[PATCH] D26569: [InstCombine] Support load(gep(A, select(idx1, idx2)))) to select(load(gep(A, idx1)), load(gep(A, idx2))) transformation

[Wei Mi via llvm-commits]

wmi added inline comments.


================
Comment at: lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp:907-908
+      } else {
+        delete NewGEP1;
+        delete NewGEP2;
+      }
----------------
majnemer wrote:
> wmi wrote:
> > majnemer wrote:
> > > Do not create IR if you don't think you will use it.
> > But I only need to insert the nodes into IR after isSafeToLoadUnconditionally return true for them.  Any suggestion for this case? 
> Something like:
>       if (isSafeToLoadUnconditionally(NewGEP1, Align, DL, GEPI) &&
>           isSafeToLoadUnconditionally(NewGEP2, Align, DL, GEPI)) {
>         GetElementPtrInst *NewGEP1 = cast<GetElementPtrInst>(GEPI->clone());
>         GetElementPtrInst *NewGEP2 = cast<GetElementPtrInst>(GEPI->clone());
>         NewGEP1->setOperand(LastIdx, SI->getOperand(1));
>         NewGEP2->setOperand(LastIdx, SI->getOperand(2));
>         ...
But then NewGEP1 will be used in the if condition before it is created.


Repository:
  rL LLVM

https://reviews.llvm.org/D26569