[lldb-dev] [Bug 33250] New: Issue with utf8 string display in the ncurses-GUI mode on a Beaglebone Black (ARMv6)

[via lldb-dev]

https://bugs.llvm.org/show_bug.cgi?id=33250

Bug ID: 33250
   Summary: Issue with utf8 string display in the ncurses-GUI mode
on a Beaglebone Black (ARMv6)
   Product: lldb
   Version: unspecified
  Hardware: Other
OS: FreeBSD
Status: NEW
  Severity: normal
  Priority: P
 Component: All Bugs
  Assignee: lldb-dev@lists.llvm.org
  Reporter: r...@obsigna.com
CC: llvm-b...@lists.llvm.org

I built (lldb + clang/lld) from the svn trunk of LLVM 5.0.0 on my Beaglebone
Black running the latest snapshot (May 26th) of FreeBSD 12.0-CURRENT.

# lldb --version
lldb version 5.0.0 (http://llvm.org/svn/llvm-project/lldb/trunk revision
304078)
  clang revision 304078
  llvm revision 304078

However, the present issue can be found in lldb at least since 3.8.


First of all, my system's locale is:

LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_ALL=

$echo $TERM
xterm-256color


Now, please consider the following tiny ncurses test program 'cursutf8.c',
which prints out the traditional German pangram for testing the special
characters 'ä', 'ö', 'ü', 'ß', each of which consists of two bytes when encoded
in UTF8:

#include 
#include 
#include 
#include 

int main(int argc, char *argv[])
{
  setlocale(LC_CTYPE, "");

  WINDOW *window = initscr();
  if (window)
  {
 mvaddstr(3, 3, "Zwölf Boxkämpfer jagen Viktor quer über den großen Sylter
Deich.");
 refresh();
 sleep(3);

 delwin(window);
 endwin();
 refresh();

 return 0;
  }

  else
 return 1;
}


I compile this using:
  $clang -g -O0 cursutf8.c -lncursesw -o cursutf8


When I run it, it correctly prints out:
  Zwölf Boxkämpfer jagen Viktor quer über den großen Sylter Deich.


Then I start this with lldb:

$lldb -- cursutf8

(lldb) breakpoint set -f cursutf8.c -l 13
(lldb) run

Process 13886 stopped
* thread #1, name = 'cursutf8', stop reason = breakpoint 1.1
   frame #0: 0x8a08 cursutf8`main(argc=1, argv=0xbfbfec74) at cursutf8.c:13
  10   WINDOW *window = initscr();
  11   if (window)
  12   {
-> 13 mvaddstr(3, 3, "Zwölf Boxkämpfer jagen Viktor quer über den
großen Sylter Deich.");
  14  refresh();
  15  sleep(3);
  16

So far this is OK as well.


The issue shows up, when I enter into the GUI mode:

(lldb) gui

│ 10 │WINDOW *window = initscr();   
│ 11 │if (window)   
│ 12 │{ 
│ 13 │◆  mvaddstr(3, 3, "ZwM-CM-6lf BoxkM-CM-$mpfer jagen Viktor quer
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Re: [lldb-dev] A bit of extra-polish for my lldb plugin

[Jim Ingham via lldb-dev]

Pavel, can you say more about your idea?  

In both ObjC and C++ methods, you can refer to an ivar either as "this->ivar" 
or just "ivar".  But the DWARF for C++ doesn't tell lldb that a particular 
language supports referring to ivars transparently this way.  It will say that 
the "this" parameter is artificial, and that it is the "object pointer".  But 
it doesn't so far as I can tell record the fact that elements of that parameter 
can be transparently accessed.

I think it would be confusing for the debug information to record the 
transparently accessed ivars as pseudo-locals, the duplication would confuse 
folks, and that isn't how they are understood by the person writing the code.  
It might be good to propose a "DW_AT_transparent" attribute, and mark the ivars 
or maybe the parameter that way.  I guessing that wasn't done because it was 
assumed that the debugger would know this sort of rule from the language in 
question.

As I understand it, problem here is that Nat's runtime has extra rules for 
transparent access that lldb doesn't know about.

