//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "inline-cost"
#include "llvm/Analysis/InlineCost.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/InstVisitor.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/CallingConv.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/Operator.h"
+#include "llvm/GlobalAlias.h"
+#include "llvm/DataLayout.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.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)
- if (isa<BranchInst>(*UI) || isa<SwitchInst>(*UI)) {
- // We will be able to eliminate all but one of the successors.
- const TerminatorInst &TI = cast<TerminatorInst>(**UI);
- 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<CallInst>(*UI)) {
- // 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<InvokeInst>(*UI)) {
- // 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<Instruction>(**UI);
-
- // 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<AllocaInst>(Inst))
- continue;
+STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed");
- bool AllOperandsConstant = true;
- for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i)
- if (!isa<Constant>(Inst.getOperand(i)) && Inst.getOperand(i) != V) {
- AllOperandsConstant = false;
- break;
- }
+namespace {
+
+class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
+ typedef InstVisitor<CallAnalyzer, bool> Base;
+ friend class InstVisitor<CallAnalyzer, bool>;
+
+ // DataLayout if available, or null.
+ const DataLayout *const TD;
+
+ // The called function.
+ Function &F;
+
+ int Threshold;
+ int Cost;
+ const bool AlwaysInline;
+
+ bool IsCallerRecursive;
+ bool IsRecursiveCall;
+ bool ExposesReturnsTwice;
+ bool HasDynamicAlloca;
+ /// 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 handleSROACandidate(bool IsSROAValid,
+ DenseMap<Value *, int>::iterator CostIt,
+ int InstructionCost);
+ bool isGEPOffsetConstant(GetElementPtrInst &GEP);
+ bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
+ ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);
+
+ // Custom analysis routines.
+ bool analyzeBlock(BasicBlock *BB);
+
+ // 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 visitICmp(ICmpInst &I);
+ bool visitSub(BinaryOperator &I);
+ bool visitBinaryOperator(BinaryOperator &I);
+ bool visitLoad(LoadInst &I);
+ bool visitStore(StoreInst &I);
+ bool visitCallSite(CallSite CS);
+
+public:
+ CallAnalyzer(const DataLayout *TD, Function &Callee, int Threshold)
+ : TD(TD), F(Callee), Threshold(Threshold), Cost(0),
+ AlwaysInline(F.getFnAttributes().hasAttribute(Attributes::AlwaysInline)),
+ IsCallerRecursive(false), IsRecursiveCall(false),
+ ExposesReturnsTwice(false), HasDynamicAlloca(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; }
+ bool isAlwaysInline() { return AlwaysInline; }
+
+ // 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 Helper for the common pattern of handling a SROA candidate.
+/// Either accumulates the cost savings if the SROA remains valid, or disables
+/// SROA for the candidate.
+bool CallAnalyzer::handleSROACandidate(bool IsSROAValid,
+ DenseMap<Value *, int>::iterator CostIt,
+ int InstructionCost) {
+ if (IsSROAValid) {
+ accumulateSROACost(CostIt, InstructionCost);
+ return true;
+ }
+
+ disableSROA(CostIt);
+ return false;
+}
+
+/// \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) {
+ if (!TD)
+ return false;
+
+ unsigned AS = GEP.getPointerAddressSpace();
+ unsigned IntPtrWidth = TD->getPointerSizeInBits(AS);
+ 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 = TD->getStructLayout(STy);
+ Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
+ continue;
+ }
+
+ APInt TypeSize(IntPtrWidth, TD->getTypeAllocSize(GTI.getIndexedType()));
+ Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
+ }
+ return true;
+}
+
+bool CallAnalyzer::visitAlloca(AllocaInst &I) {
+ // FIXME: Check whether inlining will turn a dynamic alloca into a static
+ // alloca, and handle that case.
- if (AllOperandsConstant) {
- // We will get to remove this instruction...
- Reduction += InlineConstants::InstrCost;
+ // Accumulate the allocated size.
+ if (I.isStaticAlloca()) {
+ Type *Ty = I.getAllocatedType();
+ AllocatedSize += (TD ? TD->getTypeAllocSize(Ty) :
+ Ty->getPrimitiveSizeInBits());
+ }
+
+ // We will happily inline static alloca instructions or dynamic alloca
+ // instructions in always-inline situations.
