[llvm] eca14a8 - [VPlan] Consolidate replicate region optimizations (NFC).

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2023-03-16T17:06:44Z
New Revision: eca14a810e592be7b6e8d95a77263f5131b338f2

URL: https://github.com/llvm/llvm-project/commit/eca14a810e592be7b6e8d95a77263f5131b338f2
DIFF: https://github.com/llvm/llvm-project/commit/eca14a810e592be7b6e8d95a77263f5131b338f2.diff

LOG: [VPlan] Consolidate replicate region optimizations (NFC).

As suggested in D143865, consolidate replicate region creation and
optimization in a single helper that's exposed and used by LV.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
    llvm/lib/Transforms/Vectorize/VPlanTransforms.h

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 86a190fd2bf53..18576cf3c707e 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -9068,16 +9068,7 @@ VPlanPtr LoopVectorizationPlanner::buildVPlanWithVPRecipes(
   VPlanTransforms::optimizeInductions(*Plan, *PSE.getSE());
   VPlanTransforms::removeDeadRecipes(*Plan);
 
-  // Convert masked VPReplicateRecipes to if-then region blocks.
-  VPlanTransforms::addReplicateRegions(*Plan, RecipeBuilder);
-
-  bool ShouldSimplify = true;
-  while (ShouldSimplify) {
-    ShouldSimplify = VPlanTransforms::sinkScalarOperands(*Plan);
-    ShouldSimplify |=
-        VPlanTransforms::mergeReplicateRegionsIntoSuccessors(*Plan);
-    ShouldSimplify |= VPlanTransforms::mergeBlocksIntoPredecessors(*Plan);
-  }
+  VPlanTransforms::createAndOptimizeReplicateRegions(*Plan, RecipeBuilder);
 
   VPlanTransforms::removeRedundantExpandSCEVRecipes(*Plan);
   VPlanTransforms::mergeBlocksIntoPredecessors(*Plan);

diff  --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 118124cac60d6..e642d264b1c75 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -106,7 +106,7 @@ void VPlanTransforms::VPInstructionsToVPRecipes(
   }
 }
 
-bool VPlanTransforms::sinkScalarOperands(VPlan &Plan) {
+static bool sinkScalarOperands(VPlan &Plan) {
   auto Iter = vp_depth_first_deep(Plan.getEntry());
   bool Changed = false;
   // First, collect the operands of all recipes in replicate blocks as seeds for
@@ -223,7 +223,10 @@ static VPBasicBlock *getPredicatedThenBlock(VPRegionBlock *R) {
   return nullptr;
 }
 
-bool VPlanTransforms::mergeReplicateRegionsIntoSuccessors(VPlan &Plan) {
+// Merge replicate regions in their successor region, if a replicate region
+// is connected to a successor replicate region with the same predicate by a
+// single, empty VPBasicBlock.
+static bool mergeReplicateRegionsIntoSuccessors(VPlan &Plan) {
   SetVector<VPRegionBlock *> DeletedRegions;
 
   // Collect replicate regions followed by an empty block, followed by another
@@ -311,6 +314,46 @@ bool VPlanTransforms::mergeReplicateRegionsIntoSuccessors(VPlan &Plan) {
   return !DeletedRegions.empty();
 }
 
