[llvm] r207939 - SLPVectorizer: Bring back the insertelement patch (r205965) with fixes
Hal Finkel
hfinkel at anl.gov
Sun May 4 10:34:38 PDT 2014
Was this also the root cause of the eon failure exposed by enabling SLP vectorization in LTO (r207571 which was reverted in r207693)?
-Hal
----- Original Message -----
> From: "Arnold Schwaighofer" <aschwaighofer at apple.com>
> To: llvm-commits at cs.uiuc.edu
> Sent: Sunday, May 4, 2014 12:10:15 PM
> Subject: [llvm] r207939 - SLPVectorizer: Bring back the insertelement patch (r205965) with fixes
>
> Author: arnolds
> Date: Sun May 4 12:10:15 2014
> New Revision: 207939
>
> URL: http://llvm.org/viewvc/llvm-project?rev=207939&view=rev
> Log:
> SLPVectorizer: Bring back the insertelement patch (r205965) with
> fixes
>
> When can't assume a vectorized tree is rooted in an instruction. The
> IRBuilder
> could have constant folded it. When we rebuild the build_vector (the
> series of
> InsertElement instructions) use the last original InsertElement
> instruction. The
> vectorized tree root is guaranteed to be before it.
>
> Also, we can't assume that the n-th InsertElement inserts the n-th
> element into
> a vector.
>
> This reverts r207746 which reverted the revert of the revert of
> r205018 or so.
>
> Fixes the test case in PR19621.
>
> Added:
> llvm/trunk/test/Transforms/SLPVectorizer/X86/value-bug.ll
> Modified:
> llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
> llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll
>
> Modified: llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp?rev=207939&r1=207938&r2=207939&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp (original)
> +++ llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp Sun May 4
> 12:10:15 2014
> @@ -31,6 +31,7 @@
> #include "llvm/IR/Instructions.h"
> #include "llvm/IR/IntrinsicInst.h"
> #include "llvm/IR/Module.h"
> +#include "llvm/IR/NoFolder.h"
> #include "llvm/IR/Type.h"
> #include "llvm/IR/Value.h"
> #include "llvm/IR/Verifier.h"
> @@ -357,13 +358,13 @@ public:
> /// A negative number means that this is profitable.
> int getTreeCost();
>
> - /// Construct a vectorizable tree that starts at \p Roots and is
> possibly
> - /// used by a reduction of \p RdxOps.
> - void buildTree(ArrayRef<Value *> Roots, ValueSet *RdxOps = 0);
> + /// Construct a vectorizable tree that starts at \p Roots,
> ignoring users for
> + /// the purpose of scheduling and extraction in the \p
> UserIgnoreLst.
> + void buildTree(ArrayRef<Value *> Roots,
> + ArrayRef<Value *> UserIgnoreLst = None);
>
> /// Clear the internal data structures that are created by
> 'buildTree'.
> void deleteTree() {
> - RdxOps = 0;
> VectorizableTree.clear();
> ScalarToTreeEntry.clear();
> MustGather.clear();
> @@ -526,8 +527,8 @@ private:
> return I.first->second;
> }
>
> - /// Reduction operators.
> - ValueSet *RdxOps;
> + /// List of users to ignore during scheduling and that don't need
> extracting.
> + ArrayRef<Value *> UserIgnoreList;
>
> // Analysis and block reference.
> Function *F;
> @@ -542,9 +543,10 @@ private:
> IRBuilder<> Builder;
> };
>
> -void BoUpSLP::buildTree(ArrayRef<Value *> Roots, ValueSet *Rdx) {
> +void BoUpSLP::buildTree(ArrayRef<Value *> Roots,
> + ArrayRef<Value *> UserIgnoreLst) {
> deleteTree();
> - RdxOps = Rdx;
> + UserIgnoreList = UserIgnoreLst;
> if (!getSameType(Roots))
> return;
> buildTree_rec(Roots, 0);
> @@ -576,8 +578,9 @@ void BoUpSLP::buildTree(ArrayRef<Value *
> if (!UserInst)
> continue;
>
> - // Ignore uses that are part of the reduction.
> - if (Rdx && std::find(Rdx->begin(), Rdx->end(), UserInst) !=
> Rdx->end())
> + // Ignore users in the user ignore list.
