[llvm] r235284 - [NFC] Refactor identification of reductions as common utility function.
Karthik Bhat
kv.bhat at samsung.com
Sun Apr 19 21:38:34 PDT 2015
Author: karthik
Date: Sun Apr 19 23:38:33 2015
New Revision: 235284
URL: http://llvm.org/viewvc/llvm-project?rev=235284&view=rev
Log:
[NFC] Refactor identification of reductions as common utility function.
This patch refactors reduction identification code out of LoopVectorizer and
exposes them as common utilities.
No functional change.
Review: http://reviews.llvm.org/D9046
Added:
llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
Modified:
llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h
llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
Modified: llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h?rev=235284&r1=235283&r2=235284&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h Sun Apr 19 23:38:33 2015
@@ -16,6 +16,7 @@
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IRBuilder.h"
namespace llvm {
class AliasAnalysis;
@@ -42,6 +43,132 @@ struct LICMSafetyInfo {
{}
};
+/// This POD struct holds information about a potential reduction operation.
+class ReductionInstDesc {
+
+public:
+ // This enum represents the kind of minmax reduction.
+ enum MinMaxReductionKind {
+ MRK_Invalid,
+ MRK_UIntMin,
+ MRK_UIntMax,
+ MRK_SIntMin,
+ MRK_SIntMax,
+ MRK_FloatMin,
+ MRK_FloatMax
+ };
+ ReductionInstDesc(bool IsRedux, Instruction *I)
+ : IsReduction(IsRedux), PatternLastInst(I), MinMaxKind(MRK_Invalid) {}
+
+ ReductionInstDesc(Instruction *I, MinMaxReductionKind K)
+ : IsReduction(true), PatternLastInst(I), MinMaxKind(K) {}
+
+ bool isReduction() { return IsReduction; }
+
+ MinMaxReductionKind getMinMaxKind() { return MinMaxKind; }
+
+private:
+ // Is this instruction a reduction candidate.
+ bool IsReduction;
+ // The last instruction in a min/max pattern (select of the select(icmp())
+ // pattern), or the current reduction instruction otherwise.
+ Instruction *PatternLastInst;
+ // If this is a min/max pattern the comparison predicate.
+ MinMaxReductionKind MinMaxKind;
+};
+
+/// This struct holds information about reduction variables.
+class ReductionDescriptor {
+
+public:
+ /// This enum represents the kinds of reductions that we support.
+ enum ReductionKind {
+ RK_NoReduction, ///< Not a reduction.
+ RK_IntegerAdd, ///< Sum of integers.
+ RK_IntegerMult, ///< Product of integers.
+ RK_IntegerOr, ///< Bitwise or logical OR of numbers.
+ RK_IntegerAnd, ///< Bitwise or logical AND of numbers.
+ RK_IntegerXor, ///< Bitwise or logical XOR of numbers.
+ RK_IntegerMinMax, ///< Min/max implemented in terms of select(cmp()).
+ RK_FloatAdd, ///< Sum of floats.
+ RK_FloatMult, ///< Product of floats.
+ RK_FloatMinMax ///< Min/max implemented in terms of select(cmp()).
+ };
+
+ ReductionDescriptor()
+ : StartValue(nullptr), LoopExitInstr(nullptr), Kind(RK_NoReduction),
+ MinMaxKind(ReductionInstDesc::MRK_Invalid) {}
+
+ ReductionDescriptor(Value *Start, Instruction *Exit, ReductionKind K,
+ ReductionInstDesc::MinMaxReductionKind MK)
+ : StartValue(Start), LoopExitInstr(Exit), Kind(K), MinMaxKind(MK) {}
+
+ /// Returns a struct describing if the instruction 'I' can be a reduction
+ /// variable of type 'Kind'. If the reduction is a min/max pattern of
+ /// select(icmp()) this function advances the instruction pointer 'I' from the
+ /// compare instruction to the select instruction and stores this pointer in
+ /// 'PatternLastInst' member of the returned struct.
+ static ReductionInstDesc isReductionInstr(Instruction *I, ReductionKind Kind,
+ ReductionInstDesc &Prev,
+ bool HasFunNoNaNAttr);
+
+ /// Returns true if instuction I has multiple uses in Insts
+ static bool hasMultipleUsesOf(Instruction *I,
+ SmallPtrSetImpl<Instruction *> &Insts);
+
+ /// Returns true if all uses of the instruction I is within the Set.
+ static bool areAllUsesIn(Instruction *I, SmallPtrSetImpl<Instruction *> &Set);
+
+ /// Returns a struct describing if the instruction if the instruction is a
+ /// Select(ICmp(X, Y), X, Y) instruction pattern corresponding to a min(X, Y)
+ /// or max(X, Y).
+ static ReductionInstDesc isMinMaxSelectCmpPattern(Instruction *I,
+ ReductionInstDesc &Prev);
+
+ /// Returns identity corresponding to the ReductionKind.
+ static Constant *getReductionIdentity(ReductionKind K, Type *Tp);
+
+ /// Returns the opcode of binary operation corresponding to the ReductionKind.
+ static unsigned getReductionBinOp(ReductionKind Kind);
+
+ /// Returns a Min/Max operation corresponding to MinMaxReductionKind.
+ static Value *createMinMaxOp(IRBuilder<> &Builder,
+ ReductionInstDesc::MinMaxReductionKind RK,
+ Value *Left, Value *Right);
+
+ /// Returns true if Phi is a reduction of type Kind and adds it to the
+ /// ReductionDescriptor.
+ static bool AddReductionVar(PHINode *Phi, ReductionKind Kind, Loop *TheLoop,
+ bool HasFunNoNaNAttr,
+ ReductionDescriptor &RedDes);
+
+ /// Returns true if Phi is a reduction in TheLoop. The ReductionDescriptor is
+ /// returned in RedDes.
+ static bool isReductionPHI(PHINode *Phi, Loop *TheLoop,
+ ReductionDescriptor &RedDes);
+
+ ReductionKind getReductionKind() { return Kind; }
+
+ ReductionInstDesc::MinMaxReductionKind getMinMaxReductionKind() {
+ return MinMaxKind;
+ }
+
+ TrackingVH<Value> getReductionStartValue() { return StartValue; }
+
+ Instruction *getLoopExitInstr() { return LoopExitInstr; }
+
+private:
+ // The starting value of the reduction.
+ // It does not have to be zero!
+ TrackingVH<Value> StartValue;
+ // The instruction who's value is used outside the loop.
+ Instruction *LoopExitInstr;
+ // The kind of the reduction.
+ ReductionKind Kind;
+ // If this a min/max reduction the kind of reduction.
+ ReductionInstDesc::MinMaxReductionKind MinMaxKind;
+};
+
BasicBlock *InsertPreheaderForLoop(Loop *L, Pass *P);
/// \brief Simplify each loop in a loop nest recursively.
