-//===- InlineCommon.cpp - Code common to all inliners ---------------------===//
-//
+//===- Inliner.cpp - Code common to all inliners --------------------------===//
+//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
//===----------------------------------------------------------------------===//
//
-// This file implements the code shared between the LLVM inliners. This
-// implements all of the boring mechanics of the bottom-up inlining.
+// This file implements the mechanics required to implement inlining without
+// missing any calls and updating the call graph. The decisions of which calls
+// are profitable to inline are implemented elsewhere.
//
//===----------------------------------------------------------------------===//
-#include "Inliner.h"
-#include "llvm/Constants.h" // ConstantPointerRef should die
-#include "llvm/Module.h"
-#include "llvm/iOther.h"
-#include "llvm/iTerminators.h"
+#include "llvm/Transforms/IPO/InlinerPass.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/CallGraph.h"
-#include "llvm/Support/CallSite.h"
+#include "llvm/Analysis/InlineCost.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/Cloning.h"
-#include "Support/CommandLine.h"
-#include "Support/Debug.h"
-#include "Support/Statistic.h"
+#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
-namespace {
- Statistic<> NumInlined("inline", "Number of functions inlined");
- Statistic<> NumDeleted("inline", "Number of functions deleted because all callers found");
- cl::opt<unsigned> // FIXME: 200 is VERY conservative
- InlineLimit("inline-threshold", cl::Hidden, cl::init(200),
- cl::desc("Control the amount of inlining to perform (default = 200)"));
+#define DEBUG_TYPE "inline"
+
+STATISTIC(NumInlined, "Number of functions inlined");
+STATISTIC(NumCallsDeleted, "Number of call sites deleted, not inlined");
+STATISTIC(NumDeleted, "Number of functions deleted because all callers found");
+STATISTIC(NumMergedAllocas, "Number of allocas merged together");
+
+// This weirdly named statistic tracks the number of times that, when attempting
+// to inline a function A into B, we analyze the callers of B in order to see
+// if those would be more profitable and blocked inline steps.
+STATISTIC(NumCallerCallersAnalyzed, "Number of caller-callers analyzed");
+
+static cl::opt<int>
+InlineLimit("inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore,
+ cl::desc("Control the amount of inlining to perform (default = 225)"));
+
+static cl::opt<int>
+HintThreshold("inlinehint-threshold", cl::Hidden, cl::init(325),
+ cl::desc("Threshold for inlining functions with inline hint"));
+
+// We instroduce this threshold to help performance of instrumentation based
+// PGO before we actually hook up inliner with analysis passes such as BPI and
+// BFI.
+static cl::opt<int>
+ColdThreshold("inlinecold-threshold", cl::Hidden, cl::init(225),
+ cl::desc("Threshold for inlining functions with cold attribute"));
+
+// Threshold to use when optsize is specified (and there is no -inline-limit).
+const int OptSizeThreshold = 75;
+
+Inliner::Inliner(char &ID)
+ : CallGraphSCCPass(ID), InlineThreshold(InlineLimit), InsertLifetime(true) {
}
-Inliner::Inliner() : InlineThreshold(InlineLimit) {}
+Inliner::Inliner(char &ID, int Threshold, bool InsertLifetime)
+ : CallGraphSCCPass(ID),
+ InlineThreshold(InlineLimit.getNumOccurrences() > 0 ? InlineLimit
+ : Threshold),
+ InsertLifetime(InsertLifetime) {}
-int Inliner::getRecursiveInlineCost(CallSite CS) {
- return getInlineCost(CS);
+/// For this class, we declare that we require and preserve the call graph.
+/// If the derived class implements this method, it should
+/// always explicitly call the implementation here.
+void Inliner::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<AssumptionCacheTracker>();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+ CallGraphSCCPass::getAnalysisUsage(AU);
}
-bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
- CallGraph &CG = getAnalysis<CallGraph>();
- std::set<Function*> SCCFunctions;
- DEBUG(std::cerr << "Inliner visiting SCC:");
- for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
- SCCFunctions.insert(SCC[i]->getFunction());
- DEBUG(std::cerr << " " << (SCC[i]->getFunction() ?
- SCC[i]->getFunction()->getName() : "INDIRECTNODE"));
+typedef DenseMap<ArrayType*, std::vector<AllocaInst*> >
+InlinedArrayAllocasTy;
+
+/// If it is possible to inline the specified call site,
+/// do so and update the CallGraph for this operation.
