forked from Imagelibrary/binutils-gdb
f0848033b8
I noticed that attempting to select a tail-call frame using 'frame function NAME' wouldn't work: (gdb) bt #0 func_that_never_returns () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:49 #1 0x0000000000401183 in func_that_tail_calls () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:59 #2 0x00000000004011a5 in main () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:70 (gdb) frame function func_that_tail_calls No frame for function "func_that_tail_calls". (gdb) up #1 0x0000000000401183 in func_that_tail_calls () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:59 59 func_that_never_returns (); (gdb) disassemble Dump of assembler code for function func_that_tail_calls: 0x000000000040117a <+0>: push %rbp 0x000000000040117b <+1>: mov %rsp,%rbp 0x000000000040117e <+4>: call 0x40116c <func_that_never_returns> End of assembler dump. (gdb) The problem is that the 'function' mechanism uses get_frame_pc() and then compares the address returned with the bounds of the function we're looking for. So in this case, the bounds of func_that_tail_calls are 0x40117a to 0x401183, with 0x401183 being the first address _after_ the function. However, because func_that_tail_calls ends in a tail call, then the get_frame_pc() is 0x401183, the first address after the function. As a result, GDB fails to realise that frame #1 is inside the function we're looking for, and the lookup fails. The fix is to use get_frame_address_in_block, which will return an adjusted address, in this case, 0x401182, which is within the function bounds. Now the lookup works: (gdb) frame function func_that_tail_calls #1 0x0000000000401183 in func_that_tail_calls () at /tmp/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/frame-selection.c:59 59 func_that_never_returns (); (gdb) I've extended the gdb.base/frame-selection.exp test to cover this case.
74 lines
1.4 KiB
C
74 lines
1.4 KiB
C
/* Copyright 2018-2024 Free Software Foundation, Inc.
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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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#include <stdlib.h>
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int
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frame_2 (void)
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{
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return 0;
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}
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int
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frame_1 (void)
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{
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return frame_2 ();
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}
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int
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recursive (int arg)
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{
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int v;
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if (arg < 2)
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v = recursive (arg + 1);
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else
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v = frame_2 ();
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return v;
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}
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/* A function that never returns. */
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void __attribute__((noreturn))
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func_that_never_returns (void)
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{
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exit (0);
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}
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/* A function that tail calls. Calling a 'noreturn' function isn't
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required for a tail call, but at low optimisation levels, gcc will apply
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the tail call optimisation only for 'noreturn' calls. */
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void
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func_that_tail_calls (void)
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{
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func_that_never_returns ();
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}
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int
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main (void)
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{
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int i, j;
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i = frame_1 ();
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j = recursive (0);
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func_that_tail_calls ();
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return i + j;
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}
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