[llvm] r370721 - [LV] Fix miscompiles by adding non-header PHI nodes to AllowedExit
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 5 03:27:59 PDT 2019
Merged together with r370720 to release_90 in r371044.
On Tue, Sep 3, 2019 at 11:32 AM Bjorn Pettersson via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
>
> Author: bjope
> Date: Tue Sep 3 02:33:55 2019
> New Revision: 370721
>
> URL: http://llvm.org/viewvc/llvm-project?rev=370721&view=rev
> Log:
> [LV] Fix miscompiles by adding non-header PHI nodes to AllowedExit
>
> Summary:
> Fold-tail currently supports reduction last-vector-value live-out's,
> but has yet to support last-scalar-value live-outs, including
> non-header phi's. As it relies on AllowedExit in order to detect
> them and bail out we need to add the non-header PHI nodes to
> AllowedExit, otherwise we end up with miscompiles.
>
> Solves https://bugs.llvm.org/show_bug.cgi?id=43166
>
> Reviewers: fhahn, Ayal
>
> Reviewed By: fhahn, Ayal
>
> Subscribers: anna, hiraditya, rkruppe, llvm-commits
>
> Tags: #llvm
>
> Differential Revision: https://reviews.llvm.org/D67074
>
> Modified:
> llvm/trunk/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
> llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
> llvm/trunk/test/Transforms/LoopVectorize/pr43166-fold-tail-by-masking.ll
>
> Modified: llvm/trunk/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h?rev=370721&r1=370720&r2=370721&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h (original)
> +++ llvm/trunk/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h Tue Sep 3 02:33:55 2019
> @@ -444,8 +444,8 @@ private:
> /// Holds the widest induction type encountered.
> Type *WidestIndTy = nullptr;
>
> - /// Allowed outside users. This holds the induction and reduction
> - /// vars which can be accessed from outside the loop.
> + /// Allowed outside users. This holds the variables that can be accessed from
> + /// outside the loop.
> SmallPtrSet<Value *, 4> AllowedExit;
>
> /// Can we assume the absence of NaNs.
>
> Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp?rev=370721&r1=370720&r2=370721&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp (original)
> +++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp Tue Sep 3 02:33:55 2019
> @@ -595,6 +595,7 @@ bool LoopVectorizationLegality::canVecto
> // Unsafe cyclic dependencies with header phis are identified during
> // legalization for reduction, induction and first order
> // recurrences.
> + AllowedExit.insert(&I);
> continue;
> }
>
>
> Modified: llvm/trunk/test/Transforms/LoopVectorize/pr43166-fold-tail-by-masking.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/pr43166-fold-tail-by-masking.ll?rev=370721&r1=370720&r2=370721&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/LoopVectorize/pr43166-fold-tail-by-masking.ll (original)
> +++ llvm/trunk/test/Transforms/LoopVectorize/pr43166-fold-tail-by-masking.ll Tue Sep 3 02:33:55 2019
> @@ -33,40 +33,16 @@
> ; the result is "BAD!"
>
>
> -; FIXME: The result here is incorrect! See https://bugs.llvm.org/show_bug.cgi?id=43166
> +; This test case miscompiled with clang 8.0.0 (see PR43166), now we get
> +; loop not vectorized: Cannot fold tail by masking in the presence of live outs.
> +; instead.
> define i64 @test1(i64 %y) {
> ; CHECK-LABEL: @test1(
> ; CHECK-NEXT: entry:
> -; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
> -; CHECK: vector.ph:
> -; CHECK-NEXT: [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <4 x i64> undef, i64 [[Y:%.*]], i32 0
> -; CHECK-NEXT: [[BROADCAST_SPLAT2:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT1]], <4 x i64> undef, <4 x i32> zeroinitializer
> -; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
> -; CHECK: vector.body:
> -; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
> -; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i32> undef, i32 [[INDEX]], i32 0
> -; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT]], <4 x i32> undef, <4 x i32> zeroinitializer
> -; CHECK-NEXT: [[INDUCTION:%.*]] = add <4 x i32> [[BROADCAST_SPLAT]], <i32 0, i32 1, i32 2, i32 3>
> -; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[INDEX]], 0
> -; CHECK-NEXT: [[TMP1:%.*]] = icmp eq <4 x i64> [[BROADCAST_SPLAT2]], zeroinitializer
> -; CHECK-NEXT: [[TMP2:%.*]] = xor <4 x i64> <i64 3, i64 3, i64 3, i64 3>, [[BROADCAST_SPLAT2]]
> -; CHECK-NEXT: [[TMP3:%.*]] = icmp ule <4 x i32> [[INDUCTION]], <i32 2, i32 2, i32 2, i32 2>
> -; CHECK-NEXT: [[TMP4:%.*]] = xor <4 x i1> [[TMP1]], <i1 true, i1 true, i1 true, i1 true>
> -; CHECK-NEXT: [[TMP5:%.*]] = and <4 x i1> [[TMP4]], [[TMP3]]
> -; CHECK-NEXT: [[TMP6:%.*]] = and <4 x i1> [[TMP1]], [[TMP3]]
> -; CHECK-NEXT: [[PREDPHI:%.*]] = select <4 x i1> [[TMP6]], <4 x i64> <i64 77, i64 77, i64 77, i64 77>, <4 x i64> [[TMP2]]
> -; CHECK-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 4
> -; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], 4
> -; CHECK-NEXT: br i1 [[TMP7]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0
> -; CHECK: middle.block:
> -; CHECK-NEXT: [[TMP8:%.*]] = extractelement <4 x i64> [[PREDPHI]], i32 3
> -; CHECK-NEXT: br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