+ if (AlwaysInline || 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.
- // And any other instructions that use it which become constants
- // themselves.
- Reduction += CountCodeReductionForConstant(&Inst);
+ // 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 (TD && 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.
+ if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ if (Constant *C = ConstantExpr::getBitCast(COp, I.getType())) {
+ SimplifiedValues[&I] = C;
+ return true;
}
- return Reduction;
+ // 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;
}
-// 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<Instruction>(*UI);
- if (isa<LoadInst>(I) || isa<StoreInst>(I))
- Reduction += InlineConstants::InstrCost;
- else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(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<BitCastInst>(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::visitPtrToInt(PtrToIntInst &I) {
+ // Propagate constants through ptrtoint.
+ if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ 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();
+ unsigned AS = I.getPointerAddressSpace();
+ if (TD && IntegerSize >= TD->getPointerSizeInBits(AS)) {
+ 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 isInstructionFree(&I, TD);
+}
+
+bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
+ // Propagate constants through ptrtoint.
+ if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ 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();
+ unsigned AS = I.getAddressSpace();
+ if (TD && IntegerSize <= TD->getPointerSizeInBits(AS)) {
+ std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Op);
+ if (BaseAndOffset.first)
+ ConstantOffsetPtrs[&I] = BaseAndOffset;
}
- return Reduction;
+ // "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 isInstructionFree(&I, TD);
}
-// 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?
-static bool callIsSmall(const Function *F) {
- if (!F) return false;
-
- if (F->hasLocalLinkage()) return false;
-
- if (!F->hasName()) return false;
-
- StringRef Name = F->getName();
-
- // These will all likely lower to a single selection DAG node.
- if (Name == "copysign" || Name == "copysignf" ||
- Name == "fabs" || Name == "fabsf" || Name == "fabsl" ||
- Name == "sin" || Name == "sinf" || Name == "sinl" ||
- Name == "cos" || Name == "cosf" || Name == "cosl" ||
- Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl" )
- 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 true;
-
+bool CallAnalyzer::visitCastInst(CastInst &I) {
+ // Propagate constants through ptrtoint.
+ if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ 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 isInstructionFree(&I, TD);
+}
+
+bool CallAnalyzer::visitUnaryInstruction(UnaryInstruction &I) {
+ Value *Operand = I.getOperand(0);
+ Constant *Ops[1] = { dyn_cast<Constant>(Operand) };
+ if (Ops[0] || (Ops[0] = SimplifiedValues.lookup(Operand)))
+ if (Constant *C = ConstantFoldInstOperands(I.getOpcode(), I.getType(),
+ Ops, TD)) {
+ SimplifiedValues[&I] = C;
+ return true;
+ }
+
+ // Disable any SROA on the argument to arbitrary unary operators.
+ disableSROA(Operand);
+
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<PHINode>(II)) continue; // PHI nodes don't count.
-
- // Special handling for calls.
- if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
- if (isa<DbgInfoIntrinsic>(II))
- continue; // Debug intrinsics don't count as size.
-
- CallSite CS = CallSite::get(const_cast<Instruction*>(&*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 (!isa<IntrinsicInst>(II) && !callIsSmall(CS.getCalledFunction())) {
- // Each argument to a call takes on average one instruction to set up.
- NumInsts += CS.arg_size();
- ++NumCalls;
+bool CallAnalyzer::visitICmp(ICmpInst &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::getICmp(I.getPredicate(), CLHS, CRHS)) {
+ SimplifiedValues[&I] = C;
+ return true;
+ }
+
+ // Otherwise look for a comparison between constant offset pointers with
+ // a common base.
+ Value *LHSBase, *RHSBase;
+ APInt LHSOffset, RHSOffset;
+ llvm::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
+ if (LHSBase) {
+ llvm::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 (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
- if (!AI->isStaticAlloca())
- this->usesDynamicAlloca = true;
+ }
+
+ // If the comparison is an equality comparison with null, we can simplify it
+ // for any alloca-derived argument.