Modified: llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/CMakeLists.txt?rev=235284&r1=235283&r2=235284&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/CMakeLists.txt (original)
+++ llvm/trunk/lib/Transforms/Utils/CMakeLists.txt Sun Apr 19 23:38:33 2015
@@ -21,6 +21,7 @@ add_llvm_library(LLVMTransformUtils
LoopSimplify.cpp
LoopUnroll.cpp
LoopUnrollRuntime.cpp
+ LoopUtils.cpp
LowerInvoke.cpp
LowerSwitch.cpp
Mem2Reg.cpp
Added: llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp?rev=235284&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp (added)
+++ llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp Sun Apr 19 23:38:33 2015
@@ -0,0 +1,453 @@
+//===-- LoopUtils.cpp - Loop Utility functions -------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines common loop utility functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Transforms/Utils/LoopUtils.h"
+
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+#define DEBUG_TYPE "loop-utils"
+
+bool ReductionDescriptor::areAllUsesIn(Instruction *I,
+ SmallPtrSetImpl<Instruction *> &Set) {
+ for (User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E; ++Use)
+ if (!Set.count(dyn_cast<Instruction>(*Use)))
+ return false;
+ return true;
+}
+
+bool ReductionDescriptor::AddReductionVar(PHINode *Phi, ReductionKind Kind,
+ Loop *TheLoop, bool HasFunNoNaNAttr,
+ ReductionDescriptor &RedDes) {
+ if (Phi->getNumIncomingValues() != 2)
+ return false;
+
+ // Reduction variables are only found in the loop header block.
+ if (Phi->getParent() != TheLoop->getHeader())
+ return false;
+
+ // Obtain the reduction start value from the value that comes from the loop
+ // preheader.
+ Value *RdxStart = Phi->getIncomingValueForBlock(TheLoop->getLoopPreheader());
+
+ // ExitInstruction is the single value which is used outside the loop.
+ // We only allow for a single reduction value to be used outside the loop.
+ // This includes users of the reduction, variables (which form a cycle
+ // which ends in the phi node).
+ Instruction *ExitInstruction = nullptr;
+ // Indicates that we found a reduction operation in our scan.
+ bool FoundReduxOp = false;
+
+ // We start with the PHI node and scan for all of the users of this
+ // instruction. All users must be instructions that can be used as reduction
+ // variables (such as ADD). We must have a single out-of-block user. The cycle
+ // must include the original PHI.
+ bool FoundStartPHI = false;
+
+ // To recognize min/max patterns formed by a icmp select sequence, we store
+ // the number of instruction we saw from the recognized min/max pattern,
+ // to make sure we only see exactly the two instructions.
+ unsigned NumCmpSelectPatternInst = 0;
+ ReductionInstDesc ReduxDesc(false, nullptr);
+
+ SmallPtrSet<Instruction *, 8> VisitedInsts;
+ SmallVector<Instruction *, 8> Worklist;
+ Worklist.push_back(Phi);
+ VisitedInsts.insert(Phi);
+
+ // A value in the reduction can be used:
+ // - By the reduction:
+ // - Reduction operation:
+ // - One use of reduction value (safe).
+ // - Multiple use of reduction value (not safe).
+ // - PHI:
+ // - All uses of the PHI must be the reduction (safe).
+ // - Otherwise, not safe.
+ // - By one instruction outside of the loop (safe).
+ // - By further instructions outside of the loop (not safe).
+ // - By an instruction that is not part of the reduction (not safe).
+ // This is either:
+ // * An instruction type other than PHI or the reduction operation.
+ // * A PHI in the header other than the initial PHI.
+ while (!Worklist.empty()) {
+ Instruction *Cur = Worklist.back();
+ Worklist.pop_back();
+
+ // No Users.
+ // If the instruction has no users then this is a broken chain and can't be
+ // a reduction variable.
+ if (Cur->use_empty())
+ return false;
+
+ bool IsAPhi = isa<PHINode>(Cur);
+
+ // A header PHI use other than the original PHI.
+ if (Cur != Phi && IsAPhi && Cur->getParent() == Phi->getParent())
+ return false;
+
+ // Reductions of instructions such as Div, and Sub is only possible if the
+ // LHS is the reduction variable.
+ if (!Cur->isCommutative() && !IsAPhi && !isa<SelectInst>(Cur) &&
+ !isa<ICmpInst>(Cur) && !isa<FCmpInst>(Cur) &&
+ !VisitedInsts.count(dyn_cast<Instruction>(Cur->getOperand(0))))
+ return false;
+
+ // Any reduction instruction must be of one of the allowed kinds.
+ ReduxDesc = isReductionInstr(Cur, Kind, ReduxDesc, HasFunNoNaNAttr);
+ if (!ReduxDesc.isReduction())
+ return false;
+
+ // A reduction operation must only have one use of the reduction value.
+ if (!IsAPhi && Kind != RK_IntegerMinMax && Kind != RK_FloatMinMax &&
+ hasMultipleUsesOf(Cur, VisitedInsts))
+ return false;
+
+ // All inputs to a PHI node must be a reduction value.
+ if (IsAPhi && Cur != Phi && !areAllUsesIn(Cur, VisitedInsts))
+ return false;
+
+ if (Kind == RK_IntegerMinMax &&
+ (isa<ICmpInst>(Cur) || isa<SelectInst>(Cur)))
+ ++NumCmpSelectPatternInst;
+ if (Kind == RK_FloatMinMax && (isa<FCmpInst>(Cur) || isa<SelectInst>(Cur)))
+ ++NumCmpSelectPatternInst;
+
+ // Check whether we found a reduction operator.
+ FoundReduxOp |= !IsAPhi;
+
+ // Process users of current instruction. Push non-PHI nodes after PHI nodes
+ // onto the stack. This way we are going to have seen all inputs to PHI
+ // nodes once we get to them.
+ SmallVector<Instruction *, 8> NonPHIs;
+ SmallVector<Instruction *, 8> PHIs;
+ for (User *U : Cur->users()) {
+ Instruction *UI = cast<Instruction>(U);
+
+ // Check if we found the exit user.
+ BasicBlock *Parent = UI->getParent();
+ if (!TheLoop->contains(Parent)) {
+ // Exit if you find multiple outside users or if the header phi node is
+ // being used. In this case the user uses the value of the previous
+ // iteration, in which case we would loose "VF-1" iterations of the
+ // reduction operation if we vectorize.
+ if (ExitInstruction != nullptr || Cur == Phi)
+ return false;
+
+ // The instruction used by an outside user must be the last instruction
+ // before we feed back to the reduction phi. Otherwise, we loose VF-1
+ // operations on the value.