> -; CHECK: scalar.ph:
> -; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ 4, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
> ; CHECK-NEXT: br label [[FOR_BODY:%.*]]
> ; CHECK: for.body:
> -; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC:%.*]], [[COND_END:%.*]] ]
> -; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[Y]], 0
> +; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[COND_END:%.*]] ]
> +; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[Y:%.*]], 0
> ; CHECK-NEXT: br i1 [[CMP]], label [[COND_END]], label [[COND_FALSE:%.*]]
> ; CHECK: cond.false:
> ; CHECK-NEXT: [[DIV:%.*]] = xor i64 3, [[Y]]
> @@ -75,9 +51,9 @@ define i64 @test1(i64 %y) {
> ; CHECK-NEXT: [[COND:%.*]] = phi i64 [ [[DIV]], [[COND_FALSE]] ], [ 77, [[FOR_BODY]] ]
> ; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[I]], 1
> ; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i32 [[INC]], 3
> -; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP]], label [[FOR_BODY]], !llvm.loop !2
> +; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
> ; CHECK: for.cond.cleanup:
> -; CHECK-NEXT: [[COND_LCSSA:%.*]] = phi i64 [ [[COND]], [[COND_END]] ], [ [[TMP8]], [[MIDDLE_BLOCK]] ]
> +; CHECK-NEXT: [[COND_LCSSA:%.*]] = phi i64 [ [[COND]], [[COND_END]] ]
> ; CHECK-NEXT: ret i64 [[COND_LCSSA]]
> ;
> entry:
> @@ -102,40 +78,16 @@ for.cond.cleanup:
> ret i64 %cond
> }
>
> -
> -; FIXME: The result here is incorrect! See https://bugs.llvm.org/show_bug.cgi?id=43166
> +; This test case miscompiled with clang 8.0.0 (see PR43166), now we get
> +; loop not vectorized: Cannot fold tail by masking in the presence of live outs.
> +; instead.
> define i64 @test2(i64 %y) {
> ; CHECK-LABEL: @test2(
> ; CHECK-NEXT: entry:
> -; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
> -; CHECK: vector.ph:
> -; CHECK-NEXT: [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <4 x i64> undef, i64 [[Y:%.*]], i32 0
> -; CHECK-NEXT: [[BROADCAST_SPLAT2:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT1]], <4 x i64> undef, <4 x i32> zeroinitializer
> -; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
> -; CHECK: vector.body:
> -; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
> -; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i32> undef, i32 [[INDEX]], i32 0
> -; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT]], <4 x i32> undef, <4 x i32> zeroinitializer
> -; CHECK-NEXT: [[INDUCTION:%.*]] = add <4 x i32> [[BROADCAST_SPLAT]], <i32 0, i32 1, i32 2, i32 3>
> -; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[INDEX]], 0
> -; CHECK-NEXT: [[TMP1:%.*]] = icmp eq <4 x i64> [[BROADCAST_SPLAT2]], zeroinitializer
> -; CHECK-NEXT: [[TMP2:%.*]] = icmp ule <4 x i32> [[INDUCTION]], <i32 2, i32 2, i32 2, i32 2>
> -; CHECK-NEXT: [[TMP3:%.*]] = xor <4 x i1> [[TMP1]], <i1 true, i1 true, i1 true, i1 true>
> -; CHECK-NEXT: [[TMP4:%.*]] = and <4 x i1> [[TMP3]], [[TMP2]]
> -; CHECK-NEXT: [[TMP5:%.*]] = and <4 x i1> [[TMP1]], [[TMP2]]
> -; CHECK-NEXT: [[PREDPHI:%.*]] = select <4 x i1> [[TMP5]], <4 x i64> <i64 77, i64 77, i64 77, i64 77>, <4 x i64> <i64 55, i64 55, i64 55, i64 55>
> -; CHECK-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 4
> -; CHECK-NEXT: [[TMP6:%.*]] = icmp eq i32 [[INDEX_NEXT]], 4
> -; CHECK-NEXT: br i1 [[TMP6]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !4
> -; CHECK: middle.block:
> -; CHECK-NEXT: [[TMP7:%.*]] = extractelement <4 x i64> [[PREDPHI]], i32 3
> -; CHECK-NEXT: br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
> -; CHECK: scalar.ph:
> -; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ 4, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
> ; CHECK-NEXT: br label [[FOR_BODY:%.*]]
> ; CHECK: for.body:
> -; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC:%.*]], [[COND_END:%.*]] ]
> -; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[Y]], 0
> +; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[COND_END:%.*]] ]
> +; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[Y:%.*]], 0
> ; CHECK-NEXT: br i1 [[CMP]], label [[COND_END]], label [[COND_FALSE:%.*]]
> ; CHECK: cond.false:
> ; CHECK-NEXT: br label [[COND_END]]
> @@ -143,9 +95,9 @@ define i64 @test2(i64 %y) {
> ; CHECK-NEXT: [[COND:%.*]] = phi i64 [ 55, [[COND_FALSE]] ], [ 77, [[FOR_BODY]] ]
> ; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[I]], 1
> ; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i32 [[INC]], 3
> -; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP]], label [[FOR_BODY]], !llvm.loop !5
> +; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
> ; CHECK: for.cond.cleanup:
> -; CHECK-NEXT: [[COND_LCSSA:%.*]] = phi i64 [ [[COND]], [[COND_END]] ], [ [[TMP7]], [[MIDDLE_BLOCK]] ]
> +; CHECK-NEXT: [[COND_LCSSA:%.*]] = phi i64 [ [[COND]], [[COND_END]] ]
> ; CHECK-NEXT: ret i64 [[COND_LCSSA]]
> ;
> entry:
> @@ -169,38 +121,16 @@ for.cond.cleanup:
> ret i64 %cond
> }
>
> -
> -; FIXME: The result here is incorrect! See https://bugs.llvm.org/show_bug.cgi?id=43166
> +; This test case miscompiled with clang 8.0.0 (see PR43166), now we get
> +; loop not vectorized: Cannot fold tail by masking in the presence of live outs.
