 507         self.str_types = frozenset(str_types)
 508
 509     def handles_type(self, str_type):
 510         return str_type in self.str_types
 511
 512 class GdbSubprinterRegex(GdbSubprinter):
 513     """
 514     A GdbSubprinter that handles types that match a regex
 515     """
 516     def __init__(self, regex, name, class_):
 517         super(GdbSubprinterRegex, self).__init__(name, class_)
 518         self.regex = re.compile(regex)
 519
 520     def handles_type(self, str_type):
 521         return self.regex.match(str_type)
 522
 523 class GdbPrettyPrinters(gdb.printing.PrettyPrinter):
 524     def __init__(self, name):
 525         super(GdbPrettyPrinters, self).__init__(name, [])
 526
 527     def add_printer_for_types(self, types, name, class_):
 528         self.subprinters.append(GdbSubprinterTypeList(types, name, class_))
 529
 530     def add_printer_for_regex(self, regex, name, class_):
 531         self.subprinters.append(GdbSubprinterRegex(regex, name, class_))
 532
 533     def __call__(self, gdbval):
 534         type_ = gdbval.type.unqualified()
 535         str_type = str(type_)
 536         for printer in self.subprinters:
 537             if printer.enabled and printer.handles_type(str_type):
 538                 return printer.class_(gdbval)
 539
 540         # Couldn't find a pretty printer (or it was disabled):
 541         return None
 542
 543
 544 def build_pretty_printer():
 545     pp = GdbPrettyPrinters('gcc')
 546     pp.add_printer_for_types(['tree', 'const_tree'],
 547                              'tree', TreePrinter)
 548     pp.add_printer_for_types(['cgraph_node *', 'varpool_node *', 'symtab_node *'],
 549                              'symtab_node', SymtabNodePrinter)
 550     pp.add_printer_for_types(['cgraph_edge *'],
 551                              'cgraph_edge', CgraphEdgePrinter)
 552     pp.add_printer_for_types(['ipa_ref *'],
 553                              'ipa_ref', IpaReferencePrinter)
 554     pp.add_printer_for_types(['dw_die_ref'],
 555                              'dw_die_ref', DWDieRefPrinter)
 556     pp.add_printer_for_types(['gimple', 'gimple *',
 557
 558                               # Keep this in the same order as gimple.def:
 559                               'gimple_cond', 'const_gimple_cond',
 560                               'gimple_statement_cond *',
 561                               'gimple_debug', 'const_gimple_debug',
 562                               'gimple_statement_debug *',
 563                               'gimple_label', 'const_gimple_label',
 564                               'gimple_statement_label *',
 565                               'gimple_switch', 'const_gimple_switch',
 566                               'gimple_statement_switch *',
 567                               'gimple_assign', 'const_gimple_assign',
 568                               'gimple_statement_assign *',
 569                               'gimple_bind', 'const_gimple_bind',
 570                               'gimple_statement_bind *',
 571                               'gimple_phi', 'const_gimple_phi',
 572                               'gimple_statement_phi *'],
 573
 574                              'gimple',
 575                              GimplePrinter)
 576     pp.add_printer_for_types(['basic_block', 'basic_block_def *'],
 577                              'basic_block',
 578                              BasicBlockPrinter)
 579     pp.add_printer_for_types(['edge', 'edge_def *'],
 580                              'edge',
 581                              CfgEdgePrinter)
 582     pp.add_printer_for_types(['rtx_def *'], 'rtx_def', RtxPrinter)
 583     pp.add_printer_for_types(['opt_pass *'], 'opt_pass', PassPrinter)
 584
 585     pp.add_printer_for_regex(r'vec<(\S+), (\S+), (\S+)> \*',
 586                              'vec',
 587                              VecPrinter)
 588
 589     pp.add_printer_for_regex(r'opt_mode<(\S+)>',
 590                              'opt_mode', OptMachineModePrinter)
 591     pp.add_printer_for_types(['opt_scalar_int_mode',
 592                               'opt_scalar_float_mode',
 593                               'opt_scalar_mode'],
 594                              'opt_mode', OptMachineModePrinter)
 595     pp.add_printer_for_regex(r'pod_mode<(\S+)>',
 596                              'pod_mode', MachineModePrinter)
 597     pp.add_printer_for_types(['scalar_int_mode_pod',
 598                               'scalar_mode_pod'],
 599                              'pod_mode', MachineModePrinter)
 600     for mode in ('scalar_mode', 'scalar_int_mode', 'scalar_float_mode',
 601                  'complex_mode'):
 602         pp.add_printer_for_types([mode], mode, MachineModePrinter)
 603
 604     return pp
 605
 606 gdb.printing.register_pretty_printer(
 607     gdb.current_objfile(),
 608     build_pretty_printer(),
 609     replace=True)
 610
 611 def find_gcc_source_dir():
 612     # Use location of global "g" to locate the source tree
 613     sym_g = gdb.lookup_global_symbol('g')
 614     path = sym_g.symtab.filename # e.g. '../../src/gcc/context.h'
 615     srcdir = os.path.split(path)[0] # e.g. '../../src/gcc'
 616     return srcdir
 617
 618 class PassNames:
 619     """Parse passes.def, gathering a list of pass class names"""
 620     def __init__(self):
 621         srcdir = find_gcc_source_dir()
 622         self.names = []
 623         with open(os.path.join(srcdir, 'passes.def')) as f:
 624             for line in f:
 625                 m = re.match('\s*NEXT_PASS \(([^,]+).*\);', line)
 626                 if m:
 627                     self.names.append(m.group(1))
 628
 629 class BreakOnPass(gdb.Command):
 630     """
