diff --git a/llvm/lib/Analysis/IVDescriptors.cpp b/llvm/lib/Analysis/IVDescriptors.cpp
index 6fb600114bc61d36c0eaf5ada2723dc651a2b34e..bdebd71d7f68b023e18651df85d6b8f1c692f7d2 100644
--- a/llvm/lib/Analysis/IVDescriptors.cpp
+++ b/llvm/lib/Analysis/IVDescriptors.cpp
@@ -699,25 +699,37 @@ bool RecurrenceDescriptor::isFirstOrderRecurrence(
// Ensure every user of the phi node is dominated by the previous value.
// The dominance requirement ensures the loop vectorizer will not need to
// vectorize the initial value prior to the first iteration of the loop.
- // TODO: Consider extending this sinking to handle other kinds of instructions
- // and expressions, beyond sinking a single cast past Previous.
+ // TODO: Consider extending this sinking to handle memory instructions and
+ // phis with multiple users.
+
+ // Returns true, if all users of I are dominated by DominatedBy.
+ auto allUsesDominatedBy = [DT](Instruction *I, Instruction *DominatedBy) {
+ return all_of(I->uses(), [DT, DominatedBy](Use &U) {
+ return DT->dominates(DominatedBy, U);
+ });
+ };
+
if (Phi->hasOneUse()) {
- auto *I = Phi->user_back();
- if (I->isCast() && (I->getParent() == Phi->getParent()) && I->hasOneUse() &&
- DT->dominates(Previous, I->user_back())) {
- if (!DT->dominates(Previous, I)) // Otherwise we're good w/o sinking.
- SinkAfter[I] = Previous;
+ Instruction *I = Phi->user_back();
+
+ // If the user of the PHI is also the incoming value, we potentially have a
+ // reduction and which cannot be handled by sinking.
+ if (Previous == I)
+ return false;
+
+ if (DT->dominates(Previous, I)) // We already are good w/o sinking.
return true;
- }
- }
- for (User *U : Phi->users())
- if (auto *I = dyn_cast<Instruction>(U)) {
- if (!DT->dominates(Previous, I))
- return false;
+ // We can sink any instruction without side effects, as long as all users
+ // are dominated by the instruction we are sinking after.
+ if (I->getParent() == Phi->getParent() && !I->mayHaveSideEffects() &&
+ allUsesDominatedBy(I, Previous)) {
+ SinkAfter[I] = Previous;
+ return true;
}
+ }
- return true;
+ return allUsesDominatedBy(Phi, Previous);
}
/// This function returns the identity element (or neutral element) for
diff --git a/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll b/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
new file mode 100644
index 0000000000000000000000000000000000000000..e09804276ec83a6582ccef5ac3594df8fba43150
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
@@ -0,0 +1,245 @@
+; RUN: opt -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -S %s | FileCheck %s
+
+
+@p = external local_unnamed_addr global [257 x i32], align 16
+@q = external local_unnamed_addr global [257 x i32], align 16
+
+; Test case for PR43398.
