Experimental Physics and
Industrial Control System

Michael Davidsaver via Core-talk <core-talk at aps.anl.gov> · Thu, 4 Jun 2020 06:30:18 -0700

On 6/4/20 6:10 AM, Zimoch Dirk (PSI) via Core-talk wrote:
> The problem seems to be that -fno-implicit-fp forbids to inline floating point functions into non-floating point
> functions. In case of expire, the function uses no float/double explicitly:

I had wondered about that option.  It doesn't appear in the gcc docs.
I guess it is a vxworks patch?

https://gcc.gnu.org/onlinedocs/gcc-4.3.6/gcc/Option-Summary.html#Option-Summary

> epicsTimerNotify::expireStatus timerForOldFdmgr::expire ( const epicsTime & )
> {
>     (*this->pFunc) (this->pParam);
>     return noRestart;
> }
> 
> But epicsTimerNotify::expireStatus is a class containing a double. As the error happens at the closing } it probably
> inlining the implicit operator= of the return value.
> 
> 
> What I did now to solve the problem is to remove -fno-implicit-fp from ARCH_DEP_CFLAGS (which is used for C and C++) and
> to add it to CODE_CFLAGS, which is used for C but not for C++. This is under the assumption that interrupt handlers are
> written in C, not C++. But this does not cover extern "C" ISRs in C++.
> 
> Maybe using __attribute__((optimize ("-fno-implicit-fp"))) or #pragma GCC ("-fno-implicit-fp") would be a better choice
> to treat ISRs, but unfortunately both are not understood by the VxWorks 6.9 compiler. At least it warns: "'optimize'
> attribute directive ignored".
> 
> 
> On Thu, 2020-06-04 at 09:24 +0000, Zimoch Dirk (PSI) via Core-talk wrote:
>> It was on TechTalk in 2014 already: https://epics.anl.gov/tech-talk/2014/msg01579.php
>>
>> On Thu, 2020-06-04 at 08:55 +0000, Zimoch Dirk (PSI) via Core-talk wrote:
>>> I found that the option -fno-implicit-fp causes the problem. When adding it to the generic ppc32 configuration, I get
>>> the same "unable to find a register to spill in class 'FLOAT_REGS'" error unless I add -fno-expensive-optimizations as
>>> well.
>>>
>>> I had originally added this option when I ran into strange run-time errors because an interrupt handler of some driver
>>> had used floating point registers without being asked to do so for moving "long long" values. As the floating point
>>> registers are not saved when entering interrupt mode, bad things happened to the interrupted thread.
>>>
>>>
>>> On Wed, 2020-06-03 at 17:51 +0000, Johnson, Andrew N. wrote:
>>>> I suspect that the CPU-specific code in gcc for the ppc604 target is older than for the ppc32 target and can’t cope with newer constructs, we’ve had similar issues before. That’s why I really want to encourage you try the ppc32 targets, I don’t think they will show these errors at all and switching will save you time investigating the problems.
>>>>
>>>> - Andrew
>>>>
>>>> On Jun 3, 2020, at 12:30 PM, Zimoch Dirk (PSI) via Core-talk <core-talk at aps.anl.gov> wrote:
>>>>> 3 files have problems implementing the pure virtual function epicsTimerNotify::expire(): fdmgr.cc line 152, epicsTime.cpp line 62 and epicsTimerTest.cpp line 319. What helps is -O1 or -no-expensive-optimizations.
>>>>>
>>>>> As I expect problems with any code that implements expire() I have now added 'CXXFLAGS += -fno-expensive-optimizations' to the general options for that architecture, not only for the 3 failing files.
>>>>>
>>>>> This does not yet solve the problem with typeCast.h.
>>>>>
>>>>> More tests tomorrow.
>>>>>
>>>>>> -----Ursprüngliche Nachricht-----
>>>>>> Von: Michael Davidsaver <mdavidsaver at gmail.com>
>>>>>> Gesendet: Mittwoch, 3. Juni 2020 18:48
>>>>>> An: Zimoch Dirk (PSI) <dirk.zimoch at psi.ch>; 'core-talk at aps.anl.gov' <core-
>>>>>> talk at aps.anl.gov>
>>>>>> Betreff: Re: AW: EPICS 7 and VxWorks 6.9 for PPC604?
