X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FTransforms%2FIPO%2FDeadArgumentElimination.cpp;h=c06d688b3c4816555238a453b0252fc0062a7348;hp=3253c54a681ed0eb2ae9a7f495798981feeec082;hb=d13db2c59cc94162d6cf0a04187d408bfef6d4a7;hpb=03d18569cb39b0e4bd50f5eff2d4fe61bb234678 diff --git a/lib/Transforms/IPO/DeadArgumentElimination.cpp b/lib/Transforms/IPO/DeadArgumentElimination.cpp index 3253c54a681..c06d688b3c4 100644 --- a/lib/Transforms/IPO/DeadArgumentElimination.cpp +++ b/lib/Transforms/IPO/DeadArgumentElimination.cpp @@ -24,13 +24,15 @@ #include "llvm/DerivedTypes.h" #include "llvm/Instructions.h" #include "llvm/IntrinsicInst.h" +#include "llvm/LLVMContext.h" #include "llvm/Module.h" #include "llvm/Pass.h" #include "llvm/Support/CallSite.h" #include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Statistic.h" -#include "llvm/Support/Compiler.h" +#include "llvm/ADT/StringExtras.h" #include #include using namespace llvm; @@ -41,19 +43,20 @@ STATISTIC(NumRetValsEliminated , "Number of unused return values removed"); namespace { /// DAE - The dead argument elimination pass. /// - class VISIBILITY_HIDDEN DAE : public ModulePass { + class DAE : public ModulePass { public: - /// Struct that represent either a (part of a) return value or a function + /// Struct that represents (part of) either a return value or a function /// argument. Used so that arguments and return values can be used /// interchangably. struct RetOrArg { - RetOrArg(const Function* F, unsigned Idx, bool IsArg) : F(F), Idx(Idx), IsArg(IsArg) {} + RetOrArg(const Function *F, unsigned Idx, bool IsArg) : F(F), Idx(Idx), + IsArg(IsArg) {} const Function *F; unsigned Idx; bool IsArg; - - /// Make RetOrArg comparable, so we can put it into a map + + /// Make RetOrArg comparable, so we can put it into a map. bool operator<(const RetOrArg &O) const { if (F != O.F) return F < O.F; @@ -63,26 +66,37 @@ namespace { return IsArg < O.IsArg; } - /// Make RetOrArg comparable, so we can easily iterate the multimap + /// Make RetOrArg comparable, so we can easily iterate the multimap. bool operator==(const RetOrArg &O) const { return F == O.F && Idx == O.Idx && IsArg == O.IsArg; } + + std::string getDescription() const { + return std::string((IsArg ? "Argument #" : "Return value #")) + + utostr(Idx) + " of function " + F->getNameStr(); + } }; - + /// 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). - /// - enum Liveness { Live, MaybeLive, Dead }; + /// that things are either alive or maybe alive. We don't mark anything + /// explicitly dead (even if we know they are), since anything not alive + /// with no registered uses (in Uses) will never be marked alive and will + /// thus become dead in the end. + enum Liveness { Live, MaybeLive }; /// Convenience wrapper - RetOrArg CreateRet(const Function *F, unsigned Idx) { return RetOrArg(F, Idx, false); } + RetOrArg CreateRet(const Function *F, unsigned Idx) { + return RetOrArg(F, Idx, false); + } /// Convenience wrapper - RetOrArg CreateArg(const Function *F, unsigned Idx) { return RetOrArg(F, Idx, true); } + RetOrArg CreateArg(const Function *F, unsigned Idx) { + return RetOrArg(F, Idx, true); + } typedef std::multimap UseMap; - /// This map maps a return value or argument to all return values or - /// arguments it uses. + /// This maps a return value or argument to any MaybeLive return values or + /// arguments it uses. This allows the MaybeLive values to be marked live + /// when any of its users is marked live. /// For example (indices are left out for clarity): /// - Uses[ret F] = ret G /// This means that F calls G, and F returns the value returned by G. @@ -97,27 +111,39 @@ namespace { UseMap Uses; typedef std::set LiveSet; + typedef std::set LiveFuncSet; - /// This set contains all values that have been determined to be live + /// This set contains all values that have been determined to be live. LiveSet LiveValues; - + /// This set contains all values that are cannot be changed in any way. + LiveFuncSet LiveFunctions; + typedef SmallVector UseVector; + protected: + // DAH uses this to specify a different ID. + explicit DAE(void *ID) : ModulePass(ID) {} + public: static char ID; // Pass identification, replacement for typeid - DAE() : ModulePass((intptr_t)&ID) {} + DAE() : ModulePass(&ID) {} + bool runOnModule(Module &M); virtual bool ShouldHackArguments() const { return false; } private: - Liveness IsMaybeLive(RetOrArg Use, UseVector &MaybeLiveUses); - Liveness SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses, unsigned RetValNum = 0); - Liveness SurveyUses(Value *V, UseVector &MaybeLiveUses); - - void SurveyFunction(Function &F); - void MarkValue(const RetOrArg &RA, Liveness L, const UseVector &MaybeLiveUses); - void MarkLive(RetOrArg RA); + Liveness MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses); + Liveness SurveyUse(Value::const_use_iterator U, UseVector &MaybeLiveUses, + unsigned RetValNum = 0); + Liveness SurveyUses(const Value *V, UseVector &MaybeLiveUses); + + void SurveyFunction(const Function &F); + void MarkValue(const RetOrArg &RA, Liveness L, + const UseVector &MaybeLiveUses); + void MarkLive(const RetOrArg &RA); + void MarkLive(const Function &F); + void PropagateLiveness(const RetOrArg &RA); bool RemoveDeadStuffFromFunction(Function *F); bool DeleteDeadVarargs(Function &Fn); }; @@ -125,8 +151,7 @@ namespace { char DAE::ID = 0; -static RegisterPass -X("deadargelim", "Dead Argument Elimination"); +INITIALIZE_PASS(DAE, "deadargelim", "Dead Argument Elimination", false, false); namespace { /// DAH - DeadArgumentHacking pass - Same as dead argument elimination, but @@ -134,13 +159,16 @@ namespace { /// by bugpoint. struct DAH : public DAE { static char ID; + DAH() : DAE(&ID) {} + virtual bool ShouldHackArguments() const { return true; } }; } char DAH::ID = 0; -static RegisterPass -Y("deadarghaX0r", "Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)"); +INITIALIZE_PASS(DAH, "deadarghaX0r", + "Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)", + false, false); /// createDeadArgEliminationPass - This pass removes arguments from functions /// which are not used by the body of the function. @@ -152,18 +180,11 @@ ModulePass *llvm::createDeadArgHackingPass() { return new DAH(); } /// 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.isDeclaration() || !Fn.hasInternalLinkage()) return false; + if (Fn.isDeclaration() || !Fn.hasLocalLinkage()) 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; - } + if (Fn.hasAddressTaken()) + return false; // Okay, we know we can transform this function if safe. Scan its body // looking for calls to llvm.vastart. @@ -182,8 +203,10 @@ bool DAE::DeleteDeadVarargs(Function &Fn) { // Start by computing a new prototype for the function, which is the same as // the old function, but doesn't have isVarArg set. const FunctionType *FTy = Fn.getFunctionType(); + std::vector Params(FTy->param_begin(), FTy->param_end()); - FunctionType *NFTy = FunctionType::get(FTy->getReturnType(), Params, false); + FunctionType *NFTy = FunctionType::get(FTy->getReturnType(), + Params, false); unsigned NumArgs = Params.size(); // Create the new function body and insert it into the module... @@ -204,12 +227,14 @@ bool DAE::DeleteDeadVarargs(Function &Fn) { Args.assign(CS.arg_begin(), CS.arg_begin()+NumArgs); // Drop any attributes that were on the vararg arguments. - PAListPtr PAL = CS.getParamAttrs(); + AttrListPtr PAL = CS.getAttributes(); if (!PAL.isEmpty() && PAL.getSlot(PAL.getNumSlots() - 1).Index > NumArgs) { - SmallVector ParamAttrsVec; + SmallVector AttributesVec; for (unsigned i = 0; PAL.getSlot(i).Index <= NumArgs; ++i) - ParamAttrsVec.push_back(PAL.getSlot(i)); - PAL = PAListPtr::get(ParamAttrsVec.begin(), ParamAttrsVec.end()); + AttributesVec.push_back(PAL.getSlot(i)); + if (Attributes FnAttrs = PAL.getFnAttributes()) + AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs)); + PAL = AttrListPtr::get(AttributesVec.begin(), AttributesVec.end()); } Instruction *New; @@ -217,14 +242,16 @@ bool DAE::DeleteDeadVarargs(Function &Fn) { New = InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(), Args.begin(), Args.end(), "", Call); cast(New)->setCallingConv(CS.getCallingConv()); - cast(New)->setParamAttrs(PAL); + cast(New)->setAttributes(PAL); } else { New = CallInst::Create(NF, Args.begin(), Args.end(), "", Call); cast(New)->setCallingConv(CS.getCallingConv()); - cast(New)->setParamAttrs(PAL); + cast(New)->setAttributes(PAL); if (cast(Call)->isTailCall()) cast(New)->setTailCall(); } + New->setDebugLoc(Call->getDebugLoc()); + Args.clear(); if (!Call->use_empty()) @@ -262,7 +289,7 @@ bool DAE::DeleteDeadVarargs(Function &Fn) { /// for void functions and 1 for functions not returning a struct. It returns /// the number of struct elements for functions returning a struct. static unsigned NumRetVals(const Function *F) { - if (F->getReturnType() == Type::VoidTy) + if (F->getReturnType()->isVoidTy()) return 0; else if (const StructType *STy = dyn_cast(F->getReturnType())) return STy->getNumElements(); @@ -270,11 +297,12 @@ static unsigned NumRetVals(const Function *F) { return 1; } -/// IsMaybeAlive - This checks Use for liveness. If Use is live, returns Live, -/// else returns MaybeLive. Also, adds Use to MaybeLiveUses in the latter