[llvm] r358519 - [SLP] Refactoring of the operand reordering code.

Mikael Holmén via llvm-commits llvm-commits at lists.llvm.org
Tue Apr 23 05:39:18 PDT 2019


Hi Vasileios and Simon,

With this patch the following starts crashing:

  opt -slp-vectorizer -S -o - bbi-27514.ll

I get:

opt: ../include/llvm/Support/Casting.h:264: typename cast_retty<X, Y 
*>::ret_type llvm::cast(Y *) [X = llvm::Instruction, Y = llvm::Value]: 
Assertion `isa<X>(Val) && "cast<Ty>() argument of incompatible type!"' 
failed.

Program received signal SIGABRT, Aborted.
0x00007ffff67bbc37 in __GI_raise (sig=sig at entry=6) at 
../nptl/sysdeps/unix/sysv/linux/raise.c:56
56      ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) where
#0  0x00007ffff67bbc37 in __GI_raise (sig=sig at entry=6) at 
../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007ffff67bf028 in __GI_abort () at abort.c:89
#2  0x00007ffff67b4bf6 in __assert_fail_base (fmt=0x7ffff6909058 
"%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", 
assertion=assertion at entry=0x44abf79 "isa<X>(Val) && \"cast<Ty>() 
argument of incompatible type!\"", file=file at entry=0x44abeda 
"../include/llvm/Support/Casting.h", line=line at entry=264, 
function=function at entry=0x44acbdc "typename cast_retty<X, Y *>::ret_type 
llvm::cast(Y *) [X = llvm::Instruction, Y = llvm::Value]") at assert.c:92
#3  0x00007ffff67b4ca2 in __GI___assert_fail (assertion=0x44abf79 
"isa<X>(Val) && \"cast<Ty>() argument of incompatible type!\"", 
file=0x44abeda "../include/llvm/Support/Casting.h", line=264, 
function=0x44acbdc "typename cast_retty<X, Y *>::ret_type llvm::cast(Y 
*) [X = llvm::Instruction, Y = llvm::Value]") at assert.c:101
#4  0x0000000000d6a799 in llvm::cast<llvm::Instruction, llvm::Value> 
(Val=0x6db7ac0) at ../include/llvm/Support/Casting.h:264
#5  0x0000000003a5380b in 
llvm::slpvectorizer::BoUpSLP::VLOperands::getBestOperand 
(this=0x7fffffff77d0, OpIdx=1, Lane=3, LastLane=2, 
ReorderingModes=llvm::ArrayRef of length 2 = {...}) at 
../lib/Transforms/Vectorize/SLPVectorizer.cpp:790
#6  0x0000000003a3454d in 
llvm::slpvectorizer::BoUpSLP::VLOperands::reorder (this=0x7fffffff77d0) 
at ../lib/Transforms/Vectorize/SLPVectorizer.cpp:1003
#7  0x0000000003a16815 in 
llvm::slpvectorizer::BoUpSLP::reorderInputsAccordingToOpcode 
(VL=llvm::ArrayRef of length 4 = {...}, Left=llvm::SmallVector of Size 
0, Capacity 8, Right=llvm::SmallVector of Size 0, Capacity 8, DL=..., 
SE=...) at ../lib/Transforms/Vectorize/SLPVectorizer.cpp:3259
#8  0x0000000003a12e8e in llvm::slpvectorizer::BoUpSLP::buildTree_rec 
(this=0x7fffffffc1c0, VL=llvm::ArrayRef of length 4 = {...}, Depth=1, 
UserTreeIdx=...) at ../lib/Transforms/Vectorize/SLPVectorizer.cpp:2313
#9  0x0000000003a13413 in llvm::slpvectorizer::BoUpSLP::buildTree_rec 
(this=0x7fffffffc1c0, VL=llvm::ArrayRef of length 4 = {...}, Depth=0, 
UserTreeIdx=...) at ../lib/Transforms/Vectorize/SLPVectorizer.cpp:2374
#10 0x0000000003a0f4df in llvm::slpvectorizer::BoUpSLP::buildTree 
(this=0x7fffffffc1c0, Roots=llvm::ArrayRef of length 4 = {...}, 
ExternallyUsedValues=..., UserIgnoreLst=llvm::ArrayRef of length 8 = 
{...}) at ../lib/Transforms/Vectorize/SLPVectorizer.cpp:1898
#11 0x0000000003a2c763 in (anonymous 
namespace)::HorizontalReduction::tryToReduce (this=0x7fffffffb528, 
V=..., TTI=0x6d86970) at ../lib/Transforms/Vectorize/SLPVectorizer.cpp:6108
#12 0x0000000003a27017 in 
tryToVectorizeHorReductionOrInstOperands(llvm::PHINode*, 
llvm::Instruction*, llvm::BasicBlock*, llvm::slpvectorizer::BoUpSLP&, 
llvm::TargetTransformInfo*, llvm::function_ref<bool (llvm::Instruction*, 
llvm::slpvectorizer::BoUpSLP&)>) (P=0x0, Root=0x6db93a0, BB=0x6db7b50, 
R=..., TTI=0x6d86970, Vectorize=...) at 
../lib/Transforms/Vectorize/SLPVectorizer.cpp:6461
#13 0x0000000003a26dc5 in 
llvm::SLPVectorizerPass::vectorizeRootInstruction (this=0x6dbf5a0, 
P=0x0, V=0x6db93a0, BB=0x6db7b50, R=..., TTI=0x6d86970) at 
../lib/Transforms/Vectorize/SLPVectorizer.cpp:6517
#14 0x0000000003a24453 in 
llvm::SLPVectorizerPass::vectorizeChainsInBlock (this=0x6dbf5a0, 
BB=0x6db7b50, R=...) at ../lib/Transforms/Vectorize/SLPVectorizer.cpp:6689
#15 0x0000000003a235bf in llvm::SLPVectorizerPass::runImpl 
(this=0x6dbf5a0, F=..., SE_=0x6dc3730, TTI_=0x6d86970, TLI_=0x6db5d38, 
AA_=0x6dc45f0, LI_=0x6dbf790, DT_=0x6dbf860, AC_=0x6dc3f40, 
DB_=0x6dc09b0, ORE_=0x6dc4630) at 
../lib/Transforms/Vectorize/SLPVectorizer.cpp:5000
#16 0x0000000003a2b799 in (anonymous 
namespace)::SLPVectorizer::runOnFunction (this=0x6dbf580, F=...) at 
../lib/Transforms/Vectorize/SLPVectorizer.cpp:4905
#17 0x0000000002f3131c in llvm::FPPassManager::runOnFunction 
(this=0x6dbfb10, F=...) at ../lib/IR/LegacyPassManager.cpp:1648
#18 0x0000000002f317a5 in llvm::FPPassManager::runOnModule 
(this=0x6dbfb10, M=...) at ../lib/IR/LegacyPassManager.cpp:1685
#19 0x0000000002f31f67 in (anonymous 
namespace)::MPPassManager::runOnModule (this=0x6d87a70, M=...) at 
../lib/IR/LegacyPassManager.cpp:1752
#20 0x0000000002f31a6d in llvm::legacy::PassManagerImpl::run 
(this=0x6db5580, M=...) at ../lib/IR/LegacyPassManager.cpp:1865
#21 0x0000000002f32521 in llvm::legacy::PassManager::run 
(this=0x7fffffffd4e8, M=...) at ../lib/IR/LegacyPassManager.cpp:1896
#22 0x0000000000daa124 in main (argc=6, argv=0x7fffffffda88) at 
../tools/opt/opt.cpp:901

A few ups and print OpLastLane that it tries to cast to Instruction:

#5  0x0000000003a5380b in 
llvm::slpvectorizer::BoUpSLP::VLOperands::getBestOperand 
(this=0x7fffffff77d0, OpIdx=1, Lane=3, LastLane=2, 
ReorderingModes=llvm::ArrayRef of length 2 = {...}) at 
../lib/Transforms/Vectorize/SLPVectorizer.cpp:790
790                        cast<Instruction>(OpLastLane)->getOpcode()) ||
(gdb) p OpLastLane
$1 = (llvm::Value *) 0x6db7ac0
(gdb) call OpLastLane->dump()
i64 undef

/Mikael

On 4/16/19 9:27 PM, Simon Pilgrim via llvm-commits wrote:
> Author: rksimon
> Date: Tue Apr 16 12:27:00 2019
> New Revision: 358519
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=358519&view=rev
> Log:
> [SLP] Refactoring of the operand reordering code.