+ if (std::find(Phi->op_begin(), Phi->op_end(), Cur) == Phi->op_end())
+ return false;
+
+ ExitInstruction = Cur;
+ continue;
+ }
+
+ // Process instructions only once (termination). Each reduction cycle
+ // value must only be used once, except by phi nodes and min/max
+ // reductions which are represented as a cmp followed by a select.
+ ReductionInstDesc IgnoredVal(false, nullptr);
+ if (VisitedInsts.insert(UI).second) {
+ if (isa<PHINode>(UI))
+ PHIs.push_back(UI);
+ else
+ NonPHIs.push_back(UI);
+ } else if (!isa<PHINode>(UI) &&
+ ((!isa<FCmpInst>(UI) && !isa<ICmpInst>(UI) &&
+ !isa<SelectInst>(UI)) ||
+ !isMinMaxSelectCmpPattern(UI, IgnoredVal).isReduction()))
+ return false;
+
+ // Remember that we completed the cycle.
+ if (UI == Phi)
+ FoundStartPHI = true;
+ }
+ Worklist.append(PHIs.begin(), PHIs.end());
+ Worklist.append(NonPHIs.begin(), NonPHIs.end());
+ }
+
+ // This means we have seen one but not the other instruction of the
+ // pattern or more than just a select and cmp.
+ if ((Kind == RK_IntegerMinMax || Kind == RK_FloatMinMax) &&
+ NumCmpSelectPatternInst != 2)
+ return false;
+
+ if (!FoundStartPHI || !FoundReduxOp || !ExitInstruction)
+ return false;
+
+ // We found a reduction var if we have reached the original phi node and we
+ // only have a single instruction with out-of-loop users.
+
+ // The ExitInstruction(Instruction which is allowed to have out-of-loop users)
+ // is saved as part of the ReductionDescriptor.
+
+ // Save the description of this reduction variable.
+ ReductionDescriptor RD(RdxStart, ExitInstruction, Kind,
+ ReduxDesc.getMinMaxKind());
+
+ RedDes = RD;
+
+ return true;
+}
+
+/// Returns true if the instruction is a Select(ICmp(X, Y), X, Y) instruction
+/// pattern corresponding to a min(X, Y) or max(X, Y).
+ReductionInstDesc
+ReductionDescriptor::isMinMaxSelectCmpPattern(Instruction *I,
+ ReductionInstDesc &Prev) {
+
+ assert((isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<SelectInst>(I)) &&
+ "Expect a select instruction");
+ Instruction *Cmp = nullptr;
+ SelectInst *Select = nullptr;
+
+ // We must handle the select(cmp()) as a single instruction. Advance to the
+ // select.
+ if ((Cmp = dyn_cast<ICmpInst>(I)) || (Cmp = dyn_cast<FCmpInst>(I))) {
+ if (!Cmp->hasOneUse() || !(Select = dyn_cast<SelectInst>(*I->user_begin())))
+ return ReductionInstDesc(false, I);
+ return ReductionInstDesc(Select, Prev.getMinMaxKind());
+ }
+
+ // Only handle single use cases for now.
+ if (!(Select = dyn_cast<SelectInst>(I)))
+ return ReductionInstDesc(false, I);
+ if (!(Cmp = dyn_cast<ICmpInst>(I->getOperand(0))) &&
+ !(Cmp = dyn_cast<FCmpInst>(I->getOperand(0))))
+ return ReductionInstDesc(false, I);
+ if (!Cmp->hasOneUse())
+ return ReductionInstDesc(false, I);
+
+ Value *CmpLeft;
+ Value *CmpRight;
+
+ // Look for a min/max pattern.
+ if (m_UMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_UIntMin);
+ else if (m_UMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_UIntMax);
+ else if (m_SMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_SIntMax);
+ else if (m_SMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_SIntMin);
+ else if (m_OrdFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMin);
+ else if (m_OrdFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMax);
+ else if (m_UnordFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMin);
+ else if (m_UnordFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
+ return ReductionInstDesc(Select, ReductionInstDesc::MRK_FloatMax);
+
+ return ReductionInstDesc(false, I);
+}
+
+ReductionInstDesc ReductionDescriptor::isReductionInstr(Instruction *I,
+ ReductionKind Kind,
+ ReductionInstDesc &Prev,
+ bool HasFunNoNaNAttr) {
+ bool FP = I->getType()->isFloatingPointTy();
+ bool FastMath = FP && I->hasUnsafeAlgebra();
+ switch (I->getOpcode()) {
+ default:
+ return ReductionInstDesc(false, I);
+ case Instruction::PHI:
+ if (FP &&
+ (Kind != RK_FloatMult && Kind != RK_FloatAdd && Kind != RK_FloatMinMax))
+ return ReductionInstDesc(false, I);
+ return ReductionInstDesc(I, Prev.getMinMaxKind());
+ case Instruction::Sub:
+ case Instruction::Add:
+ return ReductionInstDesc(Kind == RK_IntegerAdd, I);
+ case Instruction::Mul:
+ return ReductionInstDesc(Kind == RK_IntegerMult, I);
+ case Instruction::And:
+ return ReductionInstDesc(Kind == RK_IntegerAnd, I);
+ case Instruction::Or:
+ return ReductionInstDesc(Kind == RK_IntegerOr, I);
+ case Instruction::Xor:
+ return ReductionInstDesc(Kind == RK_IntegerXor, I);
+ case Instruction::FMul:
+ return ReductionInstDesc(Kind == RK_FloatMult && FastMath, I);
+ case Instruction::FSub:
+ case Instruction::FAdd:
+ return ReductionInstDesc(Kind == RK_FloatAdd && FastMath, I);
+ case Instruction::FCmp:
+ case Instruction::ICmp:
+ case Instruction::Select:
+ if (Kind != RK_IntegerMinMax &&
+ (!HasFunNoNaNAttr || Kind != RK_FloatMinMax))
+ return ReductionInstDesc(false, I);
+ return isMinMaxSelectCmpPattern(I, Prev);
+ }
+}
+
+bool ReductionDescriptor::hasMultipleUsesOf(
+ Instruction *I, SmallPtrSetImpl<Instruction *> &Insts) {
+ unsigned NumUses = 0;
+ for (User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E;
+ ++Use) {
+ if (Insts.count(dyn_cast<Instruction>(*Use)))
+ ++NumUses;
+ if (NumUses > 1)
+ return true;
+ }
+
+ return false;
+}
+bool ReductionDescriptor::isReductionPHI(PHINode *Phi, Loop *TheLoop,
+ ReductionDescriptor &RedDes) {
+
+ bool HasFunNoNaNAttr = false;
+ BasicBlock *Header = TheLoop->getHeader();
+ Function &F = *Header->getParent();
+ if (F.hasFnAttribute("no-nans-fp-math"))
+ HasFunNoNaNAttr =
+ F.getFnAttribute("no-nans-fp-math").getValueAsString() == "true";
+
+ if (AddReductionVar(Phi, RK_IntegerAdd, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found an ADD reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_IntegerMult, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found a MUL reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_IntegerOr, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found an OR reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_IntegerAnd, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found an AND reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_IntegerXor, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found a XOR reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_IntegerMinMax, TheLoop, HasFunNoNaNAttr,
+ RedDes)) {
+ DEBUG(dbgs() << "Found a MINMAX reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_FloatMult, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found an FMult reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_FloatAdd, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found an FAdd reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ if (AddReductionVar(Phi, RK_FloatMinMax, TheLoop, HasFunNoNaNAttr, RedDes)) {
+ DEBUG(dbgs() << "Found an float MINMAX reduction PHI." << *Phi << "\n");
+ return true;
+ }
+ // Not a reduction of known type.
