X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FIPO%2FDeadArgumentElimination.cpp;h=9d88a8879fcddec8a1411d0e65255164191dca7f;hb=86453c52ba02e743d29c08456e51006500041456;hp=6e8e7dffb930797176c48ec3e25726fe1ad1bd53;hpb=d6d0d8c18d64c5f212cd6c2b42b9bcde5acebf72;p=oota-llvm.git diff --git a/lib/Transforms/IPO/DeadArgumentElimination.cpp b/lib/Transforms/IPO/DeadArgumentElimination.cpp index 6e8e7dffb93..9d88a8879fc 100644 --- a/lib/Transforms/IPO/DeadArgumentElimination.cpp +++ b/lib/Transforms/IPO/DeadArgumentElimination.cpp @@ -1,10 +1,10 @@ //===-- DeadArgumentElimination.cpp - Eliminate dead arguments ------------===// -// +// // 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 pass deletes dead arguments from internal functions. Dead argument @@ -17,32 +17,28 @@ // //===----------------------------------------------------------------------===// +#define DEBUG_TYPE "deadargelim" #include "llvm/Transforms/IPO.h" +#include "llvm/CallingConv.h" +#include "llvm/Constant.h" +#include "llvm/DerivedTypes.h" +#include "llvm/Instructions.h" +#include "llvm/IntrinsicInst.h" #include "llvm/Module.h" #include "llvm/Pass.h" -#include "llvm/DerivedTypes.h" -#include "llvm/Constant.h" -#include "llvm/iOther.h" -#include "llvm/iTerminators.h" #include "llvm/Support/CallSite.h" -#include "Support/Debug.h" -#include "Support/Statistic.h" -#include "Support/iterator" +#include "llvm/Support/Debug.h" +#include "llvm/ADT/Statistic.h" #include +using namespace llvm; -namespace { - Statistic<> NumArgumentsEliminated("deadargelim", - "Number of unread args removed"); - Statistic<> NumRetValsEliminated("deadargelim", - "Number of unused return values removed"); +STATISTIC(NumArgumentsEliminated, "Number of unread args removed"); +STATISTIC(NumRetValsEliminated , "Number of unused return values removed"); +namespace { /// DAE - The dead argument elimination pass. /// - class DAE : public Pass { - /// DeleteFromExternalFunctions - Bugpoint sets this flag to indicate that - /// it is safe to hack apart functions without internal linkage. - bool DeleteFromExternalFunctions; - + class DAE : public ModulePass { /// Liveness enum - During our initial pass over the program, we determine /// that things are either definately alive, definately dead, or in need of /// interprocedural analysis (MaybeLive). @@ -79,34 +75,144 @@ namespace { std::multimap CallSites; public: - DAE(bool DFEF = false) : DeleteFromExternalFunctions(DFEF) {} - bool run(Module &M); + bool runOnModule(Module &M); + + virtual bool ShouldHackArguments() const { return false; } private: Liveness getArgumentLiveness(const Argument &A); bool isMaybeLiveArgumentNowLive(Argument *Arg); + bool DeleteDeadVarargs(Function &Fn); void SurveyFunction(Function &Fn); void MarkArgumentLive(Argument *Arg); void MarkRetValLive(Function *F); void MarkReturnInstArgumentLive(ReturnInst *RI); - + void RemoveDeadArgumentsFromFunction(Function *F); }; - RegisterOpt X("deadargelim", "Dead Argument Elimination"); + RegisterPass X("deadargelim", "Dead Argument Elimination"); + + /// DAH - DeadArgumentHacking pass - Same as dead argument elimination, but + /// deletes arguments to functions which are external. This is only for use + /// by bugpoint. + struct DAH : public DAE { + virtual bool ShouldHackArguments() const { return true; } + }; + RegisterPass Y("deadarghaX0r", + "Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)"); } /// createDeadArgEliminationPass - This pass removes arguments from functions -/// which are not used by the body of the function. If -/// DeleteFromExternalFunctions is true, the pass will modify functions that -/// have external linkage, which is not