[LV] Interleaved access vectorization: fix computing new alias info

As a new access is generated spanning across multiple fields, we need to
propagate alias info from all the fields to form the most generic alias info.

rdar://35602528

Differential Revision: https://reviews.llvm.org/D40617

llvm-svn: 319979

1 files changed, 16 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 3faf9f436be..c5d62d0b97d 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -943,6 +943,19 @@ public:
   Instruction *getInsertPos() const { return InsertPos; }
   void setInsertPos(Instruction *Inst) { InsertPos = Inst; }
 
+  /// Add metadata (e.g. alias info) from the instructions in this group to \p
+  /// NewInst.
+  ///
+  /// FIXME: this function currently does not add noalias metadata a'la
+  /// addNewMedata.  To do that we need to compute the intersection of the
+  /// noalias info from all members.
+  void addMetadata(Instruction *NewInst) const {
+    SmallVector<Value *, 4> VL;
+    std::transform(Members.begin(), Members.end(), std::back_inserter(VL),
+                   [](std::pair<int, Instruction *> p) { return p.second; });
+    propagateMetadata(NewInst, VL);
+  }
+
 private:
   unsigned Factor; // Interleave Factor.
   bool Reverse;
@@ -3044,7 +3057,7 @@ void InnerLoopVectorizer::vectorizeInterleaveGroup(Instruction *Instr) {
     for (unsigned Part = 0; Part < UF; Part++) {
       auto *NewLoad = Builder.CreateAlignedLoad(
           NewPtrs[Part], Group->getAlignment(), "wide.vec");
-      addMetadata(NewLoad, Instr);
+      Group->addMetadata(NewLoad);
       NewLoads.push_back(NewLoad);
     }
 
@@ -3112,7 +3125,8 @@ void InnerLoopVectorizer::vectorizeInterleaveGroup(Instruction *Instr) {
 
     Instruction *NewStoreInstr =
         Builder.CreateAlignedStore(IVec, NewPtrs[Part], Group->getAlignment());
-    addMetadata(NewStoreInstr, Instr);
+
+    Group->addMetadata(NewStoreInstr);
   }
 }