> 
> This is a refactoring patch which should have all the functionality of the current code. Its goal is twofold:
> i. Cleanup and simplify the reordering code, and
> ii. Generalize reordering so that it will work for an arbitrary number of operands, not just 2.
> 
> This is the second patch in a series of patches that will enable operand reordering across chains of operations. An example of this was presented in EuroLLVM'18 https://www.youtube.com/watch?v=gIEn34LvyNo .
> 
> Committed on behalf of @vporpo (Vasileios Porpodas)
> 
> Differential Revision: https://reviews.llvm.org/D59973
> 
> Modified:
>      llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
>      llvm/trunk/test/Transforms/SLPVectorizer/X86/alternate-int.ll
>      llvm/trunk/test/Transforms/SLPVectorizer/X86/crash_lencod.ll
>      llvm/trunk/test/Transforms/SLPVectorizer/X86/operandorder.ll
> 
> Modified: llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp?rev=358519&r1=358518&r2=358519&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp (original)
> +++ llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp Tue Apr 16 12:27:00 2019
> @@ -634,6 +634,449 @@ public:
>   #endif
>     };
>   
> +  /// A helper data structure to hold the operands of a vector of instructions.
> +  /// This supports a fixed vector length for all operand vectors.
> +  class VLOperands {
> +    /// For each operand we need (i) the value, and (ii) the opcode that it
> +    /// would be attached to if the expression was in a left-linearized form.
> +    /// This is required to avoid illegal operand reordering.
> +    /// For example:
> +    /// \verbatim
> +    ///                         0 Op1
> +    ///                         |/
> +    /// Op1 Op2   Linearized    + Op2
> +    ///   \ /     ---------->   |/
> +    ///    -                    -
> +    ///
> +    /// Op1 - Op2            (0 + Op1) - Op2
> +    /// \endverbatim
> +    ///
> +    /// Value Op1 is attached to a '+' operation, and Op2 to a '-'.
> +    ///
> +    /// Another way to think of this is to track all the operations across the
> +    /// path from the operand all the way to the root of the tree and to
> +    /// calculate the operation that corresponds to this path. For example, the
> +    /// path from Op2 to the root crosses the RHS of the '-', therefore the
> +    /// corresponding operation is a '-' (which matches the one in the
> +    /// linearized tree, as shown above).
> +    ///
> +    /// For lack of a better term, we refer to this operation as Accumulated
> +    /// Path Operation (APO).
> +    struct OperandData {
> +      OperandData() = default;
> +      OperandData(Value *V, bool APO, bool IsUsed)
> +          : V(V), APO(APO), IsUsed(IsUsed) {}
> +      /// The operand value.
> +      Value *V = nullptr;
> +      /// TreeEntries only allow a single opcode, or an alternate sequence of
> +      /// them (e.g, +, -). Therefore, we can safely use a boolean value for the
> +      /// APO. It is set to 'true' if 'V' is attached to an inverse operation
> +      /// in the left-linearized form (e.g., Sub/Div), and 'false' otherwise
> +      /// (e.g., Add/Mul)
> +      bool APO = false;
> +      /// Helper data for the reordering function.
> +      bool IsUsed = false;
> +    };
> +
> +    /// During operand reordering, we are trying to select the operand at lane
> +    /// that matches best with the operand at the neighboring lane. Our
> +    /// selection is based on the type of value we are looking for. For example,
> +    /// if the neighboring lane has a load, we need to look for a load that is
> +    /// accessing a consecutive address. These strategies are summarized in the
> +    /// 'ReorderingMode' enumerator.
> +    enum class ReorderingMode {
> +      Load,     ///< Matching loads to consecutive memory addresses
> +      Opcode,   ///< Matching instructions based on opcode (same or alternate)
> +      Constant, ///< Matching constants
> +      Splat,    ///< Matching the same instruction multiple times (broadcast)
> +      Failed,   ///< We failed to create a vectorizable group
> +    };
> +
> +    using OperandDataVec = SmallVector<OperandData, 2>;
> +
> +    /// A vector of operand vectors.
> +    SmallVector<OperandDataVec, 4> OpsVec;
> +
> +    const DataLayout &DL;
> +    ScalarEvolution &SE;
> +
> +    /// \returns the operand data at \p OpIdx and \p Lane.
> +    OperandData &getData(unsigned OpIdx, unsigned Lane) {
> +      return OpsVec[OpIdx][Lane];
> +    }
> +
> +    /// \returns the operand data at \p OpIdx and \p Lane. Const version.
> +    const OperandData &getData(unsigned OpIdx, unsigned Lane) const {
> +      return OpsVec[OpIdx][Lane];
> +    }
> +
> +    /// Clears the used flag for all entries.
> +    void clearUsed() {
> +      for (unsigned OpIdx = 0, NumOperands = getNumOperands();
> +           OpIdx != NumOperands; ++OpIdx)
> +        for (unsigned Lane = 0, NumLanes = getNumLanes(); Lane != NumLanes;
> +             ++Lane)
> +          OpsVec[OpIdx][Lane].IsUsed = false;
> +    }
> +
> +    /// Swap the operand at \p OpIdx1 with that one at \p OpIdx2.
> +    void swap(unsigned OpIdx1, unsigned OpIdx2, unsigned Lane) {
> +      std::swap(OpsVec[OpIdx1][Lane], OpsVec[OpIdx2][Lane]);
> +    }
> +
> +    // Search all operands in Ops[*][Lane] for the one that matches best
> +    // Ops[OpIdx][LastLane] and return its opreand index.
> +    // If no good match can be found, return None.