+ return false;
+}
+
+/// This function returns the identity element (or neutral element) for
+/// the operation K.
+Constant *ReductionDescriptor::getReductionIdentity(ReductionKind K, Type *Tp) {
+ switch (K) {
+ case RK_IntegerXor:
+ case RK_IntegerAdd:
+ case RK_IntegerOr:
+ // Adding, Xoring, Oring zero to a number does not change it.
+ return ConstantInt::get(Tp, 0);
+ case RK_IntegerMult:
+ // Multiplying a number by 1 does not change it.
+ return ConstantInt::get(Tp, 1);
+ case RK_IntegerAnd:
+ // AND-ing a number with an all-1 value does not change it.
+ return ConstantInt::get(Tp, -1, true);
+ case RK_FloatMult:
+ // Multiplying a number by 1 does not change it.
+ return ConstantFP::get(Tp, 1.0L);
+ case RK_FloatAdd:
+ // Adding zero to a number does not change it.
+ return ConstantFP::get(Tp, 0.0L);
+ default:
+ llvm_unreachable("Unknown reduction kind");
+ }
+}
+
+/// This function translates the reduction kind to an LLVM binary operator.
+unsigned ReductionDescriptor::getReductionBinOp(ReductionKind Kind) {
+ switch (Kind) {
+ case RK_IntegerAdd:
+ return Instruction::Add;
+ case RK_IntegerMult:
+ return Instruction::Mul;
+ case RK_IntegerOr:
+ return Instruction::Or;
+ case RK_IntegerAnd:
+ return Instruction::And;
+ case RK_IntegerXor:
+ return Instruction::Xor;
+ case RK_FloatMult:
+ return Instruction::FMul;
+ case RK_FloatAdd:
+ return Instruction::FAdd;
+ case RK_IntegerMinMax:
+ return Instruction::ICmp;
+ case RK_FloatMinMax:
+ return Instruction::FCmp;
+ default:
+ llvm_unreachable("Unknown reduction operation");
+ }
+}
+
+Value *
+ReductionDescriptor::createMinMaxOp(IRBuilder<> &Builder,
+ ReductionInstDesc::MinMaxReductionKind RK,
+ Value *Left, Value *Right) {
+ CmpInst::Predicate P = CmpInst::ICMP_NE;
+ switch (RK) {
+ default:
+ llvm_unreachable("Unknown min/max reduction kind");
+ case ReductionInstDesc::MRK_UIntMin:
+ P = CmpInst::ICMP_ULT;
+ break;
+ case ReductionInstDesc::MRK_UIntMax:
+ P = CmpInst::ICMP_UGT;
+ break;
+ case ReductionInstDesc::MRK_SIntMin:
+ P = CmpInst::ICMP_SLT;
+ break;
+ case ReductionInstDesc::MRK_SIntMax:
+ P = CmpInst::ICMP_SGT;
+ break;
+ case ReductionInstDesc::MRK_FloatMin:
+ P = CmpInst::FCMP_OLT;
+ break;
+ case ReductionInstDesc::MRK_FloatMax:
+ P = CmpInst::FCMP_OGT;
+ break;
+ }
+
+ Value *Cmp;
+ if (RK == ReductionInstDesc::MRK_FloatMin ||
+ RK == ReductionInstDesc::MRK_FloatMax)
+ Cmp = Builder.CreateFCmp(P, Left, Right, "rdx.minmax.cmp");
+ else
+ Cmp = Builder.CreateICmp(P, Left, Right, "rdx.minmax.cmp");
+
+ Value *Select = Builder.CreateSelect(Cmp, Left, Right, "rdx.minmax.select");
+ return Select;
+}
Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=235284&r1=235283&r2=235284&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Sun Apr 19 23:38:33 2015
@@ -568,20 +568,6 @@ public:
TTI(TTI), DT(DT), LAA(LAA), LAI(nullptr), Induction(nullptr),
WidestIndTy(nullptr), HasFunNoNaNAttr(false) {}
- /// This enum represents the kinds of reductions that we support.
- enum ReductionKind {
- RK_NoReduction, ///< Not a reduction.
- RK_IntegerAdd, ///< Sum of integers.
- RK_IntegerMult, ///< Product of integers.
- RK_IntegerOr, ///< Bitwise or logical OR of numbers.
- RK_IntegerAnd, ///< Bitwise or logical AND of numbers.
- RK_IntegerXor, ///< Bitwise or logical XOR of numbers.
- RK_IntegerMinMax, ///< Min/max implemented in terms of select(cmp()).
- RK_FloatAdd, ///< Sum of floats.
- RK_FloatMult, ///< Product of floats.
- RK_FloatMinMax ///< Min/max implemented in terms of select(cmp()).
- };
-
/// This enum represents the kinds of inductions that we support.
enum InductionKind {
IK_NoInduction, ///< Not an induction variable.
@@ -589,54 +575,6 @@ public:
IK_PtrInduction ///< Pointer induction var. Step = C / sizeof(elem).
};
- // This enum represents the kind of minmax reduction.
- enum MinMaxReductionKind {
- MRK_Invalid,
- MRK_UIntMin,
- MRK_UIntMax,
- MRK_SIntMin,
- MRK_SIntMax,
- MRK_FloatMin,
- MRK_FloatMax
- };
-
- /// This struct holds information about reduction variables.
- struct ReductionDescriptor {
- ReductionDescriptor() : StartValue(nullptr), LoopExitInstr(nullptr),
- Kind(RK_NoReduction), MinMaxKind(MRK_Invalid) {}
-
- ReductionDescriptor(Value *Start, Instruction *Exit, ReductionKind K,
- MinMaxReductionKind MK)
- : StartValue(Start), LoopExitInstr(Exit), Kind(K), MinMaxKind(MK) {}
-
- // The starting value of the reduction.
- // It does not have to be zero!
- TrackingVH<Value> StartValue;
- // The instruction who's value is used outside the loop.