+///
+/// This function also does some basic book-keeping to update the IR. The
+/// InlinedArrayAllocas map keeps track of any allocas that are already
+/// available from other functions inlined into the caller. If we are able to
+/// inline this call site we attempt to reuse already available allocas or add
+/// any new allocas to the set if not possible.
+static bool InlineCallIfPossible(Pass &P, CallSite CS, InlineFunctionInfo &IFI,
+ InlinedArrayAllocasTy &InlinedArrayAllocas,
+ int InlineHistory, bool InsertLifetime) {
+ Function *Callee = CS.getCalledFunction();
+ Function *Caller = CS.getCaller();
+
+ // We need to manually construct BasicAA directly in order to disable
+ // its use of other function analyses.
+ BasicAAResult BAR(createLegacyPMBasicAAResult(P, *Callee));
+
+ // Construct our own AA results for this function. We do this manually to
+ // work around the limitations of the legacy pass manager.
+ AAResults AAR(createLegacyPMAAResults(P, *Callee, BAR));
+
+ // Try to inline the function. Get the list of static allocas that were
+ // inlined.
+ if (!InlineFunction(CS, IFI, &AAR, InsertLifetime))
+ return false;
+
+ AttributeFuncs::mergeAttributesForInlining(*Caller, *Callee);
+
+ // Look at all of the allocas that we inlined through this call site. If we
+ // have already inlined other allocas through other calls into this function,
+ // then we know that they have disjoint lifetimes and that we can merge them.
+ //
+ // There are many heuristics possible for merging these allocas, and the
+ // different options have different tradeoffs. One thing that we *really*
+ // don't want to hurt is SRoA: once inlining happens, often allocas are no
+ // longer address taken and so they can be promoted.
+ //
+ // Our "solution" for that is to only merge allocas whose outermost type is an
+ // array type. These are usually not promoted because someone is using a
+ // variable index into them. These are also often the most important ones to
+ // merge.
+ //
+ // A better solution would be to have real memory lifetime markers in the IR
+ // and not have the inliner do any merging of allocas at all. This would
+ // allow the backend to do proper stack slot coloring of all allocas that
+ // *actually make it to the backend*, which is really what we want.
+ //
+ // Because we don't have this information, we do this simple and useful hack.
+ //
+ SmallPtrSet<AllocaInst*, 16> UsedAllocas;
+
+ // When processing our SCC, check to see if CS was inlined from some other
+ // call site. For example, if we're processing "A" in this code:
+ // A() { B() }
+ // B() { x = alloca ... C() }
+ // C() { y = alloca ... }
+ // Assume that C was not inlined into B initially, and so we're processing A
+ // and decide to inline B into A. Doing this makes an alloca available for
+ // reuse and makes a callsite (C) available for inlining. When we process
+ // the C call site we don't want to do any alloca merging between X and Y
+ // because their scopes are not disjoint. We could make this smarter by
+ // keeping track of the inline history for each alloca in the
+ // InlinedArrayAllocas but this isn't likely to be a significant win.
+ if (InlineHistory != -1) // Only do merging for top-level call sites in SCC.
+ return true;
+
+ // Loop over all the allocas we have so far and see if they can be merged with
+ // a previously inlined alloca. If not, remember that we had it.
+ for (unsigned AllocaNo = 0, e = IFI.StaticAllocas.size();
+ AllocaNo != e; ++AllocaNo) {
+ AllocaInst *AI = IFI.StaticAllocas[AllocaNo];
+
+ // Don't bother trying to merge array allocations (they will usually be
+ // canonicalized to be an allocation *of* an array), or allocations whose
+ // type is not itself an array (because we're afraid of pessimizing SRoA).
+ ArrayType *ATy = dyn_cast<ArrayType>(AI->getAllocatedType());
+ if (!ATy || AI->isArrayAllocation())
+ continue;
+
+ // Get the list of all available allocas for this array type.
+ std::vector<AllocaInst*> &AllocasForType = InlinedArrayAllocas[ATy];
+
+ // Loop over the allocas in AllocasForType to see if we can reuse one. Note
+ // that we have to be careful not to reuse the same "available" alloca for
+ // multiple different allocas that we just inlined, we use the 'UsedAllocas'
+ // set to keep track of which "available" allocas are being used by this
+ // function. Also, AllocasForType can be empty of course!
+ bool MergedAwayAlloca = false;
+ for (AllocaInst *AvailableAlloca : AllocasForType) {
+
+ unsigned Align1 = AI->getAlignment(),
+ Align2 = AvailableAlloca->getAlignment();
+
+ // The available alloca has to be in the right function, not in some other
+ // function in this SCC.