> +    Optional<unsigned>
> +    getBestOperand(unsigned OpIdx, int Lane, int LastLane,
> +                   ArrayRef<ReorderingMode> ReorderingModes) {
> +      unsigned NumOperands = getNumOperands();
> +
> +      // The operand of the previous lane at OpIdx.
> +      Value *OpLastLane = getData(OpIdx, LastLane).V;
> +
> +      // Our strategy mode for OpIdx.
> +      ReorderingMode RMode = ReorderingModes[OpIdx];
> +
> +      // The linearized opcode of the operand at OpIdx, Lane.
> +      bool OpIdxAPO = getData(OpIdx, Lane).APO;
> +
> +      const unsigned BestScore = 2;
> +      const unsigned GoodScore = 1;
> +
> +      // The best operand index and its score.
> +      // Sometimes we have more than one option (e.g., Opcode and Undefs), so we
> +      // are using the score to differentiate between the two.
> +      struct BestOpData {
> +        Optional<unsigned> Idx = None;
> +        unsigned Score = 0;
> +      } BestOp;
> +
> +      // Iterate through all unused operands and look for the best.
> +      for (unsigned Idx = 0; Idx != NumOperands; ++Idx) {
> +        // Get the operand at Idx and Lane.
> +        OperandData &OpData = getData(Idx, Lane);
> +        Value *Op = OpData.V;
> +        bool OpAPO = OpData.APO;
> +
> +        // Skip already selected operands.
> +        if (OpData.IsUsed)
> +          continue;
> +
> +        // Skip if we are trying to move the operand to a position with a
> +        // different opcode in the linearized tree form. This would break the
> +        // semantics.
> +        if (OpAPO != OpIdxAPO)
> +          continue;
> +
> +        // Look for an operand that matches the current mode.
> +        switch (RMode) {
> +        case ReorderingMode::Load:
> +          if (isa<LoadInst>(Op)) {
> +            // Figure out which is left and right, so that we can check for
> +            // consecutive loads
> +            bool LeftToRight = Lane > LastLane;
> +            Value *OpLeft = (LeftToRight) ? OpLastLane : Op;
> +            Value *OpRight = (LeftToRight) ? Op : OpLastLane;
> +            if (isConsecutiveAccess(cast<LoadInst>(OpLeft),
> +                                    cast<LoadInst>(OpRight), DL, SE))
> +              BestOp.Idx = Idx;
> +          }
> +          break;
> +        case ReorderingMode::Opcode:
> +          // We accept both Instructions and Undefs, but with different scores.
> +          if ((isa<Instruction>(Op) &&
> +               cast<Instruction>(Op)->getOpcode() ==
> +                   cast<Instruction>(OpLastLane)->getOpcode()) ||
> +              isa<UndefValue>(Op)) {
> +            // An instruction has a higher score than an undef.
> +            unsigned Score = (isa<UndefValue>(Op)) ? GoodScore : BestScore;
> +            if (Score > BestOp.Score) {
> +              BestOp.Idx = Idx;
> +              BestOp.Score = Score;
> +            }
> +          }
> +          break;
> +        case ReorderingMode::Constant:
> +          if (isa<Constant>(Op)) {
> +            unsigned Score = (isa<UndefValue>(Op)) ? GoodScore : BestScore;
> +            if (Score > BestOp.Score) {
> +              BestOp.Idx = Idx;
> +              BestOp.Score = Score;
> +            }
> +          }
> +          break;
> +        case ReorderingMode::Splat:
> +          if (Op == OpLastLane)
> +            BestOp.Idx = Idx;
> +          break;
> +        case ReorderingMode::Failed:
> +          return None;
> +        }
> +      }
> +
> +      if (BestOp.Idx) {
> +        getData(BestOp.Idx.getValue(), Lane).IsUsed = true;
> +        return BestOp.Idx;
> +      }
> +      // If we could not find a good match return None.
> +      return None;
> +    }
> +
> +    /// Helper for reorderOperandVecs. \Returns the lane that we should start
> +    /// reordering from. This is the one which has the least number of operands
> +    /// that can freely move about.
> +    unsigned getBestLaneToStartReordering() const {
> +      unsigned BestLane = 0;
> +      unsigned Min = UINT_MAX;
> +      for (unsigned Lane = 0, NumLanes = getNumLanes(); Lane != NumLanes;
> +           ++Lane) {
> +        unsigned NumFreeOps = getMaxNumOperandsThatCanBeReordered(Lane);
> +        if (NumFreeOps < Min) {
> +          Min = NumFreeOps;
> +          BestLane = Lane;
> +        }
> +      }
> +      return BestLane;
> +    }
> +
> +    /// \Returns the maximum number of operands that are allowed to be reordered
> +    /// for \p Lane. This is used as a heuristic for selecting the first lane to
> +    /// start operand reordering.
> +    unsigned getMaxNumOperandsThatCanBeReordered(unsigned Lane) const {
> +      unsigned CntTrue = 0;
> +      unsigned NumOperands = getNumOperands();
> +      // Operands with the same APO can be reordered. We therefore need to count
> +      // how many of them we have for each APO, like this: Cnt[APO] = x.
> +      // Since we only have two APOs, namely true and false, we can avoid using
> +      // a map. Instead we can simply count the number of operands that
> +      // correspond to one of them (in this case the 'true' APO), and calculate
> +      // the other by subtracting it from the total number of operands.
> +      for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx)
> +        if (getData(OpIdx, Lane).APO)
> +          ++CntTrue;
> +      unsigned CntFalse = NumOperands - CntTrue;
> +      return std::max(CntTrue, CntFalse);
> +    }
> +
> +    /// Go through the instructions in VL and append their operands.
> +    void appendOperandsOfVL(ArrayRef<Value *> VL) {
> +      assert(!VL.empty() && "Bad VL");
> +      assert((empty() || VL.size() == getNumLanes()) &&
> +             "Expected same number of lanes");
> +      assert(isa<Instruction>(VL[0]) && "Expected instruction");
> +      unsigned NumOperands = cast<Instruction>(VL[0])->getNumOperands();
> +      OpsVec.resize(NumOperands);
> +      unsigned NumLanes = VL.size();
> +      for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx) {
> +        OpsVec[OpIdx].resize(NumLanes);
> +        for (unsigned Lane = 0; Lane != NumLanes; ++Lane) {
> +          assert(isa<Instruction>(VL[Lane]) && "Expected instruction");
> +          // Our tree has just 3 nodes: the root and two operands.
> +          // It is therefore trivial to get the APO. We only need to check the
> +          // opcode of VL[Lane] and whether the operand at OpIdx is the LHS or
> +          // RHS operand. The LHS operand of both add and sub is never attached
> +          // to an inversese operation in the linearized form, therefore its APO
> +          // is false. The RHS is ture only if VL[Lane] is an inverse operation.
> +
> +          // Since operand reordering is performed on groups of commutative
> +          // operations or alternating sequences (e.g., +, -), we can safely
> +          // tell the inverse operations by checking commutativity.
> +          bool IsInverseOperation = !isCommutative(cast<Instruction>(VL[Lane]));
> +          bool APO = (OpIdx == 0) ? false : IsInverseOperation;
> +          OpsVec[OpIdx][Lane] = {cast<Instruction>(VL[Lane])->getOperand(OpIdx),
> +                                 APO, false};
> +        }
> +      }
> +    }
> +
> +    /// \returns the number of operands.
