Backport vDSO regression.
- Revert the makeinfo workaround from 7.8-27.fc21. - Further 1.75x improvement of the interactive symbols lookup (Doug Evans).
This commit is contained in:
Jan Kratochvil
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862e0ed47f
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@ -78,49 +78,91 @@ index 055c87e..90bcd6d 100644
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--17pEHd4RhPHOinZp--
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http://sourceware.org/ml/gdb-patches/2014-10/msg00525.html
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Subject: [patch 2/2] Accelerate lookup_symbol_aux_objfile 8x
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--K8nIJk4ghYZn606h
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http://sourceware.org/ml/gdb-patches/2014-10/msg00612.html
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Subject: [patchv2 2/2] Accelerate lookup_symbol_aux_objfile 14.5x [Re: [patch 0/2] Accelerate symbol lookups 15x]
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--vtzGhvizbBRQ85DL
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Content-Type: text/plain; charset=us-ascii
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Content-Disposition: inline
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Hi,
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On Wed, 22 Oct 2014 10:55:18 +0200, Doug Evans wrote:
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> For example, the count of calls to dict_hash before/after goes from 13.8M to 31.
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> I'm guessing one t hing we're doing here is coping with an artifact of
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> dwz:
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lookup_symbol_aux_objfile() processing is very ineffective. For each primary
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symtab it searches it and also all its secondary symtabs. But that means that
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secondary symtabs included in many primary symtabs get needlessly searched
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many times during one lookup_symbol_aux_objfile() run.
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During my simple test on non-DWZ file (./gdb itself) it went 3684->3484.
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lookup_symbol_aux_objfile does not care in which primary/secondary symtab the
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symbol is found.
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The problem is that dict_cash(val) is called for the same val for each block
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(== symtab).
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On DWZ the saving is probably much larger as there are many more symtabs due
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to DW_TAG_partial_unit ones.
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> what was once one global block to represent the entire objfile is
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> now N.
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Without DWZ there are X global blocks for X primary symtabs for X CUs of
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objfile. With DWZ there are X+Y global blocks for X+Y primary symtabs for
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X+Y CUs where Y are 'DW_TAG_partial_unit's.
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For 'DW_TAG_partial_unit's (Ys) their blockvector is usually empty. But not
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always, I have found there typedef symbols, there can IMO be optimized-out
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static variables etc.
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> [I'm sure the patches help in the non-dwz case, but I suspect it's less.
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> Which isn't to say the patches aren't useful.
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> I just need play with a few more examples.]
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I agree.
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[patch 2/2] could needlessly performance-regress non-DWZ cases, therefore
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I have put back original ALL_OBJFILE_PRIMARY_SYMTABS (instead of my
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ALL_OBJFILE_SYMTABS) as it is perfectly sufficient. For the performance
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testcase of mine:
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Benchmark on non-trivial application with 'p <tab><tab>':
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Command execution time: 4.215000 (cpu), 4.241466 (wall) --- both fixes with new [patch 2/2]
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Command execution time: 7.373000 (cpu), 7.395095 (wall) --- both fixes
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Command execution time: 13.572000 (cpu), 13.592689 (wall) --- just lookup_symbol_aux_objfile fix
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Command execution time: 113.036000 (cpu), 113.067995 (wall) --- FSF GDB HEAD
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That is additional 1.75x improvement, making the total improvement 26.8x.
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No regressions on {x86_64,x86_64-m32,i686}-fedora21pre-linux-gnu in standard
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and .gdb_index-enabled runs. Neither of the patches should cause any visible
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behavior change.
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Thanks,
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Jan
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--K8nIJk4ghYZn606h
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--vtzGhvizbBRQ85DL
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Content-Type: text/plain; charset=us-ascii
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Content-Disposition: inline; filename="idxcache2.patch"
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Content-Disposition: inline; filename="idxcache2doug.patch"
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gdb/
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2014-10-20 Jan Kratochvil <jan.kratochvil@redhat.com>
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2014-10-23 Jan Kratochvil <jan.kratochvil@redhat.com>
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* symtab.c (lookup_symbol_aux_objfile): Use ALL_OBJFILE_SYMTABS, inline
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lookup_block_symbol.
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diff --git a/gdb/symtab.c b/gdb/symtab.c
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index c530d50..bc800ef 100644
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index c530d50..da13861 100644
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--- a/gdb/symtab.c
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+++ b/gdb/symtab.c
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@@ -1657,15 +1657,25 @@ lookup_symbol_aux_objfile (struct objfile *objfile, int block_index,
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const struct block *block;
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struct symtab *s;
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- ALL_OBJFILE_PRIMARY_SYMTABS (objfile, s)
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+ gdb_assert (block_index == GLOBAL_BLOCK || block_index == STATIC_BLOCK);
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+
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+ ALL_OBJFILE_SYMTABS (objfile, s)
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ALL_OBJFILE_PRIMARY_SYMTABS (objfile, s)
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{
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+ struct dict_iterator dict_iter;
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+
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@ -145,5 +187,5 @@ index c530d50..bc800ef 100644
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}
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--K8nIJk4ghYZn606h--
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--vtzGhvizbBRQ85DL--
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@ -1770,3 +1770,101 @@ gdb/testsuite/
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--
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1.9.3
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commit 54fbc750b54271efb75ae11ce49f14c4234a9476
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Author: Jan Kratochvil <jan.kratochvil@redhat.com>
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Date: Thu Sep 18 08:21:40 2014 +0200
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Fix regression for Linux vDSO in GDB (PR gdb/17407).
