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[patch] DWARF-3+ DW_AT_accessibility defaults #2 (GCC PR debug/45124)
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Mon, 21 Mar 2011 16:44:28 +0100
- Subject: [patch] DWARF-3+ DW_AT_accessibility defaults #2 (GCC PR debug/45124)
Hi,
this is a repost for:
[patch] Fix DWARF-3+ DW_AT_accessibility default assumption
http://sourceware.org/ml/gdb-patches/2011-01/msg00507.html
Re: [patch] Fix DWARF-3+ DW_AT_accessibility default assumption
http://sourceware.org/ml/gdb-patches/2011-03/msg00546.html
revert: Re: [patch] Fix DWARF-3+ DW_AT_accessibility default assumption
http://sourceware.org/ml/gdb-patches/2011-03/msg00586.html
FSF GDB HEAD: former patch: this patch:
dw-2 dw-3 dw-2 dw-3 dw-2 dw-3
gcc-4.5 pass pass 4.5 pass FAIL 4.5 pass pass
gcc-4.6 pass FAIL 4.6 pass pass 4.6 pass pass
(set -x;for gcc in 45 46;do for dwarf in 2 3;do PATH="/your-gcc-dir/gcc${gcc}-root/bin:$PATH" runtest CXX_FOR_TARGET="g++ -gdwarf-${dwarf}" gdb.cp/casts.exp gdb.cp/classes.exp gdb.cp/virtfunc.exp gdb.mi/gdb792.exp gdb.python/py-value.exp ;done;done)
Normally it probably is not of much concern as FSF GCC defaults to -gdwarf-2
where no changes happen. Just Fedoras+RHELs default to -gdwarf-3 where the
assumed defaults have changed, therefore proposing for FSF GDB to verify
DW_AT_producer - it affects even FSF GCCs when one uses -gdwarf-3 or -gdwarf-4.
Due to the mess I did before waiting for a review. I believe this fix should
be a gdb-7.3 blocker as gcc-4.6.0 will be released far before gdb-7.4.
I do not provide a special new testcase as the testcases already exist and a
gdb.dwarf2/ code would just carbon-copy the conditionals while it is more
important the conditionals match the real compilers behavior.
Thanks,
Jan
(set -ex;echo 'class C { public: int priv; } c;' | g++ -gdwarf-3 -c -g -o 1.o -x c++ -; readelf -wi 1.o)
old = no DW_AT_accessibility
new = DW_AT_accessibility: 1 (public)
old gcc-4.4.5-6.el6.x86_64 = GNU C++ 4.4.5 20110214 (Red Hat 4.4.5-6)
old gcc-4.5.1-4.fc14.x86_64 = GNU C++ 4.5.1 20100924 (Red Hat 4.5.1-4)
new gcc-4.6.0-0.14.fc15.x86_64 = GNU C++ 4.6.0 20110318 (Red Hat 4.6.0-0.14)
new GNU C++ 4.7.0 20110321 (experimental)
new GNU C++ 4.6.0 20110321 (prerelease)
old GNU C++ 4.5.3 20110321 (prerelease)
XXX GNU C++ 4.4.6 20110321 (prerelease) [-gdwarf-3 not supported]
gdb/
2011-03-21 Jan Kratochvil <jan.kratochvil@redhat.com>
* dwarf2read.c (producer_is_gxx_lt_4_6): New function.
(dwarf2_add_field): Fix new_field->accessibility for
cu->header.version >= 3 while verifying also producer_is_gxx_lt_4_6.
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -6209,6 +6209,27 @@ dwarf2_record_block_ranges (struct die_info *die, struct block *block,
}
}
+/* Check for GCC PR debug/45124 fix which is not present in any G++ version up
+ to 4.5.any hwile it is present already in G++ 4.6.0 - the PR has been fixed
+ during 4.6.0 experimental. */
+
+static int
+producer_is_gxx_lt_4_6 (const char *producer)
+{
+ int major, minor;
+
+ /* Whitespaces are ignored in both PRODUCER and the format string. */
+ if (sscanf (producer, "GNU C++ %d.%d", &major, &minor) != 2)
+ {
+ /* For non-GCC compilers expect their behavior is DWARF version
+ compliant. */
+
+ return 0;
+ }
+
+ return major < 4 || (major == 4 && minor < 6);
+}
+
/* Add an aggregate field to the field list. */
static void
@@ -6239,13 +6260,28 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
}
fip->nfields++;
- /* Handle accessibility and virtuality of field.
- The default accessibility for members is public, the default
- accessibility for inheritance is private. */
- if (die->tag != DW_TAG_inheritance)
- new_field->accessibility = DW_ACCESS_public;
+ if (cu->header.version < 3 || producer_is_gxx_lt_4_6 (cu->producer))
+ {
+ /* The default DWARF 2 accessibility for members is public, the default
+ accessibility for inheritance is private. */
+
+ if (die->tag != DW_TAG_inheritance)
+ new_field->accessibility = DW_ACCESS_public;
+ else
+ new_field->accessibility = DW_ACCESS_private;
+ }
else
- new_field->accessibility = DW_ACCESS_private;
+ {
+ /* DWARF 3+ defines the default accessibility a different way - see
+ below - than DWARF 2 has defined. The same rules apply now for
+ DW_TAG_inheritance as for the members and it only depends on the
+ container kind. */
+
+ if (die->parent->tag == DW_TAG_class_type)
+ new_field->accessibility = DW_ACCESS_private;
+ else
+ new_field->accessibility = DW_ACCESS_public;
+ }
new_field->virtuality = DW_VIRTUALITY_none;
attr = dwarf2_attr (die, DW_AT_accessibility, cu);