> +    unsigned getNumOperands() const { return OpsVec.size(); }
> +
> +    /// \returns the number of lanes.
> +    unsigned getNumLanes() const { return OpsVec[0].size(); }
> +
> +    /// \returns the operand value at \p OpIdx and \p Lane.
> +    Value *getValue(unsigned OpIdx, unsigned Lane) const {
> +      return getData(OpIdx, Lane).V;
> +    }
> +
> +    /// \returns true if the data structure is empty.
> +    bool empty() const { return OpsVec.empty(); }
> +
> +    /// Clears the data.
> +    void clear() { OpsVec.clear(); }
> +
> +  public:
> +    /// Initialize with all the operands of the instruction vector \p RootVL.
> +    VLOperands(ArrayRef<Value *> RootVL, const DataLayout &DL,
> +               ScalarEvolution &SE)
> +        : DL(DL), SE(SE) {
> +      // Append all the operands of RootVL.
> +      appendOperandsOfVL(RootVL);
> +    }
> +
> +    /// \Returns a value vector with the operands across all lanes for the
> +    /// opearnd at \p OpIdx.
> +    ValueList getVL(unsigned OpIdx) const {
> +      ValueList OpVL(OpsVec[OpIdx].size());
> +      assert(OpsVec[OpIdx].size() == getNumLanes() &&
> +             "Expected same num of lanes across all operands");
> +      for (unsigned Lane = 0, Lanes = getNumLanes(); Lane != Lanes; ++Lane)
> +        OpVL[Lane] = OpsVec[OpIdx][Lane].V;
> +      return OpVL;
> +    }
> +
> +    // Performs operand reordering for 2 or more operands.
> +    // The original operands are in OrigOps[OpIdx][Lane].
> +    // The reordered operands are returned in 'SortedOps[OpIdx][Lane]'.
> +    void reorder() {
> +      unsigned NumOperands = getNumOperands();
> +      unsigned NumLanes = getNumLanes();
> +      // Each operand has its own mode. We are using this mode to help us select
> +      // the instructions for each lane, so that they match best with the ones
> +      // we have selected so far.
> +      SmallVector<ReorderingMode, 2> ReorderingModes(NumOperands);
> +
> +      // This is a greedy single-pass algorithm. We are going over each lane
> +      // once and deciding on the best order right away with no back-tracking.
> +      // However, in order to increase its effectiveness, we start with the lane
> +      // that has operands that can move the least. For example, given the
> +      // following lanes:
> +      //  Lane 0 : A[0] = B[0] + C[0]   // Visited 3rd
> +      //  Lane 1 : A[1] = C[1] - B[1]   // Visited 1st
> +      //  Lane 2 : A[2] = B[2] + C[2]   // Visited 2nd
> +      //  Lane 3 : A[3] = C[3] - B[3]   // Visited 4th
> +      // we will start at Lane 1, since the operands of the subtraction cannot
> +      // be reordered. Then we will visit the rest of the lanes in a circular
> +      // fashion. That is, Lanes 2, then Lane 0, and finally Lane 3.
> +
> +      // Find the first lane that we will start our search from.
> +      unsigned FirstLane = getBestLaneToStartReordering();
> +
> +      // Initialize the modes.
> +      for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx) {
> +        Value *OpLane0 = getValue(OpIdx, FirstLane);
> +        // Keep track if we have instructions with all the same opcode on one
> +        // side.
> +        if (isa<LoadInst>(OpLane0))
> +          ReorderingModes[OpIdx] = ReorderingMode::Load;
> +        else if (isa<Instruction>(OpLane0))
> +          ReorderingModes[OpIdx] = ReorderingMode::Opcode;
> +        else if (isa<Constant>(OpLane0))
> +          ReorderingModes[OpIdx] = ReorderingMode::Constant;
> +        else if (isa<Argument>(OpLane0))
> +          // Our best hope is a Splat. It may save some cost in some cases.
> +          ReorderingModes[OpIdx] = ReorderingMode::Splat;
> +        else
> +          // NOTE: This should be unreachable.
> +          ReorderingModes[OpIdx] = ReorderingMode::Failed;
> +      }
> +
> +      // If the initial strategy fails for any of the operand indexes, then we
> +      // perform reordering again in a second pass. This helps avoid assigning
> +      // high priority to the failed strategy, and should improve reordering for
> +      // the non-failed operand indexes.
> +      for (int Pass = 0; Pass != 2; ++Pass) {
> +        // Skip the second pass if the first pass did not fail.
> +        bool StrategyFailed = false;
> +        // Mark the operand data as free to use for all but the first pass.
> +        if (Pass > 0)
> +          clearUsed();
> +        // We keep the original operand order for the FirstLane, so reorder the
> +        // rest of the lanes. We are visiting the nodes in a circular fashion,
> +        // using FirstLane as the center point and increasing the radius
> +        // distance.
> +        for (unsigned Distance = 1; Distance != NumLanes; ++Distance) {
> +          // Visit the lane on the right and then the lane on the left.
> +          for (int Direction : {+1, -1}) {
> +            int Lane = FirstLane + Direction * Distance;
> +            if (Lane < 0 || Lane >= (int)NumLanes)
> +              continue;
> +            int LastLane = Lane - Direction;
> +            assert(LastLane >= 0 && LastLane < (int)NumLanes &&
> +                   "Out of bounds");
> +            // Look for a good match for each operand.
> +            for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx) {
> +              // Search for the operand that matches SortedOps[OpIdx][Lane-1].
> +              Optional<unsigned> BestIdx =
> +                  getBestOperand(OpIdx, Lane, LastLane, ReorderingModes);
> +              // By not selecting a value, we allow the operands that follow to
> +              // select a better matching value. We will get a non-null value in
> +              // the next run of getBestOperand().
> +              if (BestIdx) {
> +                // Swap the current operand with the one returned by
> +                // getBestOperand().
> +                swap(OpIdx, BestIdx.getValue(), Lane);
> +              } else {
> +                // We failed to find a best operand, set mode to 'Failed'.
> +                ReorderingModes[OpIdx] = ReorderingMode::Failed;
> +                // Enable the second pass.
> +                StrategyFailed = true;
> +              }
> +            }
> +          }
> +        }
> +        // Skip second pass if the strategy did not fail.
> +        if (!StrategyFailed)
> +          break;
> +      }
> +    }
> +
> +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
> +    LLVM_DUMP_METHOD static StringRef getModeStr(ReorderingMode RMode) {
> +      switch (RMode) {
> +      case ReorderingMode::Load:
> +        return "Load";
> +      case ReorderingMode::Opcode:
> +        return "Opcode";
> +      case ReorderingMode::Constant:
> +        return "Constant";
> +      case ReorderingMode::Splat:
> +        return "Splat";
> +      case ReorderingMode::Failed:
> +        return "Failed";
> +      }
> +      llvm_unreachable("Unimplemented Reordering Type");
> +    }
> +
> +    LLVM_DUMP_METHOD static raw_ostream &printMode(ReorderingMode RMode,
> +                                                   raw_ostream &OS) {
> +      return OS << getModeStr(RMode);
> +    }
> +
> +    /// Debug print.
