#include "llvm/Support/CallSite.h"
#include "llvm/CallingConv.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallPtrSet.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) {
+/// callIsSmall - If a call is likely to lower to a single target instruction,
+/// or is otherwise deemed small return true.
+/// TODO: Perhaps calls like memcpy, strcpy, etc?
+bool llvm::callIsSmall(const Function *F) {
+ if (!F) return false;
+
+ if (F->hasLocalLinkage()) return false;
+
+ if (!F->hasName()) return false;
+
+ StringRef Name = F->getName();
+
+ // These will all likely lower to a single selection DAG node.
+ if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" ||
+ Name == "fabs" || Name == "fabsf" || Name == "fabsl" ||
+ Name == "sin" || Name == "sinf" || Name == "sinl" ||
+ Name == "cos" || Name == "cosf" || Name == "cosl" ||
+ Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl" )
+ 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;
+
+ return false;
+}
+
+/// analyzeBasicBlock - Fill in the current structure with information gleaned
+/// from the specified block.
+void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
+ const TargetData *TD) {
+ ++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 (const IntrinsicInst *IntrinsicI = dyn_cast<IntrinsicInst>(II)) {
+ switch (IntrinsicI->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::dbg_declare:
+ case Intrinsic::dbg_value:
+ case Intrinsic::invariant_start:
+ case Intrinsic::invariant_end:
+ case Intrinsic::lifetime_start:
+ case Intrinsic::lifetime_end:
+ case Intrinsic::objectsize:
+ case Intrinsic::ptr_annotation:
+ case Intrinsic::var_annotation:
+ // These intrinsics don't count as size.
+ continue;
+ }
+ }
+
+ ImmutableCallSite CS(cast<Instruction>(II));
+
+ if (const Function *F = CS.getCalledFunction()) {
+ // If a function is both internal and has a single use, then it is
+ // extremely likely to get inlined in the future (it was probably
+ // exposed by an interleaved devirtualization pass).
+ if (!CS.isNoInline() && F->hasInternalLinkage() && F->hasOneUse())
+ ++NumInlineCandidates;
+
+ // If this call is to function itself, then the function is recursive.
+ // Inlining it into other functions is a bad idea, because this is
+ // basically just a form of loop peeling, and our metrics aren't useful
+ // for that case.
+ if (F == BB->getParent())
+ isRecursive = 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();
+
+ // We don't want inline asm to count as a call - that would prevent loop
+ // unrolling. The argument setup cost is still real, though.
+ if (!isa<InlineAsm>(CS.getCalledValue()))
+ ++NumCalls;
+ }
+ }
+
+ if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
+ if (!AI->isStaticAlloca())
+ this->usesDynamicAlloca = 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;
+ // trunc to a native type is free (assuming the target has compare and
+ // shift-right of the same width).
+ if (isa<TruncInst>(CI) && TD &&
+ TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType())))
+ 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;
+ }
+
+ ++NumInsts;
+ }
+
+ 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.
+ // 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>(BB->getTerminator()))
+ containsIndirectBr = true;
+
+ // Remember NumInsts for this BB.
+ NumBBInsts[BB] = NumInsts - NumInstsBeforeThisBB;
+}
+
+unsigned InlineCostAnalyzer::FunctionInfo::countCodeReductionForConstant(
+ const CodeMetrics &Metrics, Value *V) {
unsigned Reduction = 0;
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
- if (isa<BranchInst>(*UI))
- Reduction += 40; // Eliminating a conditional branch is a big win
- else if (SwitchInst *SI = dyn_cast<SwitchInst>(*UI))
- // Eliminating a switch is a big win, proportional to the number of edges
- // deleted.
- Reduction += (SI->getNumSuccessors()-1) * 40;
- else if (isa<IndirectBrInst>(*UI))
- // Eliminating an indirect branch is a big win.
- Reduction += 200;
- else if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
- // Turning an indirect call into a direct call is a BIG win
- Reduction += CI->getCalledValue() == V ? 500 : 0;
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) {
- // Turning an indirect call into a direct call is a BIG win
- Reduction += II->getCalledValue() == V ? 500 : 0;
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
+ User *U = *UI;
+ if (isa<BranchInst>(U) || isa<SwitchInst>(U)) {
+ // We will be able to eliminate all but one of the successors.
