[LLVMdev] <badref> showed up when duplicating a list of dependent instructions

[Duncan Sands]

Hi Chuck,

> std::vector<Instruction *>::iterator p;
> Instruction * pi = PREVIOUS_POSITION;
> BasicBlock * pb = PREVIOUS_POSITION->getParent();
>
> for(p = coll.begin(); p != coll.end(); ++p){
> Instruction * CurI = * p;
> Instruction * CloneI = CurI->clone();

clone doesn't know have any magical way of knowing that it should update the
instruction's operands to point to the clone you created earlier.  For example,
consider

  %l = load i32* @ins_h, align 4
  %s = shl i32 %l, 5

You clone %l, getting:
   %lc = load i32* @ins_h, align 4
You clone %s, getting:
   %sc = shl i32 %l, 5
But %sc still has %l as an operand.  You want it to have %lc as an
operand, which requires doing more.

Ciao, Duncan.

> CloneI->setName(CurI->getName());
> errs() << *CloneI << "\n";
> pb->getInstList().insertAfter(pi, CloneI); // Inserts newInst after pi in pb
>
> // adjust pi: point to the newly inserted inst:
> pi = CurI;
>
> }//end of for loop on p
>
>
> However, I got the following errors:
>
> --- Insert New (cloned) Instructions: ...
>     <badref>   = load i32* @strstart, align 4
>    <badref>  = add i32<badref>, 2
>    <badref>  = load i32* @ins_h, align 4
>    <badref>  = getelementptr inbounds [65536 x i8]* @window, i32 0, i32<badref>
>    <badref>  = shl i32<badref>, 5
>    <badref>  = load i8*<badref>, align 1
>    %.masked = and i32<badref>, 32736
>    <badref>  = zext i8<badref>  to i32
>    <badref>  = xor i32<badref>, %.masked
>    %.sum73 = or i32<badref>, 32768
>    <badref>  = getelementptr inbounds [65536 x i16]* @prev, i32 0, i32 %.sum73
>    %take_addr2 = getelementptr i16*<badref>
>    <badref>  = bitcast i16* %take_addr2 to i8*
>    call void @bkp_memory(i8*<badref>, i32 2)
> Instruction does not dominate all uses!
>    %95 = add i32 %93, 2
>    %90 = getelementptr inbounds [65536 x i8]* @window, i32 0, i32 %95
> Instruction does not dominate all uses!
>    %97 = getelementptr inbounds [65536 x i8]* @window, i32 0, i32 %95
>    %92 = load i8* %97, align 1
> Instruction does not dominate all uses!
>    %.masked = and i32 %91, 32736
>    %101 = xor i32 %100, %.masked
> Broken module found, compilation aborted!
>
>
> What am I doing wrong here?
> Does the<badref>  sound alarm to anyone?
> What is the right approach I should take here?
>
>
> Thank you very much
>
> Chuck
>
>
>
>
>
>
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