usually safe (this is used by bugpoint -/// to reduce testcases). +/// which are not used by the body of the function. /// -Pass *createDeadArgEliminationPass(bool DeleteFromExternalFunctions) { - return new DAE(DeleteFromExternalFunctions); +ModulePass *llvm::createDeadArgEliminationPass() { return new DAE(); } +ModulePass *llvm::createDeadArgHackingPass() { return new DAH(); } + +/// DeleteDeadVarargs - If this is an function that takes a ... list, and if +/// llvm.vastart is never called, the varargs list is dead for the function. +bool DAE::DeleteDeadVarargs(Function &Fn) { + assert(Fn.getFunctionType()->isVarArg() && "Function isn't varargs!"); + if (Fn.isExternal() || !Fn.hasInternalLinkage()) return false; + + // Ensure that the function is only directly called. + for (Value::use_iterator I = Fn.use_begin(), E = Fn.use_end(); I != E; ++I) { + // If this use is anything other than a call site, give up. + CallSite CS = CallSite::get(*I); + Instruction *TheCall = CS.getInstruction(); + if (!TheCall) return false; // Not a direct call site? + + // The addr of this function is passed to the call. + if (I.getOperandNo() != 0) return false; + } + + // Okay, we know we can transform this function if safe. Scan its body + // looking for calls to llvm.vastart. + for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) { + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { + if (IntrinsicInst *II = dyn_cast(I)) { + if (II->getIntrinsicID() == Intrinsic::vastart) + return false; + } + } + } + + // If we get here, there are no calls to llvm.vastart in the function body, + // remove the "..." and adjust all the calls. + + // Start by computing a new prototype for the function, which is the same as + // the old function, but has fewer arguments. + const FunctionType *FTy = Fn.getFunctionType(); + std::vector Params(FTy->param_begin(), FTy->param_end()); + FunctionType *NFTy = FunctionType::get(FTy->getReturnType(), Params, false); + unsigned NumArgs = Params.size(); + + // Create the new function body and insert it into the module... + Function *NF = new Function(NFTy, Fn.getLinkage(), Fn.getName()); + NF->setCallingConv(Fn.getCallingConv()); + Fn.getParent()->getFunctionList().insert(&Fn, NF); + + // Loop over all of the callers of the function, transforming the call sites + // to pass in a smaller number of arguments into the new function. + // + std::vector Args; + while (!Fn.use_empty()) { + CallSite CS = CallSite::get(Fn.use_back()); + Instruction *Call = CS.getInstruction(); + + // Loop over the operands, dropping extraneous ones at the end of the list. + Args.assign(CS.arg_begin(), CS.arg_begin()+NumArgs); + + Instruction *New; + if (InvokeInst *II = dyn_cast(Call)) { + New = new InvokeInst(NF, II->getNormalDest(), II->getUnwindDest(), + Args, "", Call); + cast(New)->setCallingConv(CS.getCallingConv()); + } else { + New = new CallInst(NF, Args, "", Call); + cast(New)->setCallingConv(CS.getCallingConv()); + if (cast(Call)->isTailCall()) + cast(New)->setTailCall(); + } + Args.clear(); + + if (!Call->use_empty()) + Call->replaceAllUsesWith(Constant::getNullValue(Call->getType())); + + if (Call->hasName()) { + std::string Name = Call->getName(); + Call->setName(""); + New->setName(Name); + } + + // Finally, remove the old call from the program, reducing the use-count of + // F. + Call->getParent()->getInstList().erase(Call); + } + + // Since we have now created the new function, splice the body of the old + // function right into the new function, leaving the old rotting hulk of the + // function empty. + NF->getBasicBlockList().splice(NF->begin(), Fn.getBasicBlockList()); + + // Loop over the argument