[LV] Cache block mask values

This patch is part of D28975's breakdown.

Add caching for block masks similar to the cache already used for edge masks,
replacing generation per user with reusing the first generated value which
dominates all uses.

Differential Revision: https://reviews.llvm.org/D32054

llvm-svn: 300557

1 files changed, 17 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 595b2ec8894..7eb8fabe0b2 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -422,7 +422,8 @@ protected:
   // When we if-convert we need to create edge masks. We have to cache values
   // so that we don't end up with exponential recursion/IR.
   typedef DenseMap<std::pair<BasicBlock *, BasicBlock *>, VectorParts>
-      EdgeMaskCache;
+      EdgeMaskCacheTy;
+  typedef DenseMap<BasicBlock *, VectorParts> BlockMaskCacheTy;
 
   /// Create an empty loop, based on the loop ranges of the old loop.
   void createEmptyLoop();
@@ -785,7 +786,8 @@ protected:
   /// Store instructions that should be predicated, as a pair
   ///   <StoreInst, Predicate>
   SmallVector<std::pair<Instruction *, Value *>, 4> PredicatedInstructions;
-  EdgeMaskCache MaskCache;
+  EdgeMaskCacheTy EdgeMaskCache;
+  BlockMaskCacheTy BlockMaskCache;
   /// Trip count of the original loop.
   Value *TripCount;
   /// Trip count of the widened loop (TripCount - TripCount % (VF*UF))
@@ -4560,8 +4562,8 @@ InnerLoopVectorizer::createEdgeMask(BasicBlock *Src, BasicBlock *Dst) {
 
   // Look for cached value.
   std::pair<BasicBlock *, BasicBlock *> Edge(Src, Dst);
-  EdgeMaskCache::iterator ECEntryIt = MaskCache.find(Edge);
-  if (ECEntryIt != MaskCache.end())
+  EdgeMaskCacheTy::iterator ECEntryIt = EdgeMaskCache.find(Edge);
+  if (ECEntryIt != EdgeMaskCache.end())
     return ECEntryIt->second;
 
   VectorParts SrcMask = createBlockInMask(Src);
@@ -4580,11 +4582,11 @@ InnerLoopVectorizer::createEdgeMask(BasicBlock *Src, BasicBlock *Dst) {
     for (unsigned part = 0; part < UF; ++part)
       EdgeMask[part] = Builder.CreateAnd(EdgeMask[part], SrcMask[part]);
 
-    MaskCache[Edge] = EdgeMask;
+    EdgeMaskCache[Edge] = EdgeMask;
     return EdgeMask;
   }
 
-  MaskCache[Edge] = SrcMask;
+  EdgeMaskCache[Edge] = SrcMask;
   return SrcMask;
 }
 
@@ -4592,10 +4594,17 @@ InnerLoopVectorizer::VectorParts
 InnerLoopVectorizer::createBlockInMask(BasicBlock *BB) {
   assert(OrigLoop->contains(BB) && "Block is not a part of a loop");
 
+  // Look for cached value.
+  BlockMaskCacheTy::iterator BCEntryIt = BlockMaskCache.find(BB);
+  if (BCEntryIt != BlockMaskCache.end())
+    return BCEntryIt->second;
+
   // Loop incoming mask is all-one.
   if (OrigLoop->getHeader() == BB) {
     Value *C = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 1);
-    return getVectorValue(C);
+    const VectorParts &BlockMask = getVectorValue(C);
+    BlockMaskCache[BB] = BlockMask;
+    return BlockMask;
   }
 
   // This is the block mask. We OR all incoming edges, and with zero.
@@ -4609,6 +4618,7 @@ InnerLoopVectorizer::createBlockInMask(BasicBlock *BB) {
       BlockMask[part] = Builder.CreateOr(BlockMask[part], EM[part]);
   }
 
+  BlockMaskCache[BB] = BlockMask;
   return BlockMask;
 }