+ if (AvailableAlloca->getParent() != AI->getParent())
+ continue;
+
+ // If the inlined function already uses this alloca then we can't reuse
+ // it.
+ if (!UsedAllocas.insert(AvailableAlloca).second)
+ continue;
+
+ // Otherwise, we *can* reuse it, RAUW AI into AvailableAlloca and declare
+ // success!
+ DEBUG(dbgs() << " ***MERGED ALLOCA: " << *AI << "\n\t\tINTO: "
+ << *AvailableAlloca << '\n');
+
+ // Move affected dbg.declare calls immediately after the new alloca to
+ // avoid the situation when a dbg.declare preceeds its alloca.
+ if (auto *L = LocalAsMetadata::getIfExists(AI))
+ if (auto *MDV = MetadataAsValue::getIfExists(AI->getContext(), L))
+ for (User *U : MDV->users())
+ if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(U))
+ DDI->moveBefore(AvailableAlloca->getNextNode());
+
+ AI->replaceAllUsesWith(AvailableAlloca);
+
+ if (Align1 != Align2) {
+ if (!Align1 || !Align2) {
+ const DataLayout &DL = Caller->getParent()->getDataLayout();
+ unsigned TypeAlign = DL.getABITypeAlignment(AI->getAllocatedType());
+
+ Align1 = Align1 ? Align1 : TypeAlign;
+ Align2 = Align2 ? Align2 : TypeAlign;
+ }
+
+ if (Align1 > Align2)
+ AvailableAlloca->setAlignment(AI->getAlignment());
+ }
+
+ AI->eraseFromParent();
+ MergedAwayAlloca = true;
+ ++NumMergedAllocas;
+ IFI.StaticAllocas[AllocaNo] = nullptr;
+ break;
+ }
+
+ // If we already nuked the alloca, we're done with it.
+ if (MergedAwayAlloca)
+ continue;
+
+ // If we were unable to merge away the alloca either because there are no
+ // allocas of the right type available or because we reused them all
+ // already, remember that this alloca came from an inlined function and mark
+ // it used so we don't reuse it for other allocas from this inline
+ // operation.
+ AllocasForType.push_back(AI);
+ UsedAllocas.insert(AI);
}
- DEBUG(std::cerr << "\n");
+
+ return true;
+}
- bool Changed = false;
- for (std::set<Function*>::iterator SCCI = SCCFunctions.begin(),
- E = SCCFunctions.end(); SCCI != E; ++SCCI) {
- Function *F = *SCCI;
- if (F == 0 || F->isExternal()) continue;
- DEBUG(std::cerr << " Inspecting function: " << F->getName() << "\n");
-
- // Scan through and identify all call sites ahead of time so that we only
- // inline call sites in the original functions, not call sites that result
- // in inlining other functions.
- std::vector<CallSite> CallSites;
- for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
- CallSite CS = CallSite::get(I);
- if (CS.getInstruction() && CS.getCalledFunction() &&
- !CS.getCalledFunction()->isExternal())
- CallSites.push_back(CS);
+unsigned Inliner::getInlineThreshold(CallSite CS) const {
+ int Threshold = InlineThreshold; // -inline-threshold or else selected by
+ // overall opt level
+
+ // If -inline-threshold is not given, listen to the optsize attribute when it
+ // would decrease the threshold.
+ Function *Caller = CS.getCaller();
+ bool OptSize = Caller && !Caller->isDeclaration() &&
+ // FIXME: Use Function::optForSize().
+ Caller->hasFnAttribute(Attribute::OptimizeForSize);
+ if (!(InlineLimit.getNumOccurrences() > 0) && OptSize &&
+ OptSizeThreshold < Threshold)
+ Threshold = OptSizeThreshold;
+
+ Function *Callee = CS.getCalledFunction();
+ if (!Callee || Callee->isDeclaration())
+ return Threshold;
+
+ // If profile information is available, use that to adjust threshold of hot
+ // and cold functions.
+ // FIXME: The heuristic used below for determining hotness and coldness are
+ // based on preliminary SPEC tuning and may not be optimal. Replace this with
+ // a well-tuned heuristic based on *callsite* hotness and not callee hotness.
+ uint64_t FunctionCount = 0, MaxFunctionCount = 0;
+ bool HasPGOCounts = false;
+ if (Callee->getEntryCount() &&
+ Callee->getParent()->getMaximumFunctionCount()) {
+ HasPGOCounts = true;
+ FunctionCount = Callee->getEntryCount().getValue();
+ MaxFunctionCount =
+ Callee->getParent()->getMaximumFunctionCount().getValue();
+ }
+
+ // Listen to the inlinehint attribute or profile based hotness information
+ // when it would increase the threshold and the caller does not need to
+ // minimize its size.