+ const TerminatorInst &TI = cast<TerminatorInst>(*U);
+ const unsigned NumSucc = TI.getNumSuccessors();
+ unsigned Instrs = 0;
+ for (unsigned I = 0; I != NumSucc; ++I)
+ Instrs += Metrics.NumBBInsts.lookup(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 {
// Figure out if this instruction will be removed due to simple constant
// propagation.
- Instruction &Inst = cast<Instruction>(**UI);
-
+ Instruction &Inst = cast<Instruction>(*U);
+
// We can't constant propagate instructions which have effects or
// read memory.
//
// 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))
+ isa<AllocaInst>(Inst))
continue;
bool AllOperandsConstant = true;
if (AllOperandsConstant) {
// We will get to remove this instruction...
- Reduction += 7;
+ Reduction += InlineConstants::InstrCost;
// And any other instructions that use it which become constants
// themselves.
- Reduction += CountCodeReductionForConstant(&Inst);
+ Reduction += countCodeReductionForConstant(Metrics, &Inst);
}
}
-
+ }
return Reduction;
}
-// 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 (!isa<PointerType>(V->getType())) return 0; // Not a pointer
+static unsigned countCodeReductionForAllocaICmp(const CodeMetrics &Metrics,
+ ICmpInst *ICI) {
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 += 10;
- 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)+15;
- } else {
- // If there is some other strange instruction, we're not going to be able
- // to do much if we inline this.
- return 0;
+
+ // Bail if this is comparing against a non-constant; there is nothing we can
+ // do there.
+ if (!isa<Constant>(ICI->getOperand(1)))
+ return Reduction;
+
+ // An icmp pred (alloca, C) becomes true if the predicate is true when
+ // equal and false otherwise.
+ bool Result = ICI->isTrueWhenEqual();
+
+ SmallVector<Instruction *, 4> Worklist;
+ Worklist.push_back(ICI);
+ do {
+ Instruction *U = Worklist.pop_back_val();
+ Reduction += InlineConstants::InstrCost;
+ for (Value::use_iterator UI = U->use_begin(), UE = U->use_end();
+ UI != UE; ++UI) {
+ Instruction *I = dyn_cast<Instruction>(*UI);
+ if (!I || I->mayHaveSideEffects()) continue;
+ if (I->getNumOperands() == 1)
+ Worklist.push_back(I);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
+ // If BO produces the same value as U, then the other operand is
+ // irrelevant and we can put it into the Worklist to continue
+ // deleting dead instructions. If BO produces the same value as the
+ // other operand, we can delete BO but that's it.
+ if (Result == true) {
+ if (BO->getOpcode() == Instruction::Or)
+ Worklist.push_back(I);
+ if (BO->getOpcode() == Instruction::And)
+ Reduction += InlineConstants::InstrCost;
+ } else {
+ if (BO->getOpcode() == Instruction::Or ||
+ BO->getOpcode() == Instruction::Xor)
+ Reduction += InlineConstants::InstrCost;
+ if (BO->getOpcode() == Instruction::And)
+ Worklist.push_back(I);
+ }
+ }
+ if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
+ BasicBlock *BB = BI->getSuccessor(Result ? 0 : 1);
+ if (BB->getSinglePredecessor())
+ Reduction
+ += InlineConstants::InstrCost * Metrics.NumBBInsts.lookup(BB);
+ }
}
- }
+ } while (!Worklist.empty());
return Reduction;
}
-/// analyzeBasicBlock - Fill in the current structure with information gleaned
-/// from the specified block.
-void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB) {
- ++NumBlocks;
+/// \brief Compute the reduction possible for a given instruction if we are able
+/// to SROA an alloca.
+///
+/// The reduction for this instruction is added to the SROAReduction output
+/// parameter. Returns false if this instruction is expected to defeat SROA in
+/// general.
+static bool countCodeReductionForSROAInst(Instruction *I,
+ SmallVectorImpl<Value *> &Worklist,
+ unsigned &SROAReduction) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ if (!LI->isSimple())
+ return false;
+ SROAReduction += InlineConstants::InstrCost;
+ return true;
+ }
- for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
- II != E; ++II) {
- if (isa<PHINode>(II)) continue; // PHI nodes don't count.
+ if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ if (!SI->isSimple())
+ return false;
+ SROAReduction += InlineConstants::InstrCost;
+ return true;
+ }
- // 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;
-
- // Calls often compile into many machine instructions. Bump up their
- // cost to reflect this.
- if (!isa<IntrinsicInst>(II))
- NumInsts += InlineConstants::CallPenalty;
+ 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())
+ return false;
+ // A non-zero GEP will likely become a mask operation after SROA.
