Chris Lattner | cf5933a | 2004-06-20 04:11:48 +0000 | [diff] [blame] | 1 | //===- Inliner.cpp - Code common to all inliners --------------------------===// |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 2 | // |
John Criswell | b576c94 | 2003-10-20 19:43:21 +0000 | [diff] [blame] | 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
Chris Lattner | 4ee451d | 2007-12-29 20:36:04 +0000 | [diff] [blame^] | 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 7 | // |
John Criswell | b576c94 | 2003-10-20 19:43:21 +0000 | [diff] [blame] | 8 | //===----------------------------------------------------------------------===// |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 9 | // |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 10 | // This file implements the mechanics required to implement inlining without |
| 11 | // missing any calls and updating the call graph. The decisions of which calls |
| 12 | // are profitable to inline are implemented elsewhere. |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 13 | // |
| 14 | //===----------------------------------------------------------------------===// |
| 15 | |
Chris Lattner | 86453c5 | 2006-12-19 22:09:18 +0000 | [diff] [blame] | 16 | #define DEBUG_TYPE "inline" |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 17 | #include "llvm/Module.h" |
Misha Brukman | 47b14a4 | 2004-07-29 17:30:56 +0000 | [diff] [blame] | 18 | #include "llvm/Instructions.h" |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 19 | #include "llvm/Analysis/CallGraph.h" |
| 20 | #include "llvm/Support/CallSite.h" |
Chris Lattner | ff2dad3 | 2007-01-30 23:28:39 +0000 | [diff] [blame] | 21 | #include "llvm/Target/TargetData.h" |
Tanya Lattner | 6f7426e | 2007-06-19 22:29:50 +0000 | [diff] [blame] | 22 | #include "llvm/Transforms/IPO/InlinerPass.h" |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 23 | #include "llvm/Transforms/Utils/Cloning.h" |
Reid Spencer | 551ccae | 2004-09-01 22:55:40 +0000 | [diff] [blame] | 24 | #include "llvm/Support/CommandLine.h" |
| 25 | #include "llvm/Support/Debug.h" |
| 26 | #include "llvm/ADT/Statistic.h" |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 27 | #include <set> |
Chris Lattner | a51bcb5 | 2003-11-21 21:45:31 +0000 | [diff] [blame] | 28 | using namespace llvm; |
Brian Gaeke | d0fde30 | 2003-11-11 22:41:34 +0000 | [diff] [blame] | 29 | |
Chris Lattner | 86453c5 | 2006-12-19 22:09:18 +0000 | [diff] [blame] | 30 | STATISTIC(NumInlined, "Number of functions inlined"); |
| 31 | STATISTIC(NumDeleted, "Number of functions deleted because all callers found"); |
| 32 | |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 33 | namespace { |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 34 | cl::opt<unsigned> // FIXME: 200 is VERY conservative |
| 35 | InlineLimit("inline-threshold", cl::Hidden, cl::init(200), |
Chris Lattner | 8acb249 | 2006-01-13 18:06:56 +0000 | [diff] [blame] | 36 | cl::desc("Control the amount of inlining to perform (default = 200)")); |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 37 | } |
| 38 | |
Chris Lattner | 1ce6f8d | 2007-05-06 23:13:56 +0000 | [diff] [blame] | 39 | Inliner::Inliner(const void *ID) |
| 40 | : CallGraphSCCPass((intptr_t)ID), InlineThreshold(InlineLimit) {} |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 41 | |
Chris Lattner | ff2dad3 | 2007-01-30 23:28:39 +0000 | [diff] [blame] | 42 | /// getAnalysisUsage - For this class, we declare that we require and preserve |
| 43 | /// the call graph. If the derived class implements this method, it should |
| 44 | /// always explicitly call the implementation here. |
| 45 | void Inliner::getAnalysisUsage(AnalysisUsage &Info) const { |
| 46 | Info.addRequired<TargetData>(); |
| 47 | CallGraphSCCPass::getAnalysisUsage(Info); |
| 48 | } |
