-//===- 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
+#define DEBUG_TYPE "inline"
#include "llvm/Module.h"
-#include "llvm/iOther.h"
-#include "llvm/iTerminators.h"
+#include "llvm/Instructions.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Support/CallSite.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/IPO/InlinerPass.h"
#include "llvm/Transforms/Utils/Cloning.h"
-#include "Support/CommandLine.h"
-#include "Support/Debug.h"
-#include "Support/Statistic.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/ADT/Statistic.h"
+#include <set>
+using namespace llvm;
+
+STATISTIC(NumInlined, "Number of functions inlined");
+STATISTIC(NumDeleted, "Number of functions deleted because all callers found");
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)"));
+ cl::desc("Control the amount of inlining to perform (default = 200)"));
}
-Inliner::Inliner() : InlineThreshold(InlineLimit) {}
+Inliner::Inliner(const void *ID)
+ : CallGraphSCCPass((intptr_t)ID), InlineThreshold(InlineLimit) {}
-int Inliner::getRecursiveInlineCost(CallSite CS) {
- return getInlineCost(CS);
+Inliner::Inliner(const void *ID, int Threshold)
+ : CallGraphSCCPass((intptr_t)ID), InlineThreshold(Threshold) {}
+
+/// getAnalysisUsage - 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 &Info) const {
+ Info.addRequired<TargetData>();
+ CallGraphSCCPass::getAnalysisUsage(Info);
+}
+
+// InlineCallIfPossible - If it is possible to inline the specified call site,
+// do so and update the CallGraph for this operation.
+static bool InlineCallIfPossible(CallSite CS, CallGraph &CG,
+ const std::set<Function*> &SCCFunctions,
+ const TargetData &TD) {
+ Function *Callee = CS.getCalledFunction();
+ if (!InlineFunction(CS, &CG, &TD)) return false;
+
+ // If we inlined the last possible call site to the function, delete the
+ // function body now.
+ if (Callee->use_empty() && Callee->hasInternalLinkage() &&
+ !SCCFunctions.count(Callee)) {
+ DOUT << " -> Deleting dead function: " << Callee->getName() << "\n";
+
+ // Remove any call graph edges from the callee to its callees.
+ CallGraphNode *CalleeNode = CG[Callee];
+ while (!CalleeNode->empty())
+ CalleeNode->removeCallEdgeTo((CalleeNode->end()-1)->second);
+
+ // Removing the node for callee from the call graph and delete it.
+ delete CG.removeFunctionFromModule(CalleeNode);
+ ++NumDeleted;
+ }
+ return true;
}
bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
CallGraph &CG = getAnalysis<CallGraph>();
std::set<Function*> SCCFunctions;
- DEBUG(std::cerr << "Inliner visiting SCC:");
+ DOUT << "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"));
+ Function *F = SCC[i]->getFunction();
+ if (F) SCCFunctions.insert(F);
+ DOUT << " " << (F ? F->getName() : "INDIRECTNODE");
}
- DEBUG(std::cerr << "\n");
- 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");
-
- for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
- bool ShouldInc = true;
- // Found a call or invoke instruction?
- if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
+ // 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.
+ std::vector<CallSite> CallSites;
+
+ for (unsigned i = 0, e = SCC.size(); i != e; ++i)
+ if (Function *F = SCC[i]->getFunction())
+ 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 (Function *Callee = CS.getCalledFunction())
- if (!Callee->isExternal() && !IsRecursiveFunction.count(Callee)) {
- // Determine whether this is a function IN the SCC...
- bool inSCC = SCCFunctions.count(Callee);
-
- // Keep track of whether this is a directly recursive function.
- if (Callee == F) IsRecursiveFunction.insert(F);
-
- // 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 << " Inlining: cost=" << InlineCost
- << ", Call: " << *CS.getInstruction());
-
- // Save an iterator to the instruction before the call if it
- // exists, otherwise get an iterator at the end of the
- // block... because the call will be destroyed.
- //
- BasicBlock::iterator SI;
- if (I != BB->begin()) {
- SI = I; --SI; // Instruction before the call...
