[LLVMdev] [REQUEST FOR FEEDBACK] Inline asm multiple alternative constraints
Dale Johannesen
dalej at apple.com
Thu Sep 2 10:55:39 PDT 2010
Actually the 2.8 fork is coming up tomorrow and I'm thinking maybe we
should wait until after that. Is this something you really want to
get in 2.8?
On Sep 1, 2010, at 6:29 PMPDT, John Thompson wrote:
> Dale,
>
> Thanks. It's not changed, but I've enclosed a fresh patch against
> today's trunk.
> However, I'm seeing 28 unexpected failing tests in llvm/test on x86
> Linux 64 today. But it's the same on an unmodified tree, so I guess
> I'm still okay. It passed at one point for me with these changes.
>
> -John
> On Wed, Sep 1, 2010 at 5:04 PM, Dale Johannesen <dalej at apple.com>
> wrote:
>
> On Sep 1, 2010, at 11:03 AMPDT, John Thompson wrote:
>
>> I'm close to confirming that I get the equivalent results from the
>> test-suite with my changes, compared to a fresh tree, on a Linux
>> x86 64 bit box.
>>
>> When that is the case, may I check in my current changes for the
>> LLVM side?
>
> In principle, yes, I'd like to rereview if it's changed.
>
>> My preference is to develop the mult-alt support incrementally,
>> rather than one big check-in, as I get nervous sitting on a lot of
>> changes for a long time.
>>
>> I feel this is relatively safe because the functional change only
>> kicks in if the new '|' delimiter is seen in the constraints.
>> Otherwise there should be no change in behavior.
>
> I agree.
>
>> -John
>> On Mon, Aug 30, 2010 at 3:34 PM, Dale Johannesen <dalej at apple.com>
>> wrote:
>>
>> On Aug 30, 2010, at 3:11 PMPDT, John Thompson wrote:
>>
>>> Dale,
>>>
>>> I took a closer look at the first llc failure, initp1. Looking at
>>> the initp1.llc file in gdb, it appears that the statically
>>> constructed objects without the init_priority attribute are being
>>> constructed before those with it, though the test seems to expect
>>> the opposite.
>>>
>>> The initp1.llc.s file seems to have the .ctors table in the right
>>> order, but the _init code is reading the table in reverse order.
>>> Since I guess the init code is coming from the local startup
>>> module, this must be a peculiarity of Linux x86, right?
>>
>> I don't know, you'll have to get help from somebody who uses Linux.
>>
>>> Is it different on other platforms?
>>> Anyway, it was a good exercise for to see how the tests are run,
>>> and and to dust off my gdb and Linux brain cells. Is there a
>>> prefered platform to run the test-suite on, where they all pass?
>>> Or is there a test output file I can compare against?
>>
>> llvm changes very quickly and at any given moment some tests might
>> be broken on some platforms. Regressions are usually fixed
>> quickly, though. Darwin x86-{32/64} gets the most attention.
>>
>>> Thanks.
>>>
>>> -John
>>>
>>> On Mon, Aug 30, 2010 at 11:10 AM, Dale Johannesen
>>> <dalej at apple.com> wrote:
>>> CBE is fairly broken everywhere AFAIK, don't worry about it.
>>> Most of the JIT failures are in tests that exercise exception
>>> handling. Not sure if that is supposed to work in your
>>> environment, it works in some JITs and not others.
>>> The LLC failures are cause for concern.
>>>
>>> On Aug 30, 2010, at 10:59 AMPDT, John Thompson wrote:
>>>
>>>> Dale,
>>>>
>>>> Thanks for reviewing this.
>>>>
>>>> I have some newbie questions regarding the test-suite for you or
>>>> anyone:
>>>>
>>>> I'm trying to run the test-suite as described in the "LLVM
>>>> Testing Infrastructure Guide" on a Ubuntu x86 64 bit system.
>>>> Initially I ran into problems with missing tools like yacc, which
>>>> I fixed as I went along until the make at the test-suite level
>>>> completed. However, I get a number of failed tests:
>>>>
>>>> john at john-ubuntu:~/llvm/projects/test-suite$ grep FAILED\!
