X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FAnalysis%2FInlineCost.cpp;h=cebc8731d4d3c30bfaf1dce20ce7743e0dfaaa86;hp=10c2d79bef3d4dd7d5651757af7459cf7b0d4006;hb=aa464aada41ae2b8ef9f3ef4147c6ef09d2879e2;hpb=9a1581b9102511282ee823ab9a29819bc060e6a5 diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp index 10c2d79bef3..cebc8731d4d 100644 --- a/lib/Analysis/InlineCost.cpp +++ b/lib/Analysis/InlineCost.cpp @@ -12,454 +12,1440 @@ //===----------------------------------------------------------------------===// #include "llvm/Analysis/InlineCost.h" -#include "llvm/Support/CallSite.h" -#include "llvm/CallingConv.h" -#include "llvm/IntrinsicInst.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SetVector.h" #include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/AssumptionCache.h" +#include "llvm/Analysis/CodeMetrics.h" +#include "llvm/Analysis/ConstantFolding.h" +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/CallingConv.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/GetElementPtrTypeIterator.h" +#include "llvm/IR/GlobalAlias.h" +#include "llvm/IR/InstVisitor.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/Operator.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" + using namespace llvm; -// CountCodeReductionForConstant - Figure out an approximation for how many -// instructions will be constant folded if the specified value is constant. -// -unsigned InlineCostAnalyzer::FunctionInfo:: -CountCodeReductionForConstant(Value *V) { - unsigned Reduction = 0; - for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){ - User *U = *UI; - if (isa(U) || isa(U)) { - // We will be able to eliminate all but one of the successors. - const TerminatorInst &TI = cast(*U); - const unsigned NumSucc = TI.getNumSuccessors(); - unsigned Instrs = 0; - for (unsigned I = 0; I != NumSucc; ++I) - Instrs += Metrics.NumBBInsts[TI.getSuccessor(I)]; - // We don't know which blocks will be eliminated, so use the average size. - Reduction += InlineConstants::InstrCost*Instrs*(NumSucc-1)/NumSucc; - } else if (CallInst *CI = dyn_cast(U)) { - // Turning an indirect call into a direct call is a BIG win - if (CI->getCalledValue() == V) - Reduction += InlineConstants::IndirectCallBonus; - } else if (InvokeInst *II = dyn_cast(U)) { - // Turning an indirect call into a direct call is a BIG win - if (II->getCalledValue() == V) - Reduction += InlineConstants::IndirectCallBonus; - } else { - // Figure out if this instruction will be removed due to simple constant - // propagation. - Instruction &Inst = cast(*U); - - // We can't constant propagate instructions which have effects or - // read memory. - // - // FIXME: It would be nice to capture the fact that a load from a - // pointer-to-constant-global is actually a *really* good thing to zap. - // Unfortunately, we don't know the pointer that may get propagated here, - // so we can't make this decision. - if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() || - isa(Inst)) - continue; +#define DEBUG_TYPE "inline-cost" - bool AllOperandsConstant = true; - for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) - if (!isa(Inst.getOperand(i)) && Inst.getOperand(i) != V) { - AllOperandsConstant = false; - break; - } +STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed"); + +namespace { + +class CallAnalyzer : public InstVisitor { + typedef InstVisitor Base; + friend class InstVisitor; + + /// The TargetTransformInfo available for this compilation. + const TargetTransformInfo &TTI; + + /// The cache of @llvm.assume intrinsics. + AssumptionCacheTracker *ACT; + + // The called function. + Function &F; + + // The candidate callsite being analyzed. Please do not use this to do + // analysis in the caller function; we want the inline cost query to be + // easily cacheable. Instead, use the cover function paramHasAttr. + CallSite CandidateCS; + + int Threshold; + int Cost; + + bool IsCallerRecursive; + bool IsRecursiveCall; + bool ExposesReturnsTwice; + bool HasDynamicAlloca; + bool ContainsNoDuplicateCall; + bool HasReturn; + bool HasIndirectBr; + bool HasFrameEscape; + + /// Number of bytes allocated statically by the callee. + uint64_t AllocatedSize; + unsigned NumInstructions, NumVectorInstructions; + int FiftyPercentVectorBonus, TenPercentVectorBonus; + int VectorBonus; + + // While we walk the potentially-inlined instructions, we build up and + // maintain a mapping of simplified values specific to this callsite. The + // idea is to propagate any special information we have about arguments to + // this call through the inlinable section of the function, and account for + // likely simplifications post-inlining. The most important aspect we track + // is CFG altering simplifications -- when we prove a basic block dead, that + // can cause dramatic shifts in the cost of inlining a function. + DenseMap SimplifiedValues; + + // Keep track of the values which map back (through function arguments) to + // allocas on the caller stack which could be simplified through SROA. + DenseMap SROAArgValues; + + // The mapping of caller Alloca values to their accumulated cost savings. If + // we have to disable SROA for one of the allocas, this tells us how much + // cost must be added. + DenseMap SROAArgCosts; + + // Keep track of values which map to a pointer base and constant offset. + DenseMap > ConstantOffsetPtrs; + + // Custom simplification helper routines. + bool isAllocaDerivedArg(Value *V); + bool lookupSROAArgAndCost(Value *V, Value *&Arg, + DenseMap::iterator &CostIt); + void disableSROA(DenseMap::iterator CostIt); + void disableSROA(Value *V); + void accumulateSROACost(DenseMap::iterator CostIt, + int InstructionCost); + bool isGEPOffsetConstant(GetElementPtrInst &GEP); + bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset); + bool simplifyCallSite(Function *F, CallSite CS); + ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V); + + /// Return true if the given argument to the function being considered for + /// inlining has the given attribute set either at the call site or the + /// function declaration. Primarily used to inspect call site specific + /// attributes since these can be more precise than the ones on the callee + /// itself. + bool paramHasAttr(Argument *A, Attribute::AttrKind Attr); + + /// Return true if the given value is known non null within the callee if + /// inlined through this particular callsite. + bool isKnownNonNullInCallee(Value *V); + + // Custom analysis routines. + bool analyzeBlock(BasicBlock *BB, SmallPtrSetImpl &EphValues); - if (AllOperandsConstant) { - // We will get to remove this instruction... - Reduction += InlineConstants::InstrCost; + // Disable several entry points to the visitor so we don't accidentally use + // them by declaring but not defining them here. + void visit(Module *); void visit(Module &); + void visit(Function *); void visit(Function &); + void visit(BasicBlock *); void visit(BasicBlock &); - // And any other instructions that use it which become constants - // themselves. - Reduction += CountCodeReductionForConstant(&Inst); + // Provide base case for our instruction visit. + bool visitInstruction(Instruction &I); + + // Our visit overrides. + bool visitAlloca(AllocaInst &I); + bool visitPHI(PHINode &I); + bool visitGetElementPtr(GetElementPtrInst &I); + bool visitBitCast(BitCastInst &I); + bool visitPtrToInt(PtrToIntInst &I); + bool visitIntToPtr(IntToPtrInst &I); + bool visitCastInst(CastInst &I); + bool visitUnaryInstruction(UnaryInstruction &I); + bool visitCmpInst(CmpInst &I); + bool visitSub(BinaryOperator &I); + bool visitBinaryOperator(BinaryOperator &I); + bool visitLoad(LoadInst &I); + bool visitStore(StoreInst &I); + bool visitExtractValue(ExtractValueInst &I); + bool visitInsertValue(InsertValueInst &I); + bool visitCallSite(CallSite CS); + bool visitReturnInst(ReturnInst &RI); + bool visitBranchInst(BranchInst &BI); + bool visitSwitchInst(SwitchInst &SI); + bool visitIndirectBrInst(IndirectBrInst &IBI); + bool visitResumeInst(ResumeInst &RI); + bool visitCleanupReturnInst(CleanupReturnInst &RI); + bool visitCatchReturnInst(CatchReturnInst &RI); + bool visitUnreachableInst(UnreachableInst &I); + +public: + CallAnalyzer(const TargetTransformInfo &TTI, AssumptionCacheTracker *ACT, + Function &Callee, int Threshold, CallSite