[Bug translator/18115] New: probe-condition mistranslated for array expressions

[Bug translator/18115] New: probe-condition mistranslated for array expressions

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18115

            Bug ID: 18115
           Summary: probe-condition mistranslated for array expressions
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
          Assignee: systemtap at sourceware dot org
          Reporter: fche at redhat dot com

% stap -p4 -e 'global foo  probe begin if (foo == 0) { foo = 1-foo }'
[ok]
% stap -p4 -e 'global foo  probe begin if (foo[0] == 0) { foo[0] = 1-foo[0] }'
/var/tmp/stapFHa0zZ/stap_b95e9e5526bc50657e775ced0c7f4234_925_src.c: In
function ‘probe_6330’:
/var/tmp/stapFHa0zZ/stap_b95e9e5526bc50657e775ced0c7f4234_925_src.c:169:6:
error: ‘struct probe_6330_locals’ has no member named ‘__tmp9’
     l->__tmp9 = _stp_map_get_ii (global(s_foo), ((int64_t)0LL));
      ^
/var/tmp/stapFHa0zZ/stap_b95e9e5526bc50657e775ced0c7f4234_925_src.c:170:6:
error: ‘struct probe_6330_locals’ has no member named ‘__tmp9’
     l->__tmp9;
      ^
etc.

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[Bug translator/18115] probe-condition mistranslated for array expressions

[brchrisman at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18115

Brian Chrisman <brchrisman at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |brchrisman at gmail dot com

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[Bug translator/18115] probe-condition mistranslated for array expressions

[jlebon at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18115

Jonathan Lebon <jlebon at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jlebon at redhat dot com

--- Comment #1 from Jonathan Lebon <jlebon at redhat dot com> ---
Created attachment 8188
  --> https://sourceware.org/bugzilla/attachment.cgi?id=8188&action=edit
patch for PR18115

These issues are due to the on-the-fly code, which doesn't account for
condition variables being map values, which require the creation of tmpvars to
get. More specifically, there were two problems:

(1) c_tmpcounter was not visiting the conditions, causing a mismatch between
c_tmpcounter and c_unparser.

(2) The emit_probe_condition_initialize() function would cause this type of
code to be emitted right in the middle of systemtap_module_init():

  stap_probes[0].cond_enabled = !!(((
  ({
    l->__tmp11 = _stp_map_get_ii (global(s_foo), ((int64_t)0LL));
    l->__tmp11;
  })) == (((int64_t)0LL))));

which will fail to compile since we are not within any probe body and thus
there is no 'l'.

The patch above changes the initialization mechanism so that a begin probe is
used rather than evaluating the conditions in systemtap_module_init(). The
begin probe is registered as artificially affecting every other probes with
conditions and thus will directly serve to initialize cond_enabled fields
through the regular emit_probe_condition_update(). This also allows us to get
rid of emit_probe_condition_initialize().

Making sure right now that the patch doesn't cause any regressions.

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[Bug translator/18115] probe-condition mistranslated for array expressions

[fche at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18115

--- Comment #2 from Frank Ch. Eigler <fche at redhat dot com> ---
(Please note that this problem was originally reported with a conditional
uprobe, not a begin probe, so the fix should not be specific to the latter
type.)

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[Bug translator/18115] probe-condition mistranslated for array expressions

[jlebon at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18115

--- Comment #3 from Jonathan Lebon <jlebon at redhat dot com> ---
(In reply to Frank Ch. Eigler from comment #2)
> (Please note that this problem was originally reported with a conditional
> uprobe, not a begin probe, so the fix should not be specific to the latter
> type.)

Yes, the patch is independent of probe type. The only difference the patch
makes is moving initialization code from systemtap_module_init() to the body of
a begin probe. Since begin probes are run prior to any other probe types
initializing, they are equivalent in effect. (We also don't need to worry about
making the synthetic probe run first among other begin probes since begin
probes themselves don't (and will never) support on-the-fly toggling).

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[Bug translator/18115] probe-condition mistranslated for array expressions

[jlebon at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18115

Jonathan Lebon <jlebon at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Jonathan Lebon <jlebon at redhat dot com> ---
Fixed in commit e6add4f and parents.

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