Jim


> On May 31, 2017, at 3:20 AM, Pavel Labath  wrote:
> 
> I think the cleanest solution would be to actually modify the compiler
> to emit "correct" dwarf (as in, dwarf representing the code as it
> actually looks like to user, and not some internal intermediate
> representation). The dwarf expression in DW_AT_location can easily
> handle the lookup of some field in a struct. Of course, this is
> assuming you are actually able to modify the compiler.
> 
> (disclaimer: I know next to nothing, when it comes to objc)
> 
> On 26 May 2017 at 23:25, Jim Ingham via lldb-dev
>  wrote:
>> Because we try as much as possible to let the compiler figure this sort of 
>> thing out for us, we implement the transparent lookups for this & self by 
>> compiling our expression in a context that poses as a method of the class 
>> whose method we are stopped in.  For instance, for ObjC, we construct a 
>> category on the class, and put the expression text in a method in that 
>> category, and then compile all that and call the method.
>> 
>> That's done in ExpressionSourceCode::GetText.
>> 
>> The one hitch to this is that this works because the compiler that is linked 
>> into lldb knows about the ObjC model we are emulating.  An unmodified clang 
>> won't do transparent lookup into some random argument that happens to be 
>> called _param.  So you would have to build lldb with a version of clang that 
>> understands your lookup rules for this to work.
>> 
>> If that's not possible then you can try to do this by monkeying with the 
>> lookup rules implemented by lldb's ClangASTSource to return "_param.a" when 
>> it is just looking up "a".  That's how we inject variables and types that 
>> are present in the local context into the expression as it is getting 
>> parsed.  But at that point you are getting your hands into some fairly deep 
>> magic, and clang's Aslan is not as forgiving as Narnia's...
>> 
>> Jim
>> 
>> 
>>> On May 26, 2017, at 2:27 PM, Nat! via lldb-dev  
>>> wrote:
>>> 
>>> Let me show you a snippet of a lldb debug session in progress in my ObjC
>>> variant:
>>> 
>>> ```
>>> -10,10,v,18.48
>>> Process 45774 stopped
>>> * thread #1, queue = 'com.apple.main-thread', stop reason = step in
>>>   frame #0: 0x00010e2a multiple.debug`+[Foo
>>> long:int:char:float:](self=Foo, _cmd=,
>>> _param=0x7fff5fbff948) at multiple.m:15
>>>  12   char:(char) c
>>>  13  float:(float) d
>>>  14  {
>>>  15 printf( "%ld,%d,%c,%.2f\n", a, b, c, d);
>>> -> 16 }
>>>  17
>>>  18  @end
>>> (lldb) p *_param
>>> (p.long:int:char:float:) $2 = (a = -10, b = 10, c = 'v', d =
>>> 18.475)
>>> ```
>>> 
>>> You can see that the parameter values `a,b,c,d` are actually fields of
>>> a struct parameter `_param`. `_param` uniformly appears as the third
>>> parameter after `self` and `_cmd`. `p _param->a` works of course, but it
>>> would be nice to be able to say 'p a', since in the source code one sees
>>> only `a`. `_param` is more or less an implementation detail.
>>> 
>>> A clue how to achieve this, would be very much appreciated.
>>> 
>>> Ciao
>>>  Nat!
>>> 
>>> 
>>> [*] except, if it's a picture of thousand words :)
>>> 
>>> https://www.mulle-kybernetik.com/weblog/2015/mulle_objc_meta_call_convention.html
>>> ___
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>>> lldb-dev@lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>> 
>> ___
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Re: [lldb-dev] issue with utf8 string display in the ncurses-GUI mode on a Beaglebone Black (ARMv6)

[Jim Ingham via lldb-dev]

Bug reports are here:

https://bugs.llvm.org

It's the same system as for llvm, just specify lldb as the product.

Jim


> On May 28, 2017, at 8:11 AM, Dr. Rolf Jansen via lldb-dev 
>  wrote:
> 
> I managed to build LLDB on a Beaglebone Black running a snapshot (May 20th) 
> of FreeBSD 12.0-CURRENT -- ARMv6. This is the first LLDB of all that I tried 
> out, which let me single step into the code, so I am already quite happy with 
> it. In the moment, I see only one minor issue left to be resolved, namely 
> UTF8 strings are not displayed correctly in the ncurses-GUI mode, while in 
> cli mode I see no issue.
> 
> This happens in the ncurses-GUI mode of LLDB 3.9.1, LLDB 4.0.1, up to LLDB 
> 5.0.0 (svn).
> 
> This is an ARM issue, since it does not occur on x86 machines. Perhaps this 
> might be related to the signed/unsigned char mismatch between ARM and x86. 
> Other ncurses software on the Beaglebone does work well under FreeBSD. 
> 
> I did not find a bug-reporting facility for LLDB. In case, I need to submit a 
> bug report on this, please may I ask for a link.
> 
> Best regards
> 
> Rolf
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Re: [lldb-dev] A bit of extra-polish for my lldb plugin

[Nat! via lldb-dev]

Pavel Labath schrieb:
> I think the cleanest solution would be to actually modify the compiler
> to emit "correct" dwarf (as in, dwarf representing the code as it
> actually looks like to user, and not some internal intermediate
> representation). The dwarf expression in DW_AT_location can easily
> handle the lookup of some field in a struct. Of course, this is
> assuming you are actually able to modify the compiler.
> 
> (disclaimer: I know next to nothing, when it comes to objc)
> 

That would probably be ideal. I have to see if I can do this. But my
metaABI is somewhat "hacked" into clang. So I am not saying it wouldn't
work, but I suspect it won't, as I am relying on existing clang code.