+ if (I.isEquality() && isa<ConstantPointerNull>(I.getOperand(1)))
+ if (isAllocaDerivedArg(I.getOperand(0))) {
+ // We can actually predict the result of comparisons between an
+ // alloca-derived value and null. Note that this fires regardless of
+ // SROA firing.
+ bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE;
+ SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType())
+ : ConstantInt::getFalse(I.getType());
+ return true;
}
- if (isa<ExtractElementInst>(II) || II->getType()->isVectorTy())
- ++NumVectorInsts;
-
- if (const CastInst *CI = dyn_cast<CastInst>(II)) {
- // Noop casts, including ptr <-> int, don't count.
- if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
- isa<PtrToIntInst>(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<CmpInst>(CI->getOperand(0)))
- continue;
- } else if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(II)){
- // If a GEP has all constant indices, it will probably be folded with
- // a load/store.
- if (GEPI->hasAllConstantIndices())
- continue;
+ // 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;
}
- ++NumInsts;
+ 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;
+ llvm::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
+ if (LHSBase) {
+ llvm::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;
+ }
+ }
}
-
- if (isa<ReturnInst>(BB->getTerminator()))
- ++NumRets;
-
- // 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<IndirectBrInst>(BB->getTerminator()))
- NeverInline = true;
-
- // Remember NumInsts for this BB.
- NumBBInsts[BB] = NumInsts - NumInstsBeforeThisBB;
+
+ // Otherwise, fall back to the generic logic for simplifying and handling
+ // instructions.
+ return Base::visitSub(I);
}
-/// 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);
+bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) {
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+ 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 = SimplifyBinOp(I.getOpcode(), LHS, RHS, TD);
+ 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;
}
-/// 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)));
+bool CallAnalyzer::visitLoad(LoadInst &I) {
+ Value *SROAArg;
+ DenseMap<Value *, int>::iterator CostIt;
+ if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
+ if (I.isSimple()) {
+ accumulateSROACost(CostIt, InlineConstants::InstrCost);
+ return true;
+ }
+
+ disableSROA(CostIt);
+ }
+
+ return false;
}
-// getInlineCost - The heuristic used to determine if we should inline the
-// function call or not.
-//
-InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
- SmallPtrSet<const Function *, 16> &NeverInline) {
- Instruction *TheCall = CS.getInstruction();
- Function *Callee = CS.getCalledFunction();
- Function *Caller = TheCall->getParent()->getParent();
+bool CallAnalyzer::visitStore(StoreInst &I) {
+ Value *SROAArg;
+ DenseMap<Value *, int>::iterator CostIt;
+ if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
+ if (I.isSimple()) {
+ accumulateSROACost(CostIt, InlineConstants::InstrCost);
+ return true;
+ }
- // Don't inline functions which can be redefined at link-time to mean
- // something else. Don't inline functions marked noinline.
- if (Callee->mayBeOverridden() ||
- Callee->hasFnAttr(Attribute::NoInline) || NeverInline.count(Callee))
- return llvm::InlineCost::getNever();
+ disableSROA(CostIt);
+ }
- // 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.
- //
- int InlineCost = 0;
-
- // 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())
- InlineCost += InlineConstants::LastCallToStaticBonus;
-
- // If this function uses the coldcc calling convention, prefer not to inline
- // it.
- if (Callee->getCallingConv() == CallingConv::Cold)
- InlineCost += InlineConstants::ColdccPenalty;
-
- // 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<InvokeInst>(TheCall)) {
- if (isa<UnreachableInst>(II->getNormalDest()->begin()))
- InlineCost += InlineConstants::NoreturnPenalty;
- } else if (isa<UnreachableInst>(++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);
-
- // If we should never inline this, return a huge cost.
- if (CalleeFI.Metrics.NeverInline)
- return InlineCost::getNever();
+ return false;
+}
- // 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);
-
- // 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();
+bool CallAnalyzer::visitCallSite(CallSite CS) {
+ if (CS.isCall() && cast<CallInst>(CS.getInstruction())->canReturnTwice() &&
+ !F.getFnAttributes().hasAttribute(Attributes::ReturnsTwice)) {
+ // This aborts the entire analysis.