- Instruction *LoopExitInstr;
- // The kind of the reduction.
- ReductionKind Kind;
- // If this a min/max reduction the kind of reduction.
- MinMaxReductionKind MinMaxKind;
- };
-
- /// This POD struct holds information about a potential reduction operation.
- struct ReductionInstDesc {
- ReductionInstDesc(bool IsRedux, Instruction *I) :
- IsReduction(IsRedux), PatternLastInst(I), MinMaxKind(MRK_Invalid) {}
-
- ReductionInstDesc(Instruction *I, MinMaxReductionKind K) :
- IsReduction(true), PatternLastInst(I), MinMaxKind(K) {}
-
- // Is this instruction a reduction candidate.
- bool IsReduction;
- // The last instruction in a min/max pattern (select of the select(icmp())
- // pattern), or the current reduction instruction otherwise.
- Instruction *PatternLastInst;
- // If this is a min/max pattern the comparison predicate.
- MinMaxReductionKind MinMaxKind;
- };
-
/// A struct for saving information about induction variables.
struct InductionInfo {
InductionInfo(Value *Start, InductionKind K, ConstantInt *Step)
@@ -759,10 +697,6 @@ public:
return LAI;
}
- /// This function returns the identity element (or neutral element) for
- /// the operation K.
- static Constant *getReductionIdentity(ReductionKind K, Type *Tp);
-
unsigned getMaxSafeDepDistBytes() { return LAI->getMaxSafeDepDistBytes(); }
bool hasStride(Value *V) { return StrideSet.count(V); }
@@ -820,20 +754,6 @@ private:
/// and we know that we can read from them without segfault.
bool blockCanBePredicated(BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs);
- /// Returns True, if 'Phi' is the kind of reduction variable for type
- /// 'Kind'. If this is a reduction variable, it adds it to ReductionList.
- bool AddReductionVar(PHINode *Phi, ReductionKind Kind);
- /// Returns a struct describing if the instruction 'I' can be a reduction
- /// variable of type 'Kind'. If the reduction is a min/max pattern of
- /// select(icmp()) this function advances the instruction pointer 'I' from the
- /// compare instruction to the select instruction and stores this pointer in
- /// 'PatternLastInst' member of the returned struct.
- ReductionInstDesc isReductionInstr(Instruction *I, ReductionKind Kind,
- ReductionInstDesc &Desc);
- /// Returns true if the instruction is a Select(ICmp(X, Y), X, Y) instruction
- /// pattern corresponding to a min(X, Y) or max(X, Y).
- static ReductionInstDesc isMinMaxSelectCmpPattern(Instruction *I,
- ReductionInstDesc &Prev);
/// Returns the induction kind of Phi and record the step. This function may
/// return NoInduction if the PHI is not an induction variable.
InductionKind isInductionVariable(PHINode *Phi, ConstantInt *&StepValue);
@@ -2469,98 +2389,6 @@ void InnerLoopVectorizer::createEmptyLoo
Hints.setAlreadyVectorized();
}
-/// This function returns the identity element (or neutral element) for
-/// the operation K.
-Constant*
-LoopVectorizationLegality::getReductionIdentity(ReductionKind K, Type *Tp) {
- switch (K) {
- case RK_IntegerXor:
- case RK_IntegerAdd:
- case RK_IntegerOr:
- // Adding, Xoring, Oring zero to a number does not change it.
- return ConstantInt::get(Tp, 0);
- case RK_IntegerMult:
- // Multiplying a number by 1 does not change it.
- return ConstantInt::get(Tp, 1);
- case RK_IntegerAnd:
- // AND-ing a number with an all-1 value does not change it.
- return ConstantInt::get(Tp, -1, true);
- case RK_FloatMult:
- // Multiplying a number by 1 does not change it.
- return ConstantFP::get(Tp, 1.0L);
- case RK_FloatAdd:
- // Adding zero to a number does not change it.
- return ConstantFP::get(Tp, 0.0L);
- default:
- llvm_unreachable("Unknown reduction kind");
- }
-}
-
-/// This function translates the reduction kind to an LLVM binary operator.
-static unsigned
-getReductionBinOp(LoopVectorizationLegality::ReductionKind Kind) {
- switch (Kind) {
- case LoopVectorizationLegality::RK_IntegerAdd:
- return Instruction::Add;
- case LoopVectorizationLegality::RK_IntegerMult:
- return Instruction::Mul;
- case LoopVectorizationLegality::RK_IntegerOr:
- return Instruction::Or;
- case LoopVectorizationLegality::RK_IntegerAnd:
- return Instruction::And;
- case LoopVectorizationLegality::RK_IntegerXor:
- return Instruction::Xor;
- case LoopVectorizationLegality::RK_FloatMult:
- return Instruction::FMul;
- case LoopVectorizationLegality::RK_FloatAdd:
- return Instruction::FAdd;
- case LoopVectorizationLegality::RK_IntegerMinMax:
- return Instruction::ICmp;
- case LoopVectorizationLegality::RK_FloatMinMax:
- return Instruction::FCmp;
- default:
- llvm_unreachable("Unknown reduction operation");
- }
-}
-
-static Value *createMinMaxOp(IRBuilder<> &Builder,
- LoopVectorizationLegality::MinMaxReductionKind RK,
- Value *Left, Value *Right) {
- CmpInst::Predicate P = CmpInst::ICMP_NE;
- switch (RK) {
- default:
- llvm_unreachable("Unknown min/max reduction kind");
- case LoopVectorizationLegality::MRK_UIntMin:
- P = CmpInst::ICMP_ULT;
- break;
- case LoopVectorizationLegality::MRK_UIntMax:
- P = CmpInst::ICMP_UGT;
- break;
- case LoopVectorizationLegality::MRK_SIntMin:
- P = CmpInst::ICMP_SLT;
- break;
- case LoopVectorizationLegality::MRK_SIntMax:
- P = CmpInst::ICMP_SGT;
- break;
- case LoopVectorizationLegality::MRK_FloatMin:
- P = CmpInst::FCMP_OLT;
- break;
- case LoopVectorizationLegality::MRK_FloatMax:
- P = CmpInst::FCMP_OGT;
- break;
- }
-
- Value *Cmp;
- if (RK == LoopVectorizationLegality::MRK_FloatMin ||
- RK == LoopVectorizationLegality::MRK_FloatMax)
- Cmp = Builder.CreateFCmp(P, Left, Right, "rdx.minmax.cmp");
- else
- Cmp = Builder.CreateICmp(P, Left, Right, "rdx.minmax.cmp");
-
- Value *Select = Builder.CreateSelect(Cmp, Left, Right, "rdx.minmax.select");
- return Select;
-}
-
namespace {
struct CSEDenseMapInfo {
static bool canHandle(Instruction *I) {
@@ -2772,10 +2600,14 @@ void InnerLoopVectorizer::vectorizeLoop(
// Find the reduction variable descriptor.