+ if (GEP->hasAllZeroIndices())
+ SROAReduction += InlineConstants::InstrCost;
+ Worklist.push_back(GEP);
+ return true;
+ }
+
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
+ // Track pointer through bitcasts.
+ Worklist.push_back(BCI);
+ SROAReduction += InlineConstants::InstrCost;
+ return true;
+ }
+
+ // We just look for non-constant operands to ICmp instructions as those will
+ // defeat SROA. The actual reduction for these happens even without SROA.
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(I))
+ return isa<Constant>(ICI->getOperand(1));
+
+ if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
+ // SROA can handle a select of alloca iff all uses of the alloca are
+ // loads, and dereferenceable. We assume it's dereferenceable since
+ // we're told the input is an alloca.
+ for (Value::use_iterator UI = SI->use_begin(), UE = SI->use_end();
+ UI != UE; ++UI) {
+ LoadInst *LI = dyn_cast<LoadInst>(*UI);
+ if (LI == 0 || !LI->isSimple())
+ return false;
}
-
- if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
- if (!AI->isStaticAlloca())
- this->usesDynamicAlloca = true;
+ // We don't know whether we'll be deleting the rest of the chain of
+ // instructions from the SelectInst on, because we don't know whether
+ // the other side of the select is also an alloca or not.
+ return true;
+ }
+
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ switch (II->getIntrinsicID()) {
+ default:
+ return false;
+ case Intrinsic::memset:
+ case Intrinsic::memcpy:
+ case Intrinsic::memmove:
+ case Intrinsic::lifetime_start:
+ case Intrinsic::lifetime_end:
+ // SROA can usually chew through these intrinsics.
+ SROAReduction += InlineConstants::InstrCost;
+ return true;
}
+ }
- if (isa<ExtractElementInst>(II) || isa<VectorType>(II->getType()))
- ++NumVectorInsts;
-
- // Noop casts, including ptr <-> int, don't count.
- if (const CastInst *CI = dyn_cast<CastInst>(II)) {
- if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
- isa<PtrToIntInst>(CI))
- 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;
+ // If there is some other strange instruction, we're not going to be
+ // able to do much if we inline this.
+ return false;
+}
+
+unsigned InlineCostAnalyzer::FunctionInfo::countCodeReductionForAlloca(
+ const CodeMetrics &Metrics, Value *V) {
+ if (!V->getType()->isPointerTy()) return 0; // Not a pointer
+ unsigned Reduction = 0;
+ unsigned SROAReduction = 0;
+ bool CanSROAAlloca = true;
+
+ SmallVector<Value *, 4> Worklist;
+ Worklist.push_back(V);
+ do {
+ Value *V = Worklist.pop_back_val();
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
+ UI != E; ++UI){
+ Instruction *I = cast<Instruction>(*UI);
+
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(I))
+ Reduction += countCodeReductionForAllocaICmp(Metrics, ICI);
+
+ if (CanSROAAlloca)
+ CanSROAAlloca = countCodeReductionForSROAInst(I, Worklist,
+ SROAReduction);
}
+ } while (!Worklist.empty());
- ++NumInsts;
- }
-
- 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;
+ return Reduction + (CanSROAAlloca ? SROAReduction : 0);
}
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
-void CodeMetrics::analyzeFunction(Function *F) {
+void CodeMetrics::analyzeFunction(Function *F, const TargetData *TD) {
+ // If this function contains a call that "returns twice" (e.g., setjmp or
+ // _setjmp) and it isn't marked with "returns twice" itself, 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.
+ exposesReturnsTwice = F->callsFunctionThatReturnsTwice() &&
+ !F->hasFnAttr(Attribute::ReturnsTwice);
+
// Look at the size of the callee.
for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- analyzeBasicBlock(&*BB);
+ analyzeBasicBlock(&*BB, TD);
}
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
-void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F) {
- Metrics.analyzeFunction(F);
+void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F,
+ const TargetData *TD) {
+ Metrics.analyzeFunction(F, TD);
// A function with exactly one return has it removed during the inlining
// process (see InlineFunction), so don't count it.