Ciao
   Nat!

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Re: [lldb-dev] issue with lldb-mi -var-update with pointers

[Abid, Hafiz via lldb-dev]

I see 2 problems here. CMICmdCmdVarUpdate::ExamineSBValueForChange seems to 
ignore the changes in in children
for pointer and references. It is easy enough to fix. The other issue is that 
we dont not print the changed child value.
For example, with the first issue fixed, I get 

-var-update 1 var0
^done,changelist=[{name="var0",value="0x7fffed30",in_scope="true",type_changed="false",has_more="0"}]

This problem exist for aggregate types too. 

I think I can put the fix for the first problem if it will help you. Please let 
me know. 

Thanks,
Abid

From: lldb-dev  on behalf of Ted Woodward via 
lldb-dev 
Sent: Tuesday, May 30, 2017 9:50 PM
To: 'LLDB'
Subject: [lldb-dev] issue with lldb-mi -var-update with pointers

I have a simple testcase that modifies the value pointed to by an int *.
I've created a variable with -var-create, and then after the value has been
updated, check it with -var-update. -var-update returns no changes, but the
value has changed.

test.c:
#include 

int main(void)
{
  int vec[] = {1, 2, 3, 4};
  int foo = 0;
  int *bar = 
  int i = 0;

  for (i = 0; i < 4; i++)
*bar += vec[i];

  return foo;
}

Commands:
-break-insert -t -f test.c:10
-break-insert -t -f test.c:13
-exec-run
-var-create --thread 1 --frame 0 - * bar
-var-list-children var0
-var-evaluate-expression var0.*bar
-exec-continue
 1 var0
-var-evaluate-expression var0.*bar


Output:
(gdb)
-var-create --thread 1 --frame 0 - * bar
^done,name="var0",numchild="1",value="0x7fffed30",type="int
*",thread-id="1",has_more="0"
(gdb)
-var-list-children var0
^done,numchild="1",children=[child={name="var0.*bar",exp="*bar",numchild="0"
,type="int",thread-id="1",has_more="0"}],has_more="0"
(gdb)
-var-evaluate-expression var0.*bar
^done,value="0"

***Value is 0

(gdb)
-exec-continue
^running
(gdb)
=thread-exited,id="1",group-id="i1"
(gdb)
*running,thread-id="all"
(gdb)
=thread-created,id="1",group-id="i1"
(gdb)
*stopped,reason="breakpoint-hit",disp="del",bkptno="2",frame={level="0",addr
="0x00400530",func="main",args=[],file="test.c",fullname="/local/scr
atch/ted/tip/newfull/test.c",line="13"},thread-id="1",stopped-threads="all"
(gdb)
-var-update 1 var0
^done,changelist=[]

***No changes

(gdb)
-var-evaluate-expression var0.*bar
^done,value="10"

***Value is 10, even though we reported no changes.

The child shows an update:
(gdb)
-var-update 1 var0.*bar
^done,changelist=[{name="var0.*bar",value="10",in_scope="true",type_changed=
"false",has_more="0"}]


--
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
Linux Foundation Collaborative Project


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Re: [lldb-dev] [llvm-dev] Running lit (googletest) tests remotely

[Pavel Labath via lldb-dev]

Thank you all for the pointers. I am going to look at these to see if
there is anything that we could reuse, and come back. In the mean
time, I'll reply to Mathiass's comments:

On 26 May 2017 at 19:11, Matthias Braun  wrote:
>> Based on a not-too-detailed examination of the lit codebase, it does
>> not seem that it would be too difficult to add this capability: During
>> test discovery phase, we could copy the required files to the remote
>> host. Then, when we run the test, we could just prefix the run command
>> similarly to how it is done for running the tests under valgrind. It
>> would be up to the user to provide a suitable command for copying and
>> running files on the remote host (using rsync, ssh, telnet or any
>> other transport he chooses).
>
> This seems to be the crux to me: What does "required files" mean?
> - All the executables mentioned in the RUN line? What llvm was compiled as a 
> library, will we copy those too?
For executables, I was considering just listing them explicitly (in
lit.local.cfg, I guess), although parsing the RUN line should be
possible as well. Even with RUN parsing, I expect we would some way to
explicitly add files to the copy list (e.g. for lldb tests we also
need to copy the program we are going to debug).

