[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

3 files changed, 36 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
diff --git a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
index 90f79a3eaf4..57567e7d843 100644
--- a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
+++ b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
@@ -59,5 +59,31 @@ TEST(VPInstructionTest, eraseFromParent) {
   EXPECT_TRUE(VPBB1.empty());
 }
 
+TEST(VPInstructionTest, moveAfter) {
+  VPInstruction *I1 = new VPInstruction(0, {});
+  VPInstruction *I2 = new VPInstruction(1, {});
+  VPInstruction *I3 = new VPInstruction(2, {});
+
+  VPBasicBlock VPBB1;
+  VPBB1.appendRecipe(I1);
+  VPBB1.appendRecipe(I2);
+  VPBB1.appendRecipe(I3);
+
+  I1->moveAfter(I2);
+
+  CHECK_ITERATOR(VPBB1, I2, I1, I3);
+
+  VPInstruction *I4 = new VPInstruction(4, {});
+  VPInstruction *I5 = new VPInstruction(5, {});
+  VPBasicBlock VPBB2;
+  VPBB2.appendRecipe(I4);
+  VPBB2.appendRecipe(I5);
+
+  I3->moveAfter(I4);
+
+  CHECK_ITERATOR(VPBB1, I2, I1);
+  CHECK_ITERATOR(VPBB2, I4, I3, I5);
+}
+
 } // namespace
 } // namespace llvm