assert(Legal->getReductionVars()->count(RdxPhi) &&
"Unable to find the reduction variable");
- LoopVectorizationLegality::ReductionDescriptor RdxDesc =
- (*Legal->getReductionVars())[RdxPhi];
+ ReductionDescriptor RdxDesc = (*Legal->getReductionVars())[RdxPhi];
- setDebugLocFromInst(Builder, RdxDesc.StartValue);
+ ReductionDescriptor::ReductionKind RK = RdxDesc.getReductionKind();
+ TrackingVH<Value> ReductionStartValue = RdxDesc.getReductionStartValue();
+ Instruction *LoopExitInst = RdxDesc.getLoopExitInstr();
+ ReductionInstDesc::MinMaxReductionKind MinMaxKind =
+ RdxDesc.getMinMaxReductionKind();
+ setDebugLocFromInst(Builder, ReductionStartValue);
// We need to generate a reduction vector from the incoming scalar.
// To do so, we need to generate the 'identity' vector and override
@@ -2784,40 +2616,38 @@ void InnerLoopVectorizer::vectorizeLoop(
Builder.SetInsertPoint(LoopBypassBlocks[1]->getTerminator());
// This is the vector-clone of the value that leaves the loop.
- VectorParts &VectorExit = getVectorValue(RdxDesc.LoopExitInstr);
+ VectorParts &VectorExit = getVectorValue(LoopExitInst);
Type *VecTy = VectorExit[0]->getType();
// Find the reduction identity variable. Zero for addition, or, xor,
// one for multiplication, -1 for And.
Value *Identity;
Value *VectorStart;
- if (RdxDesc.Kind == LoopVectorizationLegality::RK_IntegerMinMax ||
- RdxDesc.Kind == LoopVectorizationLegality::RK_FloatMinMax) {
+ if (RK == ReductionDescriptor::RK_IntegerMinMax ||
+ RK == ReductionDescriptor::RK_FloatMinMax) {
// MinMax reduction have the start value as their identify.
if (VF == 1) {
- VectorStart = Identity = RdxDesc.StartValue;
+ VectorStart = Identity = ReductionStartValue;
} else {
- VectorStart = Identity = Builder.CreateVectorSplat(VF,
- RdxDesc.StartValue,
- "minmax.ident");
+ VectorStart = Identity =
+ Builder.CreateVectorSplat(VF, ReductionStartValue, "minmax.ident");
}
} else {
// Handle other reduction kinds:
Constant *Iden =
- LoopVectorizationLegality::getReductionIdentity(RdxDesc.Kind,
- VecTy->getScalarType());
+ ReductionDescriptor::getReductionIdentity(RK, VecTy->getScalarType());
if (VF == 1) {
Identity = Iden;
// This vector is the Identity vector where the first element is the
// incoming scalar reduction.
- VectorStart = RdxDesc.StartValue;
+ VectorStart = ReductionStartValue;
} else {
Identity = ConstantVector::getSplat(VF, Iden);
// This vector is the Identity vector where the first element is the
// incoming scalar reduction.
- VectorStart = Builder.CreateInsertElement(Identity,
- RdxDesc.StartValue, Zero);
+ VectorStart =
+ Builder.CreateInsertElement(Identity, ReductionStartValue, Zero);
}
}
@@ -2846,11 +2676,11 @@ void InnerLoopVectorizer::vectorizeLoop(
Builder.SetInsertPoint(LoopMiddleBlock->getFirstInsertionPt());
VectorParts RdxParts;
- setDebugLocFromInst(Builder, RdxDesc.LoopExitInstr);
+ setDebugLocFromInst(Builder, LoopExitInst);
for (unsigned part = 0; part < UF; ++part) {
// This PHINode contains the vectorized reduction variable, or
// the initial value vector, if we bypass the vector loop.
- VectorParts &RdxExitVal = getVectorValue(RdxDesc.LoopExitInstr);
+ VectorParts &RdxExitVal = getVectorValue(LoopExitInst);
PHINode *NewPhi = Builder.CreatePHI(VecTy, 2, "rdx.vec.exit.phi");
Value *StartVal = (part == 0) ? VectorStart : Identity;
for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I)
@@ -2862,7 +2692,7 @@ void InnerLoopVectorizer::vectorizeLoop(
// Reduce all of the unrolled parts into a single vector.
Value *ReducedPartRdx = RdxParts[0];
- unsigned Op = getReductionBinOp(RdxDesc.Kind);
+ unsigned Op = ReductionDescriptor::getReductionBinOp(RK);
setDebugLocFromInst(Builder, ReducedPartRdx);
for (unsigned part = 1; part < UF; ++part) {
if (Op != Instruction::ICmp && Op != Instruction::FCmp)
@@ -2871,8 +2701,8 @@ void InnerLoopVectorizer::vectorizeLoop(
Builder.CreateBinOp((Instruction::BinaryOps)Op, RdxParts[part],
ReducedPartRdx, "bin.rdx"));
else
- ReducedPartRdx = createMinMaxOp(Builder, RdxDesc.MinMaxKind,
- ReducedPartRdx, RdxParts[part]);
+ ReducedPartRdx = ReductionDescriptor::createMinMaxOp(
+ Builder, MinMaxKind, ReducedPartRdx, RdxParts[part]);
}
if (VF > 1) {
@@ -2903,7 +2733,8 @@ void InnerLoopVectorizer::vectorizeLoop(
TmpVec = addFastMathFlag(Builder.CreateBinOp(
(Instruction::BinaryOps)Op, TmpVec, Shuf, "bin.rdx"));
else
- TmpVec = createMinMaxOp(Builder, RdxDesc.MinMaxKind, TmpVec, Shuf);
+ TmpVec = ReductionDescriptor::createMinMaxOp(Builder, MinMaxKind,
+ TmpVec, Shuf);
}
// The result is in the first element of the vector.
@@ -2915,7 +2746,7 @@ void InnerLoopVectorizer::vectorizeLoop(
// block and the middle block.
PHINode *BCBlockPhi = PHINode::Create(RdxPhi->getType(), 2, "bc.merge.rdx",
LoopScalarPreHeader->getTerminator());
- BCBlockPhi->addIncoming(RdxDesc.StartValue, LoopBypassBlocks[0]);
+ BCBlockPhi->addIncoming(ReductionStartValue, LoopBypassBlocks[0]);
BCBlockPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock);
// Now, we need to fix the users of the reduction variable
@@ -2933,7 +2764,7 @@ void InnerLoopVectorizer::vectorizeLoop(
// We found our reduction value exit-PHI. Update it with the
// incoming bypass edge.
