[Bug translator/29037] New: Systemtap unable to find struct bitfield members for gcc11 compiled code

["wcohen at redhat dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=29037

            Bug ID: 29037
           Summary: Systemtap unable to find struct bitfield members for
                    gcc11 compiled code
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
          Assignee: systemtap at sourceware dot org
          Reporter: wcohen at redhat dot com
  Target Milestone: ---

Created attachment 14053
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14053&action=edit
Tarball of the code for gcc11 bitfield reproducer

When reviewing the testsuite results for the systemtap examples I noticed
several examples (tcp_trace, tcpdumplike, and schedtimes) failed because
systemtap was not able to access various struct member bitfields for code
generated by gcc11 compiler.  GCC11 is in Fedora 34 and later, so those
examples do not work in fedora 34 or later.  However, they work in Fedora 33
and RHEL8.

Made a small reproducer to demonstrate the issue, fields.c and an associated
fields_probes.stp.  On RHEL can see that systemtap finds the bitfield and
prints out the information:

[wcohen@rhel8 ~]$ gcc -O2 -g -o fields fields.c
[wcohen@rhel8 ~]$ sudo stap -v fields_probes.stp -c "./fields"
Pass 1: parsed user script and 501 library scripts using
352200virt/152564res/18004shr/136660data kb, in 260usr/30sys/282real ms.
Pass 2: analyzed script: 1 probe, 2 functions, 0 embeds, 0 globals using
356688virt/158504res/19128shr/141148data kb, in 20usr/0sys/20real ms.
Pass 3: translated to C into
"/tmp/staplw3Mn1/stap_728fe8eaae91c669f6cd3df4b02f5bf7_1361_src.c" using
356952virt/158964res/19320shr/141412data kb, in 10usr/60sys/69real ms.
Pass 4: compiled C into "stap_728fe8eaae91c669f6cd3df4b02f5bf7_1361.ko" in
2190usr/470sys/2763real ms.
Pass 5: starting run.
a.icsk_ca_state: false
a.icsk_ca_initialized: false
a.icsk_ca_setsockopt: false
a.icsk_ca_dst_locked: false
$a->icsk_ca_state = 0
Pass 5: run completed in 30usr/40sys/326real ms.


However, on Fedora Rawhide unable to find the bitfield:


[wcohen@rawhide ~]$ gcc -O2 -g -o fields fields.c 
[wcohen@rawhide ~]$ sudo stap -v fields_probes.stp -c "./fields"
Pass 1: parsed user script and 506 library scripts using
454360virt/212868res/17668shr/195016data kb, in 390usr/70sys/463real ms.
Pass 2: analyzed script: 1 probe, 1 function, 0 embeds, 0 globals using
462060virt/222736res/19484shr/202716data kb, in 30usr/0sys/39real ms.
Pass 3: translated to C into
"/tmp/stapUdlYqF/stap_d24e675b2dbd63c03baff5e35cb87ef3_1219_src.c" using
463116virt/223908res/19612shr/203772data kb, in 10usr/60sys/63real ms.
Pass 4: compiled C into "stap_d24e675b2dbd63c03baff5e35cb87ef3_1219.ko" in
1760usr/270sys/2064real ms.
Pass 5: starting run.
a.icsk_ca_state: false
a.icsk_ca_initialized: false
a.icsk_ca_setsockopt: false
a.icsk_ca_dst_locked: false
no field icsk_ca_state
Pass 5: run completed in 10usr/40sys/342real ms.

The fields.c, fields_probes.stp and the dumps of the object code and dwarf are
in the gcc11_bitfield.tar.gz.

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