[LLVMdev] PR4174

[Eli Friedman]

On Fri, Aug 21, 2009 at 5:05 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote:
>
> On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote:
>
>> On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote:
>>>
>>> On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote:
>>>
>>>> On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote:
>>>>>
>>>>> On Aug 21, 2009, at 7:31 PM, Eli Friedman wrote:
>>>>>
>>>>>> On Fri, Aug 21, 2009 at 2:06 PM, Jakub Staszak<kuba at gcc.gnu.org>
>>>>>> wrote:
>>>>>>>
>>>>>>> Hello,
>>>>>>>
>>>>>>> This patch fixes PR4174. Two test-cases included: original one from
>>>>>>> bugzilla
>>>>>>> and a little bit complicated made be myself.
>>>>>>
>>>>>> I think you want isSafeToSpeculativelyExecute rather than
>>>>>> mayHaveSideEffects.  Otherwise, looks fine.
>>>>>
>>>>> With isSafeToSpeculativelyExecute "make check" fails on some tests,
>>>>> i.e:
>>>>> test/Transforms/LoopIndexSplit/SaveLastValue-2007-08-17.ll
>>>>> because of PHI (isSafeToSpeculativelyExecute == false).
>>>>
>>>> isSafeToSpeculativelyExecute returns false for PHI nodes because it
>>>> isn't really clear what to do in that case... here, it's safe, so
>>>> isSafeToSpeculativelyExecute || isa<PHINode> is probably best.
>>>
>>> Another two "hacks" are needed: for BranchInst and for IntrinsicInst.
>>>
>>> Patch attached.
>>
>> IntrinsicInst isn't necessarily safe...
>
>
> Without IntrinsicInst we break
> test/Transforms/LoopIndexSplit/SplitValue-2007-08-24-dbg.ll.

Checking for isa<DbgInfoIntrinsic> is safe.

-Eli