+++ /dev/null
-//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements inline cost analysis.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Analysis/InlineCost.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;
-
-#define DEBUG_TYPE "inline-cost"
-
-STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed");
-
-namespace {
-
-class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
- typedef InstVisitor<CallAnalyzer, bool> Base;
- friend class InstVisitor<CallAnalyzer, bool>;
-
- /// 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<Value *, Constant *> 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<Value *, Value *> 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<Value *, int> SROAArgCosts;
-
- // Keep track of values which map to a pointer base and constant offset.
- DenseMap<Value *, std::pair<Value *, APInt> > ConstantOffsetPtrs;
-
- // Custom simplification helper routines.
- bool isAllocaDerivedArg(Value *V);
- bool lookupSROAArgAndCost(Value *V, Value *&Arg,
- DenseMap<Value *, int>::iterator &CostIt);
- void disableSROA(DenseMap<Value *, int>::iterator CostIt);
- void disableSROA(Value *V);
- void accumulateSROACost(DenseMap<Value *, int>::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<const Value *> &EphValues);
-
- // 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 &);
-
- // 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<Value *, int>::iterator &CostIt) {
- if (SROAArgValues.empty() || SROAArgCosts.empty())
- return false;
-
- DenseMap<Value *, Value *>::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<Value *, int>::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<Value *, int>::iterator CostIt;
- if (lookupSROAArgAndCost(V, SROAArg, CostIt))
- disableSROA(CostIt);
-}
-
-/// \brief Accumulate the given cost for a particular SROA candidate.
-void CallAnalyzer::accumulateSROACost(DenseMap<Value *, int>::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<Constant>(*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<ConstantInt>(GTI.getOperand());
- if (!OpC)
- if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand()))
- OpC = dyn_cast<ConstantInt>(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<StructType>(*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<ConstantInt>(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<Value *, int>::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<Value *, APInt> 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<GEPOperator>(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;
- }
- }
-
- 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;
-}
-
-bool CallAnalyzer::visitBitCast(BitCastInst &I) {
- // Propagate constants through bitcasts.
- Constant *COp = dyn_cast<Constant>(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<Value *, APInt> 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<Value *, int>::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<Constant>(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<Value *, APInt> BaseAndOffset
- = ConstantOffsetPtrs.lookup(I.getOperand(0));
- if (BaseAndOffset.first)
- ConstantOffsetPtrs[&I] = BaseAndOffset;
- }
-
- // 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<Value *, int>::iterator CostIt;
- if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
- SROAArgValues[&I] = SROAArg;
-
- return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
-}
-
-bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
- // Propagate constants through ptrtoint.
- Constant *COp = dyn_cast<Constant>(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<Value *, APInt> 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<Value *, int>::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<Constant>(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<Constant>(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<Argument>(V))
- if (paramHasAttr(A, Attribute::NonNull))
- return true;
-
- // 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;
-
- return false;
-}
-
-bool CallAnalyzer::visitCmpInst(CmpInst &I) {
- Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
- // First try to handle simplified comparisons.
- if (!isa<Constant>(LHS))
- if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
- LHS = SimpleLHS;
- if (!isa<Constant>(RHS))
- if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
- RHS = SimpleRHS;
- if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
- if (Constant *CRHS = dyn_cast<Constant>(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<ConstantPointerNull>(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<Value *, int>::iterator CostIt;
- if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
- if (isa<ConstantPointerNull>(I.getOperand(1))) {
- accumulateSROACost(CostIt, InlineConstants::InstrCost);
- return true;
- }
-
- disableSROA(CostIt);
- }
-
- return false;
-}
-
-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<Constant>(LHS))
- if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
- LHS = SimpleLHS;
- if (!isa<Constant>(RHS))
- if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
- RHS = SimpleRHS;
- Value *SimpleV = nullptr;
- if (auto FI = dyn_cast<FPMathOperator>(&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<Constant>(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<Value *, int>::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<Value *, int>::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<Constant>(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<Constant>(I.getAggregateOperand());
- if (!AggC)
- AggC = SimplifiedValues.lookup(I.getAggregateOperand());
- Constant *InsertedC = dyn_cast<Constant>(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<Constant *, 4> 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<Constant>(*I);
- if (!C)
- C = dyn_cast_or_null<Constant>(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<CallInst>(CS.getInstruction())->cannotDuplicate())
- ContainsNoDuplicateCall = true;
-
- 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<IntrinsicInst>(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 (F == CS.getInstruction()->getParent()->getParent()) {
- // This flag will fully abort the analysis, so don't bother with anything
- // else.
