[llvm] r277980 - [PM] Invalidate CallGraphAnalysis because it holds AssertingVH

[Sean Silva via llvm-commits]

On Sun, Aug 7, 2016 at 11:40 PM, Chandler Carruth <chandlerc at google.com>
wrote:

> On Sun, Aug 7, 2016 at 10:45 PM Sean Silva via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: silvas
>> Date: Mon Aug  8 00:38:01 2016
>> New Revision: 277980
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=277980&view=rev
>> Log:
>> [PM] Invalidate CallGraphAnalysis because it holds AssertingVH
>>
>> This is essentially PR28400. The fix here is similar to that implemented
>> in r274656.
>>
>
> This patch, without a test case, is very hard to understand. It doesn't
> seem to make sense in isolation.
>
> Maybe this makes more sense in combination with the large patch around
> invalidation you mailed out? If so, I don't think it should just be
> committed.
>

No, this is unrelated to that patch. This is related to the thread "Should
analyses be able to hold AssertingVH to IR? (related to PR28400)" linked
from r274656 which was mentioned in the commit message.




>
> If this makes sense outside that patch, I would expect a test case? Maybe
> discuss this before committing it?
>
>

I described this workaround in that thread and there didn't seem to be any
objections to doing that for now.

-- Sean Silva



>
>> Modified:
>>     llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
>>
>> Modified: llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
>> Transforms/IPO/FunctionAttrs.cpp?rev=277980&r1=277979&r2=277980&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp (original)
>> +++ llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp Mon Aug  8 00:38:01
>> 2016
>> @@ -1271,6 +1271,11 @@ ReversePostOrderFunctionAttrsPass::run(M
>>    auto &CG = AM.getResult<CallGraphAnalysis>(M);
>>
>>    bool Changed = deduceFunctionAttributeInRPO(M, CG);
>> +
>> +  // CallGraphAnalysis holds AssertingVH and must be invalidated eagerly
>> so
>> +  // that other passes don't delete stuff from under it.
>> +  AM.invalidate<CallGraphAnalysis>(M);
>> +
>>    if (!Changed)
>>      return PreservedAnalyses::all();
>>    PreservedAnalyses PA;
>>
>>
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