+ bool InlineHint =
+ Callee->hasFnAttribute(Attribute::InlineHint) ||
+ (HasPGOCounts &&
+ FunctionCount >= (uint64_t)(0.3 * (double)MaxFunctionCount));
+ if (InlineHint && HintThreshold > Threshold &&
+ !Caller->hasFnAttribute(Attribute::MinSize))
+ Threshold = HintThreshold;
+
+ // Listen to the cold attribute or profile based coldness information
+ // when it would decrease the threshold.
+ bool ColdCallee =
+ Callee->hasFnAttribute(Attribute::Cold) ||
+ (HasPGOCounts &&
+ FunctionCount <= (uint64_t)(0.01 * (double)MaxFunctionCount));
+ // Command line argument for InlineLimit will override the default
+ // ColdThreshold. If we have -inline-threshold but no -inlinecold-threshold,
+ // do not use the default cold threshold even if it is smaller.
+ if ((InlineLimit.getNumOccurrences() == 0 ||
+ ColdThreshold.getNumOccurrences() > 0) && ColdCallee &&
+ ColdThreshold < Threshold)
+ Threshold = ColdThreshold;
+
+ return Threshold;
+}
+
+static void emitAnalysis(CallSite CS, const Twine &Msg) {
+ Function *Caller = CS.getCaller();
+ LLVMContext &Ctx = Caller->getContext();
+ DebugLoc DLoc = CS.getInstruction()->getDebugLoc();
+ emitOptimizationRemarkAnalysis(Ctx, DEBUG_TYPE, *Caller, DLoc, Msg);
+}
+
+/// Return true if the inliner should attempt to inline at the given CallSite.
+bool Inliner::shouldInline(CallSite CS) {
+ InlineCost IC = getInlineCost(CS);
+
+ if (IC.isAlways()) {
+ DEBUG(dbgs() << " Inlining: cost=always"
+ << ", Call: " << *CS.getInstruction() << "\n");
+ emitAnalysis(CS, Twine(CS.getCalledFunction()->getName()) +
+ " should always be inlined (cost=always)");
+ return true;
+ }
+
+ if (IC.isNever()) {
+ DEBUG(dbgs() << " NOT Inlining: cost=never"
+ << ", Call: " << *CS.getInstruction() << "\n");
+ emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
+ " should never be inlined (cost=never)"));
+ return false;
+ }
+
+ Function *Caller = CS.getCaller();
+ if (!IC) {
+ DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost()
+ << ", thres=" << (IC.getCostDelta() + IC.getCost())
+ << ", Call: " << *CS.getInstruction() << "\n");
+ emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
+ " too costly to inline (cost=") +
+ Twine(IC.getCost()) + ", threshold=" +
+ Twine(IC.getCostDelta() + IC.getCost()) + ")");
+ return false;
+ }
+
+ // Try to detect the case where the current inlining candidate caller (call
+ // it B) is a static or linkonce-ODR function and is an inlining candidate
+ // elsewhere, and the current candidate callee (call it C) is large enough
+ // that inlining it into B would make B too big to inline later. In these
+ // circumstances it may be best not to inline C into B, but to inline B into
+ // its callers.
+ //
+ // This only applies to static and linkonce-ODR functions because those are
+ // expected to be available for inlining in the translation units where they
+ // are used. Thus we will always have the opportunity to make local inlining
+ // decisions. Importantly the linkonce-ODR linkage covers inline functions
+ // and templates in C++.
+ //
+ // FIXME: All of this logic should be sunk into getInlineCost. It relies on
+ // the internal implementation of the inline cost metrics rather than
+ // treating them as truly abstract units etc.
+ if (Caller->hasLocalLinkage() || Caller->hasLinkOnceODRLinkage()) {
+ int TotalSecondaryCost = 0;
+ // The candidate cost to be imposed upon the current function.
+ int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
+ // This bool tracks what happens if we do NOT inline C into B.
+ bool callerWillBeRemoved = Caller->hasLocalLinkage();
+ // This bool tracks what happens if we DO inline C into B.
+ bool inliningPreventsSomeOuterInline = false;
+ for (User *U : Caller->users()) {
+ CallSite CS2(U);
+
+ // If this isn't a call to Caller (it could be some other sort
+ // of reference) skip it. Such references will prevent the caller
+ // from being removed.
