[PATCH] D17332: [LV] Fix PR26600: avoid out of bounds loads for interleaved access vectorization

[silviu.baranga@arm.com via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL261331: [LV] Fix PR26600: avoid out of bounds loads for interleaved access vectorization (authored by sbaranga).

Changed prior to commit:
  http://reviews.llvm.org/D17332?vs=48174&id=48495#toc

Repository:
  rL LLVM

http://reviews.llvm.org/D17332

Files:
  llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/trunk/test/Transforms/LoopVectorize/PowerPC/stride-vectorization.ll
  llvm/trunk/test/Transforms/LoopVectorize/interleaved-accesses.ll

Index: llvm/trunk/test/Transforms/LoopVectorize/interleaved-accesses.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/interleaved-accesses.ll
+++ llvm/trunk/test/Transforms/LoopVectorize/interleaved-accesses.ll
@@ -292,10 +292,8 @@
 ; }
 
 ; CHECK-LABEL: @even_load(
-; CHECK: %wide.vec = load <8 x i32>, <8 x i32>* %{{.*}}, align 4
-; CHECK: %strided.vec = shufflevector <8 x i32> %wide.vec, <8 x i32> undef, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
-; CHECK-NOT: shufflevector <8 x i32> %wide.vec, <8 x i32> undef, <4 x i32> <i32 1, i32 3, i32 5, i32 7>
-; CHECK: shl nsw <4 x i32> %strided.vec, <i32 1, i32 1, i32 1, i32 1>
+; CHECK-NOT: %wide.vec = load <8 x i32>, <8 x i32>* %{{.*}}, align 4
+; CHECK-NOT: %strided.vec = shufflevector <8 x i32> %wide.vec, <8 x i32> undef, <4 x i32> <i32 0, i32 2, i32 4, i32 6>
 
 define void @even_load(i32* noalias nocapture readonly %A, i32* noalias nocapture %B) {
 entry:
Index: llvm/trunk/test/Transforms/LoopVectorize/PowerPC/stride-vectorization.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/PowerPC/stride-vectorization.ll
+++ llvm/trunk/test/Transforms/LoopVectorize/PowerPC/stride-vectorization.ll
@@ -16,9 +16,15 @@
 for.body:                                         ; preds = %for.body, %entry
   %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
   %0 = shl nsw i64 %indvars.iv, 1
+  %odd.idx = add nsw i64 %0, 1
+
   %arrayidx = getelementptr inbounds double, double* %b, i64 %0
+  %arrayidx.odd = getelementptr inbounds double, double* %b, i64 %odd.idx
+
   %1 = load double, double* %arrayidx, align 8
-  %add = fadd double %1, 1.000000e+00
+  %2 = load double, double* %arrayidx.odd, align 8
+
+  %add = fadd double %1, %2
   %arrayidx2 = getelementptr inbounds double, double* %a, i64 %indvars.iv
   store double %add, double* %arrayidx2, align 8
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
Index: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4719,6 +4719,8 @@
 
   // Holds all interleaved store groups temporarily.
   SmallSetVector<InterleaveGroup *, 4> StoreGroups;
+  // Holds all interleaved load groups temporarily.
+  SmallSetVector<InterleaveGroup *, 4> LoadGroups;
 
   // Search the load-load/write-write pair B-A in bottom-up order and try to
   // insert B into the interleave group of A according to 3 rules:
@@ -4746,6 +4748,8 @@
 
     if (A->mayWriteToMemory())
       StoreGroups.insert(Group);
+    else
+      LoadGroups.insert(Group);
 
     for (auto II = std::next(I); II != E; ++II) {
       Instruction *B = II->first;
@@ -4793,6 +4797,12 @@
   for (InterleaveGroup *Group : StoreGroups)
     if (Group->getNumMembers() != Group->getFactor())
       releaseGroup(Group);
+
+  // Remove interleaved load groups that don't have the first and last member.
+  // This guarantees that we won't do speculative out of bounds loads.
+  for (InterleaveGroup *Group : LoadGroups)
+    if (!Group->getMember(0) || !Group->getMember(Group->getFactor() - 1))
+      releaseGroup(Group);
 }
 
 LoopVectorizationCostModel::VectorizationFactor


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