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.
On powerpc64, "disassemble foo" doesn't work properly on object files
(it can't process the relocations in .opd section) - instead, let's
link it into an executable and load that.
Also, backtrace displays .main, not main. Accept both.
gdb/testsuite/ChangeLog:
* gdb.trace/entry-values.exp: Link ${binfile}1.o to ${binfile}1 and
use it for disassembly; accept .main in addition to main in backtrace.
The PPC64 tracepoint patch added \y at the end of the call_insn pattern -
without that, it embarassed itself and matched the 'bl' in "Dump of
assem*bl*er code for function" as the powerpc call opcode. Since that
sounds like a generally good idea, I've added \y before and after
call_insn for every target. As a result, I had to change x86_64's mnemonic
to 'callq'.
gdb/testsuite/ChangeLog:
* gdb.trace/entry-values.exp: Surround $call_insn with '\y',
change x86_64 call_insn to 'callq'.
These two tests collect 64 words from $sp onwards, hoping that's enough
to capture a few whole stack frames. Unfortunately, that's not enough
for s390, which tends to have large frame sizes - minimum 24 words on
s390, 20 on s390x (which just barely passes). Bump it to 128 words,
let's hope no machine needs more.
Tested on x86_64, s390, s390x.
gdb/testsuite/ChangeLog:
* gdb.trace/backtrace.exp: Bump stack collection fudge factor.
* gdb.trace/entry-values.exp: Bump stack collection fudge factor.
These variables were used in many gdb.trace tests. Keep them in one place,
to reduce work needed for new targets.
gdb/testsuite/ChangeLog:
* gdb.trace/backtrace.exp: Use global fpreg/spreg definition, add $
in front.
* gdb.trace/change-loc.exp: Use global pcreg definition.
* gdb.trace/collection.exp: Use global pcreg/fpreg/spreg definition.
* gdb.trace/entry-values.exp: Use global spreg definition, add $
in front.
* gdb.trace/mi-trace-frame-collected.exp: Use global pcreg definition.
* gdb.trace/pending.exp: Likewise.
* gdb.trace/report.exp: Use global pcreg/fpreg/spreg definition.
* gdb.trace/trace-break.exp: Likewise.
* gdb.trace/trace-condition.exp: Use global pcreg definition, add $
in front.
* gdb.trace/unavailable.exp: Use global pcreg/fpreg/spreg definition.
* gdb.trace/while-dyn.exp: Use global fpreg definition, add $
in front.
* lib/trace-support.exp: Define fpreg, spreg, pcreg variables.
gdb/testsuite/ChangeLog:
* lib/dwarf.exp (Dwarf): Flag an error if a numeric attribute value
is given without an explicit form.
* gdb.dwarf2/arr-subrange.exp: Specify forms for all numeric
attributes.
* gdb.dwarf/corrupt.exp: Ditto.
* gdb.dwarf2/enum-type.exp: Ditto.
* gdb.trace/entry-values.exp: Ditto.
* gdb.trace/unavailable-dwarf-piece.exp: Ditto.
The test entry-values.exp doesn't recognize the call instructions
on MIPS, such as JAL, JALS and etc, so this patch sets call_insn
to match various jump and branch instructions first.
Currently, we assume the next instruction address of call instruction
is the address returned from foo, however it is not correct on MIPS
which has delay slot. We extend variable call_insn to match one
instruction after jump or branch instruction, so that
$returned_from_foo is correct on MIPS.
All tests in entry-values.exp are PASS.
gdb/testsuite:
2015-01-08 Yao Qi <yao@codesourcery.com>
* gdb.trace/entry-values.exp: Set call_insn for MIPS target.
This patch is to clean up gdb.trace/entry-values.exp as a preparation
of the next patch. It updates the comments to reflect the code.
One DIE generated in dwarf assembler is
GNU_call_site {
{low_pc "$bar_start + $bar_call_foo" addr}
{abstract_origin :$foo_label}
the DW_AT_low_pc attribute is the return address after the call, so I
rename variable bar_call_foo to returned_from_foo.
gdb/testsuite:
2014-12-29 Yao Qi <yao@codesourcery.com>
* gdb.trace/entry-values.exp: Update comments. Rename variable
bar_call_foo to returned_from_foo.
MACRO_AT_func can be used in gdb.trace/entry-values.exp to correctly
get function's address in generated debug info. As a result, the test
is more friendly to clang. Currently, there are some fails in
entry-values.exp when the test is compiled by clang. With this patch
applied, all fails go away.
gdb/testsuite:
2014-11-22 Yao Qi <yao@codesourcery.com>
* gdb.trace/entry-values.c: Remove asms.
(foo): Add foo_label.
(bar): Add bar_label.
* gdb.trace/entry-values.exp: Remove code computing foo's
length and bar's length.
(Dwarf::assemble): Invoke function_range for bar and use
MACRO_AT_func for foo.
We see some fails in gdb.trace/entry-values.exp in thumb mode
(-mthumb -march={armv4t,armv7-a}).
In thumb mode, the lsb of references to 'foo' and 'bar' in the assembly
(produced by dwarf assember) is set, so the generated debug
information is incorrect.
This patch copies the approach used by
[PATCH 4/4] Fix dw2-ifort-parameter.exp on PPC64
https://sourceware.org/ml/gdb-patches/2014-03/msg00202.html
to introduce new labels 'foo_start' and 'bar_start' which are about
the correct function address (without lsb set). This patch fixes
these fails we've seen.
gdb/testsuite:
2014-07-08 Yao Qi <yao@codesourcery.com>
* gdb.trace/entry-values.c: Define labels 'foo_start' and
'bar_start' at the beginning of functions 'foo' and 'bar'
respectively.