> + if (std::find(UserIgnoreList.begin(), UserIgnoreList.end(),
> UserInst) !=
> + UserIgnoreList.end())
> continue;
>
> DEBUG(dbgs() << "SLP: Need to extract:" << *U << " from lane
> " <<
> @@ -708,8 +711,9 @@ void BoUpSLP::buildTree_rec(ArrayRef<Val
> continue;
> }
>
> - // This user is part of the reduction.
> - if (RdxOps && RdxOps->count(UI))
> + // Ignore users in the user ignore list.
> + if (std::find(UserIgnoreList.begin(), UserIgnoreList.end(),
> UI) !=
> + UserIgnoreList.end())
> continue;
>
> // Make sure that we can schedule this unknown user.
> @@ -1747,8 +1751,9 @@ Value *BoUpSLP::vectorizeTree() {
> DEBUG(dbgs() << "SLP: \tvalidating user:" << *U << ".\n");
>
> assert((ScalarToTreeEntry.count(U) ||
> - // It is legal to replace the reduction users by
> undef.
> - (RdxOps && RdxOps->count(U))) &&
> + // It is legal to replace users in the ignorelist
> by undef.
> + (std::find(UserIgnoreList.begin(),
> UserIgnoreList.end(), U) !=
> + UserIgnoreList.end())) &&
> "Replacing out-of-tree value with undef");
> }
> #endif
> @@ -1954,8 +1959,11 @@ private:
> bool tryToVectorizePair(Value *A, Value *B, BoUpSLP &R);
>
> /// \brief Try to vectorize a list of operands.
> + /// \@param BuildVector A list of users to ignore for the purpose
> of
> + /// scheduling and that don't need extracting.
> /// \returns true if a value was vectorized.
> - bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R);
> + bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
> + ArrayRef<Value *> BuildVector = None);
>
> /// \brief Try to vectorize a chain that may start at the operands
> of \V;
> bool tryToVectorize(BinaryOperator *V, BoUpSLP &R);
> @@ -2128,7 +2136,8 @@ bool SLPVectorizer::tryToVectorizePair(V
> return tryToVectorizeList(VL, R);
> }
>
> -bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP
> &R) {
> +bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP
> &R,
> + ArrayRef<Value *>
> BuildVector) {
> if (VL.size() < 2)
> return false;
>
> @@ -2178,13 +2187,38 @@ bool SLPVectorizer::tryToVectorizeList(A
> << "\n");
> ArrayRef<Value *> Ops = VL.slice(i, OpsWidth);
>
> - R.buildTree(Ops);
> + ArrayRef<Value *> BuildVectorSlice;
> + if (!BuildVector.empty())
> + BuildVectorSlice = BuildVector.slice(i, OpsWidth);
> +
> + R.buildTree(Ops, BuildVectorSlice);
> int Cost = R.getTreeCost();
>
> if (Cost < -SLPCostThreshold) {
> DEBUG(dbgs() << "SLP: Vectorizing list at cost:" << Cost <<
> ".\n");
> - R.vectorizeTree();
> + Value *VectorizedRoot = R.vectorizeTree();
>
> + // Reconstruct the build vector by extracting the vectorized
> root. This
> + // way we handle the case where some elements of the vector
> are undefined.
> + // (return (inserelt <4 xi32> (insertelt undef (opd0) 0)
> (opd1) 2))
> + if (!BuildVectorSlice.empty()) {
> + // The insert point is the last build vector instruction.
> The vectorized
> + // root will precede it. This guarantees that we get an
> instruction. The
> + // vectorized tree could have been constant folded.
> + Instruction *InsertAfter =
> cast<Instruction>(BuildVectorSlice.back());
> + unsigned VecIdx = 0;
> + for (auto &V : BuildVectorSlice) {
> + IRBuilder<true, NoFolder> Builder(
> + ++BasicBlock::iterator(InsertAfter));
> + InsertElementInst *IE = cast<InsertElementInst>(V);
> + Instruction *Extract =
> cast<Instruction>(Builder.CreateExtractElement(
> + VectorizedRoot, Builder.getInt32(VecIdx++)));
> + IE->setOperand(1, Extract);
> + IE->removeFromParent();
> + IE->insertAfter(Extract);
> + InsertAfter = IE;
> + }
> + }
> // Move to the next bundle.
