[PATCH] D100101: [VPlan] Add VPBasicBlock::phis() helper (NFC).

[Florian Hahn via Phabricator via llvm-commits]

fhahn updated this revision to Diff 340763.
fhahn added a comment.

Updates:

1. add comment about PHI node order to VPBasicBlock
2. use existing getFirstNonPhi() in phis()
3. add VPrecipeBase::isPhi(), use it in getFirstNonPhi

In D100101#2718833 <https://reviews.llvm.org/D100101#2718833>, @Ayal wrote:

> Looks good to me!
>
> This is aligned with BasicBlock::phis(), with a simpler implementation based on finding FirstNonPHI. Number of phi's is expected to be limited, so running twice until FirstNonPHI instead of once should be tolerable.
>
> Would be good to document some place that all phi recipes appear before any non-phi recipe in VPBasicBlock, as in BasicBlock. (This assumption predates this patch.)

Thanks for taking a look! I added a sentence to the top-level comment for VPBasicBlock saying that all PHI-like recipes must come before non-phi recipes. I hope that's sufficient or were you thinking about a different place?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100101/new/

https://reviews.llvm.org/D100101

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/lib/Transforms/Vectorize/VPlan.cpp
  llvm/lib/Transforms/Vectorize/VPlan.h


Index: llvm/lib/Transforms/Vectorize/VPlan.h
===================================================================
--- llvm/lib/Transforms/Vectorize/VPlan.h
+++ llvm/lib/Transforms/Vectorize/VPlan.h
@@ -685,6 +685,12 @@
 
   /// Returns true if the recipe may have side-effects.
   bool mayHaveSideEffects() const;
+
+  /// Returns true for PHI-like recipes.
+  bool isPhi() const {
+    return getVPDefID() == VPWidenIntOrFpInductionSC || getVPDefID() == VPWidenPHISC ||
+      getVPDefID() == VPPredInstPHISC || getVPDefID() == VPWidenCanonicalIVSC;
+  }
 };
 
 inline bool VPUser::classof(const VPDef *Def) {
@@ -1433,7 +1439,7 @@
 
 /// VPBasicBlock serves as the leaf of the Hierarchical Control-Flow Graph. It
 /// holds a sequence of zero or more VPRecipe's each representing a sequence of
-/// output IR instructions.
+/// output IR instructions. All PHI-like recipes must come before any non-PHI recipes.
 class VPBasicBlock : public VPBlockBase {
 public:
   using RecipeListTy = iplist<VPRecipeBase>;
@@ -1511,6 +1517,11 @@
   /// Return the position of the first non-phi node recipe in the block.
   iterator getFirstNonPhi();
 
+  /// Returns an iterator range over the PHI-like recipes in the block.
+  iterator_range<iterator> phis() {
+    return make_range(begin(), getFirstNonPhi());
+  }
+
   void dropAllReferences(VPValue *NewValue) override;
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
Index: llvm/lib/Transforms/Vectorize/VPlan.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/VPlan.cpp
+++ llvm/lib/Transforms/Vectorize/VPlan.cpp
@@ -249,10 +249,7 @@
 
 VPBasicBlock::iterator VPBasicBlock::getFirstNonPhi() {
   iterator It = begin();
-  while (It != end() && (isa<VPWidenPHIRecipe>(&*It) ||
-                         isa<VPWidenIntOrFpInductionRecipe>(&*It) ||
-                         isa<VPPredInstPHIRecipe>(&*It) ||
-                         isa<VPWidenCanonicalIVRecipe>(&*It)))
+  while (It != end() && It->isPhi())
     It++;
   return It;
 }
Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4066,13 +4066,10 @@
   // original loop is widened to a vector form so we can use them to construct
   // the incoming edges.
   VPBasicBlock *Header = State.Plan->getEntry()->getEntryBasicBlock();
-  for (VPRecipeBase &R : *Header) {
-    if (isa<VPWidenIntOrFpInductionRecipe>(&R))
-      continue;
+  for (VPRecipeBase &R : Header->phis()) {
     VPWidenPHIRecipe *PhiR = dyn_cast<VPWidenPHIRecipe>(&R);
     if (!PhiR)
-      break;
-
+      continue;
     auto *OrigPhi = cast<PHINode>(PhiR->getUnderlyingValue());
     if (PhiR->getRecurrenceDescriptor()) {
       fixReduction(PhiR, State);


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