[M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)

Sat May 15 05:10:54 CEST 2010

http://gcc.gnu.org/ml/gcc/2006-02/msg00577.html

BIT_FIELD_REF considered harmful

We should try to use COMPONENT_REF instead.

 - Jay

----------------------------------------
> From: jay.krell at cornell.edu
> To: hosking at cs.purdue.edu
> Date: Sat, 15 May 2010 01:29:01 +0000
> CC: m3devel at elegosoft.com
> Subject: Re: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>
>
> Well I'm feeling dumb. That test case surely would print 1 for almost anything.
> A more accurate one, which shows a problem, is:
>
> #include 
>
> unsigned F1(unsigned a) { return ((a>> 22) & 1); }
> unsigned F2(unsigned a) { return ((a << 22)>> 31); }
>
> int main()
> {
>     unsigned a = 1 << 22;
>     printf("%x %x\n", F1(a), F2(a));
>     return 0;
> }
>
> But I'm still having trouble convincing myself.
> I guess the second might give you the 10th bit.
> Er, the 9th.
>
> #include 
>
> unsigned F1(unsigned a) { return ((a>> 22) & 1); }
> unsigned F2(unsigned a) { return ((a << 22)>> 31); }
>
> int main()
> {
>     unsigned a = 1 << 22;
>     printf("%x %x\n", F1(a), F2(a));
>
>     a = 1 << 9;
>     printf("%x %x\n", F1(a), F2(a));
>     return 0;
> }
>
> 1 0
> 0 1
>
>  - Jay
>
> ----------------------------------------
>> From: jay.krell at cornell.edu
>> To: hosking at cs.purdue.edu
>> Date: Sat, 15 May 2010 01:07:27 +0000
>> CC: m3devel at elegosoft.com
>> Subject: Re: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>
>>
>>> < srl %g1, 22, %g1
>>> < and %g1, 1, %g1
>>> ---
>>>> sll %g1, 22, %g1
>>>> srl %g1, 31, %g1
>>
>> Er.
>> first: a = (a>> 22) & 1;
>> second: a = (a << 22)>> 31;
>>
>> are actually darn close, maybe the same.
>> Let's just be lame and test in C:
>>
>> #include
>> int main()
>> {
>> unsigned a = ~0;
>> unsigned b = (a>> 22) & 1;
>> unsigned c = (a << 22)>> 31;
>> printf("%x %x\n", b, c);
>> return 0;
>> }
>>
>> both print 1. So I remain a bit uncertain.
>> I think undoing just that one change made it go between working and not working, but I also often lose track of what I've cleaned vs. rebuilt.
>> I might dig more before commiting the undo.
>> Maybe bit fields of multiple bits are the only ones broken.
>>
>> - Jay
>>
>>
>> ----------------------------------------
>>> From: jay.krell at cornell.edu
>>> To: hosking at cs.purdue.edu
>>> Date: Sat, 15 May 2010 00:24:03 +0000
>>> CC: m3devel at elegosoft.com
>>> Subject: Re: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>>
>>>
>>> Tony I think it is your change to extract_mn.
>>> Try it with SOLsun for example.
>>> I see these sorts of differences repeatedly (not to mention works vs. not works, having only undone that change):
>>>
>>>
>>> diff cm3-boot-SOLsun-1/Abs.ms cm3-boot-SOLsun-2/Abs.ms
>>> 77,78c77,78
>>> < srl %g1, 22, %g1
>>> < and %g1, 1, %g1
>>> ---
>>>> sll %g1, 22, %g1
>>>> srl %g1, 31, %g1
>>> 118,119c118,119
>>> < srl %g1, 22, %g1
>>> < and %g1, 1, %g1
>>> ---
>>>> sll %g1, 22, %g1
>>>> srl %g1, 31, %g1
>>> 197,198c197,198
>>> < srl %g1, 21, %g1
>>> < and %g1, 1, %g1
>>> ---
>>>> sll %g1, 21, %g1
>>>> srl %g1, 31, %g1
>>> 236,237c236,237
>>> < srl %g1, 22, %g1
>>> < and %g1, 1, %g1
>>> ---
>>>> sll %g1, 22, %g1
>>>> srl %g1, 31, %g1
>>> 273,274c273,274
>>> < srl %g1, 22, %g1
>>> < and %g1, 1, %g1
>>>
>>>
>>> This is not optimized.
>>> They seem equally optimal, but very different.
>>> Assuming shifts are fast. Could be srl+and is faster than sll+srl.
>>> srl+and is clearer.
>>> I don't remember which of these worked.
>>>
>>>
>>> < srl %g1, 22, %g1
>>>
>>> < and %g1, 1, %g1
>>>
>>> ---
>>>
>>>> sll %g1, 22, %g1
>>>
>>>> srl %g1, 31, %g1
>>>
>>>
>>>
>>> I read the first as:
>>> extract bit 22, plus or minus 1
>>> vs.
>>> extract bit 32-22=10, plus or minus 1.
>>>
>>>
>>> It would probably be ok to move bits around, but insert would have to match.
>>>
>>>
>>> - Jay
>>>
>>>
>>> ----------------------------------------
>>>> From: jay.krell at cornell.edu
>>>> To: hosking at cs.purdue.edu
>>>> Date: Fri, 14 May 2010 22:13:58 +0000
>>>> CC: m3devel at elegosoft.com
>>>> Subject: Re: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>>>
>>>>