CSArg) + : TTI(TTI), ACT(ACT), F(Callee), CandidateCS(CSArg), Threshold(Threshold), + Cost(0), IsCallerRecursive(false), IsRecursiveCall(false), + ExposesReturnsTwice(false), HasDynamicAlloca(false), + ContainsNoDuplicateCall(false), HasReturn(false), HasIndirectBr(false), + HasFrameEscape(false), AllocatedSize(0), NumInstructions(0), + NumVectorInstructions(0), FiftyPercentVectorBonus(0), + TenPercentVectorBonus(0), VectorBonus(0), NumConstantArgs(0), + NumConstantOffsetPtrArgs(0), NumAllocaArgs(0), NumConstantPtrCmps(0), + NumConstantPtrDiffs(0), NumInstructionsSimplified(0), + SROACostSavings(0), SROACostSavingsLost(0) {} + + bool analyzeCall(CallSite CS); + + int getThreshold() { return Threshold; } + int getCost() { return Cost; } + + // Keep a bunch of stats about the cost savings found so we can print them + // out when debugging. + unsigned NumConstantArgs; + unsigned NumConstantOffsetPtrArgs; + unsigned NumAllocaArgs; + unsigned NumConstantPtrCmps; + unsigned NumConstantPtrDiffs; + unsigned NumInstructionsSimplified; + unsigned SROACostSavings; + unsigned SROACostSavingsLost; + + void dump(); +}; + +} // namespace + +/// \brief Test whether the given value is an Alloca-derived function argument. +bool CallAnalyzer::isAllocaDerivedArg(Value *V) { + return SROAArgValues.count(V); +} + +/// \brief Lookup the SROA-candidate argument and cost iterator which V maps to. +/// Returns false if V does not map to a SROA-candidate. +bool CallAnalyzer::lookupSROAArgAndCost( + Value *V, Value *&Arg, DenseMap::iterator &CostIt) { + if (SROAArgValues.empty() || SROAArgCosts.empty()) + return false; + + DenseMap::iterator ArgIt = SROAArgValues.find(V); + if (ArgIt == SROAArgValues.end()) + return false; + + Arg = ArgIt->second; + CostIt = SROAArgCosts.find(Arg); + return CostIt != SROAArgCosts.end(); +} + +/// \brief Disable SROA for the candidate marked by this cost iterator. +/// +/// This marks the candidate as no longer viable for SROA, and adds the cost +/// savings associated with it back into the inline cost measurement. +void CallAnalyzer::disableSROA(DenseMap::iterator CostIt) { + // If we're no longer able to perform SROA we need to undo its cost savings + // and prevent subsequent analysis. + Cost += CostIt->second; + SROACostSavings -= CostIt->second; + SROACostSavingsLost += CostIt->second; + SROAArgCosts.erase(CostIt); +} + +/// \brief If 'V' maps to a SROA candidate, disable SROA for it. +void CallAnalyzer::disableSROA(Value *V) { + Value *SROAArg; + DenseMap::iterator CostIt; + if (lookupSROAArgAndCost(V, SROAArg, CostIt)) + disableSROA(CostIt); +} + +/// \brief Accumulate the given cost for a particular SROA candidate. +void CallAnalyzer::accumulateSROACost(DenseMap::iterator CostIt, + int InstructionCost) { + CostIt->second += InstructionCost; + SROACostSavings += InstructionCost; +} + +/// \brief Check whether a GEP's indices are all constant. +/// +/// Respects any simplified values known during the analysis of this callsite. +bool CallAnalyzer::isGEPOffsetConstant(GetElementPtrInst &GEP) { + for (User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); I != E; ++I) + if (!isa(*I) && !SimplifiedValues.lookup(*I)) + return false; + + return true; +} + +/// \brief Accumulate a constant GEP offset into an APInt if possible. +/// +/// Returns false if unable to compute the offset for any reason. Respects any +/// simplified values known during the analysis of this callsite. +bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) { + const DataLayout &DL = F.getParent()->getDataLayout(); + unsigned IntPtrWidth = DL.getPointerSizeInBits(); + assert(IntPtrWidth == Offset.getBitWidth()); + + for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP); + GTI != GTE; ++GTI) { + ConstantInt *OpC = dyn_cast(GTI.getOperand()); + if (!OpC) + if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand())) + OpC = dyn_cast(SimpleOp); + if (!OpC) + return false; + if (OpC->isZero()) continue; + + // Handle a struct index, which adds its field offset to the pointer. + if (StructType *STy = dyn_cast(*GTI)) { + unsigned ElementIdx = OpC->getZExtValue(); + const StructLayout *SL = DL.getStructLayout(STy); + Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx)); + continue; + } + + APInt TypeSize(IntPtrWidth, DL.getTypeAllocSize(GTI.getIndexedType())); + Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize; + } + return true; +} + +bool CallAnalyzer::visitAlloca(AllocaInst &I) { + // Check whether inlining will turn a dynamic alloca into a static + // alloca, and handle that case. + if (I.isArrayAllocation()) { + if (Constant *Size = SimplifiedValues.lookup(I.getArraySize())) { + ConstantInt *AllocSize = dyn_cast(Size); + assert(AllocSize && "Allocation size not a constant int?"); + Type *Ty = I.getAllocatedType(); + AllocatedSize += Ty->getPrimitiveSizeInBits() * AllocSize->getZExtValue(); + return Base::visitAlloca(I); + } + } + + // Accumulate the allocated size. + if (I.isStaticAlloca()) { + const DataLayout &DL = F.getParent()->getDataLayout(); + Type *Ty = I.getAllocatedType(); + AllocatedSize += DL.getTypeAllocSize(Ty); + } + + // We will happily inline static alloca instructions. + if (I.isStaticAlloca()) + return Base::visitAlloca(I); + + // FIXME: This is overly conservative. Dynamic allocas are inefficient for + // a variety of reasons, and so we would like to not inline them into + // functions which don't currently have a dynamic alloca. This simply + // disables inlining altogether in the presence of a dynamic alloca. + HasDynamicAlloca = true; + return false; +} + +bool CallAnalyzer::visitPHI(PHINode &I) { + // FIXME: We should potentially be tracking values through phi nodes, + // especially when they collapse to a single value due to deleted CFG edges + // during inlining. + + // FIXME: We need to propagate SROA *disabling* through phi nodes, even + // though we don't want to propagate it's bonuses. The idea is to disable + // SROA if it *might* be used in an inappropriate manner. + + // Phi nodes are always zero-cost. + return true; +} + +bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) { + Value *SROAArg; + DenseMap::iterator CostIt; + bool SROACandidate = lookupSROAArgAndCost(I.getPointerOperand(), + SROAArg, CostIt); + + // Try to fold GEPs of constant-offset call site argument pointers. This + // requires target data and inbounds GEPs. + if (I.isInBounds()) { + // Check if we have a base + offset for the pointer. + Value *Ptr = I.getPointerOperand(); + std::pair BaseAndOffset = ConstantOffsetPtrs.lookup(Ptr); + if (BaseAndOffset.first) { + // Check if the offset of this GEP is constant, and if so accumulate it + // into Offset. + if (!accumulateGEPOffset(cast(I), BaseAndOffset.second)) { + // Non-constant GEPs aren't folded, and disable SROA. + if (SROACandidate) + disableSROA(CostIt); + return false; } + + // Add the result as a new mapping to Base + Offset. + ConstantOffsetPtrs[&I] = BaseAndOffset; + + // Also handle SROA candidates here, we already know that the GEP is + // all-constant indexed. + if (SROACandidate) + SROAArgValues[&I] = SROAArg; + + return true; } } - return Reduction; + + if (isGEPOffsetConstant(I)) { + if (SROACandidate) + SROAArgValues[&I] = SROAArg; + + // Constant GEPs are modeled as free. + return true; + } + + // Variable GEPs will require math and will disable SROA. + if (SROACandidate) + disableSROA(CostIt); + return false; } -// CountCodeReductionForAlloca - Figure out an approximation of how much smaller -// the function will be if it is inlined into a context where an argument -// becomes an alloca. -// -unsigned InlineCostAnalyzer::FunctionInfo:: - CountCodeReductionForAlloca(Value *V) { - if (!V->getType()->isPointerTy()) return 0; // Not a pointer - unsigned Reduction = 0; - for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){ - Instruction *I = cast(*UI); - if (isa(I) || isa(I)) - Reduction += InlineConstants::InstrCost; - else if (GetElementPtrInst *GEP = dyn_cast(I)) { - // If the GEP has variable indices, we won't be able to do much with it. - if (GEP->hasAllConstantIndices()) - Reduction += CountCodeReductionForAlloca(GEP); - } else if (BitCastInst *BCI = dyn_cast(I)) { - // Track pointer through bitcasts. - Reduction += CountCodeReductionForAlloca(BCI); - } else { - // If there is some other strange instruction, we're not going to be able - // to do much if we inline this. - return 0; +bool CallAnalyzer::visitBitCast(BitCastInst &I) { + // Propagate constants through bitcasts. + Constant *COp = dyn_cast(I.getOperand(0)); + if (!COp) + COp = SimplifiedValues.lookup(I.getOperand(0)); + if (COp) + if (Constant *C = ConstantExpr::getBitCast(COp, I.getType())) { + SimplifiedValues[&I] = C; + return true; } + + // Track base/offsets through casts + std::pair BaseAndOffset + = ConstantOffsetPtrs.lookup(I.getOperand(0)); + // Casts don't change the offset, just wrap it up. + if (BaseAndOffset.first) + ConstantOffsetPtrs[&I] = BaseAndOffset; + + // Also look for SROA candidates here. + Value *SROAArg; + DenseMap::iterator CostIt; + if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) + SROAArgValues[&I] = SROAArg; + + // Bitcasts are always zero cost. + return true; +} + +bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) { + // Propagate constants through ptrtoint. + Constant *COp = dyn_cast(I.getOperand(0)); + if (!COp) + COp = SimplifiedValues.lookup(I.getOperand(0)); + if (COp) + if (Constant *C = ConstantExpr::getPtrToInt(COp, I.getType())) { + SimplifiedValues[&I] = C; + return true; + } + + // Track base/offset pairs when converted to a plain integer provided the + // integer is large enough to represent the pointer. + unsigned IntegerSize = I.getType()->getScalarSizeInBits(); + const DataLayout &DL = F.getParent()->getDataLayout(); + if (IntegerSize >= DL.getPointerSizeInBits()) { + std::pair BaseAndOffset + = ConstantOffsetPtrs.lookup(I.getOperand(0)); + if (BaseAndOffset.first) + ConstantOffsetPtrs[&I] = BaseAndOffset; } - return Reduction; + // This is really weird. Technically, ptrtoint will disable SROA. However, + // unless that ptrtoint is *used* somewhere in the live basic blocks after + // inlining, it will be nuked, and SROA should proceed. All of the uses which + // would block SROA would also block SROA if applied directly to a pointer, + // and so we can just add the integer in here. The only places where SROA is + // preserved either cannot fire on an integer, or won't in-and-of themselves + // disable SROA (ext) w/o some later use that we would see and disable. + Value *SROAArg; + DenseMap::iterator CostIt; + if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) + SROAArgValues[&I] = SROAArg; + + return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I); } -/// callIsSmall - If a call is likely to lower to a single target instruction, -/// or is otherwise deemed small return true. -/// TODO: Perhaps calls like memcpy, strcpy, etc? -bool llvm::callIsSmall(const Function *F) { - if (!F) return false; - - if (F->hasLocalLinkage()) return false; - - if (!F->hasName()) return false; - - StringRef Name = F->getName(); +bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) { + // Propagate constants through ptrtoint. + Constant *COp = dyn_cast(I.getOperand(0)); + if (!COp) + COp = SimplifiedValues.lookup(I.getOperand(0)); + if (COp) + if (Constant *C = ConstantExpr::getIntToPtr(COp, I.getType())) { + SimplifiedValues[&I] = C; + return true; + } + + // Track base/offset pairs when round-tripped through a pointer without + // modifications provided the integer is not too large. + Value *Op = I.getOperand(0); + unsigned IntegerSize = Op->getType()->getScalarSizeInBits(); + const DataLayout &DL = F.getParent()->getDataLayout(); + if (IntegerSize <= DL.getPointerSizeInBits()) { + std::pair BaseAndOffset = ConstantOffsetPtrs.lookup(Op); + if (BaseAndOffset.first) + ConstantOffsetPtrs[&I] = BaseAndOffset; + } + + // "Propagate" SROA here in the same manner as we do for ptrtoint above. + Value *SROAArg; + DenseMap::iterator CostIt; + if (lookupSROAArgAndCost(Op, SROAArg, CostIt)) + SROAArgValues[&I] = SROAArg; + + return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I); +} + +bool CallAnalyzer::visitCastInst(CastInst &I) { + // Propagate constants through ptrtoint. + Constant *COp = dyn_cast(I.getOperand(0)); + if (!COp) + COp = SimplifiedValues.lookup(I.getOperand(0)); + if (COp) + if (Constant *C = ConstantExpr::getCast(I.getOpcode(), COp, I.getType())) { + SimplifiedValues[&I] = C; + return true; + } + + // Disable SROA in the face of arbitrary casts we don't whitelist elsewhere. + disableSROA(I.getOperand(0)); + + return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I); +} + +bool CallAnalyzer::visitUnaryInstruction(UnaryInstruction &I) { + Value *Operand = I.getOperand(0); + Constant *COp = dyn_cast(Operand); + if (!COp) + COp = SimplifiedValues.lookup(Operand); + if (COp) { + const DataLayout &DL = F.getParent()->getDataLayout(); + if (Constant *C = ConstantFoldInstOperands(I.getOpcode(), I.getType(), + COp, DL)) { + SimplifiedValues[&I] = C; + return true; + } + } + + // Disable any SROA on the argument to arbitrary unary operators. + disableSROA(Operand); + + return false; +} + +bool CallAnalyzer::paramHasAttr(Argument *A, Attribute::AttrKind Attr) { + unsigned ArgNo = A->getArgNo(); + return CandidateCS.paramHasAttr(ArgNo+1, Attr); +} + +bool CallAnalyzer::isKnownNonNullInCallee(Value *V) { + // Does the *call site* have the NonNull attribute set on an argument? We + // use the attribute on the call site to memoize any analysis done in the + // caller. This will also trip if the callee function has a non-null + // parameter attribute, but that's a less interesting case because hopefully + // the callee would already have been simplified based on that. + if (Argument *A = dyn_cast(V)) + if (paramHasAttr(A, Attribute::NonNull)) + return true; - // These will all likely lower to a single selection DAG node. - if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" || - Name == "fabs" || Name == "fabsf" || Name == "fabsl" || - Name == "sin" || Name == "sinf" || Name == "sinl" || - Name == "cos" || Name == "cosf" || Name == "cosl" || - Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl" ) + // Is this an alloca in the caller? This is distinct from the attribute case + // above because attributes aren't updated within the inliner itself and we + // always want to catch the alloca derived case. + if (isAllocaDerivedArg(V)) + // We can actually predict the result of comparisons between an + // alloca-derived value and null. Note that this fires regardless of + // SROA firing. return true; - // These are all likely to be optimized into something smaller. - if (Name == "pow" || Name == "powf" || Name == "powl" || - Name == "exp2" || Name == "exp2l" || Name == "exp2f" || - Name == "floor" || Name == "floorf" || Name == "ceil" || - Name == "round" || Name == "ffs" || Name == "ffsl" || - Name == "abs" || Name == "labs" || Name == "llabs") + return false; +} + +bool CallAnalyzer::visitCmpInst(CmpInst &I) { + Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); + // First try to handle simplified comparisons. + if (!isa(LHS)) + if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS)) + LHS = SimpleLHS; + if (!isa(RHS)) + if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS)) + RHS = SimpleRHS; + if (Constant *CLHS = dyn_cast(LHS)) { + if (Constant *CRHS = dyn_cast(RHS)) + if (Constant *C = ConstantExpr::getCompare(I.getPredicate(), CLHS, CRHS)) { + SimplifiedValues[&I] = C; + return true; + } + } + + if (I.getOpcode() == Instruction::FCmp) + return false; + + // Otherwise look for a comparison between constant offset pointers with + // a common base. + Value *LHSBase, *RHSBase; + APInt LHSOffset, RHSOffset; + std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS); + if (LHSBase) { + std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS); + if (RHSBase && LHSBase == RHSBase) { + // We have common bases, fold the icmp to a constant based on the + // offsets. + Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset); + Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset); + if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) { + SimplifiedValues[&I] = C; + ++NumConstantPtrCmps; + return true; + } + } + } + + // If the comparison is an equality comparison with null, we can simplify it + // if we know the value (argument) can't be null + if (I.isEquality() && isa(I.getOperand(1)) && + isKnownNonNullInCallee(I.getOperand(0))) { + bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE; + SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType()) + : ConstantInt::getFalse(I.getType()); return true; - + } + // Finally check for SROA candidates in comparisons. + Value *SROAArg; + DenseMap::iterator CostIt; + if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) { + if (isa(I.getOperand(1))) { + accumulateSROACost(CostIt, InlineConstants::InstrCost); + return true; + } + + disableSROA(CostIt); + } + return false; } -/// analyzeBasicBlock - Fill in the current structure with