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* [binutils-gdb] Big-endian targets: Don't ignore offset into DW_OP_stack_value
@ 2017-03-23  8:41 sergiodj+buildbot
  2017-03-23  8:41 ` Failures on Ubuntu-AArch64-native-gdbserver-m64, branch master sergiodj+buildbot
                   ` (10 more replies)
  0 siblings, 11 replies; 12+ messages in thread
From: sergiodj+buildbot @ 2017-03-23  8:41 UTC (permalink / raw)
  To: gdb-testers

*** TEST RESULTS FOR COMMIT 7942e96e435d1cf4d4dbf58c47bb28d9f628c9e6 ***

Author: Andreas Arnez <arnez@linux.vnet.ibm.com>
Branch: master
Commit: 7942e96e435d1cf4d4dbf58c47bb28d9f628c9e6

Big-endian targets: Don't ignore offset into DW_OP_stack_value

Recently I fixed a bug that caused a DW_OP_implicit_pointer with non-zero
offset into a DW_OP_implicit_value to be handled incorrectly on big-endian
targets.  GDB ignored the offset and copied the wrong bytes:

  https://sourceware.org/ml/gdb-patches/2017-01/msg00251.html

But there is still a similar issue when a DW_OP_implicit_pointer points
into a DW_OP_stack_value instead; and again, the offset is ignored.  There
is an important difference, though: While implicit values are treated like
blocks of data and anchored at the lowest-addressed byte, stack values
traditionally contain integer numbers and are anchored at the *least
significant* byte.  Also, stack values do not come in varying sizes, but
are cut down appropriately when used.  Thus, on big-endian targets the
scenario looks like this (higher addresses shown right):

  |<- - - - - Stack value - - - - - - ->|
                  |                     |
                  |<- original object ->|
                  |
                  | offset ->|####|
			      ^^^^
                              de-referenced
			      implicit pointer

(Note how the original object's size influences the position of the
de-referenced implicit pointer within the stack value.  This is not the
case for little-endian targets, where the original object starts at offset
zero within the stack value.)

This patch implements the logic indicated in the above diagram and adds an
appropriate test case.  A new function dwarf2_fetch_die_type_sect_off is
added; it is used for retrieving the original object's type, so its size
can be determined.  That type is passed to dwarf2_evaluate_loc_desc_full
via a new parameter.

gdb/ChangeLog:

	* dwarf2loc.c (indirect_synthetic_pointer): Get data type of
	pointed-to DIE and pass it to dwarf2_evaluate_loc_desc_full.
	(dwarf2_evaluate_loc_desc_full): New parameter subobj_type; rename
	byte_offset to subobj_byte_offset.  Fix the handling of
	DWARF_VALUE_STACK on big-endian targets when coming via an
	implicit pointer.
	(dwarf2_evaluate_loc_desc): Adjust call to
	dwarf2_evaluate_loc_desc_full.
	* dwarf2loc.h (dwarf2_fetch_die_type_sect_off): New declaration.
	* dwarf2read.c (dwarf2_fetch_die_type_sect_off): New function.

gdb/testsuite/ChangeLog:

	* lib/dwarf.exp: Add support for DW_OP_implicit_pointer.
	* gdb.dwarf2/nonvar-access.exp: Add test for stack value location
	and implicit pointer into such a location.


^ permalink raw reply	[flat|nested] 12+ messages in thread
end of thread, other threads:[~2017-05-04  1:05 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-03-23  8:41 [binutils-gdb] Big-endian targets: Don't ignore offset into DW_OP_stack_value sergiodj+buildbot
2017-03-23  8:41 ` Failures on Ubuntu-AArch64-native-gdbserver-m64, branch master sergiodj+buildbot
2017-03-23  9:10 ` Failures on Ubuntu-AArch64-m64, " sergiodj+buildbot
2017-03-23 13:51 ` Failures on Ubuntu-AArch32-native-gdbserver-m32, " sergiodj+buildbot
2017-03-23 14:13 ` Failures on Ubuntu-AArch32-native-extended-gdbserver-m32, " sergiodj+buildbot
2017-03-23 14:35 ` Failures on Ubuntu-AArch32-m32, " sergiodj+buildbot
2017-04-27  6:05 ` Failures on Fedora-ppc64le-native-gdbserver-m64, " sergiodj+buildbot
2017-04-27 17:09 ` Failures on Fedora-ppc64le-native-extended-gdbserver-m64, " sergiodj+buildbot
2017-05-01  6:36 ` Failures on Debian-s390x-native-extended-gdbserver-m64, " sergiodj+buildbot
2017-05-02  0:51 ` Failures on Debian-s390x-native-gdbserver-m64, " sergiodj+buildbot
2017-05-03 15:53 ` Failures on Fedora-ppc64be-native-gdbserver-m64, " sergiodj+buildbot
2017-05-04  1:05 ` Failures on Fedora-ppc64be-native-extended-gdbserver-m64, " sergiodj+buildbot

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