// 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)));
+ ArgumentWeights.push_back(ArgInfo(countCodeReductionForConstant(Metrics, I),
+ countCodeReductionForAlloca(Metrics, I)));
}
-// 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();
+/// NeverInline - returns true if the function should never be inlined into
+/// any caller
+bool InlineCostAnalyzer::FunctionInfo::NeverInline() {
+ return (Metrics.exposesReturnsTwice || Metrics.isRecursive ||
+ Metrics.containsIndirectBr);
+}
+// getSpecializationBonus - The heuristic used to determine the per-call
+// performance boost for using a specialization of Callee with argument
+// specializedArgNo replaced by a constant.
+int InlineCostAnalyzer::getSpecializationBonus(Function *Callee,
+ SmallVectorImpl<unsigned> &SpecializedArgNos)
+{
+ if (Callee->mayBeOverridden())
+ return 0;
- // 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();
+ int Bonus = 0;
+ // If this function uses the coldcc calling convention, prefer not to
+ // specialize it.
+ if (Callee->getCallingConv() == CallingConv::Cold)
+ Bonus -= InlineConstants::ColdccPenalty;
+
+ // 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, TD);
+
+ unsigned ArgNo = 0;
+ unsigned i = 0;
+ for (Function::arg_iterator I = Callee->arg_begin(), E = Callee->arg_end();
+ I != E; ++I, ++ArgNo)
+ if (ArgNo == SpecializedArgNos[i]) {
+ ++i;
+ Bonus += CountBonusForConstant(I);
+ }
+
+ // Calls usually take a long time, so they make the specialization gain
+ // smaller.
+ Bonus -= CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty;
+
+ return Bonus;
+}
+
+// ConstantFunctionBonus - Figure out how much of a bonus we can get for
+// possibly devirtualizing a function. We'll subtract the size of the function
+// we may wish to inline from the indirect call bonus providing a limit on
+// growth. Leave an upper limit of 0 for the bonus - we don't want to penalize
+// inlining because we decide we don't want to give a bonus for
+// devirtualizing.
+int InlineCostAnalyzer::ConstantFunctionBonus(CallSite CS, Constant *C) {
+
+ // This could just be NULL.
+ if (!C) return 0;
+
+ Function *F = dyn_cast<Function>(C);
+ if (!F) return 0;
+
+ int Bonus = InlineConstants::IndirectCallBonus + getInlineSize(CS, F);
+ return (Bonus > 0) ? 0 : Bonus;
+}
+
+// CountBonusForConstant - Figure out an approximation for how much per-call
+// performance boost we can expect if the specified value is constant.
+int InlineCostAnalyzer::CountBonusForConstant(Value *V, Constant *C) {
+ unsigned Bonus = 0;
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
+ User *U = *UI;
+ if (CallInst *CI = dyn_cast<CallInst>(U)) {
+ // Turning an indirect call into a direct call is a BIG win
+ if (CI->getCalledValue() == V)
+ Bonus += ConstantFunctionBonus(CallSite(CI), C);
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) {
+ // Turning an indirect call into a direct call is a BIG win
+ if (II->getCalledValue() == V)
+ Bonus += ConstantFunctionBonus(CallSite(II), C);
+ }
+ // FIXME: Eliminating conditional branches and switches should
+ // also yield a per-call performance boost.
+ else {
+ // Figure out the bonuses that wll accrue due to simple constant
+ // propagation.
+ Instruction &Inst = cast<Instruction>(*U);
+
+ // We can't constant propagate instructions which have effects or
+ // read memory.
+ //
+ // FIXME: It would be nice to capture the fact that a load from a
+ // pointer-to-constant-global is actually a *really* good thing to zap.
+ // Unfortunately, we don't know the pointer that may get propagated here,
+ // so we can't make this decision.
+ if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() ||
+ isa<AllocaInst>(Inst))
+ continue;
+
+ 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;
+ }
+
+ if (AllOperandsConstant)
+ Bonus += CountBonusForConstant(&Inst);
+ }
+ }
+
+ return Bonus;
+}
+
+int InlineCostAnalyzer::getInlineSize(CallSite CS, Function *Callee) {
+ // 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, TD);
// 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;
-
+
+ // Compute any size reductions we can expect due to arguments being passed into
+ // the function.
+ //
+ unsigned ArgNo = 0;
+ CallSite::arg_iterator I = CS.arg_begin();
+ for (Function::arg_iterator FI = Callee->arg_begin(), FE = Callee->arg_end();
+ FI != FE; ++I, ++FI, ++ArgNo) {
+
+ // 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))
+ 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))
+ InlineCost -= CalleeFI->ArgumentWeights[ArgNo].ConstantWeight;
+ }
+
+ // 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 -= (CS.arg_size() * InlineConstants::InstrCost);
+
+ // 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;
+
+ // Look at the size of the callee. Each instruction counts as 5.
