103 lines
3.6 KiB
Diff
103 lines
3.6 KiB
Diff
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http://sourceware.org/ml/gdb-patches/2012-02/msg00673.html
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Subject: [patch] Fix regression by me for gcc-4.0...gcc-4.4 i386 -O2 -g parameters (PR 13777)
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Hi,
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http://sourceware.org/bugzilla/show_bug.cgi?id=13777
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for CentOS-5 i386 ls:
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$ gdb ls
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(gdb) start
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Temporary breakpoint 1, main (argc=Cannot access memory at address 0x81b7c7cd
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instead of GDB before my PR 12573 fix/change:
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Temporary breakpoint 1, main (argc=1, ...
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I asked before on #gcc since which versions GCC produced DW_AT_location which
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is for any PC either optimized-out or it has valid value. I was told since
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gcc-4.0. But that is not true.
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I have bisected gcc and I found 4.4.0 was still broken, 4.5.0 was correct,
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thanks to:
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commit 25e880b1917bd6bbf07e86b5574c698f3e9472d9
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Author: rth <rth@138bc75d-0d04-0410-961f-82ee72b054a4>
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Date: Sat May 30 00:33:46 2009 +0000
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git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@147995 138bc75d-0d04-0410-961f-82ee72b054a4
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unwind info for epilogues
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Curiously 4.4.x branch got later also fixed in this case by:
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commit 61db8bd232daeed3751b43570fab16146145e096
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Author: jakub <jakub@138bc75d-0d04-0410-961f-82ee72b054a4>
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Date: Tue Jun 2 07:18:16 2009 +0000
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git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_4-branch@148070 138bc75d-0d04-0410-961f-82ee72b054a4
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(but that missed 4.4.0)
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As 4.5.0 was first FSF GCC with VTA I was trusting more the validity only
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after VTA and these heuristic results seems to confirm that.
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I find the change below definitely safe.
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Someone may object the original PR 12573 (do not try to skip prologue for -O2
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-g code as it may cause more confusion than anything else) as while it fixed
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some GDB crashes there is no such purpose anymore with Tom's
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ambiguous-linespec patch. Still I believe PR 12573 was right to do.
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No regressions on {x86_64,x86_64-m32,i686}-fedora17-linux-gnu.
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I will check it in.
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Thanks,
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Jan
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gdb/
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2012-02-28 Jan Kratochvil <jan.kratochvil@redhat.com>
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PR symtab/13777
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* dwarf2read.c (process_full_comp_unit): Set LOCATIONS_VALID only for
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GCC >=4.5.
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gdb/testsuite/
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2012-02-28 Jan Kratochvil <jan.kratochvil@redhat.com>
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PR symtab/13777
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* gdb.dwarf2/dw2-skip-prologue.S (DW_AT_producer): Set it to 4.5.0.
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--- a/gdb/dwarf2read.c
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+++ b/gdb/dwarf2read.c
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@@ -4841,7 +4841,9 @@ process_full_comp_unit (struct dwarf2_per_cu_data *per_cu)
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/* GCC-4.0 has started to support -fvar-tracking. GCC-3.x still can
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produce DW_AT_location with location lists but it can be possibly
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- invalid without -fvar-tracking.
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+ invalid without -fvar-tracking. Still up to GCC-4.4.x incl. 4.4.0
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+ there were bugs in prologue debug info, fixed later in GCC-4.5
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+ by "unwind info for epilogues" patch (which is not directly related).
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For -gdwarf-4 type units LOCATIONS_VALID indication is fortunately not
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needed, it would be wrong due to missing DW_AT_producer there.
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@@ -4849,7 +4851,7 @@ process_full_comp_unit (struct dwarf2_per_cu_data *per_cu)
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Still one can confuse GDB by using non-standard GCC compilation
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options - this waits on GCC PR other/32998 (-frecord-gcc-switches).
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*/
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- if (cu->has_loclist && gcc_4_minor >= 0)
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+ if (cu->has_loclist && gcc_4_minor >= 5)
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symtab->locations_valid = 1;
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if (gcc_4_minor >= 5)
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--- a/gdb/testsuite/gdb.dwarf2/dw2-skip-prologue.S
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+++ b/gdb/testsuite/gdb.dwarf2/dw2-skip-prologue.S
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@@ -30,7 +30,7 @@
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.4byte func_start /* DW_AT_low_pc */
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.4byte func_end /* DW_AT_high_pc */
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.ascii "main.c\0" /* DW_AT_name */
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- .ascii "GNU C 4.0.0\0" /* DW_AT_producer must be >= 4.0 */
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+ .ascii "GNU C 4.5.0\0" /* DW_AT_producer must be >= 4.5 */
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.byte 2 /* DW_AT_language (DW_LANG_C) */
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.uleb128 2 /* Abbrev: DW_TAG_subprogram */
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