| 49 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 50 | // InlineCallIfPossible - If it is possible to inline the specified call site, |
| 51 | // do so and update the CallGraph for this operation. |
| 52 | static bool InlineCallIfPossible(CallSite CS, CallGraph &CG, |
Chris Lattner | ff2dad3 | 2007-01-30 23:28:39 +0000 | [diff] [blame] | 53 | const std::set<Function*> &SCCFunctions, |
| 54 | const TargetData &TD) { |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 55 | Function *Callee = CS.getCalledFunction(); |
Chris Lattner | ff2dad3 | 2007-01-30 23:28:39 +0000 | [diff] [blame] | 56 | if (!InlineFunction(CS, &CG, &TD)) return false; |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 57 | |
Chris Lattner | 54970c0 | 2004-08-08 03:29:50 +0000 | [diff] [blame] | 58 | // If we inlined the last possible call site to the function, delete the |
| 59 | // function body now. |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 60 | if (Callee->use_empty() && Callee->hasInternalLinkage() && |
| 61 | !SCCFunctions.count(Callee)) { |
Bill Wendling | 0a81aac | 2006-11-26 10:02:32 +0000 | [diff] [blame] | 62 | DOUT << " -> Deleting dead function: " << Callee->getName() << "\n"; |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 63 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 64 | // Remove any call graph edges from the callee to its callees. |
Chris Lattner | 432a205 | 2006-01-14 20:09:18 +0000 | [diff] [blame] | 65 | CallGraphNode *CalleeNode = CG[Callee]; |
Dan Gohman | cb406c2 | 2007-10-03 19:26:29 +0000 | [diff] [blame] | 66 | while (!CalleeNode->empty()) |
Chris Lattner | d85340f | 2006-07-12 18:29:36 +0000 | [diff] [blame] | 67 | CalleeNode->removeCallEdgeTo((CalleeNode->end()-1)->second); |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 68 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 69 | // Removing the node for callee from the call graph and delete it. |
| 70 | delete CG.removeFunctionFromModule(CalleeNode); |
| 71 | ++NumDeleted; |
| 72 | } |
| 73 | return true; |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 74 | } |
| 75 | |
| 76 | bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) { |
| 77 | CallGraph &CG = getAnalysis<CallGraph>(); |
| 78 | |
| 79 | std::set<Function*> SCCFunctions; |
Bill Wendling | 0a81aac | 2006-11-26 10:02:32 +0000 | [diff] [blame] | 80 | DOUT << "Inliner visiting SCC:"; |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 81 | for (unsigned i = 0, e = SCC.size(); i != e; ++i) { |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 82 | Function *F = SCC[i]->getFunction(); |
| 83 | if (F) SCCFunctions.insert(F); |
Bill Wendling | 0a81aac | 2006-11-26 10:02:32 +0000 | [diff] [blame] | 84 | DOUT << " " << (F ? F->getName() : "INDIRECTNODE"); |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 85 | } |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 86 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 87 | // Scan through and identify all call sites ahead of time so that we only |
| 88 | // inline call sites in the original functions, not call sites that result |
| 89 | // from inlining other functions. |
| 90 | std::vector<CallSite> CallSites; |
| 91 | |
Chris Lattner | cf5933a | 2004-06-20 04:11:48 +0000 | [diff] [blame] | 92 | for (unsigned i = 0, e = SCC.size(); i != e; ++i) |
| 93 | if (Function *F = SCC[i]->getFunction()) |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 94 | for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) |
| 95 | for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) { |
| 96 | CallSite CS = CallSite::get(I); |
| 97 | if (CS.getInstruction() && (!CS.getCalledFunction() || |
Reid Spencer | 5cbf985 | 2007-01-30 20:08:39 +0000 | [diff] [blame] | 98 | !CS.getCalledFunction()->isDeclaration())) |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 99 | CallSites.push_back(CS); |