+static void addReplicateRegions(VPlan &Plan, VPRecipeBuilder &Builder) {
+  SmallVector<VPReplicateRecipe *> WorkList;
+  for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
+           vp_depth_first_deep(Plan.getEntry()))) {
+    for (VPRecipeBase &R : *VPBB)
+      if (auto *RepR = dyn_cast<VPReplicateRecipe>(&R)) {
+        if (RepR->isPredicated())
+          WorkList.push_back(RepR);
+      }
+  }
+
+  unsigned BBNum = 0;
+  for (VPReplicateRecipe *RepR : WorkList) {
+    VPBasicBlock *CurrentBlock = RepR->getParent();
+    VPBasicBlock *SplitBlock = CurrentBlock->splitAt(RepR->getIterator());
+
+    BasicBlock *OrigBB = RepR->getUnderlyingInstr()->getParent();
+    SplitBlock->setName(
+        OrigBB->hasName() ? OrigBB->getName() + "." + Twine(BBNum++) : "");
+    // Record predicated instructions for above packing optimizations.
+    VPBlockBase *Region = Builder.createReplicateRegion(RepR, Plan);
+    Region->setParent(CurrentBlock->getParent());
+    VPBlockUtils::disconnectBlocks(CurrentBlock, SplitBlock);
+    VPBlockUtils::connectBlocks(CurrentBlock, Region);
+    VPBlockUtils::connectBlocks(Region, SplitBlock);
+  }
+}
+
+void VPlanTransforms::createAndOptimizeReplicateRegions(
+    VPlan &Plan, VPRecipeBuilder &Builder) {
+  // Convert masked VPReplicateRecipes to if-then region blocks.
+  addReplicateRegions(Plan, Builder);
+
+  bool ShouldSimplify = true;
+  while (ShouldSimplify) {
+    ShouldSimplify = sinkScalarOperands(Plan);
+    ShouldSimplify |= mergeReplicateRegionsIntoSuccessors(Plan);
+    ShouldSimplify |= VPlanTransforms::mergeBlocksIntoPredecessors(Plan);
+  }
+}
 bool VPlanTransforms::mergeBlocksIntoPredecessors(VPlan &Plan) {
   SmallVector<VPBasicBlock *> WorkList;
   for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
@@ -668,32 +711,3 @@ void VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan,
     RecurSplice->setOperand(0, FOR);
   }
 }
-
-void VPlanTransforms::addReplicateRegions(VPlan &Plan,
-                                          VPRecipeBuilder &Builder) {
-  SmallVector<VPReplicateRecipe *> WorkList;
-  for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
-           vp_depth_first_deep(Plan.getEntry()))) {
-    for (VPRecipeBase &R : *VPBB)
-      if (auto *RepR = dyn_cast<VPReplicateRecipe>(&R)) {
-        if (RepR->isPredicated())
-          WorkList.push_back(RepR);
-      }
-  }
-
-  unsigned BBNum = 0;
-  for (VPReplicateRecipe *RepR : WorkList) {
-    VPBasicBlock *CurrentBlock = RepR->getParent();
-    VPBasicBlock *SplitBlock = CurrentBlock->splitAt(RepR->getIterator());
-
-    BasicBlock *OrigBB = RepR->getUnderlyingInstr()->getParent();
-    SplitBlock->setName(
-        OrigBB->hasName() ? OrigBB->getName() + "." + Twine(BBNum++) : "");
-    // Record predicated instructions for above packing optimizations.
-    VPBlockBase *Region = Builder.createReplicateRegion(RepR, Plan);
-    Region->setParent(CurrentBlock->getParent());
-    VPBlockUtils::disconnectBlocks(CurrentBlock, SplitBlock);
-    VPBlockUtils::connectBlocks(CurrentBlock, Region);
-    VPBlockUtils::connectBlocks(Region, SplitBlock);
-  }
-}

diff  --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
index 26fe9f44dd8c2..4c4a11fa72506 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
@@ -39,15 +39,11 @@ struct VPlanTransforms {
                             ScalarEvolution &SE, const TargetLibraryInfo &TLI);
 
   /// Wrap predicated VPReplicateRecipes with a mask operand in an if-then
-  /// region block and remove the mask operand.
-  static void addReplicateRegions(VPlan &Plan, VPRecipeBuilder &Builder);
-
-  static bool sinkScalarOperands(VPlan &Plan);
-
-  /// Merge replicate regions in their successor region, if a replicate region
-  /// is connected to a successor replicate region with the same predicate by a
-  /// single, empty VPBasicBlock.
-  static bool mergeReplicateRegionsIntoSuccessors(VPlan &Plan);
+  /// region block and remove the mask operand. Optimize the created regions by
+  /// iteratively sinking scalar operands into the region, followed by merging
+  /// regions until no improvements are remaining.
+  static void createAndOptimizeReplicateRegions(VPlan &Plan,
+                                                VPRecipeBuilder &Builder);
 
   /// Remove redundant VPBasicBlocks by merging them into their predecessor if
   /// the predecessor has a single successor.