> i += VF - 1;
> Changed = true;
> @@ -2293,7 +2327,7 @@ static Value *createRdxShuffleMask(unsig
> /// *p =
> ///
> class HorizontalReduction {
> - SmallPtrSet<Value *, 16> ReductionOps;
> + SmallVector<Value *, 16> ReductionOps;
> SmallVector<Value *, 32> ReducedVals;
>
> BinaryOperator *ReductionRoot;
> @@ -2387,7 +2421,7 @@ public:
> // We need to be able to reassociate the adds.
> if (!TreeN->isAssociative())
> return false;
> - ReductionOps.insert(TreeN);
> + ReductionOps.push_back(TreeN);
> }
> // Retract.
> Stack.pop_back();
> @@ -2424,7 +2458,7 @@ public:
>
> for (; i < NumReducedVals - ReduxWidth + 1; i += ReduxWidth) {
> ArrayRef<Value *> ValsToReduce(&ReducedVals[i], ReduxWidth);
> - V.buildTree(ValsToReduce, &ReductionOps);
> + V.buildTree(ValsToReduce, ReductionOps);
>
> // Estimate cost.
> int Cost = V.getTreeCost() + getReductionCost(TTI,
> ReducedVals[i]);
> @@ -2543,13 +2577,16 @@ private:
> ///
> /// Returns true if it matches
> ///
> -static bool findBuildVector(InsertElementInst *IE,
> - SmallVectorImpl<Value *> &Ops) {
> - if (!isa<UndefValue>(IE->getOperand(0)))
> +static bool findBuildVector(InsertElementInst *FirstInsertElem,
> + SmallVectorImpl<Value *> &BuildVector,
> + SmallVectorImpl<Value *>
> &BuildVectorOpds) {
> + if (!isa<UndefValue>(FirstInsertElem->getOperand(0)))
> return false;
>
> + InsertElementInst *IE = FirstInsertElem;
> while (true) {
> - Ops.push_back(IE->getOperand(1));
> + BuildVector.push_back(IE);
> + BuildVectorOpds.push_back(IE->getOperand(1));
>
> if (IE->use_empty())
> return false;
> @@ -2720,12 +2757,16 @@ bool SLPVectorizer::vectorizeChainsInBlo
> }
>
> // Try to vectorize trees that start at insertelement
> instructions.
> - if (InsertElementInst *IE = dyn_cast<InsertElementInst>(it)) {
> - SmallVector<Value *, 8> Ops;
> - if (!findBuildVector(IE, Ops))
> + if (InsertElementInst *FirstInsertElem =
> dyn_cast<InsertElementInst>(it)) {
> + SmallVector<Value *, 16> BuildVector;
> + SmallVector<Value *, 16> BuildVectorOpds;
> + if (!findBuildVector(FirstInsertElem, BuildVector,
> BuildVectorOpds))
> continue;
>
> - if (tryToVectorizeList(Ops, R)) {
> + // Vectorize starting with the build vector operands ignoring
> the
> + // BuildVector instructions for the purpose of scheduling and
> user
> + // extraction.
> + if (tryToVectorizeList(BuildVectorOpds, R, BuildVector)) {
> Changed = true;
> it = BB->begin();
> e = BB->end();
>
> Modified:
> llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll?rev=207939&r1=207938&r2=207939&view=diff
> ==============================================================================
> ---
> llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll
> (original)
> +++
> llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll
> Sun May 4 12:10:15 2014
> @@ -195,6 +195,30 @@ define <4 x float> @simple_select_partia
> ret <4 x float> %rb
> }
>
> +; Make sure that vectorization happens even if insertelements
> operations
> +; must be rescheduled. The case here is from compiling Julia.
> +define <4 x float> @reschedule_extract(<4 x float> %a, <4 x float>
> %b) {
> +; CHECK-LABEL: @reschedule_extract(
> +; CHECK: %1 = fadd <4 x float> %a, %b
> + %a0 = extractelement <4 x float> %a, i32 0
> + %b0 = extractelement <4 x float> %b, i32 0
> + %c0 = fadd float %a0, %b0
> + %v0 = insertelement <4 x float> undef, float %c0, i32 0
> + %a1 = extractelement <4 x float> %a, i32 1
> + %b1 = extractelement <4 x float> %b, i32 1
> + %c1 = fadd float %a1, %b1
> + %v1 = insertelement <4 x float> %v0, float %c1, i32 1
> + %a2 = extractelement <4 x float> %a, i32 2
> + %b2 = extractelement <4 x float> %b, i32 2
> + %c2 = fadd float %a2, %b2
> + %v2 = insertelement <4 x float> %v1, float %c2, i32 2
> + %a3 = extractelement <4 x float> %a, i32 3
> + %b3 = extractelement <4 x float> %b, i32 3
> + %c3 = fadd float %a3, %b3
> + %v3 = insertelement <4 x float> %v2, float %c3, i32 3
> + ret <4 x float> %v3
> +}
> +
> ; Check that cost model for vectorization takes credit for
> ; instructions that are erased.