| 100 | } |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 101 | |
Bill Wendling | 0a81aac | 2006-11-26 10:02:32 +0000 | [diff] [blame] | 102 | DOUT << ": " << CallSites.size() << " call sites.\n"; |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 103 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 104 | // Now that we have all of the call sites, move the ones to functions in the |
| 105 | // current SCC to the end of the list. |
| 106 | unsigned FirstCallInSCC = CallSites.size(); |
| 107 | for (unsigned i = 0; i < FirstCallInSCC; ++i) |
| 108 | if (Function *F = CallSites[i].getCalledFunction()) |
| 109 | if (SCCFunctions.count(F)) |
| 110 | std::swap(CallSites[i--], CallSites[--FirstCallInSCC]); |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 111 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 112 | // Now that we have all of the call sites, loop over them and inline them if |
| 113 | // it looks profitable to do so. |
| 114 | bool Changed = false; |
| 115 | bool LocalChange; |
| 116 | do { |
| 117 | LocalChange = false; |
| 118 | // Iterate over the outer loop because inlining functions can cause indirect |
| 119 | // calls to become direct calls. |
| 120 | for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) |
| 121 | if (Function *Callee = CallSites[CSi].getCalledFunction()) { |
| 122 | // Calls to external functions are never inlinable. |
Reid Spencer | 5cbf985 | 2007-01-30 20:08:39 +0000 | [diff] [blame] | 123 | if (Callee->isDeclaration() || |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 124 | CallSites[CSi].getInstruction()->getParent()->getParent() ==Callee){ |
Chris Lattner | 08ff148 | 2006-11-09 23:36:08 +0000 | [diff] [blame] | 125 | if (SCC.size() == 1) { |
| 126 | std::swap(CallSites[CSi], CallSites.back()); |
| 127 | CallSites.pop_back(); |
| 128 | } else { |
| 129 | // Keep the 'in SCC / not in SCC' boundary correct. |
| 130 | CallSites.erase(CallSites.begin()+CSi); |
| 131 | } |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 132 | --CSi; |
| 133 | continue; |
| 134 | } |
Chris Lattner | 775cbdd | 2004-04-08 06:34:31 +0000 | [diff] [blame] | 135 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 136 | // If the policy determines that we should inline this function, |
| 137 | // try to do so. |
| 138 | CallSite CS = CallSites[CSi]; |
| 139 | int InlineCost = getInlineCost(CS); |
| 140 | if (InlineCost >= (int)InlineThreshold) { |
Bill Wendling | 0a81aac | 2006-11-26 10:02:32 +0000 | [diff] [blame] | 141 | DOUT << " NOT Inlining: cost=" << InlineCost |
| 142 | << ", Call: " << *CS.getInstruction(); |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 143 | } else { |
Bill Wendling | 0a81aac | 2006-11-26 10:02:32 +0000 | [diff] [blame] | 144 | DOUT << " Inlining: cost=" << InlineCost |
| 145 | << ", Call: " << *CS.getInstruction(); |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 146 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 147 | // Attempt to inline the function... |
Chris Lattner | ff2dad3 | 2007-01-30 23:28:39 +0000 | [diff] [blame] | 148 | if (InlineCallIfPossible(CS, CG, SCCFunctions, |
| 149 | getAnalysis<TargetData>())) { |
Chris Lattner | 08ff148 | 2006-11-09 23:36:08 +0000 | [diff] [blame] | 150 | // Remove this call site from the list. If possible, use |
| 151 | // swap/pop_back for efficiency, but do not use it if doing so would |
| 152 | // move a call site to a function in this SCC before the |
| 153 | // 'FirstCallInSCC' barrier. |
| 154 | if (SCC.size() == 1) { |
| 155 | std::swap(CallSites[CSi], CallSites.back()); |
| 156 | CallSites.pop_back(); |
| 157 | } else { |
| 158 | CallSites.erase(CallSites.begin()+CSi); |
| 159 | } |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 160 | --CSi; |
