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

[Zoltan Varga]

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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