[llvm] r289961 - Revert "dwarfdump: Support/process relocations on a CU's abbrev_off"

[George Rimar via llvm-commits]

​Hi David,


I'll can apply this patch and take a look on this closer

in a next hour or two and will be able to answer then.

​

Best regards,
George.
________________________________
От: David Blaikie <dblaikie at gmail.com>
Отправлено: 20 декабря 2016 г. 21:02
Кому: llvm-commits at lists.llvm.org; George Rimar
Копия: Rui Ueyama
Тема: Re: [llvm] r289961 - Revert "dwarfdump: Support/process relocations on a CU's abbrev_off"

Hi George,

Committing this change broke your gdb-index test in lld.

It looks like the info section had a non-zero offset in the relocation pointing to the abbrev section, but the abbrev section in the object has the data at start (& dumping the raw object file from disk shows the relocation has a zero offset)

Is this data somehow modified by lld rather than being the raw bytes from the input file? How/why/where?

Any idea how to fix this change/lld so it doesn't have this problem?

As it is, dwarfdump is crashing on inputs I care about & this change seems like a reasonable fix for it, so I'm guessing we probably want to fix lld in some way?

- Dave

On Fri, Dec 16, 2016 at 9:20 AM David Blaikie via llvm-commits <llvm-commits at lists.llvm.org<mailto:llvm-commits at lists.llvm.org>> wrote:
Author: dblaikie
Date: Fri Dec 16 11:10:17 2016
New Revision: 289961

URL: http://llvm.org/viewvc/llvm-project?rev=289961&view=rev
Log:
Revert "dwarfdump: Support/process relocations on a CU's abbrev_off"

Reverting because this breaks lld's gdb_index support - it's probably
double counting the abbrev relocation offset.

This reverts commit r289954.

Removed:
    llvm/trunk/test/DebugInfo/Inputs/dwarfdump-abbrev-off.elf-x86-64
    llvm/trunk/test/DebugInfo/dwarfdump-abbrev-off.test
Modified:
    llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp

Modified: llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp?rev=289961&r1=289960&r2=289961&view=diff
==============================================================================
--- llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp (original)
+++ llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp Fri Dec 16 11:10:17 2016
@@ -87,10 +87,7 @@ bool DWARFUnit::getStringOffsetSectionIt
 bool DWARFUnit::extractImpl(DataExtractor debug_info, uint32_t *offset_ptr) {
   Length = debug_info.getU32(offset_ptr);
   Version = debug_info.getU16(offset_ptr);
-  auto AI = InfoSection.Relocs.find(*offset_ptr);
   uint64_t AbbrOffset = debug_info.getU32(offset_ptr);
-  if (AI != InfoSection.Relocs.end())
-    AbbrOffset += AI->second.second;
   if (IndexEntry) {
     if (AbbrOffset)
       return false;

Removed: llvm/trunk/test/DebugInfo/Inputs/dwarfdump-abbrev-off.elf-x86-64
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/Inputs/dwarfdump-abbrev-off.elf-x86-64?rev=289960&view=auto
==============================================================================
Binary files llvm/trunk/test/DebugInfo/Inputs/dwarfdump-abbrev-off.elf-x86-64 (original) and llvm/trunk/test/DebugInfo/Inputs/dwarfdump-abbrev-off.elf-x86-64 (removed) differ

Removed: llvm/trunk/test/DebugInfo/dwarfdump-abbrev-off.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/dwarfdump-abbrev-off.test?rev=289960&view=auto
==============================================================================
--- llvm/trunk/test/DebugInfo/dwarfdump-abbrev-off.test (original)
+++ llvm/trunk/test/DebugInfo/dwarfdump-abbrev-off.test (removed)
@@ -1,8 +0,0 @@
-RUN: llvm-dwarfdump -debug-dump=info %p/Inputs/dwarfdump-abbrev-off.elf-x86-64 | FileCheck %s
-
-Check that we apply relocations to the abbr_offset - while LLVM never produces
-an object file like this, a reproduction can be produced by linking two simple
-object files together with ld -r.
-
-CHECK: abbr_offset = 0x0000
-CHECK: abbr_offset = 0x0010


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