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. While testing this, I also tripped across a latent bug because indirect_pieced_value does not sign-extend where needed. This patch fixes this bug as well. Finally, Pedro pointed out that a previous version implemented sign extension incorrectly. This version introduces a new gdb_sign_extend function for this. A couple of notes on this function: * It has the gdb_ prefix to avoid clashes with various libraries that felt free to avoid proper namespacing. There is a "sign_extend" function in a Tile GX header, in an SOM-related BFD header (and in sh64-tdep.c and as a macro in arm-wince-tdep.c, but those are ours...) * I looked at all the sign extensions in gdb and didn't see ones that I felt comfortable converting to use this function; in large part because I don't have a good way to test the conversion. Built and regtested on x86-64 Fedora 18. New test cases included; this required a minor addition to the DWARF assembler. Note that the DWARF CU made by implptrpiece.exp uses a funny pointer size in order to show the sign-extension bug on all platforms. * dwarf2loc.c (read_pieced_value): Truncate this_size_bits after taking bits_to_skip into account. Sign extend byte_offset. * utils.h (gdb_sign_extend): Declare. * utils.c (gdb_sign_extend): New function. * gdb.dwarf2/implptrpiece.exp: New file. * gdb.dwarf2/implptrconst.exp (d): New variable. Print d. * lib/dwarf2.exp (Dwarf::_location): Handle DW_OP_piece.
This commit is contained in:
Tom Tromey
parent
92fac8075a
commit
5bd1ef568c
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@ -1,3 +1,11 @@
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2013-06-18 Tom Tromey <tromey@redhat.com>
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PR symtab/15391:
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* dwarf2loc.c (read_pieced_value): Truncate this_size_bits
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after taking bits_to_skip into account. Sign extend byte_offset.
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* utils.h (gdb_sign_extend): Declare.
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* utils.c (gdb_sign_extend): New function.
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2013-06-18 Jan Kratochvil <jan.kratochvil@redhat.com>
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* dwarf2read.c (write_psymtabs_to_index): Ignore NULL PSYMTAB.
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@ -1641,8 +1641,6 @@ read_pieced_value (struct value *v)
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bits_to_skip -= this_size_bits;
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continue;
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}
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if (this_size_bits > type_len - offset)
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this_size_bits = type_len - offset;
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if (bits_to_skip > 0)
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{
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dest_offset_bits = 0;
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@ -1655,6 +1653,8 @@ read_pieced_value (struct value *v)
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dest_offset_bits = offset;
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source_offset_bits = 0;
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}
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if (this_size_bits > type_len - offset)
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this_size_bits = type_len - offset;
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this_size = (this_size_bits + source_offset_bits % 8 + 7) / 8;
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source_offset = source_offset_bits / 8;
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@ -2087,8 +2087,15 @@ indirect_pieced_value (struct value *value)
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frame = get_selected_frame (_("No frame selected."));
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/* This is an offset requested by GDB, such as value subcripts. */
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/* This is an offset requested by GDB, such as value subscripts.
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However, due to how synthetic pointers are implemented, this is
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always presented to us as a pointer type. This means we have to
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sign-extend it manually as appropriate. */
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byte_offset = value_as_address (value);
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if (TYPE_LENGTH (value_type (value)) < sizeof (LONGEST))
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byte_offset = gdb_sign_extend (byte_offset,
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8 * TYPE_LENGTH (value_type (value)));
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byte_offset += piece->v.ptr.offset;
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gdb_assert (piece);
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baton
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@ -2099,7 +2106,7 @@ indirect_pieced_value (struct value *value)
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if (baton.data != NULL)
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return dwarf2_evaluate_loc_desc_full (TYPE_TARGET_TYPE (type), frame,
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baton.data, baton.size, baton.per_cu,
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piece->v.ptr.offset + byte_offset);
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byte_offset);
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{
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struct obstack temp_obstack;
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@ -1,3 +1,10 @@
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2013-06-18 Tom Tromey <tromey@redhat.com>
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* gdb.dwarf2/implptrpiece.exp: New file.
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* gdb.dwarf2/implptrconst.exp (d): New variable.
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Print d.
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* lib/dwarf2.exp (Dwarf::_location): Handle DW_OP_piece.
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2013-06-18 Tom Tromey <tromey@redhat.com>
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* lib/selftest-support.exp (do_self_tests): Reject remote or
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@ -73,6 +73,14 @@ Dwarf::assemble $asm_file {
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GNU_implicit_pointer $var_label 0
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} SPECIAL_expr}
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}
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DW_TAG_variable {
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{name d}
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{type :$ptr_label}
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{location {
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GNU_implicit_pointer $var_label 2
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} SPECIAL_expr}
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}
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}
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}
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}
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@ -103,3 +111,4 @@ if ![runto_main] {
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}
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gdb_test "print *c" " = 114 'r'"
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gdb_test "print d\[-2\]" " = 114 'r'"
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@ -0,0 +1,131 @@
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# Copyright 2013 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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load_lib dwarf.exp
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# This test can only be run on targets which support DWARF-2 and use gas.