> +; instead.
> define i32 @test3(i64 %y) {
> ; CHECK-LABEL: @test3(
> ; CHECK-NEXT: entry:
> -; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
> -; CHECK: vector.ph:
> -; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i64> undef, i64 [[Y:%.*]], i32 0
> -; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i64> [[BROADCAST_SPLATINSERT]], <4 x i64> undef, <4 x i32> zeroinitializer
> -; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
> -; CHECK: vector.body:
> -; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
> -; CHECK-NEXT: [[VEC_IND:%.*]] = phi <4 x i32> [ <i32 0, i32 1, i32 2, i32 3>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
> -; CHECK-NEXT: [[TMP0:%.*]] = icmp eq <4 x i64> [[BROADCAST_SPLAT]], zeroinitializer
> -; CHECK-NEXT: [[TMP1:%.*]] = icmp ule <4 x i32> [[VEC_IND]], <i32 2, i32 2, i32 2, i32 2>
> -; CHECK-NEXT: [[TMP2:%.*]] = xor <4 x i1> [[TMP0]], <i1 true, i1 true, i1 true, i1 true>
> -; CHECK-NEXT: [[TMP3:%.*]] = and <4 x i1> [[TMP2]], [[TMP1]]
> -; CHECK-NEXT: [[TMP4:%.*]] = and <4 x i1> [[TMP0]], [[TMP1]]
> -; CHECK-NEXT: [[PREDPHI:%.*]] = select <4 x i1> [[TMP4]], <4 x i32> [[VEC_IND]], <4 x i32> <i32 55, i32 55, i32 55, i32 55>
> -; CHECK-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 4
> -; CHECK-NEXT: [[VEC_IND_NEXT]] = add <4 x i32> [[VEC_IND]], <i32 4, i32 4, i32 4, i32 4>
> -; CHECK-NEXT: [[TMP5:%.*]] = icmp eq i32 [[INDEX_NEXT]], 4
> -; CHECK-NEXT: br i1 [[TMP5]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !6
> -; CHECK: middle.block:
> -; CHECK-NEXT: [[TMP6:%.*]] = extractelement <4 x i32> [[PREDPHI]], i32 3
> -; CHECK-NEXT: br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
> -; CHECK: scalar.ph:
> -; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ 4, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
> ; CHECK-NEXT: br label [[FOR_BODY:%.*]]
> ; CHECK: for.body:
> -; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC:%.*]], [[COND_END:%.*]] ]
> -; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[Y]], 0
> +; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[COND_END:%.*]] ]
> +; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[Y:%.*]], 0
> ; CHECK-NEXT: br i1 [[CMP]], label [[COND_END]], label [[COND_FALSE:%.*]]
> ; CHECK: cond.false:
> ; CHECK-NEXT: br label [[COND_END]]
> @@ -208,9 +138,9 @@ define i32 @test3(i64 %y) {
> ; CHECK-NEXT: [[COND:%.*]] = phi i32 [ 55, [[COND_FALSE]] ], [ [[I]], [[FOR_BODY]] ]
> ; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[I]], 1
> ; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i32 [[INC]], 3
> -; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP]], label [[FOR_BODY]], !llvm.loop !7
> +; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
> ; CHECK: for.cond.cleanup:
> -; CHECK-NEXT: [[COND_LCSSA:%.*]] = phi i32 [ [[COND]], [[COND_END]] ], [ [[TMP6]], [[MIDDLE_BLOCK]] ]
> +; CHECK-NEXT: [[COND_LCSSA:%.*]] = phi i32 [ [[COND]], [[COND_END]] ]
> ; CHECK-NEXT: ret i32 [[COND_LCSSA]]
> ;
> entry:
>
>
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