case. -DAE::Liveness DAE::IsMaybeLive(RetOrArg Use, UseVector &MaybeLiveUses) { - // We're live if our use is already marked as live - if (LiveValues.count(Use)) +/// MarkIfNotLive - This checks Use for liveness in LiveValues. If Use is not +/// live, it adds Use to the MaybeLiveUses argument. Returns the determined +/// liveness of Use. +DAE::Liveness DAE::MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses) { + // We're live if our use or its Function is already marked as live. + if (LiveFunctions.count(Use.F) || LiveValues.count(Use)) return Live; // We're maybe live otherwise, but remember that we must become live if @@ -286,22 +314,26 @@ DAE::Liveness DAE::IsMaybeLive(RetOrArg Use, UseVector &MaybeLiveUses) { /// SurveyUse - This looks at a single use of an argument or return value /// and determines if it should be alive or not. Adds this use to MaybeLiveUses -/// if it causes the used value to become MaybeAlive. +/// if it causes the used value to become MaybeLive. /// /// RetValNum is the return value number to use when this use is used in a /// return instruction. This is used in the recursion, you should always leave /// it at 0. -DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses, unsigned RetValNum) { - Value *V = *U; - if (ReturnInst *RI = dyn_cast(V)) { - // The value is returned from another function. It's only live when the - // caller's return value is live +DAE::Liveness DAE::SurveyUse(Value::const_use_iterator U, + UseVector &MaybeLiveUses, unsigned RetValNum) { + const User *V = *U; + if (const ReturnInst *RI = dyn_cast(V)) { + // The value is returned from a function. It's only live when the + // function's return value is live. We use RetValNum here, for the case + // that U is really a use of an insertvalue instruction that uses the + // orginal Use. RetOrArg Use = CreateRet(RI->getParent()->getParent(), RetValNum); - // We might be live, depending on the liveness of Use - return IsMaybeLive(Use, MaybeLiveUses); - } - if (InsertValueInst *IV = dyn_cast(V)) { - if (U.getOperandNo() != InsertValueInst::getAggregateOperandIndex() && IV->hasIndices()) + // We might be live, depending on the liveness of Use. + return MarkIfNotLive(Use, MaybeLiveUses); + } + if (const InsertValueInst *IV = dyn_cast(V)) { + if (U.getOperandNo() != InsertValueInst::getAggregateOperandIndex() + && IV->hasIndices()) // The use we are examining is inserted into an aggregate. Our liveness // depends on all uses of that aggregate, but if it is used as a return // value, only index at which we were inserted counts. @@ -309,9 +341,9 @@ DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses, un // Note that if we are used as the aggregate operand to the insertvalue, // we don't change RetValNum, but do survey all our uses. - - Liveness Result = Dead; - for (Value::use_iterator I = IV->use_begin(), + + Liveness Result = MaybeLive; + for (Value::const_use_iterator I = IV->use_begin(), E = V->use_end(); I != E; ++I) { Result = SurveyUse(I, MaybeLiveUses, RetValNum); if (Result == Live) @@ -319,42 +351,47 @@ DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses, un } return Result; } - CallSite CS = CallSite::get(V); - if (CS.getInstruction()) { - Function *F = CS.getCalledFunction(); + + if (ImmutableCallSite CS = V) { + const Function *F = CS.getCalledFunction(); if (F) { - // Used in a direct call - - // Check for vararg. Do - 1 to skip the first operand to call (the - // function itself). - if (U.getOperandNo() - 1 >= F->getFunctionType()->getNumParams()) + // Used in a direct call. + + // Find the argument number. We know for sure that this use is an + // argument, since if it was the function argument this would be an + // indirect call and the we know can't be looking at a value of the + // label type (for the invoke instruction). + unsigned ArgNo = CS.getArgumentNo(U); + + if (ArgNo >= F->getFunctionType()->getNumParams()) // The value is passed in through a vararg! Must be live. return Live; + assert(CS.getArgument(ArgNo) + == CS->getOperand(U.getOperandNo()) + && "Argument is not where we expected it"); + // Value passed to a normal call. It's only live when the corresponding - // argument (operand number - 1 to skip the function pointer operand) to - // the called function turns out live - RetOrArg Use = CreateArg(F, U.getOperandNo() - 1); - return IsMaybeLive(Use, MaybeLiveUses); - } else { - // Used in any other way? Value must be live. - return Live; + // argument to the called function turns out live. + RetOrArg Use = CreateArg(F, ArgNo); + return MarkIfNotLive(Use, MaybeLiveUses); } } // Used in any other way? Value must be