+ if (!CS2 || CS2.getCalledFunction() != Caller) {
+ callerWillBeRemoved = false;
+ continue;
}
- // Now that we have all of the call sites, loop over them and inline them if
- // it looks profitable to do so.
- for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
- CallSite CS = CallSites[i];
- Function *Callee = CS.getCalledFunction();
- // Determine whether this is a function IN the SCC...
- bool inSCC = SCCFunctions.count(Callee);
+ InlineCost IC2 = getInlineCost(CS2);
+ ++NumCallerCallersAnalyzed;
+ if (!IC2) {
+ callerWillBeRemoved = false;
+ continue;
+ }
+ if (IC2.isAlways())
+ continue;
+
+ // See if inlining or original callsite would erase the cost delta of
+ // this callsite. We subtract off the penalty for the call instruction,
+ // which we would be deleting.
+ if (IC2.getCostDelta() <= CandidateCost) {
+ inliningPreventsSomeOuterInline = true;
+ TotalSecondaryCost += IC2.getCost();
+ }
+ }
+ // If all outer calls to Caller would get inlined, the cost for the last
+ // one is set very low by getInlineCost, in anticipation that Caller will
+ // be removed entirely. We did not account for this above unless there
+ // is only one caller of Caller.
+ if (callerWillBeRemoved && !Caller->use_empty())
+ TotalSecondaryCost += InlineConstants::LastCallToStaticBonus;
+
+ if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) {
+ DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction() <<
+ " Cost = " << IC.getCost() <<
+ ", outer Cost = " << TotalSecondaryCost << '\n');
+ emitAnalysis(
+ CS, Twine("Not inlining. Cost of inlining " +
+ CS.getCalledFunction()->getName() +
+ " increases the cost of inlining " +
+ CS.getCaller()->getName() + " in other contexts"));
+ return false;
+ }
+ }
+
+ DEBUG(dbgs() << " Inlining: cost=" << IC.getCost()
+ << ", thres=" << (IC.getCostDelta() + IC.getCost())
+ << ", Call: " << *CS.getInstruction() << '\n');
+ emitAnalysis(
+ CS, CS.getCalledFunction()->getName() + Twine(" can be inlined into ") +
+ CS.getCaller()->getName() + " with cost=" + Twine(IC.getCost()) +
+ " (threshold=" + Twine(IC.getCostDelta() + IC.getCost()) + ")");
+ return true;
+}
+
+/// Return true if the specified inline history ID
+/// indicates an inline history that includes the specified function.
+static bool InlineHistoryIncludes(Function *F, int InlineHistoryID,
+ const SmallVectorImpl<std::pair<Function*, int> > &InlineHistory) {
+ while (InlineHistoryID != -1) {
+ assert(unsigned(InlineHistoryID) < InlineHistory.size() &&
+ "Invalid inline history ID");
+ if (InlineHistory[InlineHistoryID].first == F)
+ return true;
+ InlineHistoryID = InlineHistory[InlineHistoryID].second;
+ }
+ return false;
+}
+
+bool Inliner::runOnSCC(CallGraphSCC &SCC) {
+ CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
+ ACT = &getAnalysis<AssumptionCacheTracker>();
+ auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+
+ SmallPtrSet<Function*, 8> SCCFunctions;
+ DEBUG(dbgs() << "Inliner visiting SCC:");
+ for (CallGraphNode *Node : SCC) {
+ Function *F = Node->getFunction();
+ if (F) SCCFunctions.insert(F);
+ DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE"));
+ }
+
+ // Scan through and identify all call sites ahead of time so that we only
+ // inline call sites in the original functions, not call sites that result
+ // from inlining other functions.
+ SmallVector<std::pair<CallSite, int>, 16> CallSites;
+
+ // When inlining a callee produces new call sites, we want to keep track of
+ // the fact that they were inlined from the callee. This allows us to avoid
+ // infinite inlining in some obscure cases. To represent this, we use an
+ // index into the InlineHistory vector.
+ SmallVector<std::pair<Function*, int>, 8> InlineHistory;
+
+ for (CallGraphNode *Node : SCC) {
+ Function *F = Node->getFunction();
+ if (!F) continue;
- // If the policy determines that we should inline this function,
- // try to do so...
- int InlineCost = inSCC ? getRecursiveInlineCost(CS) : getInlineCost(CS);
- if (InlineCost >= (int)InlineThreshold) {
- DEBUG(std::cerr << " NOT Inlining: cost=" << InlineCost
- << ", Call: " << *CS.getInstruction());
+ for (BasicBlock &BB : *F)
+ for (Instruction &I : BB) {
+ CallSite CS(cast<Value>(&I));
+ // If this isn't a call, or it is a call to an intrinsic, it can
+ // never be inlined.