+
+define void @can_sink_after_store(i32 %x, i32* %ptr, i64 %tc) local_unnamed_addr #0 {
+; CHECK-LABEL: vector.ph:
+; CHECK: %broadcast.splatinsert1 = insertelement <4 x i32> undef, i32 %x, i32 0
+; CHECK-NEXT: %broadcast.splat2 = shufflevector <4 x i32> %broadcast.splatinsert1, <4 x i32> undef, <4 x i32> zeroinitializer
+; CHECK-NEXT: %vector.recur.init = insertelement <4 x i32> undef, i32 %.pre, i32 3
+; CHECK-NEXT: br label %vector.body
+
+; CHECK-LABEL: vector.body:
+; CHECK-NEXT: %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
+; CHECK-NEXT: %vector.recur = phi <4 x i32> [ %vector.recur.init, %vector.ph ], [ %wide.load, %vector.body ]
+; CHECK-NEXT: %offset.idx = add i64 1, %index
+; CHECK-NEXT: %broadcast.splatinsert = insertelement <4 x i64> undef, i64 %offset.idx, i32 0
+; CHECK-NEXT: %broadcast.splat = shufflevector <4 x i64> %broadcast.splatinsert, <4 x i64> undef, <4 x i32> zeroinitializer
+; CHECK-NEXT: %induction = add <4 x i64> %broadcast.splat, <i64 0, i64 1, i64 2, i64 3>
+; CHECK-NEXT: %0 = add i64 %offset.idx, 0
+; CHECK-NEXT: %1 = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 %0
+; CHECK-NEXT: %2 = getelementptr inbounds i32, i32* %1, i32 0
+; CHECK-NEXT: %3 = bitcast i32* %2 to <4 x i32>*
+; CHECK-NEXT: %wide.load = load <4 x i32>, <4 x i32>* %3, align 4
+; CHECK-NEXT: %4 = shufflevector <4 x i32> %vector.recur, <4 x i32> %wide.load, <4 x i32> <i32 3, i32 4, i32 5, i32 6>
+; CHECK-NEXT: %5 = add <4 x i32> %4, %broadcast.splat2
+; CHECK-NEXT: %6 = add <4 x i32> %5, %wide.load
+; CHECK-NEXT: %7 = getelementptr inbounds [257 x i32], [257 x i32]* @q, i64 0, i64 %0
+; CHECK-NEXT: %8 = getelementptr inbounds i32, i32* %7, i32 0
+; CHECK-NEXT: %9 = bitcast i32* %8 to <4 x i32>*
+; CHECK-NEXT: store <4 x i32> %6, <4 x i32>* %9, align 4
+; CHECK-NEXT: %index.next = add i64 %index, 4
+; CHECK-NEXT: %10 = icmp eq i64 %index.next, 1996
+; CHECK-NEXT: br i1 %10, label %middle.block, label %vector.body
+;
+entry:
+ br label %preheader
+
+preheader:
+ %idx.phi.trans = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 1
+ %.pre = load i32, i32* %idx.phi.trans, align 4
+ br label %for
+
+for:
+ %pre.phi = phi i32 [ %.pre, %preheader ], [ %pre.next, %for ]
+ %iv = phi i64 [ 1, %preheader ], [ %iv.next, %for ]
+ %add.1 = add i32 %pre.phi, %x
+ %idx.1 = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 %iv
+ %pre.next = load i32, i32* %idx.1, align 4
+ %add.2 = add i32 %add.1, %pre.next
+ %idx.2 = getelementptr inbounds [257 x i32], [257 x i32]* @q, i64 0, i64 %iv
+ store i32 %add.2, i32* %idx.2, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %exitcond = icmp eq i64 %iv.next, 2000
+ br i1 %exitcond, label %exit, label %for
+
+exit:
+ ret void
+}
+
+; We can sink potential trapping instructions, as this will only delay the trap
+; and not introduce traps on additional paths.
