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173628ae68
I am looking at this code [1]:
/* Normally, the DWARF producers are expected to use a signed
constant form (Eg. DW_FORM_sdata) to express negative bounds.
But this is unfortunately not always the case, as witnessed
with GCC, for instance, where the ambiguous DW_FORM_dataN form
is used instead. To work around that ambiguity, we treat
the bounds as signed, and thus sign-extend their values, when
the base type is signed. */
negative_mask =
-((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1));
if (low.kind () == PROP_CONST
&& !base_type->is_unsigned () && (low.const_val () & negative_mask))
low.set_const_val (low.const_val () | negative_mask);
if (high.kind () == PROP_CONST
&& !base_type->is_unsigned () && (high.const_val () & negative_mask))
high.set_const_val (high.const_val () | negative_mask);
Nothing in the testsuite seems to exercise it, as when I remove it, all
of gdb.dwarf2 still passes. And tests in other directories would be
compiler-dependent, so would rely on having a buggy compiler.
Update gdb.dwarf2/subrange.exp to have a test for it. When removing the
code above, the new test fails with:
ptype array_with_buggy_negative_bounds_type^M
type = array [240..244] of signed_byte^M
(gdb) FAIL: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type
instead of the expected:
ptype array_with_buggy_negative_bounds_type^M
type = array [-16..-12] of signed_byte^M
(gdb) PASS: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type
[1] 5ea14aa4e5/gdb/dwarf2/read.c (L17681-17695)
Change-Id: I1992a3ff0cb1e90fa8a9114dae6c591792f059c2
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.