> +    LLVM_DUMP_METHOD static void dumpMode(ReorderingMode RMode) {
> +      printMode(RMode, dbgs());
> +    }
> +
> +    friend raw_ostream &operator<<(raw_ostream &OS, ReorderingMode RMode) {
> +      return printMode(RMode, OS);
> +    }
> +
> +    LLVM_DUMP_METHOD raw_ostream &print(raw_ostream &OS) const {
> +      const unsigned Indent = 2;
> +      unsigned Cnt = 0;
> +      for (const OperandDataVec &OpDataVec : OpsVec) {
> +        OS << "Operand " << Cnt++ << "\n";
> +        for (const OperandData &OpData : OpDataVec) {
> +          OS.indent(Indent) << "{";
> +          if (Value *V = OpData.V)
> +            OS << *V;
> +          else
> +            OS << "null";
> +          OS << ", APO:" << OpData.APO << "}\n";
> +        }
> +        OS << "\n";
> +      }
> +      return OS;
> +    }
> +
> +    /// Debug print.
> +    LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
> +#endif
> +  };
> +
>   private:
>     struct TreeEntry;
>   
> @@ -681,12 +1124,13 @@ private:
>     /// be beneficial even the tree height is tiny.
>     bool isFullyVectorizableTinyTree() const;
>   
> -  /// \reorder commutative operands to get better probability of
> +  /// Reorder commutative or alt operands to get better probability of
>     /// generating vectorized code.
> -  void reorderInputsAccordingToOpcode(const InstructionsState &S,
> -                                      ArrayRef<Value *> VL,
> -                                      SmallVectorImpl<Value *> &Left,
> -                                      SmallVectorImpl<Value *> &Right) const;
> +  static void reorderInputsAccordingToOpcode(ArrayRef<Value *> VL,
> +                                             SmallVectorImpl<Value *> &Left,
> +                                             SmallVectorImpl<Value *> &Right,
> +                                             const DataLayout &DL,
> +                                             ScalarEvolution &SE);
>     struct TreeEntry {
>       TreeEntry(std::vector<TreeEntry> &Container) : Container(Container) {}
>   
> @@ -1866,7 +2310,7 @@ void BoUpSLP::buildTree_rec(ArrayRef<Val
>           // Commutative predicate - collect + sort operands of the instructions
>           // so that each side is more likely to have the same opcode.
>           assert(P0 == SwapP0 && "Commutative Predicate mismatch");
> -        reorderInputsAccordingToOpcode(S, VL, Left, Right);
> +        reorderInputsAccordingToOpcode(VL, Left, Right, *DL, *SE);
>         } else {
>           // Collect operands - commute if it uses the swapped predicate.
>           for (Value *V : VL) {
> @@ -1912,7 +2356,7 @@ void BoUpSLP::buildTree_rec(ArrayRef<Val
>         // have the same opcode.
>         if (isa<BinaryOperator>(VL0) && VL0->isCommutative()) {
>           ValueList Left, Right;
> -        reorderInputsAccordingToOpcode(S, VL, Left, Right);
> +        reorderInputsAccordingToOpcode(VL, Left, Right, *DL, *SE);
>           UserTreeIdx.EdgeIdx = 0;
>           buildTree_rec(Left, Depth + 1, UserTreeIdx);
>           UserTreeIdx.EdgeIdx = 1;
> @@ -2087,7 +2531,7 @@ void BoUpSLP::buildTree_rec(ArrayRef<Val
>         // Reorder operands if reordering would enable vectorization.
>         if (isa<BinaryOperator>(VL0)) {
>           ValueList Left, Right;
> -        reorderInputsAccordingToOpcode(S, VL, Left, Right);
> +        reorderInputsAccordingToOpcode(VL, Left, Right, *DL, *SE);
>           UserTreeIdx.EdgeIdx = 0;
>           buildTree_rec(Left, Depth + 1, UserTreeIdx);
>           UserTreeIdx.EdgeIdx = 1;
> @@ -2802,171 +3246,19 @@ int BoUpSLP::getGatherCost(ArrayRef<Valu
>     return getGatherCost(VecTy, ShuffledElements);
>   }
>   
> -// Return true if the i'th left and right operands can be commuted.
> -//
> -// The vectorizer is trying to either have all elements one side being
> -// instruction with the same opcode to enable further vectorization, or having
> -// a splat to lower the vectorizing cost.
> -static bool shouldReorderOperands(int i, ArrayRef<Value *> Left,
> -                                  ArrayRef<Value *> Right,
> -                                  bool AllSameOpcodeLeft,
> -                                  bool AllSameOpcodeRight, bool SplatLeft,
> -                                  bool SplatRight) {
> -  Value *PrevLeft = Left[i - 1];
> -  Value *PrevRight = Right[i - 1];
> -  Value *CurrLeft = Left[i];
> -  Value *CurrRight = Right[i];
> -
> -  // If we have "SplatRight", try to see if commuting is needed to preserve it.
> -  if (SplatRight) {
> -    if (CurrRight == PrevRight)
> -      // Preserve SplatRight
> -      return false;
> -    if (CurrLeft == PrevRight) {
> -      // Commuting would preserve SplatRight, but we don't want to break
> -      // SplatLeft either, i.e. preserve the original order if possible.
> -      // (FIXME: why do we care?)
> -      if (SplatLeft && CurrLeft == PrevLeft)
> -        return false;
> -      return true;
> -    }
> -  }
> -  // Symmetrically handle Right side.
> -  if (SplatLeft) {
> -    if (CurrLeft == PrevLeft)
> -      // Preserve SplatLeft
> -      return false;
> -    if (CurrRight == PrevLeft)
> -      return true;
> -  }
> -
> -  Instruction *ILeft = dyn_cast<Instruction>(CurrLeft);
> -  Instruction *IRight = dyn_cast<Instruction>(CurrRight);
> -
> -  // If we have "AllSameOpcodeRight", try to see if the left operands preserves
> -  // it and not the right, in this case we want to commute.
> -  if (AllSameOpcodeRight) {
> -    unsigned RightPrevOpcode = cast<Instruction>(PrevRight)->getOpcode();
> -    if (IRight && RightPrevOpcode == IRight->getOpcode())
> -      // Do not commute, a match on the right preserves AllSameOpcodeRight
> -      return false;
> -    if (ILeft && RightPrevOpcode == ILeft->getOpcode()) {
> -      // We have a match and may want to commute, but first check if there is
> -      // not also a match on the existing operands on the Left to preserve
> -      // AllSameOpcodeLeft, i.e. preserve the original order if possible.
> -      // (FIXME: why do we care?)
> -      if (AllSameOpcodeLeft && ILeft &&
> -          cast<Instruction>(PrevLeft)->getOpcode() == ILeft->getOpcode())
> -        return false;
> -      return true;
> -    }
> -  }
> -  // Symmetrically handle Left side.
