[VPlan] Add VPInstruction to VPRecipe transformation.

This patch introduces a VPInstructionToVPRecipe transformation, which
allows us to generate code for a VPInstruction based VPlan re-using the
existing infrastructure.

Reviewers: dcaballe, hsaito, mssimpso, hfinkel, rengolin, mkuper, javed.absar, sguggill

Reviewed By: dcaballe

Differential Revision: https://reviews.llvm.org/D46827

llvm-svn: 334969

1 files changed, 73 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Vectorize/VPlanHCFGTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanHCFGTransforms.cpp
new file mode 100644
index 00000000000..e3cbab077e6
--- /dev/null
+++ b/llvm/lib/Transforms/Vectorize/VPlanHCFGTransforms.cpp
@@ -0,0 +1,73 @@
+//===-- VPlanHCFGTransforms.cpp - Utility VPlan to VPlan transforms -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements a set of utility VPlan to VPlan transformations.
+///
+//===----------------------------------------------------------------------===//
+
+#include "VPlanHCFGTransforms.h"
+#include "llvm/ADT/PostOrderIterator.h"
+
+using namespace llvm;
+
+void VPlanHCFGTransforms::VPInstructionsToVPRecipes(
+    VPlanPtr &Plan,
+    LoopVectorizationLegality::InductionList *Inductions,
+    SmallPtrSetImpl<Instruction *> &DeadInstructions) {
+
+  VPRegionBlock *TopRegion = dyn_cast<VPRegionBlock>(Plan->getEntry());
+  ReversePostOrderTraversal<VPBlockBase *> RPOT(TopRegion->getEntry());
+  for (VPBlockBase *Base : RPOT) {
+    // Do not widen instructions in pre-header and exit blocks.
+    if (Base->getNumPredecessors() == 0 || Base->getNumSuccessors() == 0)
+      continue;
+
+    VPBasicBlock *VPBB = Base->getEntryBasicBlock();
+    VPRecipeBase *LastRecipe = nullptr;
+    // Introduce each ingredient into VPlan.
+    for (auto I = VPBB->begin(), E = VPBB->end(); I != E;) {
+      VPRecipeBase *Ingredient = &*I++;
+      // Can only handle VPInstructions.
+      VPInstruction *VPInst = cast<VPInstruction>(Ingredient);
+      Instruction *Inst = cast<Instruction>(VPInst->getUnderlyingValue());
+      if (DeadInstructions.count(Inst)) {
+        Ingredient->eraseFromParent();
+        continue;
+      }
+
+      VPRecipeBase *NewRecipe = nullptr;
+      // Create VPWidenMemoryInstructionRecipe for loads and stores.
+      if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
+        NewRecipe = new VPWidenMemoryInstructionRecipe(*Inst, nullptr /*Mask*/);
+      else if (PHINode *Phi = dyn_cast<PHINode>(Inst)) {
+        InductionDescriptor II = Inductions->lookup(Phi);
+        if (II.getKind() == InductionDescriptor::IK_IntInduction ||
+            II.getKind() == InductionDescriptor::IK_FpInduction) {
+          NewRecipe = new VPWidenIntOrFpInductionRecipe(Phi);
+        } else
+          NewRecipe = new VPWidenPHIRecipe(Phi);
+      } else {
+        // If the last recipe is a VPWidenRecipe, add Inst to it instead of
+        // creating a new recipe.
+        if (VPWidenRecipe *WidenRecipe =
+                dyn_cast_or_null<VPWidenRecipe>(LastRecipe)) {
+          WidenRecipe->appendInstruction(Inst);
+          Ingredient->eraseFromParent();
+          continue;
+        }
+        NewRecipe = new VPWidenRecipe(Inst);
+      }
+
+      NewRecipe->insertBefore(Ingredient);
+      LastRecipe = NewRecipe;
+      Ingredient->eraseFromParent();
+    }
+  }
+}