[llvm-dev] Help required, Target Specifc SDNode getting optimized by ISel DAG

[vivek pandya via llvm-dev]

Hello LLVM Devs,

I am sorry if anyone have wasted his time on this mail as mistake was very
subtle,

I had a code as shown below:

  if( Chain.getNode()->getOpcode() == ISD::DELETED_NODE)
     printf("In Deleted node \n");
  // Update the DAG with the new chain value resulting from return lowering.
  DAG.setRoot(Chain);

so now I removed all printf statements with vim thus it made
DAG.setRoot(Chain); statement conditional.

thanks for helping.

Sincerely,
Vivek

On Thu, Feb 23, 2017 at 3:52 PM, vivek pandya <vivekvpandya at gmail.com>
wrote:

>
> Hi Krzysztof,
>
> Thanks for reply, I checked that and it seems to be ok.
> How ever I noticed that my build is have this problem on other
> architectures too. Only x86 is generating return instruction. Also epilogue
> loads are also missing.
>
> I think I have done some thing wrong to some target independent code.
>
> -Vivek
>
>>
>>
>> Hi Vivek,
>> Make sure that you return the correct chain from LowerReturn.
>>
>> -Krzysztof
>>
>>
>>
>> On 2/22/2017 7:17 AM, vivek pandya via llvm-dev wrote:
>> > Hello LLVM Devs,
>> >
>> > I am trying to compile following simple program for an experimental
>> backend
>> >
>> > int main()
>> > {
>> >    printf("Hello World \n");
>> >     return 0;
>> > }
>> >
>> > I have added code to lower return instruction in the backend however in
>> > assembly I don't find return instruction generated.
>> > In the debug-only=isel dump I can see that my target specific SDNode for
>> > RET_FLAG is added but it gets removed during DAG
>> > optimization phase.
>> >
>> >
>> > Initial selection DAG: BB#0 'main:entry'
>> > SelectionDAG has 18 nodes:
>> >   t5: i32 = GlobalAddress<i32 (i8*, ...)* @printf> 0
>> >         t0: ch = EntryToken
>> >       t4: ch = store<ST4[%retval]> t0, Constant:i32<0>,
>> > FrameIndex:i32<0>, undef:i32
>> >     t8: ch,glue = callseq_start t4, TargetConstant:i32<0>
>> >
>> >   t10: ch,glue = CopyToReg t8, Register:i32 %R5, GlobalAddress:i32<[14 x
>> > i8]* @.str> 0
>> >   t12: ch,glue = DummyArchISD::CALL t10, TargetGlobalAddress:i32<i32
>> > (i8*, ...)* @printf> 0, Register:i32 %R5, t10:1
>> >   t13: ch,glue = callseq_end t12, TargetConstant:i32<0>,
>> > TargetConstant:i32<0>, t12:1
>> >     t15: i32,ch,glue = CopyFromReg t13, Register:i32 %R3, t13:1
>> >
>> >   t16: ch,glue = CopyToReg t15:1, Register:i32 %R3, Constant:i32<0>
>> >
>> >   t17: ch = DummyArchISD::RET_FLAG t16, Register:i32 %R3, t16:1
>> >
>> >   t15: i32,ch,glue = CopyFromReg t13, Register:i32 %R3, t13:1
>> >
>> >
>> > Optimized lowered selection DAG: BB#0 'main:entry'
>> > SelectionDAG has 15 nodes:
>> >         t0: ch = EntryToken
>> >       t4: ch = store<ST4[%retval]> t0, Constant:i32<0>,
>> > FrameIndex:i32<0>, undef:i32
>> >     t8: ch,glue = callseq_start t4, TargetConstant:i32<0>
>> >
>> >   t10: ch,glue = CopyToReg t8, Register:i32 %R5, GlobalAddress:i32<[14 x
>> > i8]* @.str> 0
>> >   t12: ch,glue = DummyArchISD::CALL t10, TargetGlobalAddress:i32<i32
>> > (i8*, ...)* @printf> 0, Register:i32 %R5, t10:1
>> >   t13: ch,glue = callseq_end t12, TargetConstant:i32<0>,
>> > TargetConstant:i32<0>, t12:1
>> >   t15: i32,ch,glue = CopyFromReg t13, Register:i32 %R3, t13:1
>> >
>> >
>> >
>> > Can someone please guide me how to furhter debug this situation? Or any
>> > hints.
>> >
>> > Sincerely,
>> > Vivek
>> >
>> >
>> > _______________________________________________
>> > LLVM Developers mailing list
>> > llvm-dev at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>> >
>>
>> --
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>> hosted by The Linux Foundation
>>
>>
>>
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