list, transfering uses of the old arguments over to + // the new arguments, also transfering over the names as well. While we're at + // it, remove the dead arguments from the DeadArguments list. + // + for (Function::arg_iterator I = Fn.arg_begin(), E = Fn.arg_end(), + I2 = NF->arg_begin(); I != E; ++I, ++I2) { + // Move the name and users over to the new version. + I->replaceAllUsesWith(I2); + I2->setName(I->getName()); + } + + // Finally, nuke the old function. + Fn.eraseFromParent(); + return true; } + static inline bool CallPassesValueThoughVararg(Instruction *Call, const Value *Arg) { CallSite CS = CallSite::get(Call); @@ -124,7 +230,13 @@ static inline bool CallPassesValueThoughVararg(Instruction *Call, // (used in a computation), MaybeLive (only passed as an argument to a call), or // Dead (not used). DAE::Liveness DAE::getArgumentLiveness(const Argument &A) { - if (A.use_empty()) return Dead; // First check, directly dead? + // If this is the return value of a csret function, it's not really dead. + if (A.getParent()->getCallingConv() == CallingConv::CSRet && + &*A.getParent()->arg_begin() == &A) + return Live; + + if (A.use_empty()) // First check, directly dead? + return Dead; // Scan through all of the uses, looking for non-argument passing uses. for (Value::use_const_iterator I = A.use_begin(), E = A.use_end(); I!=E;++I) { @@ -163,9 +275,10 @@ void DAE::SurveyFunction(Function &F) { bool FunctionIntrinsicallyLive = false; Liveness RetValLiveness = F.getReturnType() == Type::VoidTy ? Live : Dead; - if (!F.hasInternalLinkage() && !DeleteFromExternalFunctions) + if (!F.hasInternalLinkage() && + (!ShouldHackArguments() || F.getIntrinsicID())) FunctionIntrinsicallyLive = true; - else + else for (Value::use_iterator I = F.use_begin(), E = F.use_end(); I != E; ++I) { // If this use is anything other than a call site, the function is alive. CallSite CS = CallSite::get(*I); @@ -194,7 +307,7 @@ void DAE::SurveyFunction(Function &F) { RetValLiveness = Live; break; } - + // If the function is PASSED IN as an argument, its address has been taken for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end(); AI != E; ++AI) @@ -206,8 +319,9 @@ void DAE::SurveyFunction(Function &F) { } if (FunctionIntrinsicallyLive) { - DEBUG(std::cerr << " Intrinsically live fn: " << F.getName() << "\n"); - for (Function::aiterator AI = F.abegin(), E = F.aend(); AI != E; ++AI) + DOUT << " Intrinsically live fn: " << F.getName() << "\n"; + for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); + AI != E; ++AI) LiveArguments.insert(AI); LiveRetVal.insert(&F); return; @@ -219,7 +333,7 @@ void DAE::SurveyFunction(Function &F) { case Dead: DeadRetVal.insert(&F); break; } - DEBUG(std::cerr << " Inspecting args for fn: " << F.getName() << "\n"); + DOUT << " Inspecting args for fn: " << F.getName() << "\n"; // If it is not intrinsically alive, we know that all users of the // function are call sites. Mark all of the arguments live which are @@ -227,19 +341,19 @@ void DAE::SurveyFunction(Function &F) { // if there are any arguments we assume that are dead. // bool AnyMaybeLiveArgs = false; - for (Function::aiterator AI = F.abegin(), E = F.aend(); AI != E; ++AI) + for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); + AI != E; ++AI) switch (getArgumentLiveness(*AI)) { case Live: - DEBUG(std::cerr << " Arg live by use: " << AI->getName() << "\n"); + DOUT << " Arg live by use: " << AI->getName() << "\n"; LiveArguments.insert(AI); break; case Dead: - DEBUG(std::cerr << " Arg definitely dead: " <getName()<<"\n"); + DOUT << " Arg definitely dead: " << AI->getName() <<"\n"; DeadArguments.insert(AI); break; case MaybeLive: - DEBUG(std::cerr << " Arg only passed to calls: " - << AI->getName() << "\n"); + DOUT << " Arg only passed to calls: " << AI->getName() << "\n"; AnyMaybeLiveArgs = true; MaybeLiveArguments.insert(AI); break; @@ -281,7 +395,7 @@ bool DAE::isMaybeLiveArgumentNowLive(Argument *Arg) { // Loop over all of the arguments (because Arg may be passed into the call // multiple times) and check to see if any are now alive... CallSite::arg_iterator CSAI = CS.arg_begin(); - for (Function::aiterator AI = Callee->abegin(), E = Callee->aend(); + for (Function::arg_iterator AI = Callee->arg_begin(), E = Callee->arg_end(); AI != E; ++AI, ++CSAI) // If this is the argument we are looking for, check to see if it's alive if (*CSAI == Arg && LiveArguments.count(AI)) @@ -297,16 +411,16 @@ bool DAE::isMaybeLiveArgumentNowLive(Argument *Arg) { void DAE::MarkArgumentLive(Argument *Arg) { std::set::iterator It = MaybeLiveArguments.lower_bound(Arg); if (It == MaybeLiveArguments.end() || *It != Arg) return; - - DEBUG(std::cerr << " MaybeLive argument now live: " << Arg->getName()<<"\n"); + + DOUT << " MaybeLive argument now live: " << Arg->getName() <<"\n"; MaybeLiveArguments.erase(It); LiveArguments.insert(Arg); - + // Loop over all of the call sites of the function, making any arguments // passed in to provide a value for this argument live as necessary. // Function *Fn = Arg->getParent(); - unsigned ArgNo = std::distance(Fn->abegin(), Function::aiterator(Arg)); + unsigned ArgNo = std::distance(Fn->arg_begin(), Function::arg_iterator(Arg)); std::multimap::iterator I = CallSites.lower_bound(Fn); for (; I != CallSites.end() && I->first == Fn; ++I) { @@ -336,7 +450,7 @@ void DAE::MarkRetValLive(Function *F) { std::set::iterator I = MaybeLiveRetVal.lower_bound(F); if (I == MaybeLiveRetVal.end() || *I != F) return; // It's already alive! - DEBUG(std::cerr << " MaybeLive retval now live: " << F->getName() << "\n"); + DOUT << " MaybeLive retval now live: " << F->getName() << "\n"; MaybeLiveRetVal.erase(I); LiveRetVal.insert(F); // It is now known to be live! @@ -370,7 +484,7 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { const FunctionType *FTy = F->getFunctionType(); std::vector Params; - for (Function::aiterator I = F->abegin(), E = F->aend(); I != E; ++I) + for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) if (!DeadArguments.count(I)) Params.push_back(I->getType()); @@ -383,8 +497,6 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { // Work around LLVM bug PR56: the CWriter cannot emit varargs functions which // have zero fixed arguments. // - // FIXME: once this bug is fixed in the CWriter, this hack should be removed. - // bool ExtraArgHack = false; if (Params.empty() && FTy->isVarArg()) { ExtraArgHack = true; @@ -395,6 +507,7 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { // Create the new function body and insert it into the module... Function *NF = new Function(NFTy, F->getLinkage(), F->getName()); + NF->setCallingConv(F->getCallingConv()); F->getParent()->getFunctionList().insert(F, NF); // Loop over all of the callers of the function, transforming the call sites @@ -407,12 +520,13 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { // Loop over the operands, deleting dead ones... CallSite::arg_iterator AI = CS.arg_begin(); - for (Function::aiterator I = F->abegin(), E = F->aend(); I != E; ++I, ++AI) + for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); + I != E; ++I, ++AI) if (!DeadArguments.count(I)) // Remove operands for dead arguments Args.push_back(*AI); if (ExtraArgHack) - Args.push_back(Constant::getNullValue(Type::IntTy)); + Args.push_back(UndefValue::get(Type::IntTy)); // Push any varargs arguments