#define DEBUG_TYPE "inline-cost"
#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/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/CallingConv.h"
+#include "llvm/DataLayout.h"
+#include "llvm/GlobalAlias.h"
+#include "llvm/InstVisitor.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Operator.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/Target/TargetData.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;
typedef InstVisitor<CallAnalyzer, bool> Base;
friend class InstVisitor<CallAnalyzer, bool>;
- // TargetData if available, or null.
- const TargetData *const TD;
+ // DataLayout if available, or null.
+ const DataLayout *const TD;
// The called function.
Function &F;
int Threshold;
int Cost;
- const bool AlwaysInline;
- bool IsRecursive;
+ bool IsCallerRecursive;
+ bool IsRecursiveCall;
bool ExposesReturnsTwice;
bool HasDynamicAlloca;
+ bool ContainsNoDuplicateCall;
+
+ /// Number of bytes allocated statically by the callee.
+ uint64_t AllocatedSize;
unsigned NumInstructions, NumVectorInstructions;
int FiftyPercentVectorBonus, TenPercentVectorBonus;
int VectorBonus;
int InstructionCost);
bool isGEPOffsetConstant(GetElementPtrInst &GEP);
bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
+ bool simplifyCallSite(Function *F, CallSite CS);
ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);
// Custom analysis routines.
bool visitBinaryOperator(BinaryOperator &I);
bool visitLoad(LoadInst &I);
bool visitStore(StoreInst &I);
+ bool visitExtractValue(ExtractValueInst &I);
+ bool visitInsertValue(InsertValueInst &I);
bool visitCallSite(CallSite CS);
public:
- CallAnalyzer(const TargetData *TD, Function &Callee, int Threshold)
+ CallAnalyzer(const DataLayout *TD, Function &Callee, int Threshold)
: TD(TD), F(Callee), Threshold(Threshold), Cost(0),
- AlwaysInline(F.hasFnAttr(Attribute::AlwaysInline)),
- IsRecursive(false), ExposesReturnsTwice(false), HasDynamicAlloca(false),
- NumInstructions(0), NumVectorInstructions(0),
+ IsCallerRecursive(false), IsRecursiveCall(false),
+ ExposesReturnsTwice(false), HasDynamicAlloca(false), ContainsNoDuplicateCall(false),
+ AllocatedSize(0), NumInstructions(0), NumVectorInstructions(0),
FiftyPercentVectorBonus(0), TenPercentVectorBonus(0), VectorBonus(0),
NumConstantArgs(0), NumConstantOffsetPtrArgs(0), NumAllocaArgs(0),
NumConstantPtrCmps(0), NumConstantPtrDiffs(0),
// FIXME: Check whether inlining will turn a dynamic alloca into a static
// alloca, and handle that case.
- // We will happily inline static alloca instructions or dynamic alloca
- // instructions in always-inline situations.
- if (AlwaysInline || I.isStaticAlloca())
+ // 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.
+ if (I.isStaticAlloca())
return Base::visitAlloca(I);
// FIXME: This is overly conservative. Dynamic allocas are inefficient for
bool CallAnalyzer::visitBitCast(BitCastInst &I) {
// Propagate constants through bitcasts.
- if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ 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;
bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) {
// Propagate constants through ptrtoint.
- if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ 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;
bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
// Propagate constants through ptrtoint.
- if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ 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;
bool CallAnalyzer::visitCastInst(CastInst &I) {
// Propagate constants through ptrtoint.
- if (Constant *COp = dyn_cast<Constant>(I.getOperand(0)))
+ 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;
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.isCall() && cast<CallInst>(CS.getInstruction())->canReturnTwice() &&
- !F.hasFnAttr(Attribute::ReturnsTwice)) {
+ !F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
+ Attribute::ReturnsTwice)) {
// This aborts the entire analysis.
