CoroFrame: Fix missing bitcast for some frame merges

[MatzeB]

Summary

The code to adjust types when merging fields on the coroutine frame accidentally used GetElementPtrInst::getResultElementType() which does the return the type the resulting pointer points to (so misses a pointer type). This worked most of the time by accident because the type nearly never matched, but failed to add a necessary bitcast for from i8** to i8*.

[nikic]

Please remove the test case, we do not accept new typed pointer test coverage.

[MatzeB]

Please remove the test case, we do not accept new typed pointer test coverage.

The issue does not exist for opaque pointers so I cannot convert the test.

Will remove the test then...

[MatzeB]

drop test

[nikic]

LGTM, as long as it lands before the creation of the release/16.x branch.

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

if (auto *AI = dyn_cast<AllocaInst>(Orig)) {
       }
       // If the type of GEP is not equal to the type of AllocaInst, it implies
       // that the AllocaInst may be reused in the Frame slot of other
       // AllocaInst. So We cast GEP to the AllocaInst here to re-use
       // the Frame storage.
       //
       // Note: If we change the strategy dealing with alignment, we need to refine
       // this casting.
-      if (GEP->getResultElementType() != Orig->getType())
+      if (GEP->getType() != Orig->getType())
         return Builder.CreateBitCast(GEP, Orig->getType(),
                                      Orig->getName() + Twine(".cast"));
     }
     return GEP;
   };
 
   for (auto const &E : FrameData.Spills) {
     Value *Def = E.first;