+ if (!CS || isa<IntrinsicInst>(I))
+ continue;
+
+ // If this is a direct call to an external function, we can never inline
+ // it. If it is an indirect call, inlining may resolve it to be a
+ // direct call, so we keep it.
+ if (Function *Callee = CS.getCalledFunction())
+ if (Callee->isDeclaration())
+ continue;
+
+ CallSites.push_back(std::make_pair(CS, -1));
+ }
+ }
+
+ DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n");
+
+ // If there are no calls in this function, exit early.
+ if (CallSites.empty())
+ return false;
+
+ // Now that we have all of the call sites, move the ones to functions in the
+ // current SCC to the end of the list.
+ unsigned FirstCallInSCC = CallSites.size();
+ for (unsigned i = 0; i < FirstCallInSCC; ++i)
+ if (Function *F = CallSites[i].first.getCalledFunction())
+ if (SCCFunctions.count(F))
+ std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);
+
+
+ InlinedArrayAllocasTy InlinedArrayAllocas;
+ InlineFunctionInfo InlineInfo(&CG, ACT);
+
+ // Now that we have all of the call sites, loop over them and inline them if
+ // it looks profitable to do so.
+ bool Changed = false;
+ bool LocalChange;
+ do {
+ LocalChange = false;
+ // Iterate over the outer loop because inlining functions can cause indirect
+ // calls to become direct calls.
+ // CallSites may be modified inside so ranged for loop can not be used.
+ for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) {
+ CallSite CS = CallSites[CSi].first;
+
+ Function *Caller = CS.getCaller();
+ Function *Callee = CS.getCalledFunction();
+
+ // If this call site is dead and it is to a readonly function, we should
+ // just delete the call instead of trying to inline it, regardless of
+ // size. This happens because IPSCCP propagates the result out of the
+ // call and then we're left with the dead call.
+ if (isInstructionTriviallyDead(CS.getInstruction(), &TLI)) {
+ DEBUG(dbgs() << " -> Deleting dead call: "
+ << *CS.getInstruction() << "\n");
+ // Update the call graph by deleting the edge from Callee to Caller.
+ CG[Caller]->removeCallEdgeFor(CS);
+ CS.getInstruction()->eraseFromParent();
+ ++NumCallsDeleted;
} else {
- DEBUG(std::cerr << " Inlining: cost=" << InlineCost
- << ", Call: " << *CS.getInstruction());
+ // We can only inline direct calls to non-declarations.
+ if (!Callee || Callee->isDeclaration()) continue;
- Function *Caller = CS.getInstruction()->getParent()->getParent();
-
- // Attempt to inline the function...
- if (InlineFunction(CS)) {
- ++NumInlined;
-
- // Update the call graph by deleting the edge from Callee to Caller
- CallGraphNode *CalleeNode = CG[Callee];
- CallGraphNode *CallerNode = CG[Caller];
- CallerNode->removeCallEdgeTo(CalleeNode);
-
- // Since we inlined all uninlinable call sites in the callee into the
- // caller, add edges from the caller to all of the callees of the
- // callee.
- for (CallGraphNode::iterator I = CalleeNode->begin(),
- E = CalleeNode->end(); I != E; ++I)
- CallerNode->addCalledFunction(*I);
+ // If this call site was obtained by inlining another function, verify
+ // that the include path for the function did not include the callee
+ // itself. If so, we'd be recursively inlining the same function,
+ // which would provide the same callsites, which would cause us to
+ // infinitely inline.
+ int InlineHistoryID = CallSites[CSi].second;
+ if (InlineHistoryID != -1 &&
+ InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory))
+ continue;
- // If we inlined the last possible call site to the function,
- // delete the function body now.
- if (Callee->use_empty() && Callee != Caller &&
- Callee->hasInternalLinkage()) {
- DEBUG(std::cerr << " -> Deleting dead function: "
- << Callee->getName() << "\n");
- SCCFunctions.erase(Callee); // Remove function from this SCC.
-
- // Remove any call graph edges from the callee to its callees.
- while (CalleeNode->begin() != CalleeNode->end())
- CalleeNode->removeCallEdgeTo(*(CalleeNode->end()-1));
-
- // Removing the node for callee from the call graph and delete it.
- delete CG.removeFunctionFromModule(CalleeNode);
- ++NumDeleted;
- }
- Changed = true;
+ LLVMContext &CallerCtx = Caller->getContext();
+
+ // Get DebugLoc to report. CS will be invalid after Inliner.