ExposesReturnsTwice = true;
return false;
}
+ if (CS.isCall() &&
+ cast<CallInst>(CS.getInstruction())->hasFnAttr(Attribute::NoDuplicate))
+ ContainsNoDuplicateCall = true;
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
- switch (II->getIntrinsicID()) {
- default:
- return Base::visitCallSite(CS);
+ if (Function *F = CS.getCalledFunction()) {
+ // When we have a concrete function, first try to simplify it directly.
+ if (simplifyCallSite(F, CS))
+ return true;
- case Intrinsic::memset:
- case Intrinsic::memcpy:
- case Intrinsic::memmove:
- // SROA can usually chew through these intrinsics, but they aren't free.
- return false;
+ // 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;
+ }
}
- }
- 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.
- IsRecursive = true;
+ IsRecursiveCall = true;
return false;
}
Cost += InlineConstants::InstrCost;
// If the visit this instruction detected an uninlinable pattern, abort.
- if (IsRecursive || ExposesReturnsTwice || HasDynamicAlloca)
+ 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;
if (NumVectorInstructions > NumInstructions/2)
// 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))
+ if (Cost > (Threshold + VectorBonus))
return false;
}
/// 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.
+/// some artifact of the routine.
bool CallAnalyzer::analyzeCall(CallSite CS) {
++NumCallsAnalyzed;
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 PointerSize = TD->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
- // TargetData.
- 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;
- }
+ // 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.
+ 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 PointerSize = TD->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.
- 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.
- if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
- if (isa<UnreachableInst>(II->getNormalDest()->begin()))
- Threshold = 1;
- } else if (isa<UnreachableInst>(++BasicBlock::iterator(CS.getInstruction())))
+ // 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 = 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;
+ // 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;
- }
+ // 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 (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;
+ }
+ }
+
// 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;
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))
+ if (Cost > (Threshold + VectorBonus))
break;
BasicBlock *BB = BBWorklist[Idx];
// 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.
+ // 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,
// 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 (IsRecursive || ExposesReturnsTwice || HasDynamicAlloca)
+ 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;
}
// If we're unable to select a particular successor, just count all of
// them.
- for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize; ++TIdx)
+ 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
}
}
+ // 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;
+
Threshold += VectorBonus;
- return AlwaysInline || Cost < Threshold;
+ 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) llvm::dbgs() << " " #x ": " << x << "\n"
DEBUG_PRINT_STAT(NumInstructionsSimplified);
DEBUG_PRINT_STAT(SROACostSavings);
DEBUG_PRINT_STAT(SROACostSavingsLost);
+ DEBUG_PRINT_STAT(ContainsNoDuplicateCall);
#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) {
+ // Cannot inline indirect calls.
+ if (!Callee)
+ return llvm::InlineCost::getNever();
+
+ // Calls to functions with always-inline attributes should be inlined
+ // whenever possible.
+ if (Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
+ Attribute::AlwaysInline)) {
+ if (isInlineViable(*Callee))
+ return llvm::InlineCost::getAlways();
+ 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 || Callee->mayBeOverridden() ||
- Callee->hasFnAttr(Attribute::NoInline) || CS.isNoInline())
+ if (Callee->mayBeOverridden() ||
+ Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
+ Attribute::NoInline) ||
+ CS.isNoInline())
return llvm::InlineCost::getNever();
- DEBUG(llvm::dbgs() << " Analyzing call of " << Callee->getName() << "...\n");
+ DEBUG(llvm::dbgs() << " Analyzing call of " << Callee->getName()
+ << "...\n");
CallAnalyzer CA(TD, *Callee, Threshold);
bool ShouldInline = CA.analyzeCall(CS);
return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
}
+
+bool InlineCostAnalyzer::isInlineViable(Function &F) {
+ bool ReturnsTwice =F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
+ Attribute::ReturnsTwice);
+ for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
+ // Disallow inlining of functions which contain an indirect branch.
+ if (isa<IndirectBrInst>(BI->getTerminator()))
+ 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;
+ }
+ }
+
+ return true;
+}
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