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since
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5979d6b69b20a8355ea94b75fad97415fce4788c
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https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=5979d6b69b20a8355ea94b75fad97415fce4788c
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vdso handling
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https://sourceware.org/ml/binutils/2014-03/msg00082.html
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https://sourceware.org/ml/binutils/2014-04/msg00003.html
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Message-ID: <A78C989F6D9628469189715575E55B230AA884EB@IRSMSX104.ger.corp.intel.com>
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I get on
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kernel-3.16.2-200.fc20.x86_64
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https://koji.fedoraproject.org/koji/buildinfo?buildID=575860
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attaching its vdso.bin.gz
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GDB (FSF HEAD 5e43d46791c4c66fd83947a12d4f716b561a9103) regression:
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reproducer:
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./gdb -ex start ./gdb
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actual result / FAIL:
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Got object file from memory but can't read symbols: File truncated.
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expected result / PASS:
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<nothing>
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or / PASS:
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warning: Could not load shared library symbols for linux-vdso.so.1.
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Do you need "set solib-search-path" or "set sysroot"?
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That "warning: Could not load shared library..." is mostly harmless (it is
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a bug in GDB), in the FAIL case it is not printed just because
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bfd_check_format() fails there.
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It seems logical to me this way when the 'size' parameter has been already
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added.
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Alan Modra:
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I was wrongly thinking that the section headers were
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always last when I wrote that code. (They are now! If you relink
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that vdso with current binutils master you won't hit this problem, but
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that of course doesn't help existing kernels.)
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I do not see a regression for add-symbol-file-from-memory for libncurses.so.5
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from the original thread above.
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Start of section headers: 1080 (bytes into file)
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Size of section headers: 64 (bytes)
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Number of section headers: 13
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Section header string table index: 8
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Section Headers:
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[Nr] Name Type Address Off Size ES Flg Lk Inf Al
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[ 8] .fake_shstrtab STRTAB 0000000000000780 000780 000076 00 A 0 0 32
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Program Headers:
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Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
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LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0012fe 0x0012fe R E 0x1000
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size == 0x2000
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shdr_end == 0x778 == 1080 + 13 * 64
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high_offset == 0x12fe
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else if (size >= shdr_end)
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- high_offset = shdr_end;
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+ high_offset = size;
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But then 0x778 < 0x780 for "Section header string table index" so whole
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bfd_check_format() fails because section headers were not cleared here:
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/* If the segments visible in memory didn't include the section headers,
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then clear them from the file header. */
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if (high_offset < shdr_end)
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bfd/ChangeLog
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2014-09-18 Jan Kratochvil <jan.kratochvil@redhat.com>
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PR gdb/17407
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* elfcode.h (bfd_from_remote_memory): Use SIZE for HIGH_OFFSET.
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### a/bfd/ChangeLog
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### b/bfd/ChangeLog
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## -1,3 +1,8 @@
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+2014-09-18 Jan Kratochvil <jan.kratochvil@redhat.com>
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+
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+ PR gdb/17407
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+ * elfcode.h (bfd_from_remote_memory): Use SIZE for HIGH_OFFSET.
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+
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2014-07-16 H.J. Lu <hongjiu.lu@intel.com>
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* elf32-i386.c (elf_i386_plt_sym_val): Match PLT entry only for
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--- a/bfd/elfcode.h
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+++ b/bfd/elfcode.h
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@@ -1749,7 +1749,7 @@ NAME(_bfd_elf,bfd_from_remote_memory)
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headers. */
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}
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else if (size >= shdr_end)
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- high_offset = shdr_end;
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+ high_offset = size;
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else
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{
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bfd_vma page_size = get_elf_backend_data (templ)->minpagesize;
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14
gdb.spec
14
gdb.spec
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@ -26,7 +26,7 @@ Version: 7.8
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# The release always contains a leading reserved number, start it at 1.
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# `upstream' is not a part of `name' to stay fully rpm dependencies compatible for the testing.
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Release: 28%{?dist}
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Release: 29%{?dist}
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License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ and GPLv2+ with exceptions and GPL+ and LGPLv2+ and BSD and Public Domain and GFDL
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Group: Development/Debuggers
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@ -897,9 +897,6 @@ mv -f readline-doc readline/doc
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%build
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rm -rf %{buildroot}
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# https://bugzilla.redhat.com/show_bug.cgi?id=1154436
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export PERL5LIB="$PERL5LIB${PERL5LIB:+:}/usr/share/texi2html/lib/Unicode-EastAsianWidth/lib"
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# Identify the build directory with the version of gdb as well as the
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# architecture, to allow for mutliple versions to be installed and
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# built.
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@ -1130,10 +1127,6 @@ echo ====================TESTING END=====================
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%endif
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%install
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# https://bugzilla.redhat.com/show_bug.cgi?id=1154436
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export PERL5LIB="$PERL5LIB${PERL5LIB:+:}/usr/share/texi2html/lib/Unicode-EastAsianWidth/lib"
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# Initially we're in the %{gdb_src} directory.
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cd %{gdb_build}
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rm -rf $RPM_BUILD_ROOT
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@ -1350,6 +1343,11 @@ then
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fi
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%changelog
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* Mon Oct 27 2014 Jan Kratochvil <jan.kratochvil@redhat.com> - 7.8-29.fc21
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- Backport vDSO regression.
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- Revert the makeinfo workaround from 7.8-27.fc21.
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- Further 1.75x improvement of the interactive symbols lookup (Doug Evans).
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* Mon Oct 20 2014 Jan Kratochvil <jan.kratochvil@redhat.com> - 7.8-28.fc21
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- Accelerate interactive symbols lookup 15x.
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