 631     A custom command for putting breakpoints on the execute hook of passes.
 632     This is largely a workaround for issues with tab-completion in gdb when
 633     setting breakpoints on methods on classes within anonymous namespaces.
 634
 635     Example of use: putting a breakpoint on "final"
 636       (gdb) break-on-pass
 637     Press <TAB>; it autocompletes to "pass_":
 638       (gdb) break-on-pass pass_
 639     Press <TAB>:
 640       Display all 219 possibilities? (y or n)
 641     Press "n"; then type "f":
 642       (gdb) break-on-pass pass_f
 643     Press <TAB> to autocomplete to pass classnames beginning with "pass_f":
 644       pass_fast_rtl_dce              pass_fold_builtins
 645       pass_feedback_split_functions  pass_forwprop
 646       pass_final                     pass_fre
 647       pass_fixup_cfg                 pass_free_cfg
 648     Type "in<TAB>" to complete to "pass_final":
 649       (gdb) break-on-pass pass_final
 650     ...and hit <RETURN>:
 651       Breakpoint 6 at 0x8396ba: file ../../src/gcc/final.c, line 4526.
 652     ...and we have a breakpoint set; continue execution:
 653       (gdb) cont
 654       Continuing.
 655       Breakpoint 6, (anonymous namespace)::pass_final::execute (this=0x17fb990) at ../../src/gcc/final.c:4526
 656       4526        virtual unsigned int execute (function *) { return rest_of_handle_final (); }
 657     """
 658     def __init__(self):
 659         gdb.Command.__init__(self, 'break-on-pass', gdb.COMMAND_BREAKPOINTS)
 660         self.pass_names = None
 661
 662     def complete(self, text, word):
 663         # Lazily load pass names:
 664         if not self.pass_names:
 665             self.pass_names = PassNames()
 666
 667         return [name
 668                 for name in sorted(self.pass_names.names)
 669                 if name.startswith(text)]
 670
 671     def invoke(self, arg, from_tty):
 672         sym = '(anonymous namespace)::%s::execute' % arg
 673         breakpoint = gdb.Breakpoint(sym)
 674
 675 BreakOnPass()
 676
 677 class DumpFn(gdb.Command):
 678     """
 679     A custom command to dump a gimple/rtl function to file.  By default, it
 680     dumps the current function using 0 as dump_flags, but the function and flags
 681     can also be specified. If /f <file> are passed as the first two arguments,
 682     the dump is written to that file.  Otherwise, a temporary file is created
 683     and opened in the text editor specified in the EDITOR environment variable.