information gleaned -/// from the specified block. -void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB) { - ++NumBlocks; - unsigned NumInstsBeforeThisBB = NumInsts; - for (BasicBlock::const_iterator II = BB->begin(), E = BB->end(); - II != E; ++II) { - if (isa(II)) continue; // PHI nodes don't count. - - // Special handling for calls. - if (isa(II) || isa(II)) { - if (isa(II)) - continue; // Debug intrinsics don't count as size. - - CallSite CS = CallSite::get(const_cast(&*II)); - - // If this function contains a call to setjmp or _setjmp, never inline - // it. This is a hack because we depend on the user marking their local - // variables as volatile if they are live across a setjmp call, and they - // probably won't do this in callers. - if (Function *F = CS.getCalledFunction()) { - if (F->isDeclaration() && - (F->getName() == "setjmp" || F->getName() == "_setjmp")) - NeverInline = true; - - // If this call is to function itself, then the function is recursive. - // Inlining it into other functions is a bad idea, because this is - // basically just a form of loop peeling, and our metrics aren't useful - // for that case. - if (F == BB->getParent()) - NeverInline = true; +bool CallAnalyzer::visitSub(BinaryOperator &I) { + // Try to handle a special case: we can fold computing the difference of two + // constant-related pointers. + Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); + Value *LHSBase, *RHSBase; + APInt LHSOffset, RHSOffset; + std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS); + if (LHSBase) { + std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS); + if (RHSBase && LHSBase == RHSBase) { + // We have common bases, fold the subtract to a constant based on the + // offsets. + Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset); + Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset); + if (Constant *C = ConstantExpr::getSub(CLHS, CRHS)) { + SimplifiedValues[&I] = C; + ++NumConstantPtrDiffs; + return true; } + } + } + + // Otherwise, fall back to the generic logic for simplifying and handling + // instructions. + return Base::visitSub(I); +} + +bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) { + Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); + const DataLayout &DL = F.getParent()->getDataLayout(); + if (!isa(LHS)) + if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS)) + LHS = SimpleLHS; + if (!isa(RHS)) + if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS)) + RHS = SimpleRHS; + Value *SimpleV = nullptr; + if (auto FI = dyn_cast(&I)) + SimpleV = + SimplifyFPBinOp(I.getOpcode(), LHS, RHS, FI->getFastMathFlags(), DL); + else + SimpleV = SimplifyBinOp(I.getOpcode(), LHS, RHS, DL); + + if (Constant *C = dyn_cast_or_null(SimpleV)) { + SimplifiedValues[&I] = C; + return true; + } + + // Disable any SROA on arguments to arbitrary, unsimplified binary operators. + disableSROA(LHS); + disableSROA(RHS); + + return false; +} + +bool CallAnalyzer::visitLoad(LoadInst &I) { + Value *SROAArg; + DenseMap::iterator CostIt; + if (lookupSROAArgAndCost(I.getPointerOperand(), SROAArg, CostIt)) { + if (I.isSimple()) { + accumulateSROACost(CostIt, InlineConstants::InstrCost); + return true; + } + + disableSROA(CostIt); + } + + return false; +} + +bool CallAnalyzer::visitStore(StoreInst &I) { + Value *SROAArg; + DenseMap::iterator CostIt; + if (lookupSROAArgAndCost(I.getPointerOperand(), SROAArg, CostIt)) { + if (I.isSimple()) { + accumulateSROACost(CostIt, InlineConstants::InstrCost); + return true; + } + + disableSROA(CostIt); + } + + return false; +} + +bool CallAnalyzer::visitExtractValue(ExtractValueInst &I) { + // Constant folding for extract value is trivial. + Constant *C = dyn_cast(I.getAggregateOperand()); + if (!C) + C = SimplifiedValues.lookup(I.getAggregateOperand()); + if (C) { + SimplifiedValues[&I] = ConstantExpr::getExtractValue(C, I.getIndices()); + return true; + } + + // SROA can look through these but give them a cost. + return false; +} + +bool CallAnalyzer::visitInsertValue(InsertValueInst &I) { + // Constant folding for insert value is trivial. + Constant *AggC = dyn_cast(I.getAggregateOperand()); + if (!AggC) + AggC = SimplifiedValues.lookup(I.getAggregateOperand()); + Constant *InsertedC = dyn_cast(I.getInsertedValueOperand()); + if (!InsertedC) + InsertedC = SimplifiedValues.lookup(I.getInsertedValueOperand()); + if (AggC && InsertedC) { + SimplifiedValues[&I] = ConstantExpr::getInsertValue(AggC, InsertedC, + I.getIndices()); + return true; + } + + // SROA can look through these but give them a cost. + return false; +} + +/// \brief Try to simplify a call site. +/// +/// Takes a concrete function and callsite and tries to actually simplify it by +/// analyzing the arguments and call itself with instsimplify. Returns true if +/// it has simplified the callsite to some other entity (a constant), making it +/// free. +bool CallAnalyzer::simplifyCallSite(Function *F, CallSite CS) { + // FIXME: Using the instsimplify logic directly for this is inefficient + // because we have to continually rebuild the argument list even when no + // simplifications can be performed. Until that is fixed with remapping + // inside of instsimplify, directly constant fold calls here. + if (!canConstantFoldCallTo(F)) + return false; + + // Try to re-map the arguments to constants. + SmallVector ConstantArgs; + ConstantArgs.reserve(CS.arg_size()); + for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); + I != E; ++I) { + Constant *C = dyn_cast(*I); + if (!C) + C = dyn_cast_or_null(SimplifiedValues.lookup(*I)); + if (!C) + return false; // This argument doesn't map to a constant. + + ConstantArgs.push_back(C); + } + if (Constant *C = ConstantFoldCall(F, ConstantArgs)) { + SimplifiedValues[CS.getInstruction()] = C; + return true; + } + + return false; +} + +bool CallAnalyzer::visitCallSite(CallSite CS) { + if (CS.hasFnAttr(Attribute::ReturnsTwice) && + !F.hasFnAttribute(Attribute::ReturnsTwice)) { + // This aborts the entire analysis. + ExposesReturnsTwice = true; + return false; + } + if (CS.isCall() && + cast(CS.getInstruction())->cannotDuplicate()) + ContainsNoDuplicateCall = true; - if (!isa(II) && !callIsSmall(CS.getCalledFunction())) { - // Each argument to a call takes on average one instruction to set up. - NumInsts += CS.arg_size(); - ++NumCalls; + if (Function *F = CS.getCalledFunction()) { + // When we have a concrete function, first try to simplify it directly. + if (simplifyCallSite(F, CS)) + return true; + + // Next check if it is an intrinsic we know about. + // FIXME: Lift this into part of the InstVisitor. + if (IntrinsicInst *II = dyn_cast(CS.getInstruction())) { + switch (II->getIntrinsicID()) { + default: + return Base::visitCallSite(CS); + + case Intrinsic::memset: + case Intrinsic::memcpy: + case Intrinsic::memmove: + // SROA can usually chew through these intrinsics, but they aren't free. + return false; + case Intrinsic::localescape: + HasFrameEscape = true; + return false; } } - - if (const AllocaInst *AI = dyn_cast(II)) { - if (!AI->isStaticAlloca()) - this->usesDynamicAlloca = true; + + if (F == CS.getInstruction()->getParent()->getParent()) { + // This flag will fully abort the analysis, so don't bother with anything + // else. + IsRecursiveCall = true; + return false; } - if (isa(II) || II->getType()->isVectorTy()) - ++NumVectorInsts; - - if (const CastInst *CI = dyn_cast(II)) { - // Noop casts, including ptr <-> int, don't count. - if (CI->isLosslessCast() || isa(CI) || - isa(CI)) - continue; - // Result of a cmp instruction is often extended (to be used by other - // cmp instructions, logical or return instructions). These are usually - // nop on most sane targets. - if (isa(CI->getOperand(0))) - continue; - } else if (const GetElementPtrInst *GEPI = dyn_cast(II)){ - // If a GEP has all constant indices, it will probably be folded with - // a load/store. - if (GEPI->hasAllConstantIndices()) - continue; + if (TTI.isLoweredToCall(F)) { + // We account for the average 1 instruction per call argument setup + // here. + Cost += CS.arg_size() * InlineConstants::InstrCost; + + // Everything other than inline ASM will also have a significant cost + // merely from making the call. + if (!isa(CS.getCalledValue())) + Cost += InlineConstants::CallPenalty; } - ++NumInsts; + return Base::visitCallSite(CS); } - - if (isa(BB->getTerminator())) - ++NumRets; - + + // Otherwise we're in a very special case -- an indirect function call. See + // if we can be