An earlier commit made GDB no longer assume no-debug-info functions
return int. This commit gives the same treatment to variables.
Currently, you can end misled by GDB over output like this:
(gdb) p var
$1 = -1
(gdb) p /x var
$2 = 0xffffffff
until you realize that GDB is assuming that the variable is an "int",
because:
(gdb) ptype var
type = <data variable, no debug info>
You may try to fix it by casting, but that doesn't really help:
(gdb) p /x (unsigned long long) var
$3 = 0xffffffffffffffff # incorrect
^^
That's incorrect output, because the variable was defined like this:
uint64_t var = 0x7fffffffffffffff;
^^
What happened is that with the cast, GDB did an int -> 'unsigned long
long' conversion instead of reinterpreting the variable as the cast-to
type. To get at the variable properly you have to reinterpret the
variable's address manually instead, with either:
(gdb) p /x *(unsigned long long *) &var
$4 = 0x7fffffffffffffff
(gdb) p /x {unsigned long long} &var
$5 = 0x7fffffffffffffff
After this commit GDB does it for you. This is what you'll get
instead:
(gdb) p var
'var' has unknown type; cast it to its declared type
(gdb) p /x (unsigned long long) var
$1 = 0x7fffffffffffffff
As in the functions patch, the "compile" machinery doesn't currently
have the cast-to type handy, so it continues assuming no-debug
variables have int type, though now at least it warns.
The change to gdb.cp/m-static.exp deserves an explanation:
- gdb_test "print 'gnu_obj_1::method()::sintvar'" "\\$\[0-9\]+ = 4" \
+ gdb_test "print (int) 'gnu_obj_1::method()::sintvar'" "\\$\[0-9\]+ = 4" \
That's printing the "sintvar" function local static of the
"gnu_obj_1::method()" method.
The problem with that test is that that "'S::method()::static_var'"
syntax doesn't really work in C++ as you'd expect. The way to make it
work correctly currently is to quote the method part, not the whole
expression, like:
(gdb) print 'gnu_obj_1::method()'::sintvar
If you wrap the whole expression in quotes, like in m-static.exp, what
really happens is that the parser considers the whole string as a
symbol name, but there's no debug symbol with that name. However,
local statics have linkage and are given a mangled name that demangles
to the same string as the full expression, so that's what GDB prints.
After this commit, and without the cast, the print in m-static.exp
would error out saying that the variable has unknown type:
(gdb) p 'gnu_obj_1::method()::sintvar'
'gnu_obj_1::method()::sintvar' has unknown type; cast it to its declared type
TBC, if currently (even before this series) you try to print any
function local static variable of type other than int, you'll get
bogus results. You can see that with m-static.cc as is, even.
Printing the "svar" local, which is a boolean (1 byte) still prints as
"int" (4 bytes):
(gdb) p 'gnu_obj_1::method()::svar'
$1 = 1
(gdb) ptype 'gnu_obj_1::method()::svar'
type = <data variable, no debug info>
This probably prints some random bogus value on big endian machines.
If 'svar' was of some aggregate type (etc.) we'd still print it as
int, so the problem would have been more obvious... After this
commit, you'll get instead:
(gdb) p 'gnu_obj_1::method()::svar'
'gnu_obj_1::method()::svar' has unknown type; cast it to its declared type
... so at least GDB is no longer misleading. Making GDB find the real
local static debug symbol is the subject of the following patches. In
the end, it'll all "Just Work".
gdb/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* ax-gdb.c: Include "typeprint.h".
(gen_expr_for_cast): New function.
(gen_expr) <OP_CAST, OP_CAST_TYPE>: Use it.
<OP_VAR_VALUE, OP_MSYM_VAR_VALUE>: Error out if the variable's
type is unknown.
* dwarf2read.c (new_symbol_full): Fallback to int instead of
nodebug_data_symbol.
* eval.c: Include "typeprint.h".
(evaluate_subexp_standard) <OP_VAR_VALUE, OP_VAR_MSYM_VALUE>:
Error out if symbol has unknown type.
<UNOP_CAST, UNOP_CAST_TYPE>: Common bits factored out to
evaluate_subexp_for_cast.
(evaluate_subexp_for_address, evaluate_subexp_for_sizeof): Handle
OP_VAR_MSYM_VALUE.
(evaluate_subexp_for_cast): New function.
* gdbtypes.c (init_nodebug_var_type): New function.
(objfile_type): Use it to initialize types of variables with no
debug info.
* typeprint.c (error_unknown_type): New.
* typeprint.h (error_unknown_type): New declaration.
* compile/compile-c-types.c (convert_type_basic): Handle
TYPE_CODE_ERROR; warn and fallback to int for variables with
unknown type.
gdb/testsuite/ChangeLog:
2017-09-04 Pedro Alves <palves@redhat.com>
* gdb.asm/asm-source.exp: Add casts to int.
* gdb.base/nodebug.c (dataglobal8, dataglobal32_1, dataglobal32_2)
(dataglobal64_1, dataglobal64_2): New globals.
* gdb.base/nodebug.exp: Test different expressions involving the
new globals, with print, whatis and ptype. Add casts to int.
* gdb.base/solib-display.exp: Add casts to int.
* gdb.compile/compile-ifunc.exp: Expect warning. Add cast to int.
* gdb.cp/m-static.exp: Add cast to int.
* gdb.dwarf2/dw2-skip-prologue.exp: Add cast to int.
* gdb.threads/tls-nodebug.exp: Check that gdb errors out printing
tls variable with no debug info without a cast. Test with a cast
to int too.
* gdb.trace/entry-values.exp: Add casts.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This test currently uses [is_remote target] to check if the test is
supported. This is not quite correct, as the limitation is actually
that it requires support for "running", ruling out stub-like targets.
