[PATCH] D57144: [SLPVectorizer] Get rid of IndexQueue array from vectorizeStores. NFCI.

[Yevgeny Rouban via Phabricator via llvm-commits]

yrouban created this revision.
yrouban added reviewers: RKSimon, spatel, hfinkel, fedor.sergeev, chandlerc, ABataev.
Herald added a subscriber: arphaman.

Indices are checked as they are generated. No need to fill the whole array of indices.


Repository:
  rL LLVM

https://reviews.llvm.org/D57144

Files:
  lib/Transforms/Vectorize/SLPVectorizer.cpp


Index: lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4746,38 +4746,28 @@
   BoUpSLP::ValueSet VectorizedStores;
   bool Changed = false;
 
+  auto FindConsecutiveAccess = [&] (int K, int Idx) {
+    if (!isConsecutiveAccess(Stores[K], Stores[Idx], *DL, *SE))
+      return false;
+
+    Tails.insert(Stores[Idx]);
+    Heads.insert(Stores[K]);
+    ConsecutiveChain[Stores[K]] = Stores[Idx];
+    return true;
+  };
+
   // Do a quadratic search on all of the given stores in reverse order and find
   // all of the pairs of stores that follow each other.
-  SmallVector<unsigned, 16> IndexQueue;
-  unsigned E = Stores.size();
-  IndexQueue.resize(E - 1);
-  for (unsigned I = E; I > 0; --I) {
-    unsigned Idx = I - 1;
-    // If a store has multiple consecutive store candidates, search Stores
-    // array according to the sequence: Idx-1, Idx+1, Idx-2, Idx+2, ...
+  int E = Stores.size();
+  for (int Idx = E - 1; Idx >= 0; --Idx) {
+    // If a store has multiple consecutive store candidates, search according
+    // to the sequence: Idx-1, Idx+1, Idx-2, Idx+2, ...
     // This is because usually pairing with immediate succeeding or preceding
     // candidate create the best chance to find slp vectorization opportunity.
-    unsigned Offset = 1;
-    unsigned Cnt = 0;
-    for (unsigned J = 0; J < E - 1; ++J, ++Offset) {
-      if (Idx >= Offset) {
-        IndexQueue[Cnt] = Idx - Offset;
-        ++Cnt;
-      }
-      if (Idx + Offset < E) {
-        IndexQueue[Cnt] = Idx + Offset;
-        ++Cnt;
-      }
-    }
-
-    for (auto K : IndexQueue) {
-      if (isConsecutiveAccess(Stores[K], Stores[Idx], *DL, *SE)) {
-        Tails.insert(Stores[Idx]);
-        Heads.insert(Stores[K]);
-        ConsecutiveChain[Stores[K]] = Stores[Idx];
+    for (int Offset = 1; Offset < E; ++Offset)
+      if ((Idx >= Offset && FindConsecutiveAccess(Idx - Offset, Idx)) ||
+          (Idx + Offset < E && FindConsecutiveAccess(Idx + Offset, Idx)))
         break;
-      }
-    }
   }
 
   // For stores that start but don't end a link in the chain:


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