+define void @sink_sdiv(i32 %x, i32* %ptr, i64 %tc) local_unnamed_addr #0 {
+; CHECK-LABEL: vector.ph:
+; CHECK: %broadcast.splatinsert1 = insertelement <4 x i32> undef, i32 %x, i32 0
+; CHECK-NEXT: %broadcast.splat2 = shufflevector <4 x i32> %broadcast.splatinsert1, <4 x i32> undef, <4 x i32> zeroinitializer
+; CHECK-NEXT: %vector.recur.init = insertelement <4 x i32> undef, i32 %.pre, i32 3
+; CHECK-NEXT: br label %vector.body
+
+; CHECK-LABEL: vector.body:
+; CHECK-NEXT: %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
+; CHECK-NEXT: %vector.recur = phi <4 x i32> [ %vector.recur.init, %vector.ph ], [ %wide.load, %vector.body ]
+; CHECK-NEXT: %offset.idx = add i64 1, %index
+; CHECK-NEXT: %broadcast.splatinsert = insertelement <4 x i64> undef, i64 %offset.idx, i32 0
+; CHECK-NEXT: %broadcast.splat = shufflevector <4 x i64> %broadcast.splatinsert, <4 x i64> undef, <4 x i32> zeroinitializer
+; CHECK-NEXT: %induction = add <4 x i64> %broadcast.splat, <i64 0, i64 1, i64 2, i64 3>
+; CHECK-NEXT: %0 = add i64 %offset.idx, 0
+; CHECK-NEXT: %1 = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 %0
+; CHECK-NEXT: %2 = getelementptr inbounds i32, i32* %1, i32 0
+; CHECK-NEXT: %3 = bitcast i32* %2 to <4 x i32>*
+; CHECK-NEXT: %wide.load = load <4 x i32>, <4 x i32>* %3, align 4
+; CHECK-NEXT: %4 = shufflevector <4 x i32> %vector.recur, <4 x i32> %wide.load, <4 x i32> <i32 3, i32 4, i32 5, i32 6>
+; CHECK-NEXT: %5 = sdiv <4 x i32> %4, %broadcast.splat2
+; CHECK-NEXT: %6 = add <4 x i32> %5, %wide.load
+; CHECK-NEXT: %7 = getelementptr inbounds [257 x i32], [257 x i32]* @q, i64 0, i64 %0
+; CHECK-NEXT: %8 = getelementptr inbounds i32, i32* %7, i32 0
+; CHECK-NEXT: %9 = bitcast i32* %8 to <4 x i32>*
+; CHECK-NEXT: store <4 x i32> %6, <4 x i32>* %9, align 4
+; CHECK-NEXT: %index.next = add i64 %index, 4
+; CHECK-NEXT: %10 = icmp eq i64 %index.next, 1996
+; CHECK-NEXT: br i1 %10, label %middle.block, label %vector.body
+;
+entry:
+ br label %preheader
+
+preheader:
+ %idx.phi.trans = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 1
+ %.pre = load i32, i32* %idx.phi.trans, align 4
+ br label %for
+
+for:
+ %pre.phi = phi i32 [ %.pre, %preheader ], [ %pre.next, %for ]
+ %iv = phi i64 [ 1, %preheader ], [ %iv.next, %for ]
+ %div.1 = sdiv i32 %pre.phi, %x
+ %idx.1 = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 %iv
+ %pre.next = load i32, i32* %idx.1, align 4
+ %add.2 = add i32 %div.1, %pre.next
+ %idx.2 = getelementptr inbounds [257 x i32], [257 x i32]* @q, i64 0, i64 %iv
+ store i32 %add.2, i32* %idx.2, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %exitcond = icmp eq i64 %iv.next, 2000
+ br i1 %exitcond, label %exit, label %for
+
+exit:
+ ret void
+}
+
+; FIXME: Currently we can only sink a single instruction. For the example below,
+; we also have to sink users.
+define void @cannot_sink_with_additional_user(i32 %x, i32* %ptr, i64 %tc) {
+; CHECK-LABEL: define void @cannot_sink_with_additional_user(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %preheader
+
+; CHECK-LABEL: preheader: ; preds = %entry
+; CHECK: br label %for
+
+; CHECK-LABEL: for: ; preds = %for, %preheader
+; CHECK br i1 %exitcond, label %exit, label %for
+
+; CHECK-LABEL: exit:
+; CHECK-NEXT: ret void
+
+entry:
+ br label %preheader
+
+preheader:
+ %idx.phi.trans = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 1
+ %.pre = load i32, i32* %idx.phi.trans, align 4
+ br label %for
+
+for:
+ %pre.phi = phi i32 [ %.pre, %preheader ], [ %pre.next, %for ]
+ %iv = phi i64 [ 1, %preheader ], [ %iv.next, %for ]
+ %add.1 = add i32 %pre.phi, %x
+ %add.2 = add i32 %add.1, %x
+ %idx.1 = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 %iv
+ %pre.next = load i32, i32* %idx.1, align 4
+ %add.3 = add i32 %add.1, %pre.next
+ %add.4 = add i32 %add.2, %add.3
+ %idx.2 = getelementptr inbounds [257 x i32], [257 x i32]* @q, i64 0, i64 %iv
+ store i32 %add.4, i32* %idx.2, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %exitcond = icmp eq i64 %iv.next, 2000
+ br i1 %exitcond, label %exit, label %for
+
+exit:
+ ret void
+}
+
+; FIXME: We can sink a store, if we can guarantee that it does not alias any
+; loads/stores in between.