- if (LCSSAPhi->getIncomingValue(0) == RdxDesc.LoopExitInstr) {
+ if (LCSSAPhi->getIncomingValue(0) == LoopExitInst) {
// Add an edge coming from the bypass.
LCSSAPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock);
break;
@@ -2948,7 +2779,7 @@ void InnerLoopVectorizer::vectorizeLoop(
// Pick the other block.
int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1);
(RdxPhi)->setIncomingValue(SelfEdgeBlockIdx, BCBlockPhi);
- (RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, RdxDesc.LoopExitInstr);
+ (RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, LoopExitInst);
}// end of for each redux variable.
fixLCSSAPHIs();
@@ -3712,41 +3543,9 @@ bool LoopVectorizationLegality::canVecto
continue;
}
- if (AddReductionVar(Phi, RK_IntegerAdd)) {
- DEBUG(dbgs() << "LV: Found an ADD reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_IntegerMult)) {
- DEBUG(dbgs() << "LV: Found a MUL reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_IntegerOr)) {
- DEBUG(dbgs() << "LV: Found an OR reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_IntegerAnd)) {
- DEBUG(dbgs() << "LV: Found an AND reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_IntegerXor)) {
- DEBUG(dbgs() << "LV: Found a XOR reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_IntegerMinMax)) {
- DEBUG(dbgs() << "LV: Found a MINMAX reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_FloatMult)) {
- DEBUG(dbgs() << "LV: Found an FMult reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_FloatAdd)) {
- DEBUG(dbgs() << "LV: Found an FAdd reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, RK_FloatMinMax)) {
- DEBUG(dbgs() << "LV: Found an float MINMAX reduction PHI."<< *Phi <<
- "\n");
+ if (ReductionDescriptor::isReductionPHI(Phi, TheLoop,
+ Reductions[Phi])) {
+ AllowedExit.insert(Reductions[Phi].getLoopExitInstr());
continue;
}
@@ -4029,294 +3828,6 @@ bool LoopVectorizationLegality::canVecto
return true;
}
-static bool hasMultipleUsesOf(Instruction *I,
- SmallPtrSetImpl<Instruction *> &Insts) {
- unsigned NumUses = 0;
- for(User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E; ++Use) {
- if (Insts.count(dyn_cast<Instruction>(*Use)))
- ++NumUses;
- if (NumUses > 1)
- return true;
- }
-
- return false;
-}
-
-static bool areAllUsesIn(Instruction *I, SmallPtrSetImpl<Instruction *> &Set) {
- for(User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E; ++Use)
- if (!Set.count(dyn_cast<Instruction>(*Use)))
- return false;
- return true;
-}
-
-bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
- ReductionKind Kind) {
- if (Phi->getNumIncomingValues() != 2)
- return false;
-
- // Reduction variables are only found in the loop header block.
- if (Phi->getParent() != TheLoop->getHeader())
- return false;
-
- // Obtain the reduction start value from the value that comes from the loop
- // preheader.
- Value *RdxStart = Phi->getIncomingValueForBlock(TheLoop->getLoopPreheader());
-
- // ExitInstruction is the single value which is used outside the loop.
- // We only allow for a single reduction value to be used outside the loop.
- // This includes users of the reduction, variables (which form a cycle
- // which ends in the phi node).
- Instruction *ExitInstruction = nullptr;
- // Indicates that we found a reduction operation in our scan.
- bool FoundReduxOp = false;
-
- // We start with the PHI node and scan for all of the users of this
- // instruction. All users must be instructions that can be used as reduction
- // variables (such as ADD). We must have a single out-of-block user. The cycle
- // must include the original PHI.
- bool FoundStartPHI = false;
-
- // To recognize min/max patterns formed by a icmp select sequence, we store
- // the number of instruction we saw from the recognized min/max pattern,
- // to make sure we only see exactly the two instructions.
- unsigned NumCmpSelectPatternInst = 0;
- ReductionInstDesc ReduxDesc(false, nullptr);
-
- SmallPtrSet<Instruction *, 8> VisitedInsts;
- SmallVector<Instruction *, 8> Worklist;
- Worklist.push_back(Phi);
- VisitedInsts.insert(Phi);
-
- // A value in the reduction can be used:
- // - By the reduction:
- // - Reduction operation:
- // - One use of reduction value (safe).
- // - Multiple use of reduction value (not safe).
- // - PHI:
- // - All uses of the PHI must be the reduction (safe).
- // - Otherwise, not safe.
- // - By one instruction outside of the loop (safe).
- // - By further instructions outside of the loop (not safe).
- // - By an instruction that is not part of the reduction (not safe).
- // This is either:
- // * An instruction type other than PHI or the reduction operation.
- // * A PHI in the header other than the initial PHI.
- while (!Worklist.empty()) {
- Instruction *Cur = Worklist.back();
- Worklist.pop_back();
-
- // No Users.
- // If the instruction has no users then this is a broken chain and can't be
- // a reduction variable.
- if (Cur->use_empty())
- return false;
-
- bool IsAPhi = isa<PHINode>(Cur);
-
- // A header PHI use other than the original PHI.
- if (Cur != Phi && IsAPhi && Cur->getParent() == Phi->getParent())
- return false;
-
- // Reductions of instructions such as Div, and Sub is only possible if the
- // LHS is the reduction variable.
- if (!Cur->isCommutative() && !IsAPhi && !isa<SelectInst>(Cur) &&
- !isa<ICmpInst>(Cur) && !isa<FCmpInst>(Cur) &&
- !VisitedInsts.count(dyn_cast<Instruction>(Cur->getOperand(0))))
- return false;
-
- // Any reduction instruction must be of one of the allowed kinds.
- ReduxDesc = isReductionInstr(Cur, Kind, ReduxDesc);
- if (!ReduxDesc.IsReduction)
- return false;
-
- // A reduction operation must only have one use of the reduction value.
- if (!IsAPhi && Kind != RK_IntegerMinMax && Kind != RK_FloatMinMax &&
- hasMultipleUsesOf(Cur, VisitedInsts))
- return false;
-
- // All inputs to a PHI node must be a reduction value.
- if(IsAPhi && Cur != Phi && !areAllUsesIn(Cur, VisitedInsts))
- return false;
-
- if (Kind == RK_IntegerMinMax && (isa<ICmpInst>(Cur) ||
- isa<SelectInst>(Cur)))
- ++NumCmpSelectPatternInst;
- if (Kind == RK_FloatMinMax && (isa<FCmpInst>(Cur) ||
- isa<SelectInst>(Cur)))
- ++NumCmpSelectPatternInst;
-
- // Check whether we found a reduction operator.
- FoundReduxOp |= !IsAPhi;
-
- // Process users of current instruction. Push non-PHI nodes after PHI nodes
- // onto the stack. This way we are going to have seen all inputs to PHI
- // nodes once we get to them.