particularly clever about this. + Value *Callee = CS.getCalledValue(); + + // First, pay the price of the argument setup. We account for the average + // 1 instruction per call argument setup here. + Cost += CS.arg_size() * InlineConstants::InstrCost; + + // Next, check if this happens to be an indirect function call to a known + // function in this inline context. If not, we've done all we can. + Function *F = dyn_cast_or_null(SimplifiedValues.lookup(Callee)); + if (!F) + return Base::visitCallSite(CS); + + // If we have a constant that we are calling as a function, we can peer + // through it and see the function target. This happens not infrequently + // during devirtualization and so we want to give it a hefty bonus for + // inlining, but cap that bonus in the event that inlining wouldn't pan + // out. Pretend to inline the function, with a custom threshold. + CallAnalyzer CA(TTI, ACT, *F, InlineConstants::IndirectCallThreshold, CS); + if (CA.analyzeCall(CS)) { + // We were able to inline the indirect call! Subtract the cost from the + // threshold to get the bonus we want to apply, but don't go below zero. + Cost -= std::max(0, CA.getThreshold() - CA.getCost()); + } + + return Base::visitCallSite(CS); +} + +bool CallAnalyzer::visitReturnInst(ReturnInst &RI) { + // At least one return instruction will be free after inlining. + bool Free = !HasReturn; + HasReturn = true; + return Free; +} + +bool CallAnalyzer::visitBranchInst(BranchInst &BI) { + // We model unconditional branches as essentially free -- they really + // shouldn't exist at all, but handling them makes the behavior of the + // inliner more regular and predictable. Interestingly, conditional branches + // which will fold away are also free. + return BI.isUnconditional() || isa(BI.getCondition()) || + dyn_cast_or_null( + SimplifiedValues.lookup(BI.getCondition())); +} + +bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) { + // We model unconditional switches as free, see the comments on handling + // branches. + if (isa(SI.getCondition())) + return true; + if (Value *V = SimplifiedValues.lookup(SI.getCondition())) + if (isa(V)) + return true; + + // Otherwise, we need to accumulate a cost proportional to the number of + // distinct successor blocks. This fan-out in the CFG cannot be represented + // for free even if we can represent the core switch as a jumptable that + // takes a single instruction. + // + // NB: We convert large switches which are just used to initialize large phi + // nodes to lookup tables instead in simplify-cfg, so this shouldn't prevent + // inlining those. It will prevent inlining in cases where the optimization + // does not (yet) fire. + SmallPtrSet SuccessorBlocks; + SuccessorBlocks.insert(SI.getDefaultDest()); + for (auto I = SI.case_begin(), E = SI.case_end(); I != E; ++I) + SuccessorBlocks.insert(I.getCaseSuccessor()); + // Add cost corresponding to the number of distinct destinations. The first + // we model as free because of fallthrough. + Cost += (SuccessorBlocks.size() - 1) * InlineConstants::InstrCost; + return false; +} + +bool CallAnalyzer::visitIndirectBrInst(IndirectBrInst &IBI) { // We never want to inline functions that contain an indirectbr. This is // incorrect because all the blockaddress's (in static global initializers - // for example) would be referring to the original function, and this indirect - // jump would jump from the inlined copy of the function into the original - // function which is extremely undefined behavior. - if (isa(BB->getTerminator())) - NeverInline = true; - - // Remember NumInsts for this BB. - NumBBInsts[BB] = NumInsts - NumInstsBeforeThisBB; -} - -/// analyzeFunction - Fill in the current structure with information gleaned -/// from the specified function. -void CodeMetrics::analyzeFunction(Function *F) { - // Look at the size of the callee. - for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) - analyzeBasicBlock(&*BB); -} - -/// analyzeFunction - Fill in the current structure with information gleaned -/// from the specified function. -void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F) { - Metrics.analyzeFunction(F); - - // A function with exactly one return has it removed during the inlining - // process (see InlineFunction), so don't count it. - // FIXME: This knowledge should really be encoded outside of FunctionInfo. - if (Metrics.NumRets==1) - --Metrics.NumInsts; - - // Don't bother calculating argument weights if we are never going to inline - // the function anyway. - if (Metrics.NeverInline) - return; - - // Check out all of the arguments to the function, figuring out how much - // code can be eliminated if one of the arguments is a constant. - ArgumentWeights.reserve(F->arg_size()); - for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) - ArgumentWeights.push_back(ArgInfo(CountCodeReductionForConstant(I), - CountCodeReductionForAlloca(I))); -} - -// getInlineCost - The heuristic used to determine if we should inline the -// function call or not. -// -InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, - SmallPtrSet &NeverInline) { - return getInlineCost(CS, CS.getCalledFunction(), NeverInline); + // for example) would be referring to the original function, and this + // indirect jump would jump from the inlined copy of the function into the + // original function which is extremely undefined behavior. + // FIXME: This logic isn't really right; we can safely inline functions with + // indirectbr's as long as no other function or global references the + // blockaddress of a block within the current function. + HasIndirectBr = true; + return false; +} + +bool CallAnalyzer::visitResumeInst(ResumeInst &RI) { + // FIXME: It's not clear that a single instruction is an accurate model for + // the inline cost of a resume instruction. + return false; } -InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, - Function *Callee, - SmallPtrSet &NeverInline) { - Instruction *TheCall = CS.getInstruction(); - Function *Caller = TheCall->getParent()->getParent(); - bool isDirectCall = CS.getCalledFunction() == Callee; +bool CallAnalyzer::visitCleanupReturnInst(CleanupReturnInst &CRI) { + // FIXME: It's not clear that a single instruction is an accurate model for + // the inline cost of a cleanupret instruction. + return false; +} - // Don't inline functions which can be redefined at link-time to mean - // something else. Don't inline functions marked noinline or call sites - // marked noinline. - if (Callee->mayBeOverridden() || - Callee->hasFnAttr(Attribute::NoInline) || NeverInline.count(Callee) || - CS.isNoInline()) - return llvm::InlineCost::getNever(); +bool CallAnalyzer::visitCatchReturnInst(CatchReturnInst &CRI) { + // FIXME: It's not clear that a single instruction is an accurate model for + // the inline cost of a catchret instruction. + return false; +} - // InlineCost - This value measures how good of an inline candidate this call - // site is to inline. A lower inline cost make is more likely for the call to - // be inlined. This value may go negative. +bool CallAnalyzer::visitUnreachableInst(UnreachableInst &I) { + // FIXME: It might be reasonably to discount the cost of instructions leading + // to unreachable as they have the lowest possible impact on both runtime and + // code size. + return true; // No actual code is needed for unreachable. +} + +bool CallAnalyzer::visitInstruction(Instruction &I) { + // Some instructions are free. All of the free intrinsics can also be + // handled by SROA, etc. + if (TargetTransformInfo::TCC_Free == TTI.getUserCost(&I)) + return true; + + // We found something we don't understand or can't handle. Mark any SROA-able + // values in the operand list as no longer viable. + for (User::op_iterator OI = I.op_begin(), OE = I.op_end(); OI != OE; ++OI) + disableSROA(*OI); + + return false; +} + + +/// \brief Analyze a basic block for its contribution to the inline cost. +/// +/// This method walks the analyzer over every instruction in the given basic +/// block and accounts for their cost during inlining at this callsite. It +/// aborts early if the threshold has been exceeded or an impossible to inline +/// construct has been detected. It returns false if inlining is no longer +/// viable, and true if inlining remains viable. +bool CallAnalyzer::analyzeBlock(BasicBlock *BB, + SmallPtrSetImpl &EphValues) { + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { + // FIXME: Currently, the number of instructions in a