190 lines
5.9 KiB
Diff
190 lines
5.9 KiB
Diff
commit e93523245b704bc126705620969b4736b00350c5
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Author: Andreas Arnez <arnez@linux.vnet.ibm.com>
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Date: Tue Jun 13 15:20:26 2017 +0200
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PR gdb/21226: Take DWARF stack value pieces from LSB end
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When taking a DW_OP_piece or DW_OP_bit_piece from a DW_OP_stack_value, the
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existing logic always takes the piece from the lowest-addressed end, which
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is wrong on big-endian targets. The DWARF standard states that the
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"DW_OP_bit_piece operation describes a sequence of bits using the least
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significant bits of that value", and this also matches the current logic
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in GCC. For instance, the GCC guality test case pr54970.c fails on s390x
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because of this.
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This fix adjusts the piece accordingly on big-endian targets. It is
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assumed that:
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* DW_OP_piece shall take the piece from the LSB end as well;
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* pieces reaching outside the stack value bits are considered undefined,
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and a zero value can be used instead.
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gdb/ChangeLog:
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PR gdb/21226
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* dwarf2loc.c (read_pieced_value): Anchor stack value pieces at
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the LSB end, independent of endianness.
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gdb/testsuite/ChangeLog:
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PR gdb/21226
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* gdb.dwarf2/nonvar-access.exp: Add checks for verifying that
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stack value pieces are taken from the LSB end.
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### a/gdb/ChangeLog
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### b/gdb/ChangeLog
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## -1,5 +1,11 @@
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2017-06-13 Andreas Arnez <arnez@linux.vnet.ibm.com>
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+ PR gdb/21226
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+ * dwarf2loc.c (read_pieced_value): Anchor stack value pieces at
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+ the LSB end, independent of endianness.
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+
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+2017-06-13 Andreas Arnez <arnez@linux.vnet.ibm.com>
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+
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* dwarf2loc.c (write_pieced_value): Fix order of calculations for
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size capping.
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--- a/gdb/dwarf2loc.c
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+++ b/gdb/dwarf2loc.c
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@@ -1858,6 +1858,10 @@ read_pieced_value (struct value *v)
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if (unavail)
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mark_value_bits_unavailable (v, offset, this_size_bits);
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}
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+
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+ copy_bitwise (contents, dest_offset_bits,
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+ intermediate_buffer, source_offset_bits % 8,
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+ this_size_bits, bits_big_endian);
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}
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break;
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@@ -1866,26 +1870,30 @@ read_pieced_value (struct value *v)
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p->v.mem.in_stack_memory,
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p->v.mem.addr + source_offset,
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buffer.data (), this_size);
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+ copy_bitwise (contents, dest_offset_bits,
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+ intermediate_buffer, source_offset_bits % 8,
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+ this_size_bits, bits_big_endian);
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break;
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case DWARF_VALUE_STACK:
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{
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- size_t n = this_size;
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+ struct objfile *objfile = dwarf2_per_cu_objfile (c->per_cu);
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+ struct gdbarch *objfile_gdbarch = get_objfile_arch (objfile);
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+ ULONGEST stack_value_size_bits
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+ = 8 * TYPE_LENGTH (value_type (p->v.value));
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- if (n > c->addr_size - source_offset)
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- n = (c->addr_size >= source_offset
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- ? c->addr_size - source_offset
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- : 0);
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- if (n == 0)
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- {
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- /* Nothing. */
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- }
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- else
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- {
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- const gdb_byte *val_bytes = value_contents_all (p->v.value);
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+ /* Use zeroes if piece reaches beyond stack value. */
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+ if (p->size > stack_value_size_bits)
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+ break;
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- intermediate_buffer = val_bytes + source_offset;
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- }
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+ /* Piece is anchored at least significant bit end. */
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+ if (gdbarch_byte_order (objfile_gdbarch) == BFD_ENDIAN_BIG)
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+ source_offset_bits += stack_value_size_bits - p->size;
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+
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+ copy_bitwise (contents, dest_offset_bits,
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+ value_contents_all (p->v.value),
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+ source_offset_bits,
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+ this_size_bits, bits_big_endian);
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}
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break;
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@@ -1899,6 +1907,10 @@ read_pieced_value (struct value *v)
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: 0);
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if (n != 0)
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intermediate_buffer = p->v.literal.data + source_offset;
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+
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+ copy_bitwise (contents, dest_offset_bits,
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+ intermediate_buffer, source_offset_bits % 8,
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+ this_size_bits, bits_big_endian);
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}
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break;
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@@ -1915,12 +1927,6 @@ read_pieced_value (struct value *v)
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internal_error (__FILE__, __LINE__, _("invalid location type"));
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}
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- if (p->location != DWARF_VALUE_OPTIMIZED_OUT
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- && p->location != DWARF_VALUE_IMPLICIT_POINTER)
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- copy_bitwise (contents, dest_offset_bits,
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- intermediate_buffer, source_offset_bits % 8,
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- this_size_bits, bits_big_endian);
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-
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offset += this_size_bits;
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}
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}
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### a/gdb/testsuite/ChangeLog
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### b/gdb/testsuite/ChangeLog
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## -1,5 +1,11 @@
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2017-06-13 Andreas Arnez <arnez@linux.vnet.ibm.com>
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+ PR gdb/21226
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+ * gdb.dwarf2/nonvar-access.exp: Add checks for verifying that
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+ stack value pieces are taken from the LSB end.
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+
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+2017-06-13 Andreas Arnez <arnez@linux.vnet.ibm.com>
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+
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* gdb.dwarf2/var-pieces.exp: Add test case for modifying a
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variable at nonzero offset.
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--- a/gdb/testsuite/gdb.dwarf2/nonvar-access.exp
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+++ b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp
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@@ -128,14 +128,26 @@ Dwarf::assemble $asm_file {
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{name def_t}
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{type :$struct_t_label}
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{location {
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- const1u 0
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+ const2s -184
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stack_value
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bit_piece 9 0
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- const1s -1
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+ const4u 1752286
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stack_value
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bit_piece 23 0
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} SPECIAL_expr}
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}
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+ # Composite location with some empty pieces.
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+ DW_TAG_variable {
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+ {name part_def_a}
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+ {type :$array_a9_label}
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+ {location {
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+ piece 3
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+ const4u 0xf1927314
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+ stack_value
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+ piece 4
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+ piece 2
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+ } SPECIAL_expr}
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+ }
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# Implicit location: immediate value.
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DW_TAG_variable {
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{name def_implicit_s}
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@@ -221,9 +233,12 @@ gdb_test "print/x *implicit_b_ptr" " = $val"
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# Byte-aligned fields, pieced together from DWARF stack values.
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gdb_test "print def_s" " = \\{a = 0, b = -1\\}"
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+switch $endian { big {set val 0x92} little {set val 0x73} }
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+gdb_test "print/x part_def_a\[4\]" " = $val"
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+gdb_test "print/x part_def_a\[8\]" " = <optimized out>"
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# Non-byte-aligned fields, pieced together from DWARF stack values.
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-gdb_test "print def_t" " = \\{a = 0, b = -1\\}"
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+gdb_test "print def_t" " = \\{a = -184, b = 1752286\\}"
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# Simple variable without location.
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gdb_test "print undef_int" " = <optimized out>"
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