>>>> So maybe I386_LINUX is ok..but others not..I need to test more/again/more/again/more/again....
>>>>
>>>> - Jay
>>>>
>>>> ----------------------------------------
>>>>> From: jay.krell at cornell.edu
>>>>> To: hosking at cs.purdue.edu
>>>>> CC: m3devel at elegosoft.com
>>>>> Subject: RE: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>>>> Date: Fri, 14 May 2010 18:25:59 +0000
>>>>>
>>>>>
>>>>> I should disclose that I also rolled back hand.c, though that is mostly or completely implied, due to mod/div/set.
>>>>>
>>>>>
>>>>> I have some extra time today, so, plan:
>>>>> retest head on I386_LINUX (still crossing from Darwin/x86), verify it is broken, since it is all working now
>>>>> test undo just the bitfield insert/extract change, see if that is the problem
>>>>> work through the others if not
>>>>> Possibly verify mod/div test coverage (unless it is the problem, in which
>>>>> case if I put it back, no need for test coverage, probably nobody will ever
>>>>> touch it again, which is fine. :) )
>>>>> I'm pretty sure I tested the set stuff well because I was very nervous but
>>>>> if others are ruled out I'll undo or test it.
>>>>> (To clarify, I wasn't even sure by close inspection of the correctness of my NT386
>>>>> set changes. Only through experimentation/testing could I know that
>>>>> the definition of bit indices matched up between hand.c and the btc/bts instructions,
>>>>> it appeared to be a very convenient coincidence.)
>>>>>
>>>>>
>>>>> I am surprised that I386_* working and broken.
>>>>> I would think wordsize and endian is all that matters here.
>>>>>
>>>>>
>>>>> I do worry that we are only on gcc 4.3.0 and not even 4.3.3.
>>>>> But moving up to 4.4.x or 4.5.x is welcome too. :)
>>>>>
>>>>>
>>>>> - Jay
>>>>>
>>>>>
>>>>> ----------------------------------------
>>>>>> From: jay.krell at cornell.edu
>>>>>> To: hosking at cs.purdue.edu
>>>>>> Date: Fri, 14 May 2010 17:58:29 +0000
>>>>>> CC: m3devel at elegosoft.com
>>>>>> Subject: Re: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>>>>>
>>>>>>
>>>>>> I don't think anything I've been fiddling with has been dropped by gcc, yet.
>>>>>> I might have depended on Irix o32 to get up to a working gcc, but no matter.
>>>>>> I agree if they drop it, we have to.
>>>>>> Though we could also keep multiple gcc versions if there was really something we wanted,
>>>>>> but that's not likely.
>>>>>> A C generating backend also solves this.
>>>>>>
>>>>>>
>>>>>> I think I tested my "set" changes on 32bit, 64bit, little endian, big endian, all four combinations.
>>>>>> But I won't guarantee that now and am very willing to undo them if there is a problem.
>>>>>> (big endian 64bit would be PPC64_DARWIN, which does have a strong propensity to hang, but also largely works).
>>>>>>
>>>>>>
>>>>>> I don't remember about div/mod.
>>>>>> While it seems "obvious" that the change is correct, it could be that that part of
>>>>>> gcc is little tested: C and Fortran wouldn't use it. But maybe Ada?
>>>>>>
>>>>>>
>>>>>> I'm also not optimizing at all.
>>>>>>
>>>>>>
>>>>>> I also agree that rolling forward to any newer gcc is welcome. I just don't know how to do it, at least not
>>>>>> easily, and I'm also not keen on the huge testing matrix.
>>>>>> (I think it's roughly what I did for Apple's gcc 4.2, but it was tedious.)
>>>>>>
>>>>>>
>>>>>> If it is ICEs we are after though, it is fairly easy to do cross builds and test "everything", automated, given the time to build gcc enough times. :)
>>>>>> We should really fix the few lingering 32bit/64bit cross bugs, so we can cross build everything.
>>>>>>
>>>>>>
>>>>>> Rolling back parse.c, I think every target I've tested (running cm3 bootstrap and making
>>>>>> sure it gets as far as "can't find cm3.cfg") has worked, except PPC32_OPENBSD.
>>>>>> This includes PPC_DARWIN, PPC64_DARWIN, I386_LINUX, SPARC64_SOLARIS,
>>>>>> SPARC64_OPENBSD. (SPARC64_SOLARIS now probably working).
>>>>>>
>>>>>>
>>>>>> - Jay
>>>>>>
>>>>>> ----------------------------------------
>>>>>>> From: hosking at cs.purdue.edu
>>>>>>> Date: Fri, 14 May 2010 09:59:02 -0400
>>>>>>> To: jay.krell at cornell.edu
>>>>>>> CC: m3devel at elegosoft.com
>>>>>>> Subject: Re: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>>>>>>