function regardless of + // our ability to simplify them during inline to constants or dead code, + // are actually used by the vector bonus heuristic. As long as that's true, + // we have to special case debug intrinsics here to prevent differences in + // inlining due to debug symbols. Eventually, the number of unsimplified + // instructions shouldn't factor into the cost computation, but until then, + // hack around it here. + if (isa(I)) + continue; + + // Skip ephemeral values. + if (EphValues.count(&*I)) + continue; + + ++NumInstructions; + if (isa(I) || I->getType()->isVectorTy()) + ++NumVectorInstructions; + + // If the instruction is floating point, and the target says this operation + // is expensive or the function has the "use-soft-float" attribute, this may + // eventually become a library call. Treat the cost as such. + if (I->getType()->isFloatingPointTy()) { + bool hasSoftFloatAttr = false; + + // If the function has the "use-soft-float" attribute, mark it as + // expensive. + if (F.hasFnAttribute("use-soft-float")) { + Attribute Attr = F.getFnAttribute("use-soft-float"); + StringRef Val = Attr.getValueAsString(); + if (Val == "true") + hasSoftFloatAttr = true; + } + + if (TTI.getFPOpCost(I->getType()) == TargetTransformInfo::TCC_Expensive || + hasSoftFloatAttr) + Cost += InlineConstants::CallPenalty; + } + + // If the instruction simplified to a constant, there is no cost to this + // instruction. Visit the instructions using our InstVisitor to account for + // all of the per-instruction logic. The visit tree returns true if we + // consumed the instruction in any way, and false if the instruction's base + // cost should count against inlining. + if (Base::visit(&*I)) + ++NumInstructionsSimplified; + else + Cost += InlineConstants::InstrCost; + + // If the visit this instruction detected an uninlinable pattern, abort. + if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca || + HasIndirectBr || HasFrameEscape) + return false; + + // If the caller is a recursive function then we don't want to inline + // functions which allocate a lot of stack space because it would increase + // the caller stack usage dramatically. + if (IsCallerRecursive && + AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller) + return false; + + // Check if we've past the maximum possible threshold so we don't spin in + // huge basic blocks that will never inline. + if (Cost > Threshold) + return false; + } + + return true; +} + +/// \brief Compute the base pointer and cumulative constant offsets for V. +/// +/// This strips all constant offsets off of V, leaving it the base pointer, and +/// accumulates the total constant offset applied in the returned constant. It +/// returns 0 if V is not a pointer, and returns the constant '0' if there are +/// no constant offsets applied. +ConstantInt *CallAnalyzer::stripAndComputeInBoundsConstantOffsets(Value *&V) { + if (!V->getType()->isPointerTy()) + return nullptr; + + const DataLayout &DL = F.getParent()->getDataLayout(); + unsigned IntPtrWidth = DL.getPointerSizeInBits(); + APInt Offset = APInt::getNullValue(IntPtrWidth); + + // Even though we don't look through PHI nodes, we could be called on an + // instruction in an unreachable block, which may be on a cycle. + SmallPtrSet Visited; + Visited.insert(V); + do { + if (GEPOperator *GEP = dyn_cast(V)) { + if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset)) + return nullptr; + V = GEP->getPointerOperand(); + } else if (Operator::getOpcode(V) == Instruction::BitCast) { + V = cast(V)->getOperand(0); + } else if (GlobalAlias *GA = dyn_cast(V)) { + if (GA->mayBeOverridden()) + break; + V = GA->getAliasee(); + } else { + break; + } + assert(V->getType()->isPointerTy() && "Unexpected operand type!"); + } while (Visited.insert(V).second); + + Type *IntPtrTy = DL.getIntPtrType(V->getContext()); + return cast(ConstantInt::get(IntPtrTy, Offset)); +} + +/// \brief Analyze a call site for potential inlining. +/// +/// Returns true if inlining this call is viable, and false if it is not +/// viable. It computes the cost and adjusts the threshold based on numerous +/// factors and heuristics. If this method returns false but the computed cost +/// is below the computed threshold, then inlining was forcibly disabled by +/// some artifact of the routine. +bool CallAnalyzer::analyzeCall(CallSite CS) { + ++NumCallsAnalyzed; + + // Perform some tweaks to the cost and threshold based on the direct + // callsite information. + + // We want to more aggressively inline vector-dense kernels, so up the + // threshold, and we'll lower it if the % of vector instructions gets too + // low. Note that these bonuses are some what arbitrary and evolved over time + // by accident as much as because they are principled bonuses. // - int InlineCost = 0; + // FIXME: It would be nice to remove all such bonuses. At least it would be + // nice to base the bonus values on something more scientific. + assert(NumInstructions == 0); + assert(NumVectorInstructions == 0); + FiftyPercentVectorBonus = 3 * Threshold / 2; + TenPercentVectorBonus = 3 * Threshold / 4; + const DataLayout &DL = F.getParent()->getDataLayout(); + + // Track whether the post-inlining function would have more than one basic + // block. A single basic block is often intended for inlining. Balloon the + // threshold by 50% until we pass the single-BB phase. + bool SingleBB = true; + int SingleBBBonus = Threshold / 2; + + // Speculatively apply all possible bonuses to Threshold. If cost exceeds + // this Threshold any time, and cost cannot decrease, we can stop processing + // the rest of the function body. + Threshold += (SingleBBBonus + FiftyPercentVectorBonus); + + // Give out bonuses per argument, as the instructions setting them up will + // be gone after inlining. + for (unsigned I = 0, E = CS.arg_size(); I != E; ++I) { + if (CS.isByValArgument(I)) { + // We approximate the number of loads and stores needed by dividing the + // size of the byval type by the target's pointer size. + PointerType *PTy = cast(CS.getArgument(I)->getType()); + unsigned TypeSize = DL.getTypeSizeInBits(PTy->getElementType()); + unsigned PointerSize = DL.getPointerSizeInBits(); + // Ceiling division. + unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize; + + // If it generates more than 8 stores it is likely to be expanded as an + // inline memcpy so we take that as an upper bound. Otherwise we assume + // one load and one store per word copied. + // FIXME: The maxStoresPerMemcpy setting from the target should be used + // here instead of a magic number of 8, but it's not available via + // DataLayout. + NumStores = std::min(NumStores, 8U); + + Cost -= 2 * NumStores * InlineConstants::InstrCost; + } else { + // For non-byval arguments subtract off one instruction per call + // argument. + Cost -= InlineConstants::InstrCost; + } + } // If there is only one call of the function, and it has internal linkage, - // make it almost guaranteed to be inlined. - // - if (Callee->hasLocalLinkage() && Callee->hasOneUse() && isDirectCall) - InlineCost += InlineConstants::LastCallToStaticBonus; - - // If this function uses the coldcc calling convention, prefer not to inline - // it. - if (Callee->getCallingConv() == CallingConv::Cold) - InlineCost += InlineConstants::ColdccPenalty; - + // the cost of inlining it drops dramatically. + bool OnlyOneCallAndLocalLinkage = F.hasLocalLinkage() && F.hasOneUse() && + &F == CS.getCalledFunction(); + if (OnlyOneCallAndLocalLinkage) + Cost += InlineConstants::LastCallToStaticBonus; + // If the instruction after the call, or if the normal destination of the - // invoke is an unreachable instruction, the function is noreturn. As such, - // there is little point in inlining this. - if (InvokeInst *II = dyn_cast(TheCall)) { + // invoke is an unreachable instruction, the function is noreturn. As such, + // there is little point in inlining this unless there is literally zero + // cost. + Instruction *Instr = CS.getInstruction(); + if (InvokeInst *II = dyn_cast(Instr)) { if (isa(II->getNormalDest()->begin())) - InlineCost += InlineConstants::NoreturnPenalty; - } else if (isa(++BasicBlock::iterator(TheCall))) - InlineCost += InlineConstants::NoreturnPenalty; - - // Get information about the callee. - FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee]; - - // If we haven't calculated this information yet, do so now. - if (CalleeFI->Metrics.NumBlocks == 0) - CalleeFI->analyzeFunction(Callee); + Threshold = 0; + } else if (isa(++BasicBlock::iterator(Instr))) + Threshold = 0; - // If we should never inline this, return a huge cost. - if (CalleeFI->Metrics.NeverInline) - return InlineCost::getNever(); + // If this function uses the coldcc calling convention, prefer not to inline + // it. + if (F.getCallingConv() == CallingConv::Cold) + Cost += InlineConstants::ColdccPenalty; - // FIXME: It would be nice to kill off CalleeFI->NeverInline. Then we - // could move this up and avoid computing the FunctionInfo for - // things we are going to just return always inline for. This - // requires handling setjmp somewhere else, however. - if (!Callee->isDeclaration() && Callee->hasFnAttr(Attribute::AlwaysInline)) - return InlineCost::getAlways(); - - if (CalleeFI->Metrics.usesDynamicAlloca) { - // Get infomation about the caller. - FunctionInfo &CallerFI = CachedFunctionInfo[Caller]; - - // If we haven't calculated this information yet, do so now. - if (CallerFI.Metrics.NumBlocks == 0) { - CallerFI.analyzeFunction(Caller); - - // Recompute the CalleeFI pointer, getting Caller could have invalidated - // it. - CalleeFI = &CachedFunctionInfo[Callee]; + // Check if we're done. This can happen due to bonuses and penalties. + if (Cost > Threshold) + return false; + + if (F.empty()) + return true; + + Function *Caller = CS.getInstruction()->getParent()->getParent(); + // Check if the caller function is recursive itself. + for (User *U : Caller->users()) { + CallSite Site(U); + if (!Site) + continue; + Instruction *I = Site.getInstruction(); + if (I->getParent()->getParent() == Caller) { + IsCallerRecursive = true; + break; } + } - // Don't inline a callee with dynamic alloca into a caller without them. - // Functions containing dynamic alloca's are inefficient in various ways; - // don't create more inefficiency. - if (!CallerFI.Metrics.usesDynamicAlloca) - return InlineCost::getNever(); + // Populate our simplified values by mapping from function arguments to call + // arguments with known important simplifications. + CallSite::arg_iterator CAI = CS.arg_begin(); + for (Function::arg_iterator FAI = F.arg_begin(), FAE = F.arg_end(); + FAI != FAE; ++FAI, ++CAI) { + assert(CAI != CS.arg_end()); + if (Constant *C = dyn_cast(CAI)) + SimplifiedValues[&*FAI] = C; + + Value *PtrArg = *CAI; + if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) { + ConstantOffsetPtrs[&*FAI] = std::make_pair(PtrArg, C->getValue()); + + // We can SROA any pointer arguments derived from alloca instructions. + if (isa(PtrArg)) { + SROAArgValues[&*FAI] = PtrArg; + SROAArgCosts[PtrArg] = 0; + } + } } + NumConstantArgs = SimplifiedValues.size(); + NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size(); + NumAllocaArgs = SROAArgValues.size(); - // Add to the inline quality for properties that make the call valuable to - // inline. This includes factors that indicate that the result of inlining - // the function will be optimizable. Currently this just looks at arguments - // passed into the function. - // - unsigned ArgNo = 0; - for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); - I != E; ++I, ++ArgNo) { - // Each argument passed in has a cost at both the caller and the callee - // sides. Measurements show that each argument costs about the same as an - // instruction. - InlineCost -= InlineConstants::InstrCost; - - // If an alloca is passed in, inlining this function is likely to allow - // significant future optimization possibilities (like scalar promotion, and - // scalarization), so encourage the inlining of the function. - // - if (isa(I)) { - if (ArgNo < CalleeFI->ArgumentWeights.size()) - InlineCost -= CalleeFI->ArgumentWeights[ArgNo].AllocaWeight; - - // If this is a constant being passed into the function, use the argument - // weights calculated for the callee to determine how much will be folded - // away with this information. - } else if (isa(I)) { - if (ArgNo < CalleeFI->ArgumentWeights.size()) - InlineCost -= CalleeFI->ArgumentWeights[ArgNo].ConstantWeight; + // FIXME: If a caller has multiple calls to a callee, we end up recomputing + // the ephemeral values multiple times (and they're completely determined by + // the callee, so this is purely duplicate work). + SmallPtrSet EphValues; + CodeMetrics::collectEphemeralValues(&F, &ACT->getAssumptionCache(F), EphValues); + + // The worklist of live basic blocks in the callee *after* inlining. We avoid + // adding basic blocks of the callee which can be proven to be dead for this + // particular call site in order to get more accurate cost estimates. This + // requires a somewhat heavyweight iteration pattern: we need to walk the + // basic blocks in a breadth-first order as we insert live successors. To + // accomplish this, prioritizing for small iterations because we exit after + // crossing our threshold, we use a small-size optimized SetVector. + typedef SetVector, + SmallPtrSet > BBSetVector; + BBSetVector BBWorklist; + BBWorklist.insert(&F.getEntryBlock()); + // Note that we *must not* cache the size, this loop grows the worklist. + for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) { + // Bail out the moment we cross the threshold. This means we'll under-count + // the cost, but only when undercounting doesn't matter. + if (Cost > Threshold) + break; + + BasicBlock *BB = BBWorklist[Idx]; + if (BB->empty()) + continue; + + // Disallow inlining a blockaddress. A blockaddress only has defined + // behavior for an indirect branch in the same function, and we do not + // currently support inlining indirect branches. But, the inliner may not + // see an indirect branch that ends up being dead code at a particular call + // site. If the blockaddress escapes the function, e.g., via a global + // variable, inlining may lead to an invalid cross-function reference. + if (BB->hasAddressTaken()) + return false; + + // Analyze the cost of this block. If we blow through the threshold, this + // returns false, and we can bail on out. + if (!analyzeBlock(BB, EphValues)) { + if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca || + HasIndirectBr || HasFrameEscape) + return false; + + // If the caller is a recursive function then we don't want to inline + // functions which allocate a lot of stack space because it would increase + // the caller stack usage dramatically. + if (IsCallerRecursive && + AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller) + return false; + + break; + } + + TerminatorInst *TI = BB->getTerminator(); + + // Add in the live successors by first checking whether we have terminator + // that may be simplified based on the values simplified by this call. + if (BranchInst *BI = dyn_cast(TI)) { + if (BI->isConditional()) { + Value *Cond = BI->getCondition(); + if (ConstantInt *SimpleCond + = dyn_cast_or_null(SimplifiedValues.lookup(Cond))) { + BBWorklist.insert(BI->getSuccessor(SimpleCond->isZero() ? 1 : 0)); + continue; + } + } + } else if (SwitchInst *SI = dyn_cast(TI)) { + Value *Cond = SI->getCondition(); + if (ConstantInt *SimpleCond + = dyn_cast_or_null(SimplifiedValues.lookup(Cond))) { + BBWorklist.insert(SI->findCaseValue(SimpleCond).getCaseSuccessor()); + continue; + } + } + + // If we're unable to select a particular successor, just count all of + // them. + for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize; + ++TIdx) + BBWorklist.insert(TI->getSuccessor(TIdx)); + + // If we had any successors at this point, than post-inlining is likely to + // have them as well. Note that we assume any basic blocks which existed + // due to branches or switches which folded above will also fold after + // inlining. + if (SingleBB && TI->getNumSuccessors() > 1) { + // Take off the bonus we applied to the threshold. + Threshold -= SingleBBBonus; + SingleBB = false; } } - - // Now that we have considered all of the factors that make the call site more - // likely to be inlined, look at factors that make us not want to inline it. - // Calls usually take a long time, so they make the inlining gain smaller. - InlineCost += CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty; + // If this is a noduplicate call, we can still inline as long as + // inlining this would cause the removal of the caller (so the instruction + // is not actually duplicated, just moved). + if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall) + return false; - // Look at the size of the callee. Each instruction counts as 5. - InlineCost += CalleeFI->Metrics.NumInsts*InlineConstants::InstrCost; + // We