- SmallVector<Instruction *, 8> NonPHIs;
- SmallVector<Instruction *, 8> PHIs;
- for (User *U : Cur->users()) {
- Instruction *UI = cast<Instruction>(U);
-
- // Check if we found the exit user.
- BasicBlock *Parent = UI->getParent();
- if (!TheLoop->contains(Parent)) {
- // Exit if you find multiple outside users or if the header phi node is
- // being used. In this case the user uses the value of the previous
- // iteration, in which case we would loose "VF-1" iterations of the
- // reduction operation if we vectorize.
- if (ExitInstruction != nullptr || Cur == Phi)
- return false;
-
- // The instruction used by an outside user must be the last instruction
- // before we feed back to the reduction phi. Otherwise, we loose VF-1
- // operations on the value.
- if (std::find(Phi->op_begin(), Phi->op_end(), Cur) == Phi->op_end())
- return false;
-
- ExitInstruction = Cur;
- continue;
- }
-
- // Process instructions only once (termination). Each reduction cycle
- // value must only be used once, except by phi nodes and min/max
- // reductions which are represented as a cmp followed by a select.
- ReductionInstDesc IgnoredVal(false, nullptr);
- if (VisitedInsts.insert(UI).second) {
- if (isa<PHINode>(UI))
- PHIs.push_back(UI);
- else
- NonPHIs.push_back(UI);
- } else if (!isa<PHINode>(UI) &&
- ((!isa<FCmpInst>(UI) &&
- !isa<ICmpInst>(UI) &&
- !isa<SelectInst>(UI)) ||
- !isMinMaxSelectCmpPattern(UI, IgnoredVal).IsReduction))
- return false;
-
- // Remember that we completed the cycle.
- if (UI == Phi)
- FoundStartPHI = true;
- }
- Worklist.append(PHIs.begin(), PHIs.end());
- Worklist.append(NonPHIs.begin(), NonPHIs.end());
- }
-
- // This means we have seen one but not the other instruction of the
- // pattern or more than just a select and cmp.
- if ((Kind == RK_IntegerMinMax || Kind == RK_FloatMinMax) &&
- NumCmpSelectPatternInst != 2)
- return false;
-
- if (!FoundStartPHI || !FoundReduxOp || !ExitInstruction)
- return false;
-
- // We found a reduction var if we have reached the original phi node and we
- // only have a single instruction with out-of-loop users.
-
- // This instruction is allowed to have out-of-loop users.
- AllowedExit.insert(ExitInstruction);
-
- // Save the description of this reduction variable.
- ReductionDescriptor RD(RdxStart, ExitInstruction, Kind,
- ReduxDesc.MinMaxKind);
- Reductions[Phi] = RD;
- // We've ended the cycle. This is a reduction variable if we have an
- // outside user and it has a binary op.
-
- return true;
-}
-
-/// Returns true if the instruction is a Select(ICmp(X, Y), X, Y) instruction
-/// pattern corresponding to a min(X, Y) or max(X, Y).
-LoopVectorizationLegality::ReductionInstDesc
-LoopVectorizationLegality::isMinMaxSelectCmpPattern(Instruction *I,
- ReductionInstDesc &Prev) {
-
- assert((isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<SelectInst>(I)) &&
- "Expect a select instruction");
- Instruction *Cmp = nullptr;
- SelectInst *Select = nullptr;
-
- // We must handle the select(cmp()) as a single instruction. Advance to the
- // select.
- if ((Cmp = dyn_cast<ICmpInst>(I)) || (Cmp = dyn_cast<FCmpInst>(I))) {
- if (!Cmp->hasOneUse() || !(Select = dyn_cast<SelectInst>(*I->user_begin())))
- return ReductionInstDesc(false, I);
- return ReductionInstDesc(Select, Prev.MinMaxKind);
- }
-
- // Only handle single use cases for now.
- if (!(Select = dyn_cast<SelectInst>(I)))
- return ReductionInstDesc(false, I);
- if (!(Cmp = dyn_cast<ICmpInst>(I->getOperand(0))) &&
- !(Cmp = dyn_cast<FCmpInst>(I->getOperand(0))))
- return ReductionInstDesc(false, I);
- if (!Cmp->hasOneUse())
- return ReductionInstDesc(false, I);
-
- Value *CmpLeft;
- Value *CmpRight;
-
- // Look for a min/max pattern.
- if (m_UMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_UIntMin);
- else if (m_UMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_UIntMax);
- else if (m_SMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_SIntMax);
- else if (m_SMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_SIntMin);
- else if (m_OrdFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_FloatMin);
- else if (m_OrdFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_FloatMax);
- else if (m_UnordFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_FloatMin);
- else if (m_UnordFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
- return ReductionInstDesc(Select, MRK_FloatMax);
-
- return ReductionInstDesc(false, I);
-}
-
-LoopVectorizationLegality::ReductionInstDesc
-LoopVectorizationLegality::isReductionInstr(Instruction *I,
- ReductionKind Kind,
- ReductionInstDesc &Prev) {
- bool FP = I->getType()->isFloatingPointTy();
- bool FastMath = FP && I->hasUnsafeAlgebra();
- switch (I->getOpcode()) {
- default:
- return ReductionInstDesc(false, I);
- case Instruction::PHI:
- if (FP && (Kind != RK_FloatMult && Kind != RK_FloatAdd &&
- Kind != RK_FloatMinMax))
- return ReductionInstDesc(false, I);
- return ReductionInstDesc(I, Prev.MinMaxKind);
- case Instruction::Sub:
- case Instruction::Add:
- return ReductionInstDesc(Kind == RK_IntegerAdd, I);
- case Instruction::Mul:
- return ReductionInstDesc(Kind == RK_IntegerMult, I);
- case Instruction::And:
- return ReductionInstDesc(Kind == RK_IntegerAnd, I);
- case Instruction::Or:
- return ReductionInstDesc(Kind == RK_IntegerOr, I);
- case Instruction::Xor:
- return ReductionInstDesc(Kind == RK_IntegerXor, I);
- case Instruction::FMul:
- return ReductionInstDesc(Kind == RK_FloatMult && FastMath, I);
- case Instruction::FSub:
- case Instruction::FAdd:
- return ReductionInstDesc(Kind == RK_FloatAdd && FastMath, I);
- case Instruction::FCmp:
- case Instruction::ICmp:
- case Instruction::Select:
- if (Kind != RK_IntegerMinMax &&
- (!HasFunNoNaNAttr || Kind != RK_FloatMinMax))
- return ReductionInstDesc(false, I);
- return isMinMaxSelectCmpPattern(I, Prev);
- }
-}
-
bool llvm::isInductionPHI(PHINode *Phi, ScalarEvolution *SE,
ConstantInt *&StepValue) {
Type *PhiTy = Phi->getType();
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