 684
 685     Examples of use:
 686       (gdb) dump-fn
 687       (gdb) dump-fn /f foo.1.txt
 688       (gdb) dump-fn cfun->decl
 689       (gdb) dump-fn /f foo.1.txt cfun->decl
 690       (gdb) dump-fn cfun->decl 0
 691       (gdb) dump-fn cfun->decl dump_flags
 692     """
 693
 694     def __init__(self):
 695         gdb.Command.__init__(self, 'dump-fn', gdb.COMMAND_USER)
 696
 697     def invoke(self, arg, from_tty):
 698         # Parse args, check number of args
 699         args = gdb.string_to_argv(arg)
 700         if len(args) >= 1 and args[0] == "/f":
 701             if len(args) == 1:
 702                 print ("Missing file argument")
 703                 return
 704             filename = args[1]
 705             editor_mode = False
 706             base_arg = 2
 707         else:
 708             editor = os.getenv("EDITOR", "")
 709             if editor == "":
 710                 print ("EDITOR environment variable not defined")
 711                 return
 712             editor_mode = True
 713             base_arg = 0
 714         if len(args) - base_arg > 2:
 715             print ("Too many arguments")
 716             return
 717
 718         # Set func
 719         if len(args) - base_arg >= 1:
 720             funcname = args[base_arg]
 721             printfuncname = "function %s" % funcname
 722         else:
 723             funcname = "cfun ? cfun->decl : current_function_decl"
 724             printfuncname = "current function"
 725         func = gdb.parse_and_eval(funcname)
 726         if func == 0:
 727             print ("Could not find %s" % printfuncname)
 728             return
 729         func = "(tree)%u" % func
 730
 731         # Set flags
 732         if len(args) - base_arg >= 2:
 733             flags = gdb.parse_and_eval(args[base_arg + 1])
 734         else:
 735             flags = 0
 736
 737         # Get tempory file, if necessary
 738         if editor_mode:
 739             f = tempfile.NamedTemporaryFile(delete=False, suffix=".txt")
 740             filename = f.name
 741             f.close()
 742
 743         # Open file
 744         fp = gdb.parse_and_eval("(FILE *) fopen (\"%s\", \"w\")" % filename)
 745         if fp == 0:
 746             print ("Could not open file: %s" % filename)
 747             return
 748
 749         # Dump function to file
 750         _ = gdb.parse_and_eval("dump_function_to_file (%s, %s, %u)" %
 751                                (func, fp, flags))
 752
 753         # Close file
 754         ret = gdb.parse_and_eval("(int) fclose (%s)" % fp)
 755         if ret != 0:
 756             print ("Could not close file: %s" % filename)
 757             return
 758
 759         # Open file in editor, if necessary
 760         if editor_mode:
 761             os.system("( %s \"%s\"; rm \"%s\" ) &" %
 762                       (editor, filename, filename))
 763
 764 DumpFn()
 765
 766 class DotFn(gdb.Command):
 767     """
 768     A custom command to show a gimple/rtl function control flow graph.
 769     By default, it show the current function, but the function can also be
 770     specified.
 771
 772     Examples of use:
 773       (gdb) dot-fn
 774       (gdb) dot-fn cfun
 775       (gdb) dot-fn cfun 0
 776       (gdb) dot-fn cfun dump_flags
 777     """
 778     def __init__(self):
 779         gdb.Command.__init__(self, 'dot-fn', gdb.COMMAND_USER)
 780
 781     def invoke(self, arg, from_tty):
 782         # Parse args, check number of args
 783         args = gdb.string_to_argv(arg)
 784         if len(args) > 2:
 785             print("Too many arguments")
 786             return
 787
 788         # Set func
 789         if len(args) >= 1:
 790             funcname = args[0]
 791             printfuncname = "function %s" % funcname
 792         else:
 793             funcname = "cfun"
 794             printfuncname = "current function"
 795         func = gdb.parse_and_eval(funcname)
 796         if func == 0:
 797             print("Could not find %s" % printfuncname)
 798             return
 799         func = "(struct function *)%s" % func
 800
 801         # Set flags
 802         if len(args) >= 2:
 803             flags = gdb.parse_and_eval(args[1])
 804         else:
 805             flags = 0
 806
 807         # Get temp file
 808         f = tempfile.NamedTemporaryFile(delete=False)
 809         filename = f.name
 810
 811         # Close and reopen temp file to get C FILE*
 812         f.close()
 813         fp = gdb.parse_and_eval("(FILE *) fopen (\"%s\", \"w\")" % filename)
 814         if fp == 0:
 815             print("Cannot open temp file")
 816             return
 817
 818         # Write graph to temp file
 819         _ = gdb.parse_and_eval("start_graph_dump (%s, \"<debug>\")" % fp)
 820         _ = gdb.parse_and_eval("print_graph_cfg (%s, %s, %u)"
 821                                % (fp, func, flags))
 822         _ = gdb.parse_and_eval("end_graph_dump (%s)" % fp)
 823
 824         # Close temp file
 825         ret = gdb.parse_and_eval("(int) fclose (%s)" % fp)
 826         if ret != 0:
 827             print("Could not close temp file: %s" % filename)
 828             return
 829
 830         # Show graph in temp file
 831         os.system("( dot -Tx11 \"%s\"; rm \"%s\" ) &" % (filename, filename))
 832
 833 DotFn()
 834
 835 print('Successfully loaded GDB hooks for GCC')