[llvm] eaff300 - Revert f0c2a5a "[LV] Generalize conditions for sinking instrs for first order recurrences."
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 7 02:05:09 PST 2019
Author: Hans Wennborg
Date: 2019-11-07T11:00:02+01:00
New Revision: eaff3004019f97c64c88ab76da6b25106b659b30
URL: https://github.com/llvm/llvm-project/commit/eaff3004019f97c64c88ab76da6b25106b659b30
DIFF: https://github.com/llvm/llvm-project/commit/eaff3004019f97c64c88ab76da6b25106b659b30.diff
LOG: Revert f0c2a5a "[LV] Generalize conditions for sinking instrs for first order recurrences."
It broke Chromium, causing "Instruction does not dominate all uses!" errors.
See https://bugs.chromium.org/p/chromium/issues/detail?id=1022297#c1 for a
reproducer.
> If the recurrence PHI node has a single user, we can sink any
> instruction without side effects, given that all users are dominated by
> the instruction computing the incoming value of the next iteration
> ('Previous'). We can sink instructions that may cause traps, because
> that only causes the trap to occur later, but not on any new paths.
>
> With the relaxed check, we also have to make sure that we do not have a
> direct cycle (meaning PHI user == 'Previous), which indicates a
> reduction relation, which potentially gets missed by
> ReductionDescriptor.
>
> As follow-ups, we can also sink stores, iff they do not alias with
> other instructions we move them across and we could also support sinking
> chains of instructions and multiple users of the PHI.
>
> Fixes PR43398.
>
> Reviewers: hsaito, dcaballe, Ayal, rengolin
>
> Reviewed By: Ayal
>
> Differential Revision: https://reviews.llvm.org/D69228
Added:
Modified:
llvm/lib/Analysis/IVDescriptors.cpp
Removed:
llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
################################################################################
diff --git a/llvm/lib/Analysis/IVDescriptors.cpp b/llvm/lib/Analysis/IVDescriptors.cpp
index bdebd71d7f68..6fb600114bc6 100644
--- a/llvm/lib/Analysis/IVDescriptors.cpp
+++ b/llvm/lib/Analysis/IVDescriptors.cpp
@@ -699,37 +699,25 @@ 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 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);
- });
- };
-
+ // TODO: Consider extending this sinking to handle other kinds of instructions
+ // and expressions, beyond sinking a single cast past Previous.
if (Phi->hasOneUse()) {
- 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;
-
- // 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;
+ 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;
return true;
}
}
- return allUsesDominatedBy(Phi, Previous);
+ for (User *U : Phi->users())
+ if (auto *I = dyn_cast<Instruction>(U)) {
+ if (!DT->dominates(Previous, I))
+ return false;
+ }
+
+ return true;
}
/// 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
deleted file mode 100644
index e09804276ec8..000000000000
--- a/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
+++ /dev/null
@@ -1,245 +0,0 @@
-; RUN: opt -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -S %s | FileCheck %s
-
-
- at p = external local_unnamed_addr global [257 x i32], align 16
- at 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
-}
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