[llvm] r312165 - Refactor DIBuilder::createFragmentExpression into a static DIExpression member

[Francois Pichet via llvm-commits]

On Mon, Oct 30, 2017 at 5:15 PM, Adrian Prantl <aprantl at apple.com> wrote:

>
>
> On Oct 30, 2017, at 2:12 PM, Francois Pichet <pichet2000 at gmail.com> wrote:
>
>
>
> On Wed, Aug 30, 2017 at 4:04 PM, Adrian Prantl via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: adrian
>> Date: Wed Aug 30 13:04:17 2017
>> New Revision: 312165
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=312165&view=rev
>> Log:
>> Refactor DIBuilder::createFragmentExpression into a static DIExpression
>> member
>>
>> NFC
>>
>> Modified:
>>     llvm/trunk/include/llvm/IR/DIBuilder.h
>>     llvm/trunk/include/llvm/IR/DebugInfoMetadata.h
>>     llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
>>     llvm/trunk/lib/IR/DIBuilder.cpp
>>     llvm/trunk/lib/IR/DebugInfoMetadata.cpp
>>     llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp
>>     llvm/trunk/lib/Transforms/Scalar/SROA.cpp
>>
>>
>>
>> Modified: llvm/trunk/lib/IR/DebugInfoMetadata.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/
>> DebugInfoMetadata.cpp?rev=312165&r1=312164&r2=312165&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/IR/DebugInfoMetadata.cpp (original)
>> +++ llvm/trunk/lib/IR/DebugInfoMetadata.cpp Wed Aug 30 13:04:17 2017
>> @@ -724,6 +724,34 @@ DIExpression *DIExpression::prepend(cons
>>    return DIExpression::get(Expr->getContext(), Ops);
>>  }
>>
>> +DIExpression *DIExpression::createFragmentExpression(const DIExpression
>> *Expr,
>> +                                                     unsigned
>> OffsetInBits,
>> +                                                     unsigned
>> SizeInBits) {
>> +  SmallVector<uint64_t, 8> Ops;
>> +  // Copy over the expression, but leave off any trailing
>> DW_OP_LLVM_fragment.
>> +  if (Expr) {
>> +    for (auto Op : Expr->expr_ops()) {
>> +      if (Op.getOp() == dwarf::DW_OP_LLVM_fragment) {
>> +        // Make the new offset point into the existing fragment.
>> +        uint64_t FragmentOffsetInBits = Op.getArg(0);
>> +        // Op.getArg(0) is FragmentOffsetInBits.
>> +        // Op.getArg(1) is FragmentSizeInBits.
>> +        assert((OffsetInBits + SizeInBits <= Op.getArg(0) +
>> Op.getArg(1)) &&
>> +               "new fragment outside of original fragment");
>>
>
>
>  Hi,
>
> I am getting an assert here on an (out of tree) big-endian target where
> 64-bit variables are splitted on 2 32-bit variables.
> assert where: OffsetInBits=32, SizeInBits=32 and
> Expr: !DIExpression(DW_OP_LLVM_fragment, 0, 32)
> so 32 + 32 <= 32 is not true.
>
> I might be wrong but I think the assert is only valid on little endian
> target?
>
>
> I'm not sure I understand your example. Are you saying that you are
> calling createFragmentExpression on something that is already 32-bit
> fragment? Which pass is calling it? It seems more likely that there is
> something wrong with the call site.
>
> -- adrian
>
>
> DAGTypeLegalizer::SetExpandedInteger is the call site:

  if (DAG.getDataLayout().isBigEndian()) {
    transferDbgValues(DAG, Op, Hi, 0);
    transferDbgValues(DAG, Op, Lo, Hi.getValueSizeInBits());  // <---
assert
  } else {
    transferDbgValues(DAG, Op, Lo, 0);
    transferDbgValues(DAG, Op, Hi, Lo.getValueSizeInBits());
  }

The first call to transferDbgValues will create
!DIExpression(DW_OP_LLVM_fragment,
0, 32)
The second call will assert because OffsetInBits= 32 and SizeInBits=32

I believe the assert is only valid on little-endian target.
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