[VPlan] Add moveAfter to VPRecipeBase.

This patch adds a moveAfter method to VPRecipeBase, which can be used to
move elements after other elements, across VPBasicBlocks, if necessary.

Reviewers: dcaballe, hsaito, rengolin, hfinkel

Reviewed By: dcaballe

Differential Revision: https://reviews.llvm.org/D46825

llvm-svn: 374565

2 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Vectorize/VPlan.cpp b/llvm/lib/Transforms/Vectorize/VPlan.cpp
index f2420f6f656..4b80d1fb20a 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlan.cpp
@@ -283,6 +283,12 @@ iplist<VPRecipeBase>::iterator VPRecipeBase::eraseFromParent() {
   return getParent()->getRecipeList().erase(getIterator());
 }
 
+void VPRecipeBase::moveAfter(VPRecipeBase *InsertPos) {
+  InsertPos->getParent()->getRecipeList().splice(
+      std::next(InsertPos->getIterator()), getParent()->getRecipeList(),
+      getIterator());
+}
+
 void VPInstruction::generateInstruction(VPTransformState &State,
                                         unsigned Part) {
   IRBuilder<> &Builder = State.Builder;
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 8a06412ad59..44d8a198f27 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -615,6 +615,10 @@ public:
   /// the specified recipe.
   void insertBefore(VPRecipeBase *InsertPos);
 
+  /// Unlink this recipe from its current VPBasicBlock and insert it into
+  /// the VPBasicBlock that MovePos lives in, right after MovePos.
+  void moveAfter(VPRecipeBase *MovePos);
+
   /// This method unlinks 'this' from the containing basic block and deletes it.
   ///
   /// \returns an iterator pointing to the element after the erased one