old-cross-binutils/gdb/testsuite/gdb.dwarf2/dw2-abs-hi-pc-world.c

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DWARF: Read constant-class addresses correctly Starting with DWARF version 4, the description of the DW_AT_high_pc attribute was amended to say: if it is of class constant, the value is an unsigned integer offset which when added to the low PC gives the address of the first location past the last instruction associated with the entity. A change was made in Apr 27th, 2012 to reflect that change: | commit 91da14142c0171e58a91ad58a32fd010b700e761 | Author: Mark Wielaard <mjw@redhat.com> | Date: Fri Apr 27 18:55:19 2012 +0000 | | * dwarf2read.c (dwarf2_get_pc_bounds): Check DW_AT_high_pc form to | see whether it is an address or a constant offset from DW_AT_low_pc. | (dwarf2_record_block_ranges): Likewise. | (read_partial_die): Likewise. Unfortunately, this new interpretation is now used regardless of the CU's DWARF version. It turns out that one of WindRiver's compilers (FTR: Diabdata 4.4) is generating DWARF version 2 info with DW_AT_high_pc attributes improperly using the data4 form. Because of that, we miscompute all high PCs incorrectly. This leads to a lot of symtabs having overlapping ranges, which in turn causes havoc in pc-to-symtab-and-line translations. One visible effect is when inserting a breakpoint on a given function: (gdb) b world Breakpoint 1 at 0x4005c4 The source location of the breakpoint is missing. The output should be: (gdb) b world Breakpoint 1 at 0x4005c8: file dw2-rel-hi-pc-world.c, line 24. What happens in this case is that the pc-to-SAL translation first starts be trying to find the symtab associated to our PC using each symtab's ranges. Because of the high_pc miscomputation, many symtabs end up matching, and the heuristic trying to select the most probable one unfortunately returns one that is unrelated (it really had no change in this case to do any better). Once we have the wrong symtab, the start searching the associated linetable, where the addresses are correct, thus finding no match, and therefore no SAL. This patch is an attempt at handling the situation as gracefully as we can, without guarantees. It introduces a new function "attr_value_as_address" which uses the correct accessor for getting the value of a given attribute. It then adjust the code throughout this unit to use this function instead of assuming that addresses always have the DW_FORM_addr format. It also fixes the original issue of miscomputing the high_pc by limiting the new interpretation of constant form DW_AT_high_pc attributes to units using DWARF version 4 or later. gdb/ChangeLog: * dwarf2read.c (attr_value_as_address): New function. (dwarf2_find_base_address, read_call_site_scope): Use attr_value_as_address in place of DW_ADDR. (dwarf2_get_pc_bounds): Use attr_value_as_address to get the low and high addresses. Slight rework of the handling of the high pc being a constant form, and limit it to DWARF verson 4 or higher. (dwarf2_record_block_ranges): Likewise. (read_partial_die): Likewise. (new_symbol_full): Use attr_value_as_address in place of DW_ADDR. gdb/testsuite/ChangeLog: * gdb.dwarf2/dw2-abs-hi-pc-hello-dbg.S: New file. * gdb.dwarf2/dw2-abs-hi-pc-hello.c: New file. * gdb.dwarf2/dw2-abs-hi-pc-world-dbg.S: New file. * gdb.dwarf2/dw2-abs-hi-pc-world.c: New file. * gdb.dwarf2/dw2-abs-hi-pc.c: New file. * gdb.dwarf2/dw2-abs-hi-pc.exp: New file. Tested on x86_64-linux.
2014-02-15 15:09:58 +00:00
/* Copyright 2014 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
extern int v;
asm (".world_start: .globl .world_start\n");
void
world (void)
{
asm (".world0: .globl .world0\n");
v++;
asm (".world1: .globl .world1\n");
}
asm (".world_end: .globl .world_end\n");