[LLVMdev] [PATH] Add sub.ovf/mul.ovf intrinsics

[Bill Wendling]

It's the DAG combiner that's barfing. I'll look into it.

-bw

On Dec 9, 2008, at 3:59 PM, Zoltan Varga wrote:

> Hi,
>
>  The add.with.overflow instrinsics don't seem to work with constant
> arguments, i.e.
> changing the call in add-with-overflow.ll to:
>  %t = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 0, i32 0)
>
> causes the following exception when running the codegen tests:
>
> llc: DAGCombiner.cpp:646:
> void<unnamed>::DAGCombiner::Run(llvm::CombineLevel): Assertion
> `N->getValueType(0) == RV.getValueType() && N->getNumValues() == 1 &&
> "Type mismatch"' failed.
> 0   llc       0x00000000010601ef
> 1   llc       0x00000000010604ec
> 2   libc.so.6 0x00007f58a754df60
> 3   libc.so.6 0x00007f58a754ded5 gsignal + 53
> 4   libc.so.6 0x00007f58a754f3f3 abort + 387
> 5   libc.so.6 0x00007f58a7546dc9 __assert_fail + 233
> 6   llc       0x0000000000cd0444
> 7   llc       0x0000000000cd0575
> llvm::SelectionDAG::Combine(llvm::CombineLevel, llvm::AliasAnalysis&,
> bool) + 55
> 8   llc       0x0000000000d5075a
> llvm::SelectionDAGISel::CodeGenAndEmitDAG() + 2176
> 9   llc       0x0000000000d52a6e
> llvm::SelectionDAGISel::SelectBasicBlock(llvm::BasicBlock*,
> llvm::ilist_iterator<llvm::Instruction>,
> llvm::ilist_iterator<llvm::Instruction>) + 642
> 10  llc       0x0000000000d533e5
> llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function&,
> llvm::MachineFunction&, llvm::MachineModuleInfo*,
> llvm::TargetInstrInfo const&) + 2175
> 11  llc       0x0000000000d540f6
> llvm::SelectionDAGISel::runOnFunction(llvm::Function&) + 778
> 12  llc       0x0000000000fedd1d
> llvm::FPPassManager::runOnFunction(llvm::Function&) + 239
> 13  llc       0x0000000000fee860
> llvm::FunctionPassManagerImpl::run(llvm::Function&) + 116
> 14  llc       0x0000000000fee9be
> llvm::FunctionPassManager::run(llvm::Function&) + 128
> 15  llc       0x0000000000822a95 main + 2234
>
>                         Zoltan
>
> On Tue, Dec 9, 2008 at 11:08 PM, Bill Wendling <isanbard at gmail.com>  
> wrote:
>> Applied. Thanks, Zoltan!
>>
>> -bw
>>
>> On Tue, Dec 9, 2008 at 1:12 PM, Zoltan Varga <vargaz at gmail.com>  
>> wrote:
>>> Hi,
>>>
>>> Attached is the final version of the patch, adding the requested
>>> FIXME. If this is ok, can
>>> somebody check it in ?
>>>
>>>                               thanks
>>>
>>>                                     Zoltan
>>>
>>> On Tue, Dec 9, 2008 at 9:58 PM, Bill Wendling <isanbard at gmail.com>  
>>> wrote:
>>>> On Tue, Dec 9, 2008 at 6:11 AM, Zoltan Varga <vargaz at gmail.com>  
>>>> wrote:
>>>>> Hi,
>>>>>
>>>>> Here is the next iteration of the patch. The only comment not
>>>>> addressed is this one:
>>>>>
>>>> Thanks! It's looking good.
>>>>
>>>>>> It would be better to implement a target-independent check for
>>>>>> overflow for the "Legal" case (like how SADDO does). Hacker's >  
>>>>>> Delight
>>>>>> has some hints on how to do this. It's not easy for the signed  
>>>>>> case,
>>>>>> but is do-able.
>>>>>
>>>>> It can be lowered to a division + a branch, so it would be
>>>>> inefficient, plus it would
>>>>> be a lot of work to implement it correctly (for me at least).
>>>>>
>>>> Okay. It would be tricky. Please put a "FIXME" in there indicating
>>>> that it would be nice to have at some point. It's okay to submit  
>>>> this.
>>>>
>>>> -bw
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