[LLVMdev] Nested functions

[S. Bharadwaj Yadavalli]

Nice! Thanks for the tip, Devang. That helped.

Bharadwaj

On Wed, Mar 4, 2009 at 4:46 PM, Devang Patel <dpatel at apple.com> wrote:

>
> On Mar 4, 2009, at 1:33 PM, S. Bharadwaj Yadavalli wrote:
>
> Hi Duncan,
>
> Thanks for your reply.
>
> I did try the method suggested by you. I got a foo.bc with -emit-llvm
> switch. llc on foo.bc gets me the same assertion failure, as you pointed
> out.
>
> Then I ran bugpoint to generate bugpoint-reduced-simplified.bc and
> bugpoint-reduced-function.bc. My previous experience is that if I compile
> either if them, I would get the same failure as I did with foo.bc. That is
> not the case. I get a different assertion failure when I compile either of
> them with llc which is as follows:
>
> llc: <llvm-src>/llvm/lib/CodeGen/AsmPrinter/DwarfWriter.cpp:2808: void
> llvm::DwarfDebug::ConstructCompileUnits(): Assertion
> `Root->hasLinkOnceLinkage() && Root->hasOneUse() && "Malformed compile unit
> descriptor anchor type"' failed.
>
>
> This is because bugpoint tool does not understand debug info intrinsics.
> To avoid this, when you generate foo.bc with -emit-llvm switch, do not use
> -g on the llvm-gcc command line.
>
> -
> Devang
>
>
>
> This makes it hard for me to easily create a test case and submit a bug
> report.
>
> Hence, I thought I should take this opportunity to delve deeper into LLVM
> and look at this issue.
>
> Any further nudges / help is highly appreciated!
>
> Thanks,
>
> Bharadwaj
>
> On Wed, Mar 4, 2009 at 3:59 PM, Duncan Sands <baldrick at free.fr> wrote:
>
>> Hi Bharadwaj,
>>
>> > I get the following error during compilation using the LLVM
>> cross-compiler
>> > (x86_64->arm).
>> >
>> > error: nested functions are disabled, use -fnested-functions to
>> re-enable
>>
>> yes, nested functions are disabled by default in llvm-gcc (not sure why -
>> maybe a historical hang over from the days when they were not supported?).
>>
>> > With -fnested-functions switch, I get the following error:
>> >
>> > <llvm-src-dir>/llvm/lib/Target/ARM/ARMISelLowering.cpp:1439: virtual
>> > llvm::SDValue llvm::ARMTargetLowering::LowerOperation(llvm::SDValue,
>> > llvm::SelectionDAG&): Assertion `0 && "Don't know how to custom lower
>> > this!"' failed.
>> > frobos/tests/hello.c:453: internal compiler error: Aborted
>> > Please submit a full bug report,
>> > with preprocessed source if appropriate.
>> > See <URL:http://developer.apple.com/bugreporter> for instructions.
>> >
>> > I'd like to investigate this but am wondering if anyone has any
>> > thoughts/suggestions in this area.
>>
>> I don't know anything about cross-compiling, but the usual way
>> to debug this kind of thing is to re-run by hand the line that
>> caused this assertion, but adding -emit-llvm to the command line.
>> The output will then contain LLVM bitcode.  If you are lucky,
>> then running llc on the bitcode will give the same assertion
>> failure.  If so, then "bugpoint --run-llc the_bit_code" should
>> automatically reduce a minimal testcase.
>>
>> Ciao,
>>
>> Duncan.
>>
>
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>
> -
> Devang
>
>
>
>
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