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authorTom Tromey <tromey@redhat.com>2013-06-18 18:11:19 +0000
committerTom Tromey <tromey@redhat.com>2013-06-18 18:11:19 +0000
commit5bd1ef568c63cbcf6ed99a083eeb18cf940871dd (patch)
tree053e51b5c75e50567212a6b7edb5094b3a8dc555
parent92fac8075afdfdd75ab752de80c1e7b0cbcc5303 (diff)
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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.
-rw-r--r--gdb/ChangeLog8
-rw-r--r--gdb/dwarf2loc.c15
-rw-r--r--gdb/testsuite/ChangeLog7
-rw-r--r--gdb/testsuite/gdb.dwarf2/implptrconst.exp9
-rw-r--r--gdb/testsuite/gdb.dwarf2/implptrpiece.exp131
-rw-r--r--gdb/testsuite/lib/dwarf.exp7
-rw-r--r--gdb/utils.c17
-rw-r--r--gdb/utils.h5
8 files changed, 194 insertions, 5 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1743bfa..16fc351 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2013-06-18 Tom Tromey <tromey@redhat.com>
+
+ PR symtab/15391:
+ * 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.
+
2013-06-18 Jan Kratochvil <jan.kratochvil@redhat.com>
* dwarf2read.c (write_psymtabs_to_index): Ignore NULL PSYMTAB.
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 9e44096..bb600d1 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;
@@ -2087,8 +2087,15 @@ indirect_pieced_value (struct value *value)
frame = get_selected_frame (_("No frame selected."));
- /* This is an offset requested by GDB, such as value subcripts. */
+ /* This is an offset requested by GDB, such as value subscripts.
+ However, due to how synthetic pointers are implemented, this is
+ always presented to us as a pointer type. This means we have to
+ sign-extend it manually as appropriate. */
byte_offset = value_as_address (value);
+ if (TYPE_LENGTH (value_type (value)) < sizeof (LONGEST))
+ byte_offset = gdb_sign_extend (byte_offset,
+ 8 * TYPE_LENGTH (value_type (value)));
+ byte_offset += piece->v.ptr.offset;
gdb_assert (piece);
baton
@@ -2099,7 +2106,7 @@ indirect_pieced_value (struct value *value)
if (baton.data != NULL)
return dwarf2_evaluate_loc_desc_full (TYPE_TARGET_TYPE (type), frame,
baton.data, baton.size, baton.per_cu,
- piece->v.ptr.offset + byte_offset);
+ byte_offset);
{
struct obstack temp_obstack;
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7c659ca..2c9e13a 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,12 @@
2013-06-18 Tom Tromey <tromey@redhat.com>
+ * gdb.dwarf2/implptrpiece.exp: New file.
+ * gdb.dwarf2/implptrconst.exp (d): New variable.
+ Print d.
+ * lib/dwarf2.exp (Dwarf::_location): Handle DW_OP_piece.
+
+2013-06-18 Tom Tromey <tromey@redhat.com>
+
* lib/selftest-support.exp (do_self_tests): Reject remote or
non-native targets.
* gdb.gdb/complaints.exp: Remove check.
diff --git a/gdb/testsuite/gdb.dwarf2/implptrconst.exp b/gdb/testsuite/gdb.dwarf2/implptrconst.exp
index 1c89c43..4e82295 100644
--- a/gdb/testsuite/gdb.dwarf2/implptrconst.exp
+++ b/gdb/testsuite/gdb.dwarf2/implptrconst.exp
@@ -73,6 +73,14 @@ Dwarf::assemble $asm_file {
GNU_implicit_pointer $var_label 0
} SPECIAL_expr}
}
+
+ DW_TAG_variable {
+ {name d}
+ {type :$ptr_label}
+ {location {
+ GNU_implicit_pointer $var_label 2
+ } SPECIAL_expr}
+ }
}
}
}
@@ -103,3 +111,4 @@ if ![runto_main] {
}
gdb_test "print *c" " = 114 'r'"
+gdb_test "print d\[-2\]" " = 114 'r'"
diff --git a/gdb/testsuite/gdb.dwarf2/implptrpiece.exp b/gdb/testsuite/gdb.dwarf2/implptrpiece.exp
new file mode 100644
index 0000000..3f14a66
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/implptrpiece.exp
@@ -0,0 +1,131 @@
+# 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 $asm_file {
+ # Using a funny address size here and in the pointer type lets us
+ # also check for a sign-extension bug in the
+ # DW_OP_GNU_implicit_pointer code.
+ cu { addr_size 2 } {
+ compile_unit {} {
+ declare_labels struct_label short_type_label
+ declare_labels char_type_label ptr_label
+ declare_labels var_label
+
+ struct_label: structure_type {
+ {name S}
+ {byte_size 4 DW_FORM_sdata}
+ } {
+ member {
+ {name a}
+ {type :$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}
+ }
+
+ # See comment above to understand the pointer size.
+ ptr_label: pointer_type {
+ {byte_size 2 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 7efaaca..5b19bb8 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -611,6 +611,7 @@ namespace eval Dwarf {
variable _constants
variable _cu_label
variable _cu_addr_size
+ variable _cu_offset_size
foreach line [split $body \n] {
if {[lindex $line 0] == ""} {
@@ -651,6 +652,10 @@ 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"
@@ -658,7 +663,7 @@ namespace eval Dwarf {
# Here label is a section offset.
set label [lindex $line 1]
- _op .${_cu_addr_size}byte $label
+ _op .${_cu_offset_size}byte $label
_op .sleb128 [lindex $line 2]
}
diff --git a/gdb/utils.c b/gdb/utils.c
index 18ee9bb..f5c1339 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -3234,6 +3234,23 @@ align_down (ULONGEST v, int n)
return (v & -n);
}
+/* See utils.h. */
+
+LONGEST
+gdb_sign_extend (LONGEST value, int bit)
+{
+ gdb_assert (bit >= 1 && bit <= 8 * sizeof (LONGEST));
+
+ if (((value >> (bit - 1)) & 1) != 0)
+ {
+ LONGEST signbit = ((LONGEST) 1) << (bit - 1);
+
+ value = (value ^ signbit) - signbit;
+ }
+
+ return value;
+}
+
/* Allocation function for the libiberty hash table which uses an
obstack. The obstack is passed as DATA. */
diff --git a/gdb/utils.h b/gdb/utils.h
index 71ce867..9356658 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -377,4 +377,9 @@ extern int myread (int, char *, int);
extern ULONGEST align_up (ULONGEST v, int n);
extern ULONGEST align_down (ULONGEST v, int n);
+/* Sign extend VALUE. BIT is the (1-based) index of the bit in VALUE
+ to sign-extend. */
+
+extern LONGEST gdb_sign_extend (LONGEST value, int bit);
+
#endif /* UTILS_H */