+ ExposesReturnsTwice = true;
+ return false;
+ }
+
+ 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;
+ }
}
- // 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<AllocaInst>(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<Constant>(I)) {
- if (ArgNo < CalleeFI.ArgumentWeights.size())
- InlineCost -= CalleeFI.ArgumentWeights[ArgNo].ConstantWeight;
+ if (Function *F = CS.getCalledFunction()) {
+ 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 (!callIsSmall(CS)) {
+ // 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(TD, *F, InlineConstants::IndirectCallThreshold);
+ 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());
}
-
- // 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;
+ return Base::visitCallSite(CS);
+}
+
+bool CallAnalyzer::visitInstruction(Instruction &I) {
+ // Some instructions are free. All of the free intrinsics can also be
+ // handled by SROA, etc.
+ if (isInstructionFree(&I, TD))
+ 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) {
+ for (BasicBlock::iterator I = BB->begin(), E = llvm::prior(BB->end());
+ I != E; ++I) {
+ ++NumInstructions;
+ if (isa<ExtractElementInst>(I) || I->getType()->isVectorTy())
+ ++NumVectorInstructions;
+
+ // 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)
+ return false;
- // Look at the size of the callee. Each instruction counts as 5.
- InlineCost += CalleeFI.Metrics.NumInsts*InlineConstants::InstrCost;
+ // 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;
- return llvm::InlineCost::get(InlineCost);
+ if (NumVectorInstructions > NumInstructions/2)
+ VectorBonus = FiftyPercentVectorBonus;
+ else if (NumVectorInstructions > NumInstructions/10)
+ VectorBonus = TenPercentVectorBonus;
+ else
+ VectorBonus = 0;
+
+ // Check if we've past the threshold so we don't spin in huge basic
+ // blocks that will never inline.
+ if (!AlwaysInline && Cost > (Threshold + VectorBonus))
+ return false;
+ }
+
+ return true;
}
-// 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;
+/// \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 (!TD || !V->getType()->isPointerTy())
+ return 0;
+
+ unsigned AS = cast<PointerType>(V->getType())->getAddressSpace();;
+ unsigned IntPtrWidth = TD->getPointerSizeInBits(AS);
+ 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 0;
+ 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));
+
+ Type *IntPtrTy = TD->getIntPtrType(V->getContext());
+ return cast<ConstantInt>(ConstantInt::get(IntPtrTy, Offset));
}
-/// growCachedCostInfo - update the cached cost info for Caller after Callee has
-/// been inlined.
-void
-InlineCostAnalyzer::growCachedCostInfo(Function* Caller, Function* Callee) {
- FunctionInfo &CallerFI = CachedFunctionInfo[Caller];
+/// \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 rountine.
+bool CallAnalyzer::analyzeCall(CallSite CS) {
+ ++NumCallsAnalyzed;
+
+ // 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;
+ Threshold += SingleBBBonus;
+
+ // Unless we are always-inlining, perform some tweaks to the cost and
+ // threshold based on the direct callsite information.
+ if (!AlwaysInline) {
+ // 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.
+ assert(NumInstructions == 0);
+ assert(NumVectorInstructions == 0);
+ FiftyPercentVectorBonus = Threshold;
+ TenPercentVectorBonus = Threshold / 2;
+
+ // 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 (TD && 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 = TD->getTypeSizeInBits(PTy->getElementType());
+ unsigned AS = PTy->getAddressSpace();
+ unsigned PointerSize = TD->getPointerSizeInBits(AS);
+ // 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.
+ if (F.hasLocalLinkage() && F.hasOneUse() && &F == CS.getCalledFunction())
+ 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 = 1;
+ } else if (isa<UnreachableInst>(++BasicBlock::iterator(Instr)))
+ Threshold = 1;
+
+ // 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;
- // For small functions we prefer to recalculate the cost for better accuracy.
- if (CallerFI.Metrics.NumBlocks < 10 || CallerFI.Metrics.NumInsts < 1000) {
- resetCachedCostInfo(Caller);
- return;
+ Function *Caller = CS.getInstruction()->getParent()->getParent();
+ // Check if the caller function is recursive itself.