Therefore, it should check for use_gdb_stub.
This has no visible effect right now, but it will once we make the
native-gdbserver board non-dejagnu-remote.
gdb/testsuite/ChangeLog:
* gdb.base/solib-display.exp: Check for [use_gdb_stub] instead
of [is_remote target],
Before:
(gdb) info display
Auto-display expressions now in effect:
Num Enb Expression
3: y 1
2: y 1
1: y 1
After:
(gdb) info display
Auto-display expressions now in effect:
Num Enb Expression
1: y 1
2: y 1
3: y 1
gdb/ChangeLog:
2015-11-24 Pedro Alves <palves@redhat.com>
PR 17539
* printcmd.c (display_command): Append new display at the end of
the list.
gdb/testsuite/ChangeLog:
2015-11-24 Pedro Alves <palves@redhat.com>
PR 17539
* gdb.base/display.exp: Expect displays to be sorted in ascending
order. Use multi_line.
* gdb.base/solib-display.exp: Likewise.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
Tom Tromey <tromey@redhat.com>
* lib/gdb.exp: Add description of test prefixes.
(with_test_prefix): New procedure.
* gdb.arch/altivec-abi.exp: Use with_test_prefix.
* gdb.base/attach-pie-misread.exp: Use with_test_prefix.
* gdb.base/break-interp.exp: Use with_test_prefix. Use append
instead of lappend to append to pf_prefix.
* gdb.base/catch-load.exp: Use with_test_prefix.
* gdb.base/disp-step-syscall.exp: Use with_test_prefix.
* gdb.base/jit-so.exp: Use with_test_prefix.
* gdb.base/jit.exp: Use with_test_prefix.
* gdb.base/return-nodebug.exp (do_test): Use append instead of
lappend to append to pf_prefix.
* gdb.base/sepdebug.exp: Use with_test_prefix.
* gdb.base/solib-display.exp: Use with_test_prefix.
* gdb.base/solib-overlap.exp: Use with_test_prefix.
* gdb.base/watch-cond-infcall.exp: Use with_test_prefix.
* gdb.base/watchpoint.exp: Use with_test_prefix.
* gdb.dwarf2/dw2-noloc.exp: Use with_test_prefix.
* gdb.mi/mi-watch.exp: Use with_test_prefix.
* gdb.mi/mi2-watch.exp: Use with_test_prefix.
* gdb.threads/non-ldr-exc-1.exp: Use with_test_prefix.
* gdb.threads/non-ldr-exc-2.exp: Use with_test_prefix.
* gdb.threads/non-ldr-exc-3.exp: Use with_test_prefix.
* gdb.threads/non-ldr-exc-4.exp: Use with_test_prefix.
* gdb.threads/watchpoint-fork.exp: Use with_test_prefix. Use
append instead of lappend to append to pf_prefix.
* gdb.threads/watchthreads-reorder.exp: Use with_test_prefix.
* gdb.trace/change-loc.exp: Use with_test_prefix.
* gdb.trace/pending.exp: Use with_test_prefix.
* gdb.trace/status-stop.exp: Use with_test_prefix.
* gdb.trace/strace.exp: Use with_test_prefix.
* gdb.trace/trace-break.exp: Use with_test_prefix.
* gdb.trace/unavailable.exp: Use with_test_prefix. Use append
instead of lappend to append to pf_prefix.
Fix crashes on dangling display expressions.
* ada-lang.c (ada_operator_check): New function.
(ada_exp_descriptor): Fill-in the field operator_check.
* c-lang.c (exp_descriptor_c): Fill-in the field operator_check.
* jv-lang.c (exp_descriptor_java): Likewise.
* m2-lang.c (exp_descriptor_modula2): Likewise.
* scm-lang.c (exp_descriptor_scm): Likewise.
* parse.c (exp_descriptor_standard): Likewise.
(operator_check_standard): New function.
(exp_iterate, exp_uses_objfile_iter, exp_uses_objfile): New functions.
* parser-defs.h (struct exp_descriptor): New field operator_check.
(operator_check_standard, exp_uses_objfile): New declarations.
* printcmd.c: Remove the inclusion of solib.h.
(display_uses_solib_p): Remove the function.
(clear_dangling_display_expressions): Call lookup_objfile_from_block
and exp_uses_objfile instead of display_uses_solib_p.
* solist.h (struct so_list) <objfile>: New comment.
* symtab.c (lookup_objfile_from_block): Remove the static qualifier.
* symtab.h (lookup_objfile_from_block): New declaration.
(struct general_symbol_info) <obj_section>: Extend the comment.
gdb/testsuite/
Fix crashes on dangling display expressions.
* gdb.base/solib-display.exp: Call gdb_gnu_strip_debug if LIBSEPDEBUG
is SEP.
(lib_flags): Remove the "debug" keyword.
(libsepdebug): New variable for iterating new loop.
(save_pf_prefix): New variable wrapping the loop.
(sep_lib_flags): New variable derived from LIB_FLAGS. Use it.
* lib/gdb.exp (gdb_gnu_strip_debug): Document the return code.
* gdb.base/solib-display.exp: Replace gdb_exit, gdb_start,
gdb_reinitialize_dir and gdb_load by clean_restart. Remove trailing
gdb_exit and return.
(executable): New variable.
(binfile): Use it.
* printcmd.c (do_one_display): Reparse exp_string.
(display_uses_solib_p): New function.
(clear_dangling_display_expressions): New function.
(_initialize_printcmd): Add observer.
* solib.c (no_shared_libraries): Swap order of calls to
clear_solib and objfile_purge_solibs.
Pedro Alves
Joel Brobecker
Luis Machado
Simon Marchi
Tom Tromey
Joel Brobecker
Jan Kratochvil
Paul Pluzhnikov