> define <4 x float> @take_credit(<4 x float> %a, <4 x float> %b) {
> @@ -219,4 +243,40 @@ define <4 x float> @take_credit(<4 x flo
> ret <4 x float> %v3
> }
>
> +; Make sure we handle multiple trees that feed one build vector
> correctly.
> +define <4 x double> @multi_tree(double %w, double %x, double %y,
> double %z) {
> +entry:
> + %t0 = fadd double %w , 0.000000e+00
> + %t1 = fadd double %x , 1.000000e+00
> + %t2 = fadd double %y , 2.000000e+00
> + %t3 = fadd double %z , 3.000000e+00
> + %t4 = fmul double %t0, 1.000000e+00
> + %i1 = insertelement <4 x double> undef, double %t4, i32 3
> + %t5 = fmul double %t1, 1.000000e+00
> + %i2 = insertelement <4 x double> %i1, double %t5, i32 2
> + %t6 = fmul double %t2, 1.000000e+00
> + %i3 = insertelement <4 x double> %i2, double %t6, i32 1
> + %t7 = fmul double %t3, 1.000000e+00
> + %i4 = insertelement <4 x double> %i3, double %t7, i32 0
> + ret <4 x double> %i4
> +}
> +; CHECK-LABEL: @multi_tree
> +; CHECK-DAG: %[[V0:.+]] = insertelement <2 x double> undef, double
> %w, i32 0
> +; CHECK-DAG: %[[V1:.+]] = insertelement <2 x double> %[[V0]],
> double %x, i32 1
> +; CHECK-DAG: %[[V2:.+]] = fadd <2 x double> %[[V1]], <double
> 0.000000e+00, double 1.000000e+00>
> +; CHECK-DAG: %[[V3:.+]] = insertelement <2 x double> undef, double
> %y, i32 0
> +; CHECK-DAG: %[[V4:.+]] = insertelement <2 x double> %[[V3]],
> double %z, i32 1
> +; CHECK-DAG: %[[V5:.+]] = fadd <2 x double> %[[V4]], <double
> 2.000000e+00, double 3.000000e+00>
> +; CHECK-DAG: %[[V6:.+]] = fmul <2 x double> <double 1.000000e+00,
> double 1.000000e+00>, %[[V2]]
> +; CHECK-DAG: %[[V7:.+]] = extractelement <2 x double> %[[V6]], i32
> 0
> +; CHECK-DAG: %[[I1:.+]] = insertelement <4 x double> undef, double
> %[[V7]], i32 3
> +; CHECK-DAG: %[[V8:.+]] = extractelement <2 x double> %[[V6]], i32
> 1
> +; CHECK-DAG: %[[I2:.+]] = insertelement <4 x double> %[[I1]],
> double %[[V8]], i32 2
> +; CHECK-DAG: %[[V9:.+]] = fmul <2 x double> <double 1.000000e+00,
> double 1.000000e+00>, %[[V5]]
> +; CHECK-DAG: %[[V10:.+]] = extractelement <2 x double> %[[V9]], i32
> 0
> +; CHECK-DAG: %[[I3:.+]] = insertelement <4 x double> %i2, double
> %[[V10]], i32 1
> +; CHECK-DAG: %[[V11:.+]] = extractelement <2 x double> %[[V9]], i32
> 1
> +; CHECK-DAG: %[[I4:.+]] = insertelement <4 x double> %i3, double
> %[[V11]], i32 0
> +; CHECK: ret <4 x double> %[[I4]]
> +
> attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false"
> "no-frame-pointer-elim"="true"
> "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false"
> "no-nans-fp-math"="false" "stack-protector-buffer-size"="8"
> "unsafe-fp-math"="false" "use-soft-float"="false" }
>
> Added: llvm/trunk/test/Transforms/SLPVectorizer/X86/value-bug.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/value-bug.ll?rev=207939&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/SLPVectorizer/X86/value-bug.ll (added)
> +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/value-bug.ll Sun May
> 4 12:10:15 2014
> @@ -0,0 +1,80 @@
> +; RUN: opt -slp-vectorizer < %s -S
> -mtriple="x86_64-grtev3-linux-gnu" -mcpu=corei7-avx | FileCheck %s
> +
> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-grtev3-linux-gnu"
> +
> +; We used to crash on this example because we were building a
> constant
> +; expression during vectorization and the vectorizer expects
> instructions
> +; as elements of the vectorized tree.