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if {![dwarf2_support]} {
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return 0
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}
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if { [skip_cplus_tests] } { continue }
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standard_testfile main.c implptrpiece-dw.S
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# Make some DWARF for the test.
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set asm_file [standard_output_file $srcfile2]
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Dwarf::assemble $asm_file {
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# Using a funny address size here and in the pointer type lets us
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# also check for a sign-extension bug in the
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# DW_OP_GNU_implicit_pointer code.
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cu { addr_size 2 } {
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compile_unit {} {
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declare_labels struct_label short_type_label
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declare_labels char_type_label ptr_label
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declare_labels var_label
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struct_label: structure_type {
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{name S}
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{byte_size 4 DW_FORM_sdata}
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} {
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member {
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{name a}
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{type :$short_type_label}
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{data_member_location 0 DW_FORM_sdata}
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}
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member {
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{name b}
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{type :$char_type_label}
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{data_member_location 2 DW_FORM_sdata}
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}
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member {
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{name c}
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{type :$char_type_label}
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{data_member_location 3 DW_FORM_sdata}
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}
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}
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short_type_label: base_type {
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{name "short int"}
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{encoding @DW_ATE_signed}
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{byte_size 2 DW_FORM_sdata}
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}
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char_type_label: base_type {
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{name "signed char"}
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{encoding @DW_ATE_signed}
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{byte_size 1 DW_FORM_sdata}
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}
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# See comment above to understand the pointer size.
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ptr_label: pointer_type {
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{byte_size 2 DW_FORM_sdata}
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{type :$char_type_label}
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}
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var_label: DW_TAG_variable {
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{name s}
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{type :$struct_label}
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{location {
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const1u 1
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stack_value
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piece 2
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const1u 2
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stack_value
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piece 1
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const1u 3
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stack_value
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piece 1
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} SPECIAL_expr}
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}
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DW_TAG_variable {
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{name p}
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{type :$ptr_label}
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{location {
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GNU_implicit_pointer $var_label 2
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} SPECIAL_expr}
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}
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}
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}
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}
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if {[gdb_compile ${srcdir}/${subdir}/${srcfile} ${binfile}1.o \
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object {nodebug}] != ""} {
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return -1
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}
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if {[gdb_compile $asm_file ${binfile}2.o object {nodebug}] != ""} {
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return -1
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}
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if {[gdb_compile [list ${binfile}1.o ${binfile}2.o] \
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"${binfile}" executable {}] != ""} {
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return -1
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}
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# We need --readnow because otherwise we never read in the CU we
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# created above.
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set saved_gdbflags $GDBFLAGS
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set GDBFLAGS "$GDBFLAGS -readnow"
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clean_restart ${testfile}
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set GDBFLAGS $saved_gdbflags
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if ![runto_main] {
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return -1
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}
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gdb_test "print/d p\[-1\]" " = 0"
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@ -611,6 +611,7 @@ namespace eval Dwarf {
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variable _constants
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variable _cu_label
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variable _cu_addr_size
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variable _cu_offset_size
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foreach line [split $body \n] {
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if {[lindex $line 0] == ""} {
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@ -651,6 +652,10 @@ namespace eval Dwarf {
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_op .sleb128 [lindex $line 1]
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}
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DW_OP_piece {
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_op .uleb128 [lindex $line 1]
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}
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DW_OP_GNU_implicit_pointer {
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if {[llength $line] != 3} {
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error "usage: DW_OP_GNU_implicit_pointer LABEL OFFSET"
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@ -658,7 +663,7 @@ namespace eval Dwarf {
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# Here label is a section offset.
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set label [lindex $line 1]
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_op .${_cu_addr_size}byte $label
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_op .${_cu_offset_size}byte $label
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_op .sleb128 [lindex $line 2]
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}
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17
gdb/utils.c
17
gdb/utils.c
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@ -3234,6 +3234,23 @@ align_down (ULONGEST v, int n)
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return (v & -n);
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}
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/* See utils.h. */
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LONGEST
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gdb_sign_extend (LONGEST value, int bit)
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{
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gdb_assert (bit >= 1 && bit <= 8 * sizeof (LONGEST));
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if (((value >> (bit - 1)) & 1) != 0)
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{
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LONGEST signbit = ((LONGEST) 1) << (bit - 1);
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value = (value ^ signbit) - signbit;
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}
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return value;
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}
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/* Allocation function for the libiberty hash table which uses an
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obstack. The obstack is passed as DATA. */
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@ -377,4 +377,9 @@ extern int myread (int, char *, int);
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extern ULONGEST align_up (ULONGEST v, int n);
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extern ULONGEST align_down (ULONGEST v, int n);
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/* Sign extend VALUE. BIT is the (1-based) index of the bit in VALUE
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to sign-extend. */
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extern LONGEST gdb_sign_extend (LONGEST value, int bit);
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#endif /* UTILS_H */
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