+define void @cannot_sink_store(i32 %x, i32* %ptr, i64 %tc) {
+; CHECK-LABEL: define void @cannot_sink_store(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %preheader
+
+; CHECK-LABEL: preheader: ; preds = %entry
+; CHECK: br label %for
+
+; CHECK-LABEL: for: ; preds = %for, %preheader
+; CHECK br i1 %exitcond, label %exit, label %for
+
+; CHECK-LABEL: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %preheader
+
+preheader:
+ %idx.phi.trans = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 1
+ %.pre = load i32, i32* %idx.phi.trans, align 4
+ br label %for
+
+for:
+ %pre.phi = phi i32 [ %.pre, %preheader ], [ %pre.next, %for ]
+ %iv = phi i64 [ 1, %preheader ], [ %iv.next, %for ]
+ %add.1 = add i32 %pre.phi, %x
+ store i32 %add.1, i32* %ptr
+ %idx.1 = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 %iv
+ %pre.next = load i32, i32* %idx.1, align 4
+ %add.2 = add i32 %add.1, %pre.next
+ %idx.2 = getelementptr inbounds [257 x i32], [257 x i32]* @q, i64 0, i64 %iv
+ store i32 %add.2, i32* %idx.2, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %exitcond = icmp eq i64 %iv.next, 2000
+ br i1 %exitcond, label %exit, label %for
+
+exit:
+ ret void
+}
+
+; Some kinds of reductions are not detected by IVDescriptors. If we have a
+; cycle, we cannot sink it.
+define void @cannot_sink_reduction(i32 %x, i32* %ptr, i64 %tc) {
+; CHECK-LABEL: define void @cannot_sink_reduction(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %preheader
+
+; CHECK-LABEL: preheader: ; preds = %entry
+; CHECK: br label %for
+
+; CHECK-LABEL: for: ; preds = %for, %preheader
+; CHECK br i1 %exitcond, label %exit, label %for
+
+; CHECK-LABEL: exit: ; preds = %for
+; CHECK-NET: ret void
+;
+entry:
+ br label %preheader
+
+preheader:
+ %idx.phi.trans = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 1
+ %.pre = load i32, i32* %idx.phi.trans, align 4
+ br label %for
+
+for:
+ %pre.phi = phi i32 [ %.pre, %preheader ], [ %d, %for ]
+ %iv = phi i64 [ 1, %preheader ], [ %iv.next, %for ]
+ %d = sdiv i32 %pre.phi, %x
+ %idx.1 = getelementptr inbounds [257 x i32], [257 x i32]* @p, i64 0, i64 %iv
+ %pre.next = load i32, i32* %idx.1, align 4
+ %add.2 = add i32 %x, %pre.next
+ %idx.2 = getelementptr inbounds [257 x i32], [257 x i32]* @q, i64 0, i64 %iv
+ store i32 %add.2, i32* %idx.2, align 4
+ %iv.next = add nuw nsw i64 %iv, 1
+ %exitcond = icmp eq i64 %iv.next, 2000
+ br i1 %exitcond, label %exit, label %for
+
+exit:
+ ret void
+}