+ InlineCost += CalleeFI->Metrics.NumInsts * InlineConstants::InstrCost;
+
+ return InlineCost;
+}
+
+int InlineCostAnalyzer::getInlineBonuses(CallSite CS, Function *Callee) {
+ // 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, TD);
+
+ bool isDirectCall = CS.getCalledFunction() == Callee;
+ Instruction *TheCall = CS.getInstruction();
+ int Bonus = 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 (Callee->hasLocalLinkage() && Callee->hasOneUse() && isDirectCall)
+ Bonus += InlineConstants::LastCallToStaticBonus;
+
// If the instruction after the call, or if the normal destination of the
// invoke is an unreachable instruction, the function is noreturn. As such,
// there is little point in inlining this.
if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
if (isa<UnreachableInst>(II->getNormalDest()->begin()))
- InlineCost += InlineConstants::NoreturnPenalty;
+ Bonus += InlineConstants::NoreturnPenalty;
} else if (isa<UnreachableInst>(++BasicBlock::iterator(TheCall)))
- InlineCost += InlineConstants::NoreturnPenalty;
-
- // Get information about the callee...
- FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
-
+ Bonus += InlineConstants::NoreturnPenalty;
+
+ // If this function uses the coldcc calling convention, prefer not to inline
+ // it.
+ if (Callee->getCallingConv() == CallingConv::Cold)
+ Bonus += InlineConstants::ColdccPenalty;
+
+ // 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.
+ //
+ CallSite::arg_iterator I = CS.arg_begin();
+ for (Function::arg_iterator FI = Callee->arg_begin(), FE = Callee->arg_end();
+ FI != FE; ++I, ++FI)
+ // Compute any constant bonus due to inlining we want to give here.
+ if (isa<Constant>(I))
+ Bonus += CountBonusForConstant(FI, cast<Constant>(I));
+
+ return Bonus;
+}
+
+// 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) {
+ return getInlineCost(CS, CS.getCalledFunction(), NeverInline);
+}
+
+InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
+ Function *Callee,
+ SmallPtrSet<const Function*, 16> &NeverInline) {
+ Instruction *TheCall = CS.getInstruction();
+ Function *Caller = TheCall->getParent()->getParent();
+
+ // Don't inline functions which can be redefined at link-time to mean
+ // something else. Don't inline functions marked noinline or call sites
+ // marked noinline.
+ if (Callee->mayBeOverridden() ||
+ Callee->hasFnAttr(Attribute::NoInline) || NeverInline.count(Callee) ||
+ CS.isNoInline())
+ return llvm::InlineCost::getNever();
+
+ // 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 (CalleeFI->Metrics.NumBlocks == 0)
+ CalleeFI->analyzeFunction(Callee, TD);
// If we should never inline this, return a huge cost.
- if (CalleeFI.Metrics.NeverInline)
+ if (CalleeFI->NeverInline())
return InlineCost::getNever();
- // FIXME: It would be nice to kill off CalleeFI.NeverInline. Then we
+ // 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...
+
+ if (CalleeFI->Metrics.usesDynamicAlloca) {
+ // Get information 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);
+ if (CallerFI.Metrics.NumBlocks == 0) {
+ CallerFI.analyzeFunction(Caller, TD);
+
+ // Recompute the CalleeFI pointer, getting Caller could have invalidated
+ // it.
+ CalleeFI = &CachedFunctionInfo[Callee];
+ }
// Don't inline a callee with dynamic alloca into a caller without them.
// Functions containing dynamic alloca's are inefficient in various ways;
return InlineCost::getNever();
}
- // 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. This favors functions that take many arguments over functions
- // that take few arguments.
- InlineCost -= 20;
-
- // If this is a function being passed in, it is very likely that we will be
- // able to turn an indirect function call into a direct function call.
- if (isa<Function>(I))
- InlineCost -= 100;
-
- // 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.
- //
- else 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;
- }
- }
-
- // 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.
-
- // Don't inline into something too big, which would make it bigger.
- // "size" here is the number of basic blocks, not instructions.
+ // 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 due to the fact that bonuses
+ // are negative numbers.
//
- InlineCost += Caller->size()/15;
-
- // Look at the size of the callee. Each instruction counts as 5.
