[PATCH] D31962: DAG: Set hasCalls on frame info earlier

[Matt Arsenault via llvm-commits]

> On Jun 19, 2017, at 14:23, Justin Bogner via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Matt Arsenault via Phabricator <reviews at reviews.llvm.org <mailto:reviews at reviews.llvm.org>> writes:
>> 
>> +bool SITargetLowering::shouldAssumeEmittedAsCall(ImmutableCallSite CS) const {
>> +  const Function *F = CS.getCalledFunction();
>> +  return !F || !F->isIntrinsic();
> 
> When does the !F case come up?

Indirect calls (also I think some cases where the function is bitcast to a different type).


> 
>> +}
>> +
>> bool SITargetLowering::isShuffleMaskLegal(const SmallVectorImpl<int> &,
>>                                           EVT) const {
>>   // SI has some legal vector types, but no legal vector operations. Say no
>> Index: lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
>> ===================================================================
>> --- lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
>> +++ lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
>> @@ -190,6 +190,8 @@
>>                 MF->getFrameInfo().setHasOpaqueSPAdjustment(true);
>>             }
>>           }
>> +        } else if (TLI->shouldAssumeEmittedAsCall(CS)) {
>> +          MF->getFrameInfo().setHasCalls(true);
>>         }
>>       }
>> 
>> Index: include/llvm/Target/TargetLowering.h
>> ===================================================================
>> --- include/llvm/Target/TargetLowering.h
>> +++ include/llvm/Target/TargetLowering.h
>> @@ -2811,6 +2811,12 @@
>>     return false;
>>   }
>> 
>> +  /// Return true if it should be assumed this will be emitted as a call, not a
>> +  /// tail call or special instruction.
>> +  virtual bool shouldAssumeEmittedAsCall(ImmutableCallSite CS) const {
>> +    return false;
>> +  }
> 
> Based on the comment, defaulting to returning false seems a bit funny
> (won't most of these be emitted as a call?).

That would nice, but this is to fix a bunch of random backend test failures. This whole thing is kind of problematic because it involves predicting whether or not the call will be a tail call or not. With the more correct conservative answer many tests fail, mostly due to emitting tail calls which don’t count or special lib calls replaced with instructions.

-Matt
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170619/e6f7fff4/attachment.html>