* gdb.trace/entry-values.exp: Use 'foo_start' and 'bar_start'
instead of 'foo' and 'bar'.
does in a way, because the arm/aarch64 branch instruction is the
same as powerpc's, but the target triplet pattern is not there.
In summary, the testcase fails to locate the branch offset and causes
a failure and the early termination of the test.
The following patch adds a separate conditional block for powerpc (to keep
things organized), allowing the testcase to continue.
2014-07-02 Luis Machado <lgustavo@codesourcery.com>
* gdb.trace/entry-values.exp: Handle powerpc-specific branch
instruction.
The trace-specific test case 'entry-values' concludes fairly late in
the process that this platform doesn't support trace. Before that,
there are some platform specifics that don't work on s390x. The fix
addresses two aspects:
(1) Removal of an excess space character in the regex for the
disassembly. This is needed when there is a function alignment
gap, because then the hex address is immediately followed by a
colon, like in the first 'nopr' line below:
(gdb) disassemble foo+50,+10
Dump of assembler code from 0x32 to 0x3c:
0x0000000000000032 <foo+50>: br %r4
0x0000000000000034: nopr %r7
0x0000000000000036: nopr %r7
0x0000000000000038 <bar+0>: stmg %r11,%r15,88(%r15)
End of assembler dump.
(2) Handling for the s390-specific call instruction.
gdb/testsuite/ChangeLog:
* gdb.trace/entry-values.exp: Remove excess space character from
regex patterns. Handle s390 call instruction.
This is the patch to add new option '--skip-unavailable' to MI
commands '-stack-list-{locals, arguments, variables}'. This patch
extends list_args_or_locals to add a new parameter 'skip_unavailable',
and don't list locals or arguments if values are unavailable and
'skip_unavailable' is true.
This is inspecting a trace frame (tfind mode), where only a few
locals have been collected.
-stack-list-locals, no switch vs new switch:
-stack-list-locals --simple-values
^done,locals=[{name="array",type="unsigned char [2]"},{name="i",type="int",value="<unavailable>"}]
-stack-list-locals --skip-unavailable --simple-values
^done,locals=[{name="array",type="unsigned char [2]"}]
-stack-list-arguments, no switch vs new switch:
-stack-list-arguments --simple-values
^done,stack-args=[frame={level="0",args=[{name="j",type="int",value="4"},{name="s",type="char *",value="<unavailable>"}]},frame={level="1",args=[]}]
-stack-list-arguments --skip-unavailable --simple-values
^done,stack-args=[frame={level="0",args=[{name="j",type="int",value="4"}]},frame={level="1",args=[]}]
-stack-list-variables, no switch vs new switch:
-stack-list-variables --simple-values
^done,variables=[{name="j",arg="1",type="int",value="4"},{name="s",arg="1",type="char *",value="<unavailable>"},{name="array",type="unsigned char [2]"},{name="i",type="int",value="<unavailable>"}]
-stack-list-variables --skip-unavailable --simple-values
^done,variables=[{name="j",arg="1",type="int",value="4"},{name="array",type="unsigned char [2]"}]
tests are added to test these new options.
gdb:
2013-08-27 Pedro Alves <pedro@codesourcery.com>
Yao Qi <yao@codesourcery.com>
* mi/mi-cmd-stack.c (list_args_or_locals): Adjust prototype.
(parse_no_frames_option): Remove.
(mi_cmd_stack_list_locals): Handle --skip-unavailable.
(mi_cmd_stack_list_args): Adjust.
(mi_cmd_stack_list_variables): Handle --skip-unavailable.
(list_arg_or_local): Add new parameter 'skip_unavailable'. Return
early if SKIP_UNAVAILABLE is true and ARG->val is unavailable.
Caller update.
(list_args_or_locals): New parameter 'skip_unavailable'.
Handle it.
* valprint.c (scalar_type_p): Rename to ...
(val_print_scalar_type_p): ... this. Make extern.
(val_print, value_check_printable): Adjust.
* valprint.h (val_print_scalar_type_p): Declare.
* value.c (value_entirely_unavailable): New function.
* value.h (value_entirely_unavailable): Declare.
* NEWS: Mention the new option "--skip-unavailable" to MI
commands '-stack-list-locals', '-stack-list-arguments' and
'-stack-list-variables'.
gdb/doc:
2013-08-27 Pedro Alves <pedro@codesourcery.com>
Yao Qi <yao@codesourcery.com>
* gdb.texinfo (GDB/MI Stack Manipulation) <-stack-list-locals>:
Document new --skip-unavailable option.
<-stack-list-variables>: Document new --skip-unavailable option.
gdb/testsuite:
2013-08-27 Yao Qi <yao@codesourcery.com>
* gdb.trace/entry-values.exp: Test unavailable entry value is
not shown when option '--skip-unavailable' is specified.
* gdb.trace/mi-trace-unavailable.exp (test_trace_unavailable):
Add tests for new option '--skip-unavailable'.
* gdb.trace/entry-values.c (end): New
(main): Call end.
* gdb.trace/entry-values.exp: Load trace-support.exp. Set
tracepoint and collect data. Test entry value is unavailable.
Joel Brobecker
Pedro Alves
Luis Machado
Marcin Kościelnicki
Doug Evans
Yao Qi
Andreas Arnez
Yufeng Zhang