- InlineCost += CalleeFI.Metrics.NumInsts*5;
-
+ int InlineCost = getInlineSize(CS, Callee) + getInlineBonuses(CS, Callee);
return llvm::InlineCost::get(InlineCost);
}
+// getSpecializationCost - The heuristic used to determine the code-size
+// impact of creating a specialized version of Callee with argument
+// SpecializedArgNo replaced by a constant.
+InlineCost InlineCostAnalyzer::getSpecializationCost(Function *Callee,
+ SmallVectorImpl<unsigned> &SpecializedArgNos)
+{
+ // Don't specialize functions which can be redefined at link-time to mean
+ // something else.
+ if (Callee->mayBeOverridden())
+ return llvm::InlineCost::getNever();
+
+ // 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, TD);
+
+ int Cost = 0;
+
+ // Look at the original size of the callee. Each instruction counts as 5.
+ Cost += CalleeFI->Metrics.NumInsts * InlineConstants::InstrCost;
+
+ // Offset that with the amount of code that can be constant-folded
+ // away with the given arguments replaced by constants.
+ for (SmallVectorImpl<unsigned>::iterator an = SpecializedArgNos.begin(),
+ ae = SpecializedArgNos.end(); an != ae; ++an)
+ Cost -= CalleeFI->ArgumentWeights[*an].ConstantWeight;
+
+ return llvm::InlineCost::get(Cost);
+}
+
// 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...
+
+ // 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);
+ CalleeFI.analyzeFunction(Callee, TD);
float Factor = 1.0f;
// Single BB functions are often written to be inlined.
Factor += 1.5f;
return Factor;
}
+
+/// growCachedCostInfo - update the cached cost info for Caller after Callee has
+/// been inlined.
+void
+InlineCostAnalyzer::growCachedCostInfo(Function *Caller, Function *Callee) {
+ CodeMetrics &CallerMetrics = CachedFunctionInfo[Caller].Metrics;
+
+ // For small functions we prefer to recalculate the cost for better accuracy.
+ if (CallerMetrics.NumBlocks < 10 && CallerMetrics.NumInsts < 1000) {
+ resetCachedCostInfo(Caller);
+ return;
+ }
+
+ // For large functions, we can save a lot of computation time by skipping
+ // recalculations.
+ if (CallerMetrics.NumCalls > 0)
+ --CallerMetrics.NumCalls;
+
+ if (Callee == 0) return;
+
+ CodeMetrics &CalleeMetrics = CachedFunctionInfo[Callee].Metrics;
+
+ // If we don't have metrics for the callee, don't recalculate them just to
+ // update an approximation in the caller. Instead, just recalculate the
+ // caller info from scratch.
+ if (CalleeMetrics.NumBlocks == 0) {
+ resetCachedCostInfo(Caller);
+ return;
+ }
+
+ // Since CalleeMetrics were already calculated, we know that the CallerMetrics
+ // reference isn't invalidated: both were in the DenseMap.
+ CallerMetrics.usesDynamicAlloca |= CalleeMetrics.usesDynamicAlloca;
+
+ // FIXME: If any of these three are true for the callee, the callee was
+ // not inlined into the caller, so I think they're redundant here.
+ CallerMetrics.exposesReturnsTwice |= CalleeMetrics.exposesReturnsTwice;
+ CallerMetrics.isRecursive |= CalleeMetrics.isRecursive;
+ CallerMetrics.containsIndirectBr |= CalleeMetrics.containsIndirectBr;
+
+ CallerMetrics.NumInsts += CalleeMetrics.NumInsts;
+ CallerMetrics.NumBlocks += CalleeMetrics.NumBlocks;
+ CallerMetrics.NumCalls += CalleeMetrics.NumCalls;
+ CallerMetrics.NumVectorInsts += CalleeMetrics.NumVectorInsts;
+ CallerMetrics.NumRets += CalleeMetrics.NumRets;
+
+ // analyzeBasicBlock counts each function argument as an inst.
+ if (CallerMetrics.NumInsts >= Callee->arg_size())
+ CallerMetrics.NumInsts -= Callee->arg_size();
+ else
+ CallerMetrics.NumInsts = 0;
+
+ // We are not updating the argument weights. We have already determined that
+ // Caller is a fairly large function, so we accept the loss of precision.
+}
+
+/// clear - empty the cache of inline costs
+void InlineCostAnalyzer::clear() {
+ CachedFunctionInfo.clear();
+}
projects / oota-llvm.git / blobdiff