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RFC Fix PR symtab/15391
- From: Tom Tromey <tromey at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Tue, 23 Apr 2013 11:53:14 -0600
- Subject: RFC Fix PR symtab/15391
PR symtab/15391 is a failure with the DW_OP_GNU_implicit_pointer
feature.
I tracked it down to a logic error in read_pieced_value. The code
truncates this_size_bits according to the type size and offset too
early -- it should do it after taking bits_to_skip into account.
This patch fixes the bug.
Built and regtested on x86-64 Fedora 18. New test case included; this
required a minor addition to the DWARF assembler.
* dwarf2loc.c (read_pieced_value): Truncate this_size_bits
after taking bits_to_skip into account.
* gdb.dwarf2/implptrpiece.exp: New file.
* lib/dwarf2.exp (Dwarf::_location): Handle DW_OP_piece.
---
gdb/dwarf2loc.c | 4 +-
gdb/testsuite/gdb.dwarf2/implptrpiece.exp | 126 ++++++++++++++++++++++++++++++
gdb/testsuite/lib/dwarf.exp | 4 +
3 files changed, 132 insertions(+), 2 deletions(-)
create mode 100644 gdb/testsuite/gdb.dwarf2/implptrpiece.exp
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 9e44096..492098d 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -1641,8 +1641,6 @@ read_pieced_value (struct value *v)
bits_to_skip -= this_size_bits;
continue;
}
- if (this_size_bits > type_len - offset)
- this_size_bits = type_len - offset;
if (bits_to_skip > 0)
{
dest_offset_bits = 0;
@@ -1655,6 +1653,8 @@ read_pieced_value (struct value *v)
dest_offset_bits = offset;
source_offset_bits = 0;
}
+ if (this_size_bits > type_len - offset)
+ this_size_bits = type_len - offset;
this_size = (this_size_bits + source_offset_bits % 8 + 7) / 8;
source_offset = source_offset_bits / 8;
diff --git a/gdb/testsuite/gdb.dwarf2/implptrpiece.exp b/gdb/testsuite/gdb.dwarf2/implptrpiece.exp
new file mode 100644
index 0000000..8468f71
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/implptrpiece.exp
@@ -0,0 +1,126 @@
+# Copyright 2013 Free Software Foundation, Inc.
+
+# 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/>.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+ return 0
+}
+
+if { [skip_cplus_tests] } { continue }
+
+standard_testfile main.c implptrpiece-dw.S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+ cu 0 2 8 {
+ compile_unit {} {
+ declare_labels struct_label short_type_label
+ declare_labels char_type_label ptr_label
+ declare_labels var_label
+
+ struct_label: structure_type {
+ {name S}
+ {byte_size 4 DW_FORM_sdata}
+ } {
+ member {
+ {name a}
+ {type :$short_type_label}
+ {data_member_location 0 DW_FORM_sdata}
+ }
+ member {
+ {name b}
+ {type :$char_type_label}
+ {data_member_location 2 DW_FORM_sdata}
+ }
+ member {
+ {name c}
+ {type :$char_type_label}
+ {data_member_location 3 DW_FORM_sdata}
+ }
+ }
+
+ short_type_label: base_type {
+ {name "short int"}
+ {encoding @DW_ATE_signed}
+ {byte_size 2 DW_FORM_sdata}
+ }
+
+ char_type_label: base_type {
+ {name "signed char"}
+ {encoding @DW_ATE_signed}
+ {byte_size 1 DW_FORM_sdata}
+ }
+
+ ptr_label: pointer_type {
+ {byte_size 8 DW_FORM_sdata}
+ {type :$char_type_label}
+ }
+
+ var_label: DW_TAG_variable {
+ {name s}
+ {type :$struct_label}
+ {location {
+ const1u 1
+ stack_value
+ piece 2
+ const1u 2
+ stack_value
+ piece 1
+ const1u 3
+ stack_value
+ piece 1
+ } SPECIAL_expr}
+ }
+
+ DW_TAG_variable {
+ {name p}
+ {type :$ptr_label}
+ {location {
+ GNU_implicit_pointer $var_label 2
+ } SPECIAL_expr}
+ }
+ }
+ }
+}
+
+if {[gdb_compile ${srcdir}/${subdir}/${srcfile} ${binfile}1.o \
+ object {nodebug}] != ""} {
+ return -1
+}
+
+if {[gdb_compile $asm_file ${binfile}2.o object {nodebug}] != ""} {
+ return -1
+}
+
+if {[gdb_compile [list ${binfile}1.o ${binfile}2.o] \
+ "${binfile}" executable {}] != ""} {
+ return -1
+}
+
+# We need --readnow because otherwise we never read in the CU we
+# created above.
+set saved_gdbflags $GDBFLAGS
+set GDBFLAGS "$GDBFLAGS -readnow"
+clean_restart ${testfile}
+set GDBFLAGS $saved_gdbflags
+
+if ![runto_main] {
+ return -1
+}
+
+gdb_test "print/d p\[-1\]" " = 0"
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index 2e5a3f7..b73784f 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -646,6 +646,10 @@ namespace eval Dwarf {
_op .sleb128 [lindex $line 1]
}
+ DW_OP_piece {
+ _op .uleb128 [lindex $line 1]
+ }
+
DW_OP_GNU_implicit_pointer {
if {[llength $line] != 3} {
error "usage: DW_OP_GNU_implicit_pointer LABEL OFFSET"
--
1.8.1.4