As for libraries, I see a couple of solutions:
- declare these configurations unsupported for remote executions
- copy over ALL shared libraries
- have automatic tracking of runtime dependencies - all of this
information should pass through llvm_add_library macro, so it should
be mostly a matter of exporting this information out of cmake.
These can be combined in the sense that we can start in the
"unsupported" state, and then add some support for it once there is a
need for it (we don't need it right now).

> - Can tests include other files? Do they need special annotations for that?
My initial idea was to just copy over all files in the Inputs folder.
Do you know of any other dependencies that I should consider?

>
> As another example: The llvm-testsuite can perform remote runs 
> (test-suite/litsupport/remote.py if you want to see the implementation) that 
> code makes the assumption that the remote devices has an NFS mount so the 
> relevant parts of the filesystem look alike on the host and remote device. 
> I'm not sure that is the best solution as NFS introduces its own sort of 
> flakiness and potential skew in I/O heavy benchmarks but it avoids the 
> question of what to copy to the device.

Requiring an NFS mount is a non-starter for us (no way to get an
android device to create one), although if we would be able to hook in
a custom script which does a copy to simulate the "mount", we might be
able to work with it. Presently I am mostly thinking about correctness
tests, and I am not worried about benchmark skews

regards,
pl
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Re: [lldb-dev] A bit of extra-polish for my lldb plugin

[Pavel Labath via lldb-dev]

I think the cleanest solution would be to actually modify the compiler
to emit "correct" dwarf (as in, dwarf representing the code as it
actually looks like to user, and not some internal intermediate
representation). The dwarf expression in DW_AT_location can easily
handle the lookup of some field in a struct. Of course, this is
assuming you are actually able to modify the compiler.

(disclaimer: I know next to nothing, when it comes to objc)

On 26 May 2017 at 23:25, Jim Ingham via lldb-dev
 wrote:
> Because we try as much as possible to let the compiler figure this sort of 
> thing out for us, we implement the transparent lookups for this & self by 
> compiling our expression in a context that poses as a method of the class 
> whose method we are stopped in.  For instance, for ObjC, we construct a 
> category on the class, and put the expression text in a method in that 
> category, and then compile all that and call the method.
>
> That's done in ExpressionSourceCode::GetText.
>
> The one hitch to this is that this works because the compiler that is linked 
> into lldb knows about the ObjC model we are emulating.  An unmodified clang 
> won't do transparent lookup into some random argument that happens to be 
> called _param.  So you would have to build lldb with a version of clang that 
> understands your lookup rules for this to work.
>
> If that's not possible then you can try to do this by monkeying with the 
> lookup rules implemented by lldb's ClangASTSource to return "_param.a" when 
> it is just looking up "a".  That's how we inject variables and types that are 
> present in the local context into the expression as it is getting parsed.  
> But at that point you are getting your hands into some fairly deep magic, and 
> clang's Aslan is not as forgiving as Narnia's...
>
> Jim
>
>
>> On May 26, 2017, at 2:27 PM, Nat! via lldb-dev  
>> wrote:
>>
>> Let me show you a snippet of a lldb debug session in progress in my ObjC
>> variant:
>>
>> ```
>> -10,10,v,18.48
>> Process 45774 stopped
>> * thread #1, queue = 'com.apple.main-thread', stop reason = step in
>>frame #0: 0x00010e2a multiple.debug`+[Foo
>> long:int:char:float:](self=Foo, _cmd=,
>> _param=0x7fff5fbff948) at multiple.m:15
>>   12   char:(char) c
>>   13  float:(float) d
>>   14  {
>>   15 printf( "%ld,%d,%c,%.2f\n", a, b, c, d);
>> -> 16 }
>>   17
>>   18  @end
>> (lldb) p *_param
>> (p.long:int:char:float:) $2 = (a = -10, b = 10, c = 'v', d =
>> 18.475)
>> ```
>>
>> You can see that the parameter values `a,b,c,d` are actually fields of
>> a struct parameter `_param`. `_param` uniformly appears as the third
>> parameter after `self` and `_cmd`. `p _param->a` works of course, but it
>> would be nice to be able to say 'p a', since in the source code one sees
>> only `a`. `_param` is more or less an implementation detail.
>>
>> A clue how to achieve this, would be very much appreciated.
>>
>> Ciao
>>   Nat!
>>
>>
>> [*] except, if it's a picture of thousand words :)
>>
>> https://www.mulle-kybernetik.com/weblog/2015/mulle_objc_meta_call_convention.html
>> ___
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>
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