>>>> jttestlog.txt
>>>> ******************** TEST (jit) 'tls' FAILED! ********************
>>>> ******************** TEST (llc) 'initp1' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'initp1' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'ctor_dtor_count-2' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'ctor_dtor_count' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'exception_spec_test' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'function_try_block' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'simple_rethrow' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'simple_throw' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'throw_rethrow_test' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'ctor_dtor_count-2' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'ctor_dtor_count' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'exception_spec_test' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'function_try_block' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'simple_rethrow' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'simple_throw' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'throw_rethrow_test' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) '2004-03-15-IndirectGoto' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'except' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'except' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'bigfib' FAILED!
>>>> ********************
>>>> ******************** TEST (llc) 'spirit' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'spirit' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'spirit' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'burg' FAILED! ********************
>>>> ******************** TEST (cbe) 'sgefa' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'make_dparser' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'spiff' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'oggenc' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'lencod' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'SIBsim4' FAILED!
>>>> ********************
>>>> ******************** TEST (llc) 'clamscan' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'clamscan' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'clamscan' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'sqlite3' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'lemon' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'OpenSSL' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'OpenSSL' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'minisat' FAILED!
>>>> ********************
>>>> ******************** TEST (jit) 'minisat' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'lua' FAILED! ********************
>>>> ******************** TEST (cbe) 'Obsequi' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'kc' FAILED! ********************
>>>> ******************** TEST (cbe) 'fhourstones3.1' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'bh' FAILED! ********************
>>>> ******************** TEST (cbe) 'health' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'cfrac' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'espresso' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'gs' FAILED! ********************
>>>> ******************** TEST (cbe) 'agrep' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'archie' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'unix-smail' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'rawcaudio' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'rawdaudio' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'encode' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'mpeg2decode' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'consumer-lame' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'consumer-typeset' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'office-ispell' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'telecomm-fft' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'enc-3des' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'enc-pc1' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'enc-rc4' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'tramp3d-v4' FAILED!
>>>> ********************
>>>> ******************** TEST (cbe) 'bullet' FAILED!
>>>> ********************
>>>>
>>>> At this point I'm not sure if its because I'm still missing
>>>> tools, these errors are expected on this platform, or there's
>>>> some problem with my tree. Any suggestions?
>>>>
>>>> -John
>>>>
>>>> On Thu, Aug 26, 2010 at 7:23 PM, Dale Johannesen
>>>> <dalej at apple.com> wrote:
>>>>
>>>> On Aug 25, 2010, at 12:45 PM, John Thompson wrote:
>>>>
>>>> Hi,
>>>>
>>>> I'm looking for some feedback on the changes represented in the
>>>> attached patches, which I'll describe below.
>>>>
>>>> I'm sending this to both the LLVM and Clang list because it
>>>> affects both, though the main focus here is LLVM.
>>>> Basically, I've partially implemented some changes for choosing
>>>> multiple alternative constraints largely on the LLVM side.
>>>>
>>>> The Clang change is to output the multiple constraints using a
>>>> '|' character in the constraint strings to delimit the
>>>> alternatives.
>>>>
>>>> This part is simple, and it can't be worse than it is now.
>>>>
>>>>
>>>> The LLVM change is as follows.
>>>>
>>>> In an earlier attempt, I just hacked up
>>>> SelectionDAGBuilder::visitInlineAsm, and pretty much used the
>>>> same logic in TargetLowering::ComputeConstraintToUse/
>>>> ChooseConstraint. But then I discovered that
>>>> InlineAsm::ParseConstraints was called in a couple of other
>>>> places, and in one of those places (IsOperandAMemoryOperand in
>>>> AddrModeMatcher.cpp), there wasn't a DAG pointer handy (at least
>>>> I don't think there is, as I'm not too familiar yet with LLVM
>>>> internals), which meant that I needed to handle multiple
>>>> alternative constraints in other places besides just
>>>> SelectionDAGBuilder::visitInlineAsm.
>>>>
>>>> That's too bad, I didn't know about the AddrModeMatcher
>>>> reference. I don't see a DAG pointer either; it seems to be an
>>>> argument in some places. Regardless, unifying the three loops
>>>> that do pretty much the same thing is surely a good idea.