+ for (Value::use_iterator U = Caller->use_begin(), E = Caller->use_end();
+ U != E; ++U) {
+ CallSite Site(cast<Value>(*U));
+ if (!Site)
+ continue;
+ Instruction *I = Site.getInstruction();
+ if (I->getParent()->getParent() == Caller) {
+ IsCallerRecursive = true;
+ break;
+ }
}
- // For large functions, we can save a lot of computation time by skipping
- // recalculations.
- if (CallerFI.Metrics.NumCalls > 0)
- --CallerFI.Metrics.NumCalls;
+ // Track whether we've seen a return instruction. The first return
+ // instruction is free, as at least one will usually disappear in inlining.
+ bool HasReturn = false;
+
+ // 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;
- if (Callee) {
- FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
- if (!CalleeFI.Metrics.NumBlocks) {
- resetCachedCostInfo(Caller);
- return;
+ 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;
+ }
}
- CallerFI.Metrics.NeverInline |= CalleeFI.Metrics.NeverInline;
- CallerFI.Metrics.usesDynamicAlloca |= CalleeFI.Metrics.usesDynamicAlloca;
-
- CallerFI.Metrics.NumInsts += CalleeFI.Metrics.NumInsts;
- CallerFI.Metrics.NumBlocks += CalleeFI.Metrics.NumBlocks;
- CallerFI.Metrics.NumCalls += CalleeFI.Metrics.NumCalls;
- CallerFI.Metrics.NumVectorInsts += CalleeFI.Metrics.NumVectorInsts;
- CallerFI.Metrics.NumRets += CalleeFI.Metrics.NumRets;
-
- // analyzeBasicBlock counts each function argument as an inst.
- if (CallerFI.Metrics.NumInsts >= Callee->arg_size())
- CallerFI.Metrics.NumInsts -= Callee->arg_size();
+ }
+ NumConstantArgs = SimplifiedValues.size();
+ NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
+ NumAllocaArgs = SROAArgValues.size();
+
+ // 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 (!AlwaysInline && Cost > (Threshold + VectorBonus))
+ break;
+
+ BasicBlock *BB = BBWorklist[Idx];
+ if (BB->empty())
+ continue;
+
+ // Handle the terminator cost here where we can track returns and other
+ // function-wide constructs.
+ TerminatorInst *TI = BB->getTerminator();
+
+ // 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. And as a QOI issue,
+ // if someone is using a blockaddress without an indirectbr, and that
+ // reference somehow ends up in another function or global, we probably
+ // don't want to inline this function.
+ if (isa<IndirectBrInst>(TI))
+ return false;
+
+ if (!HasReturn && isa<ReturnInst>(TI))
+ HasReturn = true;
else
- CallerFI.Metrics.NumInsts = 0;
+ Cost += InlineConstants::InstrCost;
+
+ // Analyze the cost of this block. If we blow through the threshold, this
+ // returns false, and we can bail on out.
+ if (!analyzeBlock(BB)) {
+ if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca)
+ 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;
+ }
+
+ // 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;
+ }
}
- // We are not updating the argumentweights. We have already determined that
- // Caller is a fairly large function, so we accept the loss of precision.
+
+ Threshold += VectorBonus;
+
+ return AlwaysInline || 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) llvm::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(SROACostSavings);
+ DEBUG_PRINT_STAT(SROACostSavingsLost);
+#undef DEBUG_PRINT_STAT
+}
+#endif
+
+InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, int Threshold) {
+ return getInlineCost(CS, CS.getCalledFunction(), Threshold);
+}
+
+InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, Function *Callee,
+ int Threshold) {
+ // 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 || Callee->mayBeOverridden() ||
+ Callee->getFnAttributes().hasAttribute(Attributes::NoInline) ||
+ CS.isNoInline())
+ return llvm::InlineCost::getNever();
+
+ DEBUG(llvm::dbgs() << " Analyzing call of " << Callee->getName()
+ << "...\n");
+
+ CallAnalyzer CA(TD, *Callee, Threshold);
+ 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.isAlwaysInline() ||
+ CA.getCost() >= CA.getThreshold()))
+ return InlineCost::getAlways();
+
+ return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
}
projects / oota-llvm.git / blobdiff