> -  if (AllSameOpcodeLeft) {
> -    unsigned LeftPrevOpcode = cast<Instruction>(PrevLeft)->getOpcode();
> -    if (ILeft && LeftPrevOpcode == ILeft->getOpcode())
> -      return false;
> -    if (IRight && LeftPrevOpcode == IRight->getOpcode())
> -      return true;
> -  }
> -  return false;
> -}
> -
> +// Perform operand reordering on the instructions in VL and return the reordered
> +// operands in Left and Right.
>   void BoUpSLP::reorderInputsAccordingToOpcode(
> -    const InstructionsState &S, ArrayRef<Value *> VL,
> -    SmallVectorImpl<Value *> &Left, SmallVectorImpl<Value *> &Right) const {
> -  assert(!VL.empty() && Left.empty() && Right.empty() &&
> -         "Unexpected instruction/operand lists");
> -
> -  // Push left and right operands of binary operation into Left and Right
> -  for (Value *V : VL) {
> -    auto *I = cast<Instruction>(V);
> -    assert(S.isOpcodeOrAlt(I) && "Incorrect instruction in vector");
> -    Left.push_back(I->getOperand(0));
> -    Right.push_back(I->getOperand(1));
> -  }
> -
> -  // Keep track if we have instructions with all the same opcode on one side.
> -  bool AllSameOpcodeLeft = isa<Instruction>(Left[0]);
> -  bool AllSameOpcodeRight = isa<Instruction>(Right[0]);
> -  // Keep track if we have one side with all the same value (broadcast).
> -  bool SplatLeft = true;
> -  bool SplatRight = true;
> -
> -  for (unsigned i = 1, e = VL.size(); i != e; ++i) {
> -    Instruction *I = cast<Instruction>(VL[i]);
> -    // Commute to favor either a splat or maximizing having the same opcodes on
> -    // one side.
> -    if (isCommutative(I) &&
> -        shouldReorderOperands(i, Left, Right, AllSameOpcodeLeft,
> -                              AllSameOpcodeRight, SplatLeft, SplatRight))
> -      std::swap(Left[i], Right[i]);
> -
> -    // Update Splat* and AllSameOpcode* after the insertion.
> -    SplatRight = SplatRight && (Right[i - 1] == Right[i]);
> -    SplatLeft = SplatLeft && (Left[i - 1] == Left[i]);
> -    AllSameOpcodeLeft = AllSameOpcodeLeft && isa<Instruction>(Left[i]) &&
> -                        (cast<Instruction>(Left[i - 1])->getOpcode() ==
> -                         cast<Instruction>(Left[i])->getOpcode());
> -    AllSameOpcodeRight = AllSameOpcodeRight && isa<Instruction>(Right[i]) &&
> -                         (cast<Instruction>(Right[i - 1])->getOpcode() ==
> -                          cast<Instruction>(Right[i])->getOpcode());
> -  }
> -
> -  // If one operand end up being broadcast, return this operand order.
> -  if (SplatRight || SplatLeft)
> +    ArrayRef<Value *> VL, SmallVectorImpl<Value *> &Left,
> +    SmallVectorImpl<Value *> &Right, const DataLayout &DL,
> +    ScalarEvolution &SE) {
> +  if (VL.empty())
>       return;
> -
> -  // Finally check if we can get longer vectorizable chain by reordering
> -  // without breaking the good operand order detected above.
> -  // E.g. If we have something like-
> -  // load a[0] - load b[0]
> -  // load b[1] + load a[1]
> -  // load a[2] - load b[2]
> -  // load a[3] + load b[3]
> -  // Reordering the second load b[1] + load a[1] would allow us to vectorize
> -  // this code and we still retain AllSameOpcode property.
> -  // FIXME: This load reordering might break AllSameOpcode in some rare cases
> -  // such as-
> -  // add a[0],c[0]  load b[0]
> -  // add a[1],c[2]  load b[1]
> -  // b[2]           load b[2]
> -  // add a[3],c[3]  load b[3]
> -  for (unsigned j = 0, e = VL.size() - 1; j < e; ++j) {
> -    if (LoadInst *L = dyn_cast<LoadInst>(Left[j])) {
> -      if (LoadInst *L1 = dyn_cast<LoadInst>(Right[j + 1])) {
> -        if (isConsecutiveAccess(L, L1, *DL, *SE)) {
> -          auto *VL1 = cast<Instruction>(VL[j]);
> -          auto *VL2 = cast<Instruction>(VL[j + 1]);
> -          if (isCommutative(VL2)) {
> -            std::swap(Left[j + 1], Right[j + 1]);
> -            continue;
> -          }
> -          if (isCommutative(VL1)) {
> -            std::swap(Left[j], Right[j]);
> -            continue;
> -          }
> -        }
> -      }
> -    }
> -    if (LoadInst *L = dyn_cast<LoadInst>(Right[j])) {
> -      if (LoadInst *L1 = dyn_cast<LoadInst>(Left[j + 1])) {
> -        if (isConsecutiveAccess(L, L1, *DL, *SE)) {
> -          auto *VL1 = cast<Instruction>(VL[j]);
> -          auto *VL2 = cast<Instruction>(VL[j + 1]);
> -          if (isCommutative(VL2)) {
> -            std::swap(Left[j + 1], Right[j + 1]);
> -            continue;
> -          }
> -          if (isCommutative(VL1)) {
> -            std::swap(Left[j], Right[j]);
> -            continue;
> -          }
> -        }
> -      }
> -    }
> -    // else unchanged
> -  }
> +  VLOperands Ops(VL, DL, SE);
> +  // Reorder the operands in place.
