[llvm] [VPlan] Extract reverse interleave pointer adjustment into VPReverseInterleavePtrRecipe (PR #144864)

[Mel Chen via llvm-commits]

================
@@ -3223,25 +3251,6 @@ void VPInterleaveRecipe::execute(VPTransformState &State) {
   if (auto *I = dyn_cast<Instruction>(ResAddr))
     State.setDebugLocFrom(I->getDebugLoc());
 
-  // If the group is reverse, adjust the index to refer to the last vector lane
-  // instead of the first. We adjust the index from the first vector lane,
-  // rather than directly getting the pointer for lane VF - 1, because the
-  // pointer operand of the interleaved access is supposed to be uniform.
-  if (Group->isReverse()) {
-    Value *RuntimeVF =
-        getRuntimeVF(State.Builder, State.Builder.getInt32Ty(), State.VF);
-    Value *Index =
-        State.Builder.CreateSub(RuntimeVF, State.Builder.getInt32(1));
-    Index = State.Builder.CreateMul(Index,
-                                    State.Builder.getInt32(Group->getFactor()));
-    Index = State.Builder.CreateNeg(Index);
-
-    bool InBounds = false;
-    if (auto *Gep = dyn_cast<GetElementPtrInst>(ResAddr->stripPointerCasts()))
-      InBounds = Gep->isInBounds();
----------------
Mel-Chen wrote:

I think if we've already replaced the VF operand of VPVectorEndPointerRecipe with EVL, then we should be able to restore the inbounds flag (if the underlying GEP had it originally). After all, we shouldn't be computing beyond the allocation range in that case, right?

https://github.com/llvm/llvm-project/pull/144864