>>>>>>> Argh. I worried about that when I made my changes, but all seemed to be well for bootstraps on Darwin/x86.
>>>>>>>
>>>>>>> Also, we need to have regular testing of the compiler at both -O1 and -O2 or -O3 optimisation levels. I know of at least one gcc ICE on one platform (I forget which) that manifests only at -O3 compiling just one module in the entire CM3 distribution. This is fragile stuff... and it may just be a bug in gcc that we are exercising.
>>>>>>>
>>>>>>> It may be that we just need to update the backend to a newer version of gcc. It has been a couple of years, and Jay is pushing the target envelope much further than it ever has been. Problem is that newer gcc may not play nice with older targets. I strongly suggest that we focus effort on modern targets and not older targets, which implies we probably want to roll the gcc-based backend forward to a more current gcc release.
>>>>>>>
>>>>>>> On 14 May 2010, at 06:27, Jay K wrote:
>>>>>>>
>>>>>>>>
>>>>>>>> ok, bringing parse.c mostly back to what it is in release, has cleared up a lot of this, I haven't nested it all.
>>>>>>>> Then I'll have to narrow it down some -- there are two main sets of changes:
>>>>>>>> - my changes to set operations
>>>>>>>> - my change to div/mod
>>>>>>>> - Tony's to bit field operations
>>>>>>>>
>>>>>>>> It is also conceivable that mixing release/head cm3 with head/release cm3cg 1) doesn't work 2) I was doing it.
>>>>>>>>
>>>>>>>> I thought I had tested my changes thoroughly but at this point, I don't know, and don't care much
>>>>>>>> to keep them if they don't work.
>>>>>>>> (Well, hopefully the NT386 versions can stay. :) )
>>>>>>>>
>>>>>>>> - Jay
>>>>>>>>
>>>>>>>>
>>>>>>>> ----------------------------------------
>>>>>>>>> From: jay.krell at cornell.edu
>>>>>>>>> To: m3devel at elegosoft.com
>>>>>>>>> Date: Fri, 14 May 2010 09:08:58 +0000
>>>>>>>>> Subject: Re: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Hm. Something is wrong on many platforms, in head, at least with my boot archives.
>>>>>>>>> PPC_DARWIN, SOLsun, I386_LINUX
>>>>>>>>> I'll figure it out. Hopefully soon.
>>>>>>>>>
>>>>>>>>> - Jay
>>>>>>>>>
>>>>>>>>> ----------------------------------------
>>>>>>>>>> From: jay.krell at cornell.edu
>>>>>>>>>> To: m3devel at elegosoft.com
>>>>>>>>>> Date: Fri, 14 May 2010 06:37:07 +0000
>>>>>>>>>> Subject: [M3devel] some other ports.. (PPC32_OPENBSD, SPARC64_OPENBSD, SPARC64_SOLARIS)
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I've tried SPARC64_OPENBSD, SPARC64_SOLARIS, PPC32_OPENBSD recently (this week).
>>>>>>>>>>
>>>>>>>>>> SPARC64_SOLARIS gets far through RTLinker__InitRuntime, but ultimately bus errors in around the first line of RTType__UpdateCell, something in PolyBasis.
>>>>>>>>>> The data in the assembly looks like. Maybe a runtime memory corruption.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> PPC32_OPENBSD complains something like in TextCat that a type is missing.
>>>>>>>>>> I think it used to mostly work since I deleted some install I had there.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> SPARC64_OPENBSD bus errors just a few instructions into RTLinker__InitRuntime.
>>>>>>>>>> (gdb) disassem
>>>>>>>>>> Dump of assembler code for function RTLinker__InitRuntime:
>>>>>>>>>> 0x00000000004bd01c : save %sp, -224, %sp
>>>>>>>>>> 0x00000000004bd020 : sethi %hi(0xd18800), %l7
>>>>>>>>>> 0x00000000004bd024 : add %l7, 0x1fc, %l7 ! 0xd189fc
>>>>>>>>>> 0x00000000004bd028 : call 0x4bd010 <_m3_fault+60>
>>>>>>>>>> 0x00000000004bd02c : nop
>>>>>>>>>> 0x00000000004bd030 : stx %i0, [ %fp + 0x87f ]
>>>>>>>>>> 0x00000000004bd034 : stx %i1, [ %fp + 0x887 ]
>>>>>>>>>> 0x00000000004bd038 : stx %i2, [ %fp + 0x88f ]
>>>>>>>>>> 0x00000000004bd03c : stx %i3, [ %fp + 0x897 ]
>>>>>>>>>> 0x00000000004bd040 : sethi %hi(0x942c00), %g1
>>>>>>>>>> 0x00000000004bd044 : or %g1, 0x290, %g1 ! 0x942e90
>>>>>>>>>> 0x00000000004bd048 : ldx [ %l7 + %g1 ], %g1 << here
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> This seems like it'll be tough going. :(
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I think I'll try with PIC turned off.
>>>>>>>>>>
>>>>>>>>>> - Jay
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>