>>>>>>
>>>>>> On 6/3/20 8:31 AM, Zimoch Dirk (PSI) wrote:
>>>>>>> I will try the selective -fno-inline ...
>>>>>>
>>>>>>  
>>>>>> If vxworks 6.7 had gcc 4.1 then the threshold for using
>>>>>> __attribute__((always_inline)) is now being crossed.
>>>>>>
>>>>>> https://github.com/epics-
>>>>>> base/pvDataCPP/blob/0fa927afa7d92f490f92eb4906e27046080309e2/src/misc
>>>>>> /pv/templateMeta.h#L15-L16
>>>>>>
>>>>>>>> -----Ursprüngliche Nachricht-----
>>>>>>>> Von: Zimoch Dirk (PSI)
>>>>>>>> Gesendet: Mittwoch, 3. Juni 2020 17:30
>>>>>>>> An: 'Michael Davidsaver' <mdavidsaver at gmail.com>; 'core-
>>>>>>
>>>>>>  talk at aps.anl.gov'
>>>>>>>> <core-talk at aps.anl.gov>
>>>>>>>> Betreff: AW: EPICS 7 and VxWorks 6.9 for PPC604?
>>>>>>>>
>>>>>>>> It's gcc 4.3.3.
>>>>>>>>
>>>>>>>> Using -O0 (as used to fix bug 1702298) in helps for fdmgr.cpp but not for
>>>>>>>> typeCast.h.
>>>>>>>>
>>>>>>>>> -----Ursprüngliche Nachricht-----
>>>>>>>>> Von: Michael Davidsaver <mdavidsaver at gmail.com>
>>>>>>>>> Gesendet: Mittwoch, 3. Juni 2020 17:13
>>>>>>>>> An: Zimoch Dirk (PSI) <dirk.zimoch at psi.ch>; 'core-talk at aps.anl.gov' <core-
>>>>>>>>> talk at aps.anl.gov>
>>>>>>>>> Betreff: Re: EPICS 7 and VxWorks 6.9 for PPC604?
>>>>>>>>>
>>>>>>>>> For those of us who aren't so familiar with vxworks, which GCC version(s)
>>>>>>
>>>>>>  are
>>>>>>>>> involved.
>>>>>>>>>
>>>>>>>>> You may remember https://bugs.launchpad.net/epics-base/+bug/1702298
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 6/3/20 8:04 AM, Zimoch Dirk (PSI) via Core-talk wrote:
>>>>>>>>>> Has anyone already compiled EPICS 7 for VxWorks 6.9 for PPC604?
>>>>>>>>>> I have problems:
>>>>>>>>>>
>>>>>>>>>> With -O2 it fails here:
>>>>>>>>>>
>>>>>>>>>> ../fdmgr/fdmgr.cpp: In member function 'virtual
>>>>>>>>>
>>>>>>>>>  epicsTimerNotify::expireStatus timerForOldFdmgr::expire(const
>>>>>>
>>>>>>  epicsTime&)':
>>>>>>>>>> ../fdmgr/fdmgr.cpp:152: error: unable to find a register to spill in class
>>>>>>>>>
>>>>>>>>>  'FLOAT_REGS'
>>>>>>>>>> ../fdmgr/fdmgr.cpp:152: error: this is the insn:
>>>>>>>>>> (insn:HI 16 15 17 2 ../fdmgr/fdmgr.cpp:151 (set (reg:DF 126 [
>>>>>>
>>>>>>  D.11913.delay
>>>>>>>> ])
>>>>>>>>>>        (mem/s/j/c:DF (plus:SI (reg/f:SI 113 sfp)
>>>>>>>>>>                (const_int 8 [0x8])) [0 D.11913.delay+0 S8 A64])) 336
>>>>>>>>>
>>>>>>>>>  {*movdf_hardfloat32} (expr_list:REG_EQUIV (mem/s/j/c:DF (plus:SI (reg/f:SI
>>>>>>>>
>>>>>>>>  113
>>>>>>>>> sfp)
>>>>>>>>>>                (const_int 8 [0x8])) [0 D.11913.delay+0 S8 A64])
>>>>>>>>>>        (nil)))
>>>>>>>>>> ../fdmgr/fdmgr.cpp:152: confused by earlier errors, bailing out
>>>>>>>>>>
>>>>>>>>>> With -O1 (or lower) it comliles the above but then fails here:
>>>>>>>>>>
>>>>>>>>>> ../../src/misc/pv/typeCast.h: In function
>>>>>>>>
>>>>>>>>  'void<unnamed>::castVTyped(size_t,
>>>>>>>>> void*, const void*) [with TO = std::basic_string<char, std::char_traits<char>,
>>>>>>>>> std::allocator<char> >, FROM = float]':
>>>>>>>>>> ../../src/misc/pv/typeCast.h:195: sorry, unimplemented: inlining failed in
>>>>>>
>>>>>>  call
>>>>>>>>> to 'TO epics::pvData::castUnsafe(const FROM&) [with TO =
>>>>>>>>> std::basic_string<char, std::char_traits<char>, std::allocator<char> >, FROM
>>>>>>
>>>>>>  =
>>>>>>>>> float]': recursive inlining
>>>>>>>>>> ../../src/misc/typeCast.cpp:38: sorry, unimplemented: called from here
>>>>>>>>>>
>>>>>>>>>> At least the compiler is "sorry".  I feel much better.
>>>>>>>>>>
>>>>>>>>>> BTW: VxWorks 6.7 has no such problems.
>>>>>>>>>>
>>>>>>>>>> Dirk
>>>>>>>>>>
>>>>>>>
>>>>>>>  
>>>>>
>>>>>  
>>>>
>>>> -- 
>>>> Complexity comes for free, simplicity you have to work for.
>>>>

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System