> +  Ops.reorder();
> +  Left = Ops.getVL(0);
> +  Right = Ops.getVL(1);
>   }
>   
>   void BoUpSLP::setInsertPointAfterBundle(ArrayRef<Value *> VL,
> 
> Modified: llvm/trunk/test/Transforms/SLPVectorizer/X86/alternate-int.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/alternate-int.ll?rev=358519&r1=358518&r2=358519&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SLPVectorizer/X86/alternate-int.ll (original)
> +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/alternate-int.ll Tue Apr 16 12:27:00 2019
> @@ -536,13 +536,11 @@ define <8 x i32> @sdiv_v8i32_undefs(<8 x
>   
>   define <8 x i32> @add_sub_v8i32_splat(<8 x i32> %a, i32 %b) {
>   ; CHECK-LABEL: @add_sub_v8i32_splat(
> -; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <8 x i32> [[A:%.*]], <8 x i32> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
> -; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <4 x i32> undef, i32 [[B:%.*]], i32 0
> -; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <4 x i32> [[TMP2]], <4 x i32> undef, <4 x i32> zeroinitializer
> -; CHECK-NEXT:    [[TMP4:%.*]] = add <4 x i32> [[TMP1]], [[TMP3]]
> -; CHECK-NEXT:    [[TMP5:%.*]] = shufflevector <8 x i32> [[A]], <8 x i32> undef, <4 x i32> <i32 4, i32 5, i32 6, i32 7>
> -; CHECK-NEXT:    [[TMP6:%.*]] = sub <4 x i32> [[TMP3]], [[TMP5]]
> -; CHECK-NEXT:    [[R7:%.*]] = shufflevector <4 x i32> [[TMP4]], <4 x i32> [[TMP6]], <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
> +; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <8 x i32> undef, i32 [[B:%.*]], i32 0
> +; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <8 x i32> [[TMP1]], <8 x i32> undef, <8 x i32> zeroinitializer
> +; CHECK-NEXT:    [[TMP3:%.*]] = add <8 x i32> [[TMP2]], [[A:%.*]]
> +; CHECK-NEXT:    [[TMP4:%.*]] = sub <8 x i32> [[TMP2]], [[A]]
> +; CHECK-NEXT:    [[R7:%.*]] = shufflevector <8 x i32> [[TMP3]], <8 x i32> [[TMP4]], <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 12, i32 13, i32 14, i32 15>
>   ; CHECK-NEXT:    ret <8 x i32> [[R7]]
>   ;
>     %a0 = extractelement <8 x i32> %a, i32 0
> 
> Modified: llvm/trunk/test/Transforms/SLPVectorizer/X86/crash_lencod.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/crash_lencod.ll?rev=358519&r1=358518&r2=358519&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SLPVectorizer/X86/crash_lencod.ll (original)
> +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/crash_lencod.ll Tue Apr 16 12:27:00 2019
> @@ -126,14 +126,15 @@ entry:
>   define fastcc void @dct36(double* %inbuf) {
>   ; CHECK-LABEL: @dct36(
>   ; CHECK-NEXT:  entry:
> -; CHECK-NEXT:    [[ARRAYIDX41:%.*]] = getelementptr inbounds double, double* [[INBUF:%.*]], i64 2
> -; CHECK-NEXT:    [[ARRAYIDX44:%.*]] = getelementptr inbounds double, double* [[INBUF]], i64 1
> -; CHECK-NEXT:    [[TMP0:%.*]] = load double, double* [[ARRAYIDX44]], align 8
> -; CHECK-NEXT:    [[ADD46:%.*]] = fadd double [[TMP0]], undef
> -; CHECK-NEXT:    store double [[ADD46]], double* [[ARRAYIDX41]], align 8
> -; CHECK-NEXT:    [[TMP1:%.*]] = load double, double* [[INBUF]], align 8
> -; CHECK-NEXT:    [[ADD49:%.*]] = fadd double [[TMP1]], [[TMP0]]
> -; CHECK-NEXT:    store double [[ADD49]], double* [[ARRAYIDX44]], align 8
> +; CHECK-NEXT:    [[ARRAYIDX44:%.*]] = getelementptr inbounds double, double* [[INBUF:%.*]], i64 1
> +; CHECK-NEXT:    [[TMP0:%.*]] = bitcast double* [[INBUF]] to <2 x double>*
> +; CHECK-NEXT:    [[TMP1:%.*]] = load <2 x double>, <2 x double>* [[TMP0]], align 8
> +; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <2 x double> [[TMP1]], i32 1
> +; CHECK-NEXT:    [[TMP3:%.*]] = insertelement <2 x double> undef, double [[TMP2]], i32 0
> +; CHECK-NEXT:    [[TMP4:%.*]] = insertelement <2 x double> [[TMP3]], double undef, i32 1
> +; CHECK-NEXT:    [[TMP5:%.*]] = fadd <2 x double> [[TMP1]], [[TMP4]]
> +; CHECK-NEXT:    [[TMP6:%.*]] = bitcast double* [[ARRAYIDX44]] to <2 x double>*
> +; CHECK-NEXT:    store <2 x double> [[TMP5]], <2 x double>* [[TMP6]], align 8
>   ; CHECK-NEXT:    ret void
>   ;
>   entry:
> 
> Modified: llvm/trunk/test/Transforms/SLPVectorizer/X86/operandorder.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/operandorder.ll?rev=358519&r1=358518&r2=358519&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SLPVectorizer/X86/operandorder.ll (original)
> +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/operandorder.ll Tue Apr 16 12:27:00 2019
> @@ -28,19 +28,16 @@ define void @shuffle_operands1(double *
>     ret void
>   }
>   
> -define void @shuffle_preserve_broadcast(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> -; CHECK-LABEL: @shuffle_preserve_broadcast(
> +define void @vecload_vs_broadcast(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> +; CHECK-LABEL: @vecload_vs_broadcast(
>   ; CHECK-NEXT:  entry:
>   ; CHECK-NEXT:    br label [[LP:%.*]]
>   ; CHECK:       lp:
>   ; CHECK-NEXT:    [[P:%.*]] = phi double [ 1.000000e+00, [[LP]] ], [ 0.000000e+00, [[ENTRY:%.*]] ]
> -; CHECK-NEXT:    [[FROM_1:%.*]] = getelementptr double, double* [[FROM:%.*]], i32 1
> -; CHECK-NEXT:    [[V0_1:%.*]] = load double, double* [[FROM]], align 4
> -; CHECK-NEXT:    [[V0_2:%.*]] = load double, double* [[FROM_1]], align 4
> -; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <2 x double> undef, double [[V0_1]], i32 0
> -; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <2 x double> [[TMP0]], <2 x double> undef, <2 x i32> zeroinitializer
> +; CHECK-NEXT:    [[TMP0:%.*]] = bitcast double* [[FROM:%.*]] to <2 x double>*
> +; CHECK-NEXT:    [[TMP1:%.*]] = load <2 x double>, <2 x double>* [[TMP0]], align 4
>   ; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <2 x double> undef, double [[P]], i32 0
> -; CHECK-NEXT:    [[TMP3:%.*]] = insertelement <2 x double> [[TMP2]], double [[V0_2]], i32 1
> +; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <2 x double> [[TMP2]], <2 x double> [[TMP1]], <2 x i32> <i32 0, i32 2>
>   ; CHECK-NEXT:    [[TMP4:%.*]] = fadd <2 x double> [[TMP1]], [[TMP3]]
>   ; CHECK-NEXT:    [[TMP5:%.*]] = bitcast double* [[TO:%.*]] to <2 x double>*
>   ; CHECK-NEXT:    store <2 x double> [[TMP4]], <2 x double>* [[TMP5]], align 4
> @@ -67,20 +64,17 @@ ext:
>     ret void
>   }
>   