+ DebugLoc DLoc = CS.getInstruction()->getDebugLoc();
+
+ // If the policy determines that we should inline this function,
+ // try to do so.
+ if (!shouldInline(CS)) {
+ emitOptimizationRemarkMissed(CallerCtx, DEBUG_TYPE, *Caller, DLoc,
+ Twine(Callee->getName() +
+ " will not be inlined into " +
+ Caller->getName()));
+ continue;
+ }
+
+ // Attempt to inline the function.
+ if (!InlineCallIfPossible(*this, CS, InlineInfo, InlinedArrayAllocas,
+ InlineHistoryID, InsertLifetime)) {
+ emitOptimizationRemarkMissed(CallerCtx, DEBUG_TYPE, *Caller, DLoc,
+ Twine(Callee->getName() +
+ " will not be inlined into " +
+ Caller->getName()));
+ continue;
+ }
+ ++NumInlined;
+
+ // Report the inline decision.
+ emitOptimizationRemark(
+ CallerCtx, DEBUG_TYPE, *Caller, DLoc,
+ Twine(Callee->getName() + " inlined into " + Caller->getName()));
+
+ // If inlining this function gave us any new call sites, throw them
+ // onto our worklist to process. They are useful inline candidates.
+ if (!InlineInfo.InlinedCalls.empty()) {
+ // Create a new inline history entry for this, so that we remember
+ // that these new callsites came about due to inlining Callee.
+ int NewHistoryID = InlineHistory.size();
+ InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID));
+
+ for (Value *Ptr : InlineInfo.InlinedCalls)
+ CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID));
}
}
+
+ // If we inlined or deleted the last possible call site to the function,
+ // delete the function body now.
+ if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() &&
+ // TODO: Can remove if in SCC now.
+ !SCCFunctions.count(Callee) &&
+
+ // The function may be apparently dead, but if there are indirect
+ // callgraph references to the node, we cannot delete it yet, this
+ // could invalidate the CGSCC iterator.
+ CG[Callee]->getNumReferences() == 0) {
+ DEBUG(dbgs() << " -> Deleting dead function: "
+ << Callee->getName() << "\n");
+ CallGraphNode *CalleeNode = CG[Callee];
+
+ // Remove any call graph edges from the callee to its callees.
+ CalleeNode->removeAllCalledFunctions();
+
+ // Removing the node for callee from the call graph and delete it.
+ delete CG.removeFunctionFromModule(CalleeNode);
+ ++NumDeleted;
+ }
+
+ // Remove this call site from the list. If possible, use
+ // swap/pop_back for efficiency, but do not use it if doing so would
+ // move a call site to a function in this SCC before the
+ // 'FirstCallInSCC' barrier.
+ if (SCC.isSingular()) {
+ CallSites[CSi] = CallSites.back();
+ CallSites.pop_back();
+ } else {
+ CallSites.erase(CallSites.begin()+CSi);
+ }
+ --CSi;
+
+ Changed = true;
+ LocalChange = true;
}
- }
+ } while (LocalChange);
return Changed;
}
-// doFinalization - Remove now-dead linkonce functions at the end of
-// processing to avoid breaking the SCC traversal.
+/// Remove now-dead linkonce functions at the end of
+/// processing to avoid breaking the SCC traversal.
bool Inliner::doFinalization(CallGraph &CG) {
- std::set<CallGraphNode*> FunctionsToRemove;
+ return removeDeadFunctions(CG);
+}
+
+/// Remove dead functions that are not included in DNR (Do Not Remove) list.
+bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) {
+ SmallVector<CallGraphNode*, 16> FunctionsToRemove;
+ SmallVector<CallGraphNode *, 16> DeadFunctionsInComdats;
+ SmallDenseMap<const Comdat *, int, 16> ComdatEntriesAlive;
+
+ auto RemoveCGN = [&](CallGraphNode *CGN) {
+ // Remove any call graph edges from the function to its callees.
+ CGN->removeAllCalledFunctions();
+
+ // Remove any edges from the external node to the function's call graph
+ // node. These edges might have been made irrelegant due to
+ // optimization of the program.
+ CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);
+
+ // Removing the node for callee from the call graph and delete it.
+ FunctionsToRemove.push_back(CGN);
+ };
// Scan for all of the functions, looking for ones that should now be removed
// from the program. Insert the dead ones in the FunctionsToRemove set.
- for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
- CallGraphNode *CGN = I->second;
- Function *F = CGN ? CGN->getFunction() : 0;
-
- // If the only remaining use of the function is a dead constant
- // pointer ref, remove it.