applied the maximum possible vector bonus at the beginning. Now, + // subtract the excess bonus, if any, from the Threshold before + // comparing against Cost. + if (NumVectorInstructions <= NumInstructions / 10) + Threshold -= FiftyPercentVectorBonus; + else if (NumVectorInstructions <= NumInstructions / 2) + Threshold -= (FiftyPercentVectorBonus - TenPercentVectorBonus); - return llvm::InlineCost::get(InlineCost); + return Cost <= std::max(0, Threshold); } -// getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a -// higher threshold to determine if the function call should be inlined. -float InlineCostAnalyzer::getInlineFudgeFactor(CallSite CS) { - Function *Callee = CS.getCalledFunction(); - - // Get information about the callee. - FunctionInfo &CalleeFI = CachedFunctionInfo[Callee]; - - // If we haven't calculated this information yet, do so now. - if (CalleeFI.Metrics.NumBlocks == 0) - CalleeFI.analyzeFunction(Callee); - - float Factor = 1.0f; - // Single BB functions are often written to be inlined. - if (CalleeFI.Metrics.NumBlocks == 1) - Factor += 0.5f; - - // Be more aggressive if the function contains a good chunk (if it mades up - // at least 10% of the instructions) of vector instructions. - if (CalleeFI.Metrics.NumVectorInsts > CalleeFI.Metrics.NumInsts/2) - Factor += 2.0f; - else if (CalleeFI.Metrics.NumVectorInsts > CalleeFI.Metrics.NumInsts/10) - Factor += 1.5f; - return Factor; -} - -/// growCachedCostInfo - update the cached cost info for Caller after Callee has -/// been inlined. -void -InlineCostAnalyzer::growCachedCostInfo(Function *Caller, Function *Callee) { - CodeMetrics &CallerMetrics = CachedFunctionInfo[Caller].Metrics; - - // For small functions we prefer to recalculate the cost for better accuracy. - if (CallerMetrics.NumBlocks < 10 || CallerMetrics.NumInsts < 1000) { - resetCachedCostInfo(Caller); - return; - } +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +/// \brief Dump stats about this call's analysis. +void CallAnalyzer::dump() { +#define DEBUG_PRINT_STAT(x) dbgs() << " " #x ": " << x << "\n" + DEBUG_PRINT_STAT(NumConstantArgs); + DEBUG_PRINT_STAT(NumConstantOffsetPtrArgs); + DEBUG_PRINT_STAT(NumAllocaArgs); + DEBUG_PRINT_STAT(NumConstantPtrCmps); + DEBUG_PRINT_STAT(NumConstantPtrDiffs); + DEBUG_PRINT_STAT(NumInstructionsSimplified); + DEBUG_PRINT_STAT(NumInstructions); + DEBUG_PRINT_STAT(SROACostSavings); + DEBUG_PRINT_STAT(SROACostSavingsLost); + DEBUG_PRINT_STAT(ContainsNoDuplicateCall); + DEBUG_PRINT_STAT(Cost); + DEBUG_PRINT_STAT(Threshold); +#undef DEBUG_PRINT_STAT +} +#endif - // For large functions, we can save a lot of computation time by skipping - // recalculations. - if (CallerMetrics.NumCalls > 0) - --CallerMetrics.NumCalls; +INITIALIZE_PASS_BEGIN(InlineCostAnalysis, "inline-cost", "Inline Cost Analysis", + true, true) +INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass) +INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) +INITIALIZE_PASS_END(InlineCostAnalysis, "inline-cost", "Inline Cost Analysis", + true, true) - if (Callee == 0) return; - - CodeMetrics &CalleeMetrics = CachedFunctionInfo[Callee].Metrics; - - // If we don't have metrics for the callee, don't recalculate them just to - // update an approximation in the caller. Instead, just recalculate the - // caller info from scratch. - if (CalleeMetrics.NumBlocks == 0) { - resetCachedCostInfo(Caller); - return; +char InlineCostAnalysis::ID = 0; + +InlineCostAnalysis::InlineCostAnalysis() : CallGraphSCCPass(ID) {} + +InlineCostAnalysis::~InlineCostAnalysis() {} + +void InlineCostAnalysis::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesAll(); + AU.addRequired(); + AU.addRequired(); + CallGraphSCCPass::getAnalysisUsage(AU); +} + +bool InlineCostAnalysis::runOnSCC(CallGraphSCC &SCC) { + TTIWP = &getAnalysis(); + ACT = &getAnalysis(); + return false; +} + +InlineCost InlineCostAnalysis::getInlineCost(CallSite CS, int Threshold) { + return getInlineCost(CS, CS.getCalledFunction(), Threshold); +} + +/// \brief Test that two functions either have or have not the given attribute +/// at the same time. +template +static bool attributeMatches(Function *F1, Function *F2, AttrKind Attr) { + return F1->getFnAttribute(Attr) == F2->getFnAttribute(Attr); +} + +/// \brief Test that there are no attribute conflicts between Caller and Callee +/// that prevent inlining. +static bool functionsHaveCompatibleAttributes(Function *Caller, + Function *Callee, + TargetTransformInfo &TTI) { + return TTI.areInlineCompatible(Caller, Callee) && + attributeMatches(Caller, Callee, Attribute::SanitizeAddress) && + attributeMatches(Caller, Callee, Attribute::SanitizeMemory) && + attributeMatches(Caller, Callee, Attribute::SanitizeThread); +} + +InlineCost InlineCostAnalysis::getInlineCost(CallSite CS, Function *Callee, + int Threshold) { + // Cannot inline indirect calls. + if (!Callee) + return llvm::InlineCost::getNever(); + + // Calls to functions with always-inline attributes should be inlined + // whenever possible. + if (CS.hasFnAttr(Attribute::AlwaysInline)) { + if (isInlineViable(*Callee)) + return llvm::InlineCost::getAlways(); + return llvm::InlineCost::getNever(); } - - // Since CalleeMetrics were already calculated, we know that the CallerMetrics - // reference isn't invalidated: both were in the DenseMap. - CallerMetrics.NeverInline |= CalleeMetrics.NeverInline; - CallerMetrics.usesDynamicAlloca |= CalleeMetrics.usesDynamicAlloca; - - CallerMetrics.NumInsts += CalleeMetrics.NumInsts; - CallerMetrics.NumBlocks += CalleeMetrics.NumBlocks; - CallerMetrics.NumCalls += CalleeMetrics.NumCalls; - CallerMetrics.NumVectorInsts += CalleeMetrics.NumVectorInsts; - CallerMetrics.NumRets += CalleeMetrics.NumRets; - - // analyzeBasicBlock counts each function argument as an inst. - if (CallerMetrics.NumInsts >= Callee->arg_size()) - CallerMetrics.NumInsts -= Callee->arg_size(); - else - CallerMetrics.NumInsts = 0; - - // We are not updating the argument weights. We have already determined that - // Caller is a fairly large function, so we accept the loss of precision. + + // Never inline functions with conflicting attributes (unless callee has + // always-inline attribute). + if (!functionsHaveCompatibleAttributes(CS.getCaller(), Callee, + TTIWP->getTTI(*Callee))) + return llvm::InlineCost::getNever(); + + // Don't inline this call if the caller has the optnone attribute. + if (CS.getCaller()->hasFnAttribute(Attribute::OptimizeNone)) + return llvm::InlineCost::getNever(); + + // Don't inline functions which can be redefined at link-time to mean + // something else. Don't inline functions marked noinline or call sites + // marked noinline. + if (Callee->mayBeOverridden() || + Callee->hasFnAttribute(Attribute::NoInline) || CS.isNoInline()) + return llvm::InlineCost::getNever(); + + DEBUG(llvm::dbgs() << " Analyzing call of " << Callee->getName() + << "...\n"); + + CallAnalyzer CA(TTIWP->getTTI(*Callee), ACT, *Callee, Threshold, CS); + bool ShouldInline = CA.analyzeCall(CS); + + DEBUG(CA.dump()); + + // Check if there was a reason to force inlining or no inlining. + if (!ShouldInline && CA.getCost() < CA.getThreshold()) + return InlineCost::getNever(); + if (ShouldInline && CA.getCost() >= CA.getThreshold()) + return InlineCost::getAlways(); + + return llvm::InlineCost::get(CA.getCost(), CA.getThreshold()); } -/// clear - empty the cache of inline costs -void InlineCostAnalyzer::clear() { - CachedFunctionInfo.clear(); +bool InlineCostAnalysis::isInlineViable(Function &F) { + bool ReturnsTwice = F.hasFnAttribute(Attribute::ReturnsTwice); + for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) { + // Disallow inlining of functions which contain indirect branches or + // blockaddresses. + if (isa(BI->getTerminator()) || BI->hasAddressTaken()) + return false; + + for (auto &II : *BI) { + CallSite CS(&II); + if (!CS) + continue; + + // Disallow recursive calls. + if (&F == CS.getCalledFunction()) + return false; + + // Disallow calls which expose returns-twice to a function not previously + // attributed as such. + if (!ReturnsTwice && CS.isCall() && + cast(CS.getInstruction())->canReturnTwice()) + return false; + + // Disallow inlining functions that call @llvm.localescape. Doing this + // correctly would require major changes to the inliner. + if (CS.getCalledFunction() && + CS.getCalledFunction()->getIntrinsicID() == + llvm::Intrinsic::localescape) + return false; + } + } + + return true; }