[PATCH] D109749: Experimental Partial Mem2Reg

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added a comment.

In D109749#3078247 <https://reviews.llvm.org/D109749#3078247>, @huntergr wrote:

> In D109749#3078176 <https://reviews.llvm.org/D109749#3078176>, @jdoerfert wrote:
>
>> Does this work for you:
>>
>>   diff --git a/llvm/lib/Analysis/CaptureTracking.cpp b/llvm/lib/Analysis/CaptureTracking.cpp
>>   index 8955658cb9e7..41251d2676e6 100644
>>   --- a/llvm/lib/Analysis/CaptureTracking.cpp
>>   +++ b/llvm/lib/Analysis/CaptureTracking.cpp
>>   @@ -373,9 +373,13 @@ void llvm::PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker,
>>        case Instruction::Store:
>>          // Stored the pointer - conservatively assume it may be captured.
>>          // Volatile stores make the address observable.
>>   -      if (U->getOperandNo() == 0 || cast<StoreInst>(I)->isVolatile())
>>   +      if (U->getOperandNo() == 0 || cast<StoreInst>(I)->isVolatile()) {
>>   +        if (auto *AI = dyn_cast<AllocaInst>(I->getOperand(1)->stripInBoundsOffsets()))
>>   +          if (AI->hasMetadata("nocapture_storage"))
>>   +            break;
>>            if (Tracker->captured(U))
>>              return;
>>   +      }
>>          break;
>>        case Instruction::AtomicRMW: {
>>          // atomicrmw conceptually includes both a load and store from
>>
>> And then add `!nocapture_storage !0` after the alloca in your example as well as `!0 = !{!0}` in the end of that file
>
> Ah, the 'nocapture_storage' metadata is what I've been missing, thanks. I'll update the diff once I've added that and adjusted the tests.

Technically, this is not yet something we have in the IR. We can reply to the old thread in which different solutions were discussed and
propose this one again. Then modify Clang to emit the metadata for the reduction case and land the diff I posted. All that said, it works
for your case, right?


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