>>>>
>>>>
>>>> Basically I see that there are three layers of contraint info
>>>> classes, SDISelAsmOperandInfo -> AsmOperandInfo ->
>>>> ConstraintInfo. Therefore, I implemented a different scheme,
>>>> putting a ParseConstraints function in TargetLowering that
>>>> returns a vector of AsmOperandInfo objects, and which will do the
>>>> constraint selection without needing the DAG. I'm assuming the
>>>> value info in the operands from the callsite object is sufficient
>>>> to choose the constraints. I also added some other virtual
>>>> functions to TargetLowering to allow the different targets to
>>>> handle the target-specific contraints. At present, I only
>>>> overrode the getSingleConstraintMatchWeight function in
>>>> X86TargetLowering, and just for one constraint letter, as an
>>>> example.
>>>>
>>>> In the three places where the original
>>>> InlineAsm::ParseConstraints was called (CodeGenPrepare.cpp,
>>>> AddrModeMatcher.cpp, and SelectionDAGBuilder), I replaced the
>>>> calls with calls to TargetLowering::ParseConstraints, and revised
>>>> the loops over the constraints accordingly, which were still
>>>> needed to set up SDISelAsmOperandInfo objects or get other
>>>> information the code was looking for.
>>>> SelectionDAGBuilder::visitInlineAsm I especially reordered bit at
>>>> the front, to make things work. I left in a little bit of
>>>> overlap in the setting of the CallOperandVal member in the first
>>>> for loop, which I could factor out, as I really just need the
>>>> output and input counts.
>>>>
>>>> Bascially, I wanted to get some feedback before I went too much
>>>> farther down this road.
>>>>
>>>> I don't have that good a sense of good class design, but this
>>>> looks OK to me.
>>>>
>>>>
>>>> I think the main work left is to add support for all or some
>>>> subset of both the generic and target-specific constraints, and
>>>> to write tests for them all.
>>>>
>>>> Since I had trouble with running tests on a Windows box, I set up
>>>> a Linux box so I could run the regression tests. The tests still
>>>> pass with these changes.
>>>>
>>>> Those tests don't include any for multiple alternative
>>>> constraints, since the expectation is the llvm-gcc FE will have
>>>> removed them. You should really run the gcc testsuite as well;
>>>> that's a much better test of inline asm. If you get this working
>>>> right there should be some new passes. I'm not sure how to run
>>>> it using clang as the compiler, but I think Daniel got it to work.
>>>>
>>>>
>>>> So, my main question is, am I on the right track? And either
>>>> way, specific information on problems would be appreciated too.
>>>>
>>>> Another question concerns the weighting I used for choosing the
>>>> constraints. Bascially I pretty much used the same
>>>> prioritization used in TargetLowering::ComputeConstraintToUse/
>>>> ChooseConstraint, which will chose memory operands over
>>>> register. I would have thought a register operand would have
>>>> been a better choice over memory, but then that raises the
>>>> question of whether you can know what's already in a register
>>>> when this instruction is reached. I haven't gotten deep enough
>>>> to know yet. I assume it's like this because it is more likely
>>>> to be a correct fit, if not optimal.
>>>>
>>>> I think it's that it's possible to run out of registers if you
>>>> pick "r" for a large number of "rm" constraints. This mainly
>>>> affects asm blocks, where you have hundreds of lines of asm in a
>>>> single statement.
>>>>
>>>>
>>>> It seems that if the value info in the operands from the callsite
>>>> object is sufficient to choose the constraints, the
>>>> ComputeConstraintToUse/ChooseConstraint function could also use
>>>> this scheme, probably just calling the same get weight functions,
>>>> to be a bit more efficient. I left it alone for now, because I
>>>> know it works as it is.
>>>>
>>>> Thanks for working on this.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> John Thompson
>>>> John.Thompson.JTSoftware at gmail.com
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>>
>>>
>>>
>>> --
>>> John Thompson
>>> John.Thompson.JTSoftware at gmail.com
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>>
>>
>> --
>> John Thompson
>> John.Thompson.JTSoftware at gmail.com
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
>
>
> --
> John Thompson
> John.Thompson.JTSoftware at gmail.com
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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