> +; CHECK-LABEL: @test
> +; PR19621
> +
> +define void @test() {
> +bb279:
> + br label %bb283
> +
> +bb283:
> + %Av.sroa.8.0 = phi float [ undef, %bb279 ], [ %tmp315, %exit ]
> + %Av.sroa.5.0 = phi float [ undef, %bb279 ], [ %tmp319, %exit ]
> + %Av.sroa.3.0 = phi float [ undef, %bb279 ], [ %tmp307, %exit ]
> + %Av.sroa.0.0 = phi float [ undef, %bb279 ], [ %tmp317, %exit ]
> + br label %bb284
> +
> +bb284:
> + %tmp7.i = fpext float %Av.sroa.3.0 to double
> + %tmp8.i = fsub double %tmp7.i, undef
> + %tmp9.i = fsub double %tmp8.i, undef
> + %tmp17.i = fpext float %Av.sroa.8.0 to double
> + %tmp19.i = fsub double %tmp17.i, undef
> + %tmp20.i = fsub double %tmp19.i, undef
> + br label %bb21.i
> +
> +bb21.i:
> + br i1 undef, label %bb22.i, label %exit
> +
> +bb22.i:
> + %tmp24.i = fadd double undef, %tmp9.i
> + %tmp26.i = fadd double undef, %tmp20.i
> + br label %bb32.i
> +
> +bb32.i:
> + %xs.0.i = phi double [ %tmp24.i, %bb22.i ], [ 0.000000e+00,
> %bb32.i ]
> + %ys.0.i = phi double [ %tmp26.i, %bb22.i ], [ 0.000000e+00,
> %bb32.i ]
> + br i1 undef, label %bb32.i, label %bb21.i
> +
> +exit:
> + %tmp303 = fpext float %Av.sroa.0.0 to double
> + %tmp304 = fmul double %tmp303, undef
> + %tmp305 = fadd double undef, %tmp304
> + %tmp306 = fadd double %tmp305, undef
> + %tmp307 = fptrunc double %tmp306 to float
> + %tmp311 = fpext float %Av.sroa.5.0 to double
> + %tmp312 = fmul double %tmp311, 0.000000e+00
> + %tmp313 = fadd double undef, %tmp312
> + %tmp314 = fadd double %tmp313, undef
> + %tmp315 = fptrunc double %tmp314 to float
> + %tmp317 = fptrunc double undef to float
> + %tmp319 = fptrunc double undef to float
> + br label %bb283
> +}
> +
> +; Make sure that we probably handle constant folded vectorized
> trees. The
> +; vectorizer starts at the type (%t2, %t3) and wil constant fold the
> tree.
> +; The code that handles insertelement instructions must handle this.
> +define <4 x double> @constant_folding() {
> +entry:
> + %t0 = fadd double 1.000000e+00 , 0.000000e+00
> + %t1 = fadd double 1.000000e+00 , 1.000000e+00
> + %t2 = fmul double %t0, 1.000000e+00
> + %i1 = insertelement <4 x double> undef, double %t2, i32 1
> + %t3 = fmul double %t1, 1.000000e+00
> + %i2 = insertelement <4 x double> %i1, double %t3, i32 0
> + ret <4 x double> %i2
> +}
> +
> +; CHECK-LABEL: @constant_folding
> +; CHECK: %[[V0:.+]] = extractelement <2 x double> <double
> 1.000000e+00, double 2.000000e+00>, i32 0
> +; CHECK: %[[V1:.+]] = insertelement <4 x double> undef, double
> %[[V0]], i32 1
> +; CHECK: %[[V2:.+]] = extractelement <2 x double> <double
> 1.000000e+00, double 2.000000e+00>, i32 1
> +; CHECK: %[[V3:.+]] = insertelement <4 x double> %[[V1]], double
> %[[V2]], i32 0
> +; CHECK: ret <4 x double> %[[V3]]
>
>
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--
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory
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