llvm dev - Jun 2017 - Instruction does not dominate all uses!

LLVM 3.8.0, Ubuntu 16.04.2, 64 bit is being used to instrument IR.

===================================================
define i32 @bar() #0 {
entry:
  %var = alloca [3 x i32], align 4
  %0 = bitcast [3 x i32]* %var to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* bitcast ([3 x i32]*
@bar.var to i8*), i64 12, i32 4, i1 false)
  %arrayidx = getelementptr inbounds [3 x i32], [3 x i32]* %var, i64 0, i64
0
  %1 = load i32, i32* %arrayidx, align 4
  ret i32 %1
}

====================================================
if (AllocaInst *alloca_inst = dyn_cast<AllocaInst>(&I)) {
                   .
                   .
                   .
                    Value* var_addr = builder.CreateBitCast(alloca_inst,
Type::getInt8PtrTy(Ctx));
                   .
                   .
                   .
                }

====================================================
I am receiving the following error:

Instruction does not dominate all uses!

  %var = alloca [3 x i32], align 4
  %0 = bitcast [3 x i32]* %var to i8*

====================================================
I can't even see any conditional statement in the IR. Can someone please
point out what I am missing?

-- 

Thanks & Regards,
Dipanjan
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On 9 June 2017 at 21:00, Dipanjan Das via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Instruction does not dominate all uses!
>   %var = alloca [3 x i32], align 4
>   %0 = bitcast [3 x i32]* %var to i8*
It looks like your IRBuilder may be inserting the instruction in the
wrong place. I'd use the debugger to call Module::dump after that
fault to see where the bitcast really lives. If it's before the alloca
(or even not guaranteed to be afterwards) then that's your problem.

Tim.

On 9 June 2017 at 21:14, Tim Northover <t.p.northover at gmail.com> wrote:
> On 9 June 2017 at 21:00, Dipanjan Das via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > Instruction does not dominate all uses!
> >   %var = alloca [3 x i32], align 4
> >   %0 = bitcast [3 x i32]* %var to i8*
>
> It looks like your IRBuilder may be inserting the instruction in the
> wrong place.

Indeed. Thank you so much. I was scratching my head all day today. I wish
I'd have mailed in the morning, could have saved my day.

> I'd use the debugger to call Module::dump after that
> fault to see where the bitcast really lives. If it's before the alloca
> (or even not guaranteed to be afterwards) then that's your problem.
>
Out of curiosity, do my mean to fire up gdb? Can it call Module:dump()
after a breakpoint is hit?

>
> Tim.
>


-- 

Thanks & Regards,
Dipanjan
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