on the list for (; AI != CS.arg_end(); ++AI) @@ -420,10 +534,14 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { Instruction *New; if (InvokeInst *II = dyn_cast(Call)) { - New = new InvokeInst(NF, II->getNormalDest(), II->getExceptionalDest(), + New = new InvokeInst(NF, II->getNormalDest(), II->getUnwindDest(), Args, "", Call); + cast(New)->setCallingConv(CS.getCallingConv()); } else { New = new CallInst(NF, Args, "", Call); + cast(New)->setCallingConv(CS.getCallingConv()); + if (cast(Call)->isTailCall()) + cast(New)->setTailCall(); } Args.clear(); @@ -437,7 +555,7 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { New->setName(Name); } } - + // Finally, remove the old call from the program, reducing the use-count of // F. Call->getParent()->getInstList().erase(Call); @@ -452,7 +570,8 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { // the new arguments, also transfering over the names as well. While we're at // it, remove the dead arguments from the DeadArguments list. // - for (Function::aiterator I = F->abegin(), E = F->aend(), I2 = NF->abegin(); + for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(), + I2 = NF->arg_begin(); I != E; ++I) if (!DeadArguments.count(I)) { // If this is a live argument, move the name and users over to the new @@ -481,14 +600,20 @@ void DAE::RemoveDeadArgumentsFromFunction(Function *F) { F->getParent()->getFunctionList().erase(F); } -bool DAE::run(Module &M) { +bool DAE::runOnModule(Module &M) { // First phase: loop through the module, determining which arguments are live. // We assume all arguments are dead unless proven otherwise (allowing us to // determine that dead arguments passed into recursive functions are dead). // - DEBUG(std::cerr << "DAE - Determining liveness\n"); - for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) - SurveyFunction(*I); + DOUT << "DAE - Determining liveness\n"; + for (Module::iterator I = M.begin(), E = M.end(); I != E; ) { + Function &F = *I++; + if (F.getFunctionType()->isVarArg()) + if (DeleteDeadVarargs(F)) + continue; + + SurveyFunction(F); + } // Loop over the instructions to inspect, propagating liveness among arguments // and return values which are MaybeLive. @@ -496,7 +621,7 @@ bool DAE::run(Module &M) { while (!InstructionsToInspect.empty()) { Instruction *I = InstructionsToInspect.back(); InstructionsToInspect.pop_back(); - + if (ReturnInst *RI = dyn_cast(I)) { // For return instructions, we just have to check to see if the return // value for the current function is known now to be alive. If so, any @@ -510,14 +635,14 @@ bool DAE::run(Module &M) { assert(CS.getInstruction() && "Unknown instruction for the I2I list!"); Function *Callee = CS.getCalledFunction(); - + // If we found a call or invoke instruction on this list, that means that // an argument of the function is a call instruction. If the argument is // live, then the return value of the called instruction is now live. // CallSite::arg_iterator AI = CS.arg_begin(); // ActualIterator - for (Function::aiterator FI = Callee->abegin(), E = Callee->aend(); - FI != E; ++AI, ++FI) { + for (Function::arg_iterator FI = Callee->arg_begin(), + E = Callee->arg_end(); FI != E; ++AI, ++FI) { // If this argument is another call... CallSite ArgCS = CallSite::get(*AI); if (ArgCS.getInstruction() && LiveArguments.count(FI)) @@ -553,7 +678,7 @@ bool DAE::run(Module &M) { if (MaybeLiveArguments.empty() && DeadArguments.empty() && MaybeLiveRetVal.empty() && DeadRetVal.empty()) return false; - + // Otherwise, compact into one set, and start eliminating the arguments from // the functions. DeadArguments.insert(MaybeLiveArguments.begin(), MaybeLiveArguments.end());