- if (F && F->hasOneUse())
- if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(F->use_back()))
- if (CPR->use_empty()) {
- CPR->destroyConstant();
- if (F->hasInternalLinkage()) {
- // There *MAY* be an edge from the external call node to this
- // function. If so, remove it.
- CallGraphNode *EN = CG.getExternalCallingNode();
- CallGraphNode::iterator I = std::find(EN->begin(), EN->end(), CGN);
- if (I != EN->end()) EN->removeCallEdgeTo(CGN);
- }
- }
+ for (const auto &I : CG) {
+ CallGraphNode *CGN = I.second.get();
+ Function *F = CGN->getFunction();
+ if (!F || F->isDeclaration())
+ continue;
- if (F && (F->hasLinkOnceLinkage() || F->hasInternalLinkage()) &&
- F->use_empty()) {
- // Remove any call graph edges from the function to its callees.
- while (CGN->begin() != CGN->end())
- CGN->removeCallEdgeTo(*(CGN->end()-1));
-
- // If the function has external linkage (basically if it's a linkonce
- // function) remove the edge from the external node to the callee node.
- if (!F->hasInternalLinkage())
- CG.getExternalCallingNode()->removeCallEdgeTo(CGN);
-
- // Removing the node for callee from the call graph and delete it.
- FunctionsToRemove.insert(CGN);
+ // Handle the case when this function is called and we only want to care
+ // about always-inline functions. This is a bit of a hack to share code
+ // between here and the InlineAlways pass.
+ if (AlwaysInlineOnly && !F->hasFnAttribute(Attribute::AlwaysInline))
+ continue;
+
+ // If the only remaining users of the function are dead constants, remove
+ // them.
+ F->removeDeadConstantUsers();
+
+ if (!F->isDefTriviallyDead())
+ continue;
+
+ // It is unsafe to drop a function with discardable linkage from a COMDAT
+ // without also dropping the other members of the COMDAT.
+ // The inliner doesn't visit non-function entities which are in COMDAT
+ // groups so it is unsafe to do so *unless* the linkage is local.
+ if (!F->hasLocalLinkage()) {
+ if (const Comdat *C = F->getComdat()) {
+ --ComdatEntriesAlive[C];
+ DeadFunctionsInComdats.push_back(CGN);
+ continue;
+ }
+ }
+
+ RemoveCGN(CGN);
+ }
+ if (!DeadFunctionsInComdats.empty()) {
+ // Count up all the entities in COMDAT groups
+ auto ComdatGroupReferenced = [&](const Comdat *C) {
+ auto I = ComdatEntriesAlive.find(C);
+ if (I != ComdatEntriesAlive.end())
+ ++(I->getSecond());
+ };
+ for (const Function &F : CG.getModule())
+ if (const Comdat *C = F.getComdat())
+ ComdatGroupReferenced(C);
+ for (const GlobalVariable &GV : CG.getModule().globals())
+ if (const Comdat *C = GV.getComdat())
+ ComdatGroupReferenced(C);
+ for (const GlobalAlias &GA : CG.getModule().aliases())
+ if (const Comdat *C = GA.getComdat())
+ ComdatGroupReferenced(C);
+ for (CallGraphNode *CGN : DeadFunctionsInComdats) {
+ Function *F = CGN->getFunction();
+ const Comdat *C = F->getComdat();
+ int NumAlive = ComdatEntriesAlive[C];
+ // We can remove functions in a COMDAT group if the entire group is dead.
+ assert(NumAlive >= 0);
+ if (NumAlive > 0)
+ continue;
+
+ RemoveCGN(CGN);
}
}
+ if (FunctionsToRemove.empty())
+ return false;
+
// Now that we know which functions to delete, do so. We didn't want to do
// this inline, because that would invalidate our CallGraph::iterator
// objects. :(
- bool Changed = false;
- for (std::set<CallGraphNode*>::iterator I = FunctionsToRemove.begin(),
- E = FunctionsToRemove.end(); I != E; ++I) {
- delete CG.removeFunctionFromModule(*I);
+ //
+ // Note that it doesn't matter that we are iterating over a non-stable order
+ // here to do this, it doesn't matter which order the functions are deleted
+ // in.
+ array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
+ FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(),
+ FunctionsToRemove.end()),
+ FunctionsToRemove.end());
+ for (CallGraphNode *CGN : FunctionsToRemove) {
+ delete CG.removeFunctionFromModule(CGN);
++NumDeleted;
- Changed = true;
}
-
- return Changed;
+ return true;
}
projects / oota-llvm.git / blobdiff