live. return Live; } -/// SurveyUses - This looks at all the uses of the given return value -/// (possibly a partial return value from a function returning a struct). +/// SurveyUses - This looks at all the uses of the given value /// Returns the Liveness deduced from the uses of this value. /// -/// Adds all uses that cause the result to be MaybeLive to MaybeLiveRetUses. -DAE::Liveness DAE::SurveyUses(Value *V, UseVector &MaybeLiveUses) { - // Assume it's dead (which will only hold if there are no uses at all..) - Liveness Result = Dead; - // Check each use - for (Value::use_iterator I = V->use_begin(), +/// Adds all uses that cause the result to be MaybeLive to MaybeLiveRetUses. If +/// the result is Live, MaybeLiveUses might be modified but its content should +/// be ignored (since it might not be complete). +DAE::Liveness DAE::SurveyUses(const Value *V, UseVector &MaybeLiveUses) { + // Assume it's dead (which will only hold if there are no uses at all..). + Liveness Result = MaybeLive; + // Check each use. + for (Value::const_use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) { Result = SurveyUse(I, MaybeLiveUses); if (Result == Live) @@ -365,168 +402,174 @@ DAE::Liveness DAE::SurveyUses(Value *V, UseVector &MaybeLiveUses) { // SurveyFunction - This performs the initial survey of the specified function, // checking out whether or not it uses any of its incoming arguments or whether -// any callers use the return value. This fills in the -// (Dead|MaybeLive|Live)(Arguments|RetVal) sets. +// any callers use the return value. This fills in the LiveValues set and Uses +// map. // // We consider arguments of non-internal functions to be intrinsically alive as // well as arguments to functions which have their "address taken". // -void DAE::SurveyFunction(Function &F) { - bool FunctionIntrinsicallyLive = false; +void DAE::SurveyFunction(const Function &F) { unsigned RetCount = NumRetVals(&F); // Assume all return values are dead typedef SmallVector RetVals; - RetVals RetValLiveness(RetCount, Dead); + RetVals RetValLiveness(RetCount, MaybeLive); - // These vectors maps each return value to the uses that make it MaybeLive, so - // we can add those to the MaybeLiveRetVals list if the return value - // really turns out to be MaybeLive. Initializes to RetCount empty vectors typedef SmallVector RetUses; - // Intialized to a list of RetCount empty lists + // These vectors map each return value to the uses that make it MaybeLive, so + // we can add those to the Uses map if the return value really turns out to be + // MaybeLive. Initialized to a list of RetCount empty lists. RetUses MaybeLiveRetUses(RetCount); - - for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) - if (ReturnInst *RI = dyn_cast(BB->getTerminator())) - if (RI->getNumOperands() != 0 && RI->getOperand(0)->getType() != F.getFunctionType()->getReturnType()) { - // We don't support old style multiple return values - FunctionIntrinsicallyLive = true; - break; - } - if (!F.hasInternalLinkage() && (!ShouldHackArguments() || F.isIntrinsic())) - FunctionIntrinsicallyLive = true; - - if (!FunctionIntrinsicallyLive) { - DOUT << "DAE - Inspecting callers for fn: " << F.getName() << "\n"; - // Keep track of the number of live retvals, so we can skip checks once all - // of them turn out to be live. - unsigned NumLiveRetVals = 0; - const Type *STy = dyn_cast(F.getReturnType()); - // Loop all uses of the function - for (Value::use_iterator I = F.use_begin(), E = F.use_end(); I != E; ++I) { - // If the function is PASSED IN as an argument, its address has been taken - if (I.getOperandNo() != 0) { - FunctionIntrinsicallyLive = true; - break; + for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) + if (const ReturnInst *RI = dyn_cast(BB->getTerminator())) + if (RI->getNumOperands() != 0 && RI->getOperand(0)->getType() + != F.getFunctionType()->getReturnType()) { + // We don't support old style multiple return values. + MarkLive(F); + return; } - // If this use is anything other than a call site, the function is alive. - CallSite CS = CallSite::get(*I); - Instruction *TheCall = CS.getInstruction(); - if (!TheCall) { // Not a direct call site? - FunctionIntrinsicallyLive = true; - break; - } - - // If we end up here, we are looking at a direct call to our function. - - // Now, check how our return value(s) is/are used in this caller. Don't - // bother checking return values if all of them are live already - if (NumLiveRetVals != RetCount) { - if (STy) { - // Check all uses of the return value - for (Value::use_iterator I = TheCall->use_begin(), - E = TheCall->use_end(); I != E; ++I) { - ExtractValueInst *Ext = dyn_cast(*I); - if (Ext && Ext->hasIndices()) { - // This use uses a part of our return value, survey the uses of that - // part and store the results for this index only. - unsigned Idx = *Ext->idx_begin(); - if (RetValLiveness[Idx] != Live) { - RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]); - if (RetValLiveness[Idx] == Live) - NumLiveRetVals++; - } - } else { - // Used by something else than extractvalue. Mark all - // return values as live. - for (unsigned i = 0; i != RetCount; ++i ) - RetValLiveness[i] = Live; - NumLiveRetVals = RetCount; - break; + if (!F.hasLocalLinkage() && (!ShouldHackArguments() || F.isIntrinsic())) { + MarkLive(F); + return; + } + + DEBUG(dbgs() << "DAE - Inspecting callers for fn: " << F.getName() << "\n"); + // Keep track of the number of live retvals, so we can skip checks once all + // of them turn out to be live. + unsigned NumLiveRetVals = 0; + const Type *STy = dyn_cast(F.getReturnType()); + // Loop all uses of the function. + for (Value::const_use_iterator I = F.use_begin(), E = F.use_end(); + I != E; ++I) { + // If the function is PASSED IN as an argument, its address has been + // taken. + ImmutableCallSite CS(*I); + if (!CS || !CS.isCallee(I)) { + MarkLive(F); + return; + } + + // If this use is anything other than a call site, the function is alive. + const Instruction *TheCall = CS.getInstruction(); + if (!TheCall) { // Not a direct call site? + MarkLive(F); + return; + } + + // If we end up here, we are looking at a direct call to our function. + + // Now, check how our return value(s) is/are used in this caller. Don't + // bother checking return values if all of them are live already. + if (NumLiveRetVals != RetCount) { + if (STy) { + // Check all uses of the return value. + for (Value::const_use_iterator I = TheCall->use_begin(), + E = TheCall->use_end(); I != E; ++I) { + const ExtractValueInst *Ext = dyn_cast(*I); + if (Ext && Ext->hasIndices()) { + // This use uses a part of our return value, survey the uses of + // that part and store the results for this index only. + unsigned Idx = *Ext->idx_begin(); + if (RetValLiveness[Idx] != Live) { + RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]); + if (RetValLiveness[Idx] == Live) + NumLiveRetVals++; } - } - } else { - // Single return value - RetValLiveness[0] = SurveyUses(TheCall, MaybeLiveRetUses[0]); - if (RetValLiveness[0] == Live) + } else { + // Used by something else than extractvalue. Mark all return + // values as live. + for (unsigned i = 0; i != RetCount; ++i ) + RetValLiveness[i] = Live; NumLiveRetVals = RetCount; + break; + } } + } else { + // Single return value + RetValLiveness[0] = SurveyUses(TheCall, MaybeLiveRetUses[0]); + if (RetValLiveness[0] == Live) + NumLiveRetVals = RetCount; } } } - if (FunctionIntrinsicallyLive) { - DOUT << "DAE - Intrinsically live fn: " << F.getName() << "\n"; - // Mark all arguments as live - unsigned i = 0; - for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); - AI != E; ++AI, ++i) - MarkLive(CreateArg(&F, i)); - // Mark all return values as live - i = 0; - for (unsigned i = 0, e = RetValLiveness.size(); i != e; ++i) - MarkLive(CreateRet(&F, i)); - return; - } - + // Now we've inspected all callers, record the liveness of our return values. - for (unsigned i = 0, e = RetValLiveness.size(); i != e; ++i) { - RetOrArg Ret = CreateRet(&F, i); - // Mark the result down - MarkValue(Ret, RetValLiveness[i], MaybeLiveRetUses[i]); - } - DOUT << "DAE - Inspecting args for fn: " << F.getName() << "\n"; + for (unsigned i = 0; i != RetCount; ++i) + MarkValue(CreateRet(&F, i), RetValLiveness[i], MaybeLiveRetUses[i]); - // Now, check all of our arguments + DEBUG(dbgs() << "DAE - Inspecting args for fn: " << F.getName() << "\n"); + + // Now, check all of our arguments. unsigned i = 0; UseVector MaybeLiveArgUses; - for (Function::arg_iterator AI = F.arg_begin(), + for (Function::const_arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E; ++AI, ++i) { // See what the effect of this use is (recording any uses that cause - // MaybeLive in MaybeLiveArgUses) + // MaybeLive in MaybeLiveArgUses). Liveness Result = SurveyUses(AI, MaybeLiveArgUses); - RetOrArg Arg = CreateArg(&F, i); - // Mark the result down - MarkValue(Arg, Result, MaybeLiveArgUses); - // Clear the vector again for the next iteration + // Mark the result. + MarkValue(CreateArg(&F, i), Result, MaybeLiveArgUses); + // Clear the vector again for the next iteration. MaybeLiveArgUses.clear(); } } /// MarkValue - This function marks the liveness of RA depending on L. If L is -/// MaybeLive, it also records any uses in MaybeLiveUses such