> -define void @shuffle_preserve_broadcast2(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> -; CHECK-LABEL: @shuffle_preserve_broadcast2(
> +define void @vecload_vs_broadcast2(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> +; CHECK-LABEL: @vecload_vs_broadcast2(
>   ; CHECK-NEXT:  entry:
>   ; CHECK-NEXT:    br label [[LP:%.*]]
>   ; CHECK:       lp:
>   ; CHECK-NEXT:    [[P:%.*]] = phi double [ 1.000000e+00, [[LP]] ], [ 0.000000e+00, [[ENTRY:%.*]] ]
> -; CHECK-NEXT:    [[FROM_1:%.*]] = getelementptr double, double* [[FROM:%.*]], i32 1
> -; CHECK-NEXT:    [[V0_1:%.*]] = load double, double* [[FROM]], align 4
> -; CHECK-NEXT:    [[V0_2:%.*]] = load double, double* [[FROM_1]], align 4
> -; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <2 x double> undef, double [[P]], i32 0
> -; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <2 x double> [[TMP0]], double [[V0_2]], i32 1
> -; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <2 x double> undef, double [[V0_1]], i32 0
> -; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <2 x double> [[TMP2]], <2 x double> undef, <2 x i32> zeroinitializer
> -; CHECK-NEXT:    [[TMP4:%.*]] = fadd <2 x double> [[TMP1]], [[TMP3]]
> +; CHECK-NEXT:    [[TMP0:%.*]] = bitcast double* [[FROM:%.*]] to <2 x double>*
> +; CHECK-NEXT:    [[TMP1:%.*]] = load <2 x double>, <2 x double>* [[TMP0]], align 4
> +; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <2 x double> undef, double [[P]], i32 0
> +; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <2 x double> [[TMP2]], <2 x double> [[TMP1]], <2 x i32> <i32 0, i32 2>
> +; CHECK-NEXT:    [[TMP4:%.*]] = fadd <2 x double> [[TMP3]], [[TMP1]]
>   ; CHECK-NEXT:    [[TMP5:%.*]] = bitcast double* [[TO:%.*]] to <2 x double>*
>   ; CHECK-NEXT:    store <2 x double> [[TMP4]], <2 x double>* [[TMP5]], align 4
>   ; CHECK-NEXT:    br i1 undef, label [[LP]], label [[EXT:%.*]]
> @@ -106,20 +100,17 @@ ext:
>     ret void
>   }
>   
> -define void @shuffle_preserve_broadcast3(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> -; CHECK-LABEL: @shuffle_preserve_broadcast3(
> +define void @vecload_vs_broadcast3(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> +; CHECK-LABEL: @vecload_vs_broadcast3(
>   ; CHECK-NEXT:  entry:
>   ; CHECK-NEXT:    br label [[LP:%.*]]
>   ; CHECK:       lp:
>   ; CHECK-NEXT:    [[P:%.*]] = phi double [ 1.000000e+00, [[LP]] ], [ 0.000000e+00, [[ENTRY:%.*]] ]
> -; CHECK-NEXT:    [[FROM_1:%.*]] = getelementptr double, double* [[FROM:%.*]], i32 1
> -; CHECK-NEXT:    [[V0_1:%.*]] = load double, double* [[FROM]], align 4
> -; CHECK-NEXT:    [[V0_2:%.*]] = load double, double* [[FROM_1]], align 4
> -; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <2 x double> undef, double [[P]], i32 0
> -; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <2 x double> [[TMP0]], double [[V0_2]], i32 1
> -; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <2 x double> undef, double [[V0_1]], i32 0
> -; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <2 x double> [[TMP2]], <2 x double> undef, <2 x i32> zeroinitializer
> -; CHECK-NEXT:    [[TMP4:%.*]] = fadd <2 x double> [[TMP1]], [[TMP3]]
> +; CHECK-NEXT:    [[TMP0:%.*]] = bitcast double* [[FROM:%.*]] to <2 x double>*
> +; CHECK-NEXT:    [[TMP1:%.*]] = load <2 x double>, <2 x double>* [[TMP0]], align 4
> +; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <2 x double> undef, double [[P]], i32 0
> +; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <2 x double> [[TMP2]], <2 x double> [[TMP1]], <2 x i32> <i32 0, i32 2>
> +; CHECK-NEXT:    [[TMP4:%.*]] = fadd <2 x double> [[TMP3]], [[TMP1]]
>   ; CHECK-NEXT:    [[TMP5:%.*]] = bitcast double* [[TO:%.*]] to <2 x double>*
>   ; CHECK-NEXT:    store <2 x double> [[TMP4]], <2 x double>* [[TMP5]], align 4
>   ; CHECK-NEXT:    br i1 undef, label [[LP]], label [[EXT:%.*]]
> @@ -184,22 +175,21 @@ ext:
>     ret void
>   }
>   
> -define void @shuffle_preserve_broadcast5(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> -; CHECK-LABEL: @shuffle_preserve_broadcast5(
> +define void @vecload_vs_broadcast5(double * noalias %from, double * noalias %to, double %v1, double %v2) {
> +; CHECK-LABEL: @vecload_vs_broadcast5(
>   ; CHECK-NEXT:  entry:
>   ; CHECK-NEXT:    br label [[LP:%.*]]
>   ; CHECK:       lp:
>   ; CHECK-NEXT:    [[P:%.*]] = phi double [ 1.000000e+00, [[LP]] ], [ 0.000000e+00, [[ENTRY:%.*]] ]
> -; CHECK-NEXT:    [[FROM_1:%.*]] = getelementptr double, double* [[FROM:%.*]], i32 1
> -; CHECK-NEXT:    [[V0_1:%.*]] = load double, double* [[FROM]], align 4
> -; CHECK-NEXT:    [[V0_2:%.*]] = load double, double* [[FROM_1]], align 4
> -; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <2 x double> undef, double [[V0_1]], i32 0
> -; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <2 x double> [[TMP0]], <2 x double> undef, <2 x i32> zeroinitializer
> -; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <2 x double> undef, double [[V0_2]], i32 0
> -; CHECK-NEXT:    [[TMP3:%.*]] = insertelement <2 x double> [[TMP2]], double [[P]], i32 1
> -; CHECK-NEXT:    [[TMP4:%.*]] = fadd <2 x double> [[TMP1]], [[TMP3]]
> -; CHECK-NEXT:    [[TMP5:%.*]] = bitcast double* [[TO:%.*]] to <2 x double>*
> -; CHECK-NEXT:    store <2 x double> [[TMP4]], <2 x double>* [[TMP5]], align 4
> +; CHECK-NEXT:    [[TMP0:%.*]] = bitcast double* [[FROM:%.*]] to <2 x double>*
> +; CHECK-NEXT:    [[TMP1:%.*]] = load <2 x double>, <2 x double>* [[TMP0]], align 4
> +; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <2 x double> [[TMP1]], i32 0
> +; CHECK-NEXT:    [[TMP3:%.*]] = insertelement <2 x double> undef, double [[TMP2]], i32 0
> +; CHECK-NEXT:    [[TMP4:%.*]] = insertelement <2 x double> [[TMP3]], double [[P]], i32 1
> +; CHECK-NEXT:    [[TMP5:%.*]] = shufflevector <2 x double> [[TMP1]], <2 x double> undef, <2 x i32> <i32 1, i32 0>
> +; CHECK-NEXT:    [[TMP6:%.*]] = fadd <2 x double> [[TMP4]], [[TMP5]]
> +; CHECK-NEXT:    [[TMP7:%.*]] = bitcast double* [[TO:%.*]] to <2 x double>*
> +; CHECK-NEXT:    store <2 x double> [[TMP6]], <2 x double>* [[TMP7]], align 4
>   ; CHECK-NEXT:    br i1 undef, label [[LP]], label [[EXT:%.*]]
>   ; CHECK:       ext:
>   ; CHECK-NEXT:    ret void
> 
> 
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