- IsRecursiveCall = true;
- return false;
- }
-
- 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<InlineAsm>(CS.getCalledValue()))
- Cost += InlineConstants::CallPenalty;
- }
-
- return Base::visitCallSite(CS);
- }
-
- // 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<Function>(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
- // bonus we want to apply, but don't go below zero.
- Cost -= std::max(0, InlineConstants::IndirectCallThreshold - 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<ConstantInt>(BI.getCondition()) ||
- dyn_cast_or_null<ConstantInt>(
- SimplifiedValues.lookup(BI.getCondition()));
-}
-
-bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
- // We model unconditional switches as free, see the comments on handling
- // branches.
- if (isa<ConstantInt>(SI.getCondition()))
- return true;
- if (Value *V = SimplifiedValues.lookup(SI.getCondition()))
- if (isa<ConstantInt>(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<BasicBlock *, 8> 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.
- // 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;
-}
-
-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;
-}
-
-bool CallAnalyzer::visitCatchReturnInst(CatchReturnInst &CRI) {
- // FIXME: It's not clear that a single instruction is an accurate model for
- // the inline cost of a cleanupret instruction.
- return false;
-}
-
-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<const Value *> &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<DbgInfoIntrinsic>(I))
- continue;
-
- // Skip ephemeral values.
- if (EphValues.count(I))
- continue;
-
- ++NumInstructions;
- if (isa<ExtractElementInst>(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<Value *, 4> Visited;
- Visited.insert(V);
- do {
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
- if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset))
- return nullptr;
- V = GEP->getPointerOperand();
- } else if (Operator::getOpcode(V) == Instruction::BitCast) {
- V = cast<Operator>(V)->getOperand(0);
- } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(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>(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.
- //
- // 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<PointerType>(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,
- // 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 unless there is literally zero
- // cost.
- Instruction *Instr = CS.getInstruction();
- if (InvokeInst *II = dyn_cast<InvokeInst>(Instr)) {
- if (isa<UnreachableInst>(II->getNormalDest()->begin()))
- Threshold = 0;
- } else if (isa<UnreachableInst>(++BasicBlock::iterator(Instr)))
- Threshold = 0;
-
- // If this function uses the coldcc calling convention, prefer not to inline
- // it.
- if (F.getCallingConv() == CallingConv::Cold)
- Cost += InlineConstants::ColdccPenalty;
-
- // 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;
- }
- }
-
- // 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<Constant>(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<AllocaInst>(PtrArg)) {
- SROAArgValues[FAI] = PtrArg;
- SROAArgCosts[PtrArg] = 0;
- }
- }
- }
- NumConstantArgs = SimplifiedValues.size();
- NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
- NumAllocaArgs = SROAArgValues.size();
-
- // 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<const Value *, 32> 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<BasicBlock *, SmallVector<BasicBlock *, 16>,
- SmallPtrSet<BasicBlock *, 16> > 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<BranchInst>(TI)) {
- if (BI->isConditional()) {
- Value *Cond = BI->getCondition();
- if (ConstantInt *SimpleCond
- = dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
- BBWorklist.insert(BI->getSuccessor(SimpleCond->isZero() ? 1 : 0));
- continue;
- }
- }
- } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
- Value *Cond = SI->getCondition();
- if (ConstantInt *SimpleCond
- = dyn_cast_or_null<ConstantInt>(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;
- }
- }
-
- // 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;
-
- // 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 Cost < Threshold;
-}
-
-#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
-
-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)
-
-char InlineCostAnalysis::ID = 0;
-
-InlineCostAnalysis::InlineCostAnalysis() : CallGraphSCCPass(ID) {}
-
-InlineCostAnalysis::~InlineCostAnalysis() {}
-
-void InlineCostAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesAll();
- AU.addRequired<AssumptionCacheTracker>();
- AU.addRequired<TargetTransformInfoWrapperPass>();
- CallGraphSCCPass::getAnalysisUsage(AU);
-}
-
-bool InlineCostAnalysis::runOnSCC(CallGraphSCC &SCC) {
- TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
- ACT = &getAnalysis<AssumptionCacheTracker>();
- 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<typename AttrKind>
-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();
- }
-
- // 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());
-}
-
-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<IndirectBrInst>(BI->getTerminator()) || BI->hasAddressTaken())
- return false;
-
- for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;
- ++II) {
- 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<CallInst>(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;
-}
projects / oota-llvm.git / blobdiff