Chris Lattner | ce1a3a2 | 2004-04-12 05:37:29 +0000 | [diff] [blame] | 161 | |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 162 | ++NumInlined; |
| 163 | Changed = true; |
| 164 | LocalChange = true; |
Chris Lattner | 775cbdd | 2004-04-08 06:34:31 +0000 | [diff] [blame] | 165 | } |
Chris Lattner | 775cbdd | 2004-04-08 06:34:31 +0000 | [diff] [blame] | 166 | } |
| 167 | } |
Chris Lattner | befa499 | 2004-05-23 21:22:17 +0000 | [diff] [blame] | 168 | } while (LocalChange); |
Chris Lattner | 775cbdd | 2004-04-08 06:34:31 +0000 | [diff] [blame] | 169 | |
Chris Lattner | 237ef56 | 2003-08-31 19:10:30 +0000 | [diff] [blame] | 170 | return Changed; |
| 171 | } |
| 172 | |
Chris Lattner | 68d57e7 | 2004-04-20 22:06:53 +0000 | [diff] [blame] | 173 | // doFinalization - Remove now-dead linkonce functions at the end of |
| 174 | // processing to avoid breaking the SCC traversal. |
| 175 | bool Inliner::doFinalization(CallGraph &CG) { |
Chris Lattner | 3e1358a | 2004-04-21 20:44:33 +0000 | [diff] [blame] | 176 | std::set<CallGraphNode*> FunctionsToRemove; |
| 177 | |
| 178 | // Scan for all of the functions, looking for ones that should now be removed |
| 179 | // from the program. Insert the dead ones in the FunctionsToRemove set. |
| 180 | for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) { |
| 181 | CallGraphNode *CGN = I->second; |
Chris Lattner | 54970c0 | 2004-08-08 03:29:50 +0000 | [diff] [blame] | 182 | if (Function *F = CGN ? CGN->getFunction() : 0) { |
Chris Lattner | 0c0aa71 | 2004-09-18 21:37:03 +0000 | [diff] [blame] | 183 | // If the only remaining users of the function are dead constants, remove |
| 184 | // them. |
Chris Lattner | 54970c0 | 2004-08-08 03:29:50 +0000 | [diff] [blame] | 185 | F->removeDeadConstantUsers(); |
Chris Lattner | 3e1358a | 2004-04-21 20:44:33 +0000 | [diff] [blame] | 186 | |
Chris Lattner | 54970c0 | 2004-08-08 03:29:50 +0000 | [diff] [blame] | 187 | if ((F->hasLinkOnceLinkage() || F->hasInternalLinkage()) && |
| 188 | F->use_empty()) { |
Chris Lattner | 0c0aa71 | 2004-09-18 21:37:03 +0000 | [diff] [blame] | 189 | |
Chris Lattner | 54970c0 | 2004-08-08 03:29:50 +0000 | [diff] [blame] | 190 | // Remove any call graph edges from the function to its callees. |
Dan Gohman | cb406c2 | 2007-10-03 19:26:29 +0000 | [diff] [blame] | 191 | while (!CGN->empty()) |
Chris Lattner | d85340f | 2006-07-12 18:29:36 +0000 | [diff] [blame] | 192 | CGN->removeCallEdgeTo((CGN->end()-1)->second); |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 193 | |
Chris Lattner | 0c0aa71 | 2004-09-18 21:37:03 +0000 | [diff] [blame] | 194 | // Remove any edges from the external node to the function's call graph |
| 195 | // node. These edges might have been made irrelegant due to |
| 196 | // optimization of the program. |
| 197 | CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN); |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 198 | |
Chris Lattner | 54970c0 | 2004-08-08 03:29:50 +0000 | [diff] [blame] | 199 | // Removing the node for callee from the call graph and delete it. |
| 200 | FunctionsToRemove.insert(CGN); |
| 201 | } |
Chris Lattner | 68d57e7 | 2004-04-20 22:06:53 +0000 | [diff] [blame] | 202 | } |
| 203 | } |
Chris Lattner | 3e1358a | 2004-04-21 20:44:33 +0000 | [diff] [blame] | 204 | |
| 205 | // Now that we know which functions to delete, do so. We didn't want to do |
| 206 | // this inline, because that would invalidate our CallGraph::iterator |
| 207 | // objects. :( |
| 208 | bool Changed = false; |
| 209 | for (std::set<CallGraphNode*>::iterator I = FunctionsToRemove.begin(), |
| 210 | E = FunctionsToRemove.end(); I != E; ++I) { |
| 211 | delete CG.removeFunctionFromModule(*I); |
| 212 | ++NumDeleted; |
| 213 | Changed = true; |
| 214 | } |
| 215 | |
Chris Lattner | 68d57e7 | 2004-04-20 22:06:53 +0000 | [diff] [blame] | 216 | return Changed; |
| 217 | } |