- } else {
- SI = BB->end();
- }
-
- if (performInlining(CS, SCCFunctions)) {
- // Move to instruction before the call...
- I = (SI == BB->end()) ? BB->begin() : SI;
- ShouldInc = false; // Don't increment iterator until next time
- Changed = true;
- }
- }
+ if (CS.getInstruction() && (!CS.getCalledFunction() ||
+ !CS.getCalledFunction()->isDeclaration()))
+ CallSites.push_back(CS);
+ }
+
+ DOUT << ": " << CallSites.size() << " call sites.\n";
+
+ // 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].getCalledFunction())
+ if (SCCFunctions.count(F))
+ std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);
+
+ // 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.
+ for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi)
+ if (Function *Callee = CallSites[CSi].getCalledFunction()) {
+ // Calls to external functions are never inlinable.
+ if (Callee->isDeclaration() ||
+ CallSites[CSi].getInstruction()->getParent()->getParent() ==Callee){
+ if (SCC.size() == 1) {
+ std::swap(CallSites[CSi], CallSites.back());
+ CallSites.pop_back();
+ } else {
+ // Keep the 'in SCC / not in SCC' boundary correct.
+ CallSites.erase(CallSites.begin()+CSi);
+ }
+ --CSi;
+ continue;
+ }
+
+ // If the policy determines that we should inline this function,
+ // try to do so.
+ CallSite CS = CallSites[CSi];
+ int InlineCost = getInlineCost(CS);
+ if (InlineCost >= (int)InlineThreshold) {
+ DOUT << " NOT Inlining: cost=" << InlineCost
+ << ", Call: " << *CS.getInstruction();
+ } else {
+ DOUT << " Inlining: cost=" << InlineCost
+ << ", Call: " << *CS.getInstruction();
+
+ // Attempt to inline the function...
+ if (InlineCallIfPossible(CS, CG, SCCFunctions,
+ getAnalysis<TargetData>())) {
+ // 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.size() == 1) {
+ std::swap(CallSites[CSi], CallSites.back());
+ CallSites.pop_back();
+ } else {
+ CallSites.erase(CallSites.begin()+CSi);
}
+ --CSi;
+
+ ++NumInlined;
+ Changed = true;
+ LocalChange = true;
+ }
}
- if (ShouldInc) ++I;
}
- }
+ } while (LocalChange);
+
return Changed;
}
-bool Inliner::performInlining(CallSite CS, std::set<Function*> &SCC) {
- Function *Callee = CS.getCalledFunction();
- Function *Caller = CS.getInstruction()->getParent()->getParent();
-
- // Attempt to inline the function...
- if (!InlineFunction(CS)) return false;
- ++NumInlined;
-
- if (Callee->hasOneUse())
- if (ConstantPointerRef *CPR =
- dyn_cast<ConstantPointerRef>(Callee->use_back()))
- if (CPR->use_empty())
- CPR->destroyConstant();
-
- // If we inlined the last possible call site to the function,
- // delete the function body now.
- if (Callee->use_empty() && Callee != Caller &&
- (Callee->hasInternalLinkage() || Callee->hasLinkOnceLinkage())) {
- DEBUG(std::cerr << " -> Deleting dead function: " << (void*)Callee
- << Callee->getName() << "\n");
- std::set<Function*>::iterator I = SCC.find(Callee);
- if (I != SCC.end()) // Remove function from this SCC...
- SCC.erase(I);
-
- Callee->getParent()->getFunctionList().erase(Callee);
+// doFinalization - 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;
+
+ // 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;
+ if (Function *F = CGN ? CGN->getFunction() : 0) {
+ // If the only remaining users of the function are dead constants, remove
+ // them.
+ F->removeDeadConstantUsers();
+
+ if ((F->hasLinkOnceLinkage() || F->hasInternalLinkage()) &&
+ F->use_empty()) {
+
+ // Remove any call graph edges from the function to its callees.
+ while (!CGN->empty())
+ CGN->removeCallEdgeTo((CGN->end()-1)->second);
+
+ // 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.insert(CGN);
+ }
+ }
+ }
+
+ // 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);
++NumDeleted;
+ Changed = true;
}
- return true;
+
+ return Changed;
}
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