2018-01-01 12:43:02 +08:00
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/* Copyright (C) 2016-2018 Free Software Foundation, Inc.
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[PR gdb/19893] Fix handling of synthetic C++ references
https://sourceware.org/bugzilla/show_bug.cgi?id=19893
I've traced the main source of the problem to pieced_value_funcs.coerce_ref not being
implemented. Since gdb always assumes references are implemented as pointers, this
causes it to think that it's dealing with a NULL pointer, thus breaking any operations
involving synthetic references.
What I did here was implementing pieced_value_funcs.coerce_ref using some of the synthetic
pointer handling code from indirect_pieced_value, as Pedro suggested. I also made a few
adjustments to the reference printing code so that it correctly shows either the address
of the referenced value or (if it's non-addressable) the "<synthetic pointer>" string.
I also wrote some unit tests based on Dwarf::assemble; these took a while to make
because in most cases I needed a synthetic reference to a physical variable. Additionally,
I started working on a unit test for classes that have a vtable, but ran into a few issues
so that'll probably go in a future patch. One thing that should definitely be fixed is that
proc function_range (called for MACRO_AT_func) will always try to compile/link using gcc
with the default options instead of g++, thus breaking C++ compilations that require e.g. libstdc++.
gdb/ChangeLog:
* dwarf2loc.c (coerce_pieced_ref, indirect_synthetic_pointer,
fetch_const_value_from_synthetic_pointer): New functions.
(indirect_pieced_value): Move lower half to indirect_synthetic_pointer.
(pieced_value_funcs): Implement coerce_ref.
* valops.c (value_addr): Call coerce_ref for synthetic references.
* valprint.c (valprint_check_validity): Return true for synthetic
references. Also, don't show "<synthetic pointer>" if they reference
addressable values.
(generic_val_print_ref): Handle synthetic references. Also move some
code to print_ref_address.
(print_ref_address, get_value_addr_contents): New functions.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/implref.exp: Rename to...
* gdb.dwarf2/implref-const.exp: ...this. Also add more test statements.
* gdb.dwarf2/implref-array.c: New file.
* gdb.dwarf2/implref-array.exp: Likewise.
* gdb.dwarf2/implref-global.c: Likewise.
* gdb.dwarf2/implref-global.exp: Likewise.
* gdb.dwarf2/implref-struct.c: Likewise.
* gdb.dwarf2/implref-struct.exp: Likewise.
2016-06-01 02:54:01 +08:00
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Test program for synthetic C++ references to structs. */
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struct S {
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int a;
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int b;
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int c;
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};
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struct S s1 = {
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0,
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1,
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2
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};
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struct S s2 = {
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10,
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11,
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12
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};
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int
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main (void)
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{
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asm ("main_label: .globl main_label");
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return 0;
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}
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