that RA will be -/// marked live if any use in MaybeLiveUses gets marked live later on. -void DAE::MarkValue(const RetOrArg &RA, Liveness L, const UseVector &MaybeLiveUses) { +/// MaybeLive, it also takes all uses in MaybeLiveUses and records them in Uses, +/// such that RA will be marked live if any use in MaybeLiveUses gets marked +/// live later on. +void DAE::MarkValue(const RetOrArg &RA, Liveness L, + const UseVector &MaybeLiveUses) { switch (L) { case Live: MarkLive(RA); break; case MaybeLive: { // Note any uses of this value, so this return value can be // marked live whenever one of the uses becomes live. - UseMap::iterator Where = Uses.begin(); - for (UseVector::const_iterator UI = MaybeLiveUses.begin(), + for (UseVector::const_iterator UI = MaybeLiveUses.begin(), UE = MaybeLiveUses.end(); UI != UE; ++UI) - Where = Uses.insert(Where, UseMap::value_type(*UI, RA)); + Uses.insert(std::make_pair(*UI, RA)); break; } - case Dead: break; } } +/// MarkLive - Mark the given Function as alive, meaning that it cannot be +/// changed in any way. Additionally, +/// mark any values that are used as this function's parameters or by its return +/// values (according to Uses) live as well. +void DAE::MarkLive(const Function &F) { + DEBUG(dbgs() << "DAE - Intrinsically live fn: " << F.getName() << "\n"); + // Mark the function as live. + LiveFunctions.insert(&F); + // Mark all arguments as live. + for (unsigned i = 0, e = F.arg_size(); i != e; ++i) + PropagateLiveness(CreateArg(&F, i)); + // Mark all return values as live. + for (unsigned i = 0, e = NumRetVals(&F); i != e; ++i) + PropagateLiveness(CreateRet(&F, i)); +} + /// MarkLive - Mark the given return value or argument as live. Additionally, /// mark any values that are used by this value (according to Uses) live as /// well. -void DAE::MarkLive(RetOrArg RA) { +void DAE::MarkLive(const RetOrArg &RA) { + if (LiveFunctions.count(RA.F)) + return; // Function was already marked Live. + if (!LiveValues.insert(RA).second) - return; // We were already marked Live + return; // We were already marked Live. - if (RA.IsArg) - DOUT << "DAE - Marking argument " << RA.Idx << " to function " << RA.F->getNameStart() << " live\n"; - else - DOUT << "DAE - Marking return value " << RA.Idx << " of function " << RA.F->getNameStart() << " live\n"; + DEBUG(dbgs() << "DAE - Marking " << RA.getDescription() << " live\n"); + PropagateLiveness(RA); +} +/// PropagateLiveness - Given that RA is a live value, propagate it's liveness +/// to any other values it uses (according to Uses). +void DAE::PropagateLiveness(const RetOrArg &RA) { // We don't use upper_bound (or equal_range) here, because our recursive call - // to ourselves is likely to mark the upper_bound (which is the first value + // to ourselves is likely to cause the upper_bound (which is the first value // not belonging to RA) to become erased and the iterator invalidated. UseMap::iterator Begin = Uses.lower_bound(RA); UseMap::iterator E = Uses.end(); @@ -540,14 +583,12 @@ void DAE::MarkLive(RetOrArg RA) { } // RemoveDeadStuffFromFunction - Remove any arguments and return values from F -// that are not in LiveValues. This function is a noop for any Function created -// by this function before, or any function that was not inspected for liveness. -// specified by the DeadArguments list. Transform the function and all of the -// callees of the function to not have these arguments. +// that are not in LiveValues. Transform the function and all of the callees of +// the function to not have these arguments and return values. // bool DAE::RemoveDeadStuffFromFunction(Function *F) { - // Quick exit path for external functions - if (!F->hasInternalLinkage() && (!ShouldHackArguments() || F->isIntrinsic())) + // Don't modify fully live functions + if (LiveFunctions.count(F)) return false; // Start by computing a new prototype for the function, which is the same as @@ -555,28 +596,29 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) { const FunctionType *FTy = F->getFunctionType(); std::vector Params; - // Set up to build a new list of parameter attributes - SmallVector ParamAttrsVec; - const PAListPtr &PAL = F->getParamAttrs(); + // Set up to build a new list of parameter attributes. + SmallVector AttributesVec; + const AttrListPtr &PAL = F->getAttributes(); // The existing function return attributes. - ParameterAttributes RAttrs = PAL.getParamAttrs(0); + Attributes RAttrs = PAL.getRetAttributes(); + Attributes FnAttrs = PAL.getFnAttributes(); + + // Find out the new return value. - - // Find out the new return value - const Type *RetTy = FTy->getReturnType(); - const Type *NRetTy; + const Type *NRetTy = NULL; unsigned RetCount = NumRetVals(F); - // Explicitely track if anything changed, for debugging - bool Changed = false; + // -1 means unused, other numbers are the new index SmallVector NewRetIdxs(RetCount, -1); std::vector RetTypes; - if (RetTy != Type::VoidTy) { + if (RetTy->isVoidTy()) { + NRetTy = RetTy; + } else { const StructType *STy = dyn_cast(RetTy); if (STy) - // Look at each of the original return values individually + // Look at each of the original return values individually. for (unsigned i = 0; i != RetCount; ++i) { RetOrArg Ret = CreateRet(F, i); if (LiveValues.erase(Ret)) { @@ -584,45 +626,53 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) { NewRetIdxs[i] = RetTypes.size() - 1; } else { ++NumRetValsEliminated; - DOUT << "DAE - Removing return value " << i << " from " << F->getNameStart() << "\n"; - Changed = true; + DEBUG(dbgs() << "DAE - Removing return value " << i << " from " + << F->getName() << "\n"); } } else - // We used to return a single value + // We used to return a single value. if (LiveValues.erase(CreateRet(F, 0))) { RetTypes.push_back(RetTy); NewRetIdxs[0] = 0; } else { - DOUT << "DAE - Removing return value from " << F->getNameStart() << "\n"; + DEBUG(dbgs() << "DAE - Removing return value from " << F->getName() + << "\n"); ++NumRetValsEliminated; - Changed = true; - } - if (RetTypes.size() > 1 || (STy && STy->getNumElements() == RetTypes.size())) + } + if (RetTypes.size() > 1) // More than one return type? Return a struct with them. Also, if we used // to return a struct and didn't change the number of return values, - // return a struct again. This prevents chaning {something} into something - // and {} into void. + // return a struct again. This prevents changing {something} into + // something and {} into void. // Make the new struct packed if we used to return a packed struct - // already. - NRetTy = StructType::get(RetTypes, STy->isPacked()); + // already. + NRetTy = StructType::get(STy->getContext(), RetTypes, STy->isPacked()); else if (RetTypes.size() == 1) // One return type? Just a simple value then, but only if we didn't use to // return a struct with that simple value before. NRetTy = RetTypes.front(); else if (RetTypes.size() == 0) - // No return types? Make it void, but only if we didn't use to return {} - NRetTy = Type::VoidTy; - } else { - NRetTy = Type::VoidTy; + // No return types? Make it void, but only if we didn't use to return {}. + NRetTy = Type::getVoidTy(F->getContext()); } - - // Remove any incompatible attributes - RAttrs &= ~ParamAttr::typeIncompatible(NRetTy); + + assert(NRetTy && "No new return type found?"); + + // Remove any incompatible attributes, but only if we removed all return + // values. Otherwise, ensure that we don't have any conflicting attributes + // here. Currently, this should not be possible, but special handling might be + // required when new return value attributes are added. + if (NRetTy->isVoidTy()) + RAttrs &= ~Attribute::typeIncompatible(NRetTy); + else + assert((RAttrs & Attribute::typeIncompatible(NRetTy)) == 0 + && "Return attributes no longer compatible?"); + if (RAttrs) - ParamAttrsVec.push_back(ParamAttrsWithIndex::get(0, RAttrs)); - - // Remember which arguments are still alive + AttributesVec.push_back(AttributeWithIndex::get(0, RAttrs)); + + // Remember which arguments are still alive. SmallVector ArgAlive(FTy->getNumParams(), false); // Construct the new parameter list from non-dead arguments. Also construct // a new set of parameter attributes to correspond. Skip the first parameter @@ -634,50 +684,38 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) { if (LiveValues.erase(Arg)) { Params.push_back(I->getType()); ArgAlive[i] = true; - + // Get the original parameter attributes (skipping the first one, that is - // for the return value - if (ParameterAttributes Attrs = PAL.getParamAttrs(i + 1)) - ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Params.size(), Attrs)); + // for the return value. + if (Attributes Attrs = PAL.getParamAttributes(i + 1)) + AttributesVec.push_back(AttributeWithIndex::get(Params.size(), Attrs)); } else { ++NumArgumentsEliminated; - DOUT << "DAE - Removing argument " << i << " (" << I->getNameStart() << ") from " << F->getNameStart() << "\n"; - Changed = true; + DEBUG(dbgs() << "DAE - Removing argument " << i << " (" << I->getName() + << ") from " << F->getName() << "\n"); } } - // Reconstruct the ParamAttrsList based on the vector we constructed. - PAListPtr NewPAL = PAListPtr::get(ParamAttrsVec.begin(), ParamAttrsVec.end()); + if (FnAttrs != Attribute::None) + AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs)); - // Work around LLVM bug PR56: the CWriter cannot emit varargs functions which - // have zero fixed arguments. - // - // Not that we apply this hack for a vararg fuction that does not have any - // arguments anymore, but did have them before (so don't bother fixing - // functions that were already broken wrt CWriter). - bool ExtraArgHack = false; - if (Params.empty() && FTy->isVarArg() && FTy->getNumParams() != 0) { - ExtraArgHack = true; - Params.push_back(Type::Int32Ty); - } + // Reconstruct the AttributesList based on the vector we constructed. + AttrListPtr NewPAL = AttrListPtr::get(AttributesVec.begin(), + AttributesVec.end()); // Create the new function type based on the recomputed parameters. FunctionType *NFTy = FunctionType::get(NRetTy, Params, FTy->isVarArg()); - + // No change? if (NFTy == FTy) return false; - // The function type is only allowed to be different if we actually left out - // an argument or return value - assert(Changed && "Function type changed while no arguments or retrurn values were removed!"); - // Create the new function body and insert it into the module... Function *NF = Function::Create(NFTy, F->getLinkage()); NF->copyAttributesFrom(F); - NF->setParamAttrs(NewPAL); + NF->setAttributes(NewPAL); // Insert the new function before the old function, so we won't be processing - // it again + // it again. F->getParent()->getFunctionList().insert(F, NF); NF->takeName(F); @@ -689,101 +727,105 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) { CallSite CS = CallSite::get(F->use_back()); Instruction *Call = CS.getInstruction(); - ParamAttrsVec.clear(); - const PAListPtr &CallPAL = CS.getParamAttrs(); + AttributesVec.clear(); + const AttrListPtr &CallPAL = CS.getAttributes(); // The call return attributes. - ParameterAttributes RAttrs = CallPAL.getParamAttrs(0); + Attributes RAttrs = CallPAL.getRetAttributes(); + Attributes FnAttrs = CallPAL.getFnAttributes(); // Adjust in case the function was changed to return void. - RAttrs &= ~ParamAttr::typeIncompatible(NF->getReturnType()); + RAttrs &= ~Attribute::typeIncompatible(NF->getReturnType()); if (RAttrs) - ParamAttrsVec.push_back(ParamAttrsWithIndex::get(0, RAttrs)); + AttributesVec.push_back(AttributeWithIndex::get(0, RAttrs)); // Declare these outside of the loops, so we can reuse them for the second - // loop, which loops the varargs + // loop, which loops the varargs. CallSite::arg_iterator I = CS.arg_begin(); - unsigned i = 0; + unsigned i = 0; // Loop over those operands, corresponding to the normal arguments to the // original function, and add those that are still alive. for (unsigned e = FTy->getNumParams(); i != e; ++I, ++i) if (ArgAlive[i]) { Args.push_back(*I); - // Get original parameter attributes, but skip return attributes - if (ParameterAttributes Attrs = CallPAL.getParamAttrs(i + 1)) - ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Args.size(), Attrs)); + // Get original parameter attributes, but skip return attributes. + if (Attributes Attrs = CallPAL.getParamAttributes(i + 1)) + AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs)); } - if (ExtraArgHack) - Args.push_back(UndefValue::get(Type::Int32Ty)); - // Push any varargs arguments on the list. Don't forget their attributes. for (CallSite::arg_iterator E = CS.arg_end(); I != E; ++I, ++i) { Args.push_back(*I); - if (ParameterAttributes Attrs = CallPAL.getParamAttrs(i + 1)) - ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Args.size(), Attrs)); + if (Attributes Attrs = CallPAL.getParamAttributes(i + 1)) + AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs)); } - // Reconstruct the ParamAttrsList based on the vector we constructed. - PAListPtr NewCallPAL = PAListPtr::get(ParamAttrsVec.begin(), - ParamAttrsVec.end()); + if (FnAttrs != Attribute::None) + AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs)); + + // Reconstruct the AttributesList based on the vector we constructed. + AttrListPtr NewCallPAL = AttrListPtr::get(AttributesVec.begin(), + AttributesVec.end()); Instruction *New; if (InvokeInst *II = dyn_cast(Call)) { New = InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(), Args.begin(), Args.end(), "", Call); cast(New)->setCallingConv(CS.getCallingConv()); - cast(New)->setParamAttrs(NewCallPAL); + cast(New)->setAttributes(NewCallPAL); } else { New = CallInst::Create(NF, Args.begin(), Args.end(), "", Call); cast(New)->setCallingConv(CS.getCallingConv()); - cast(New)->setParamAttrs(NewCallPAL); + cast(New)->setAttributes(NewCallPAL); if (cast(Call)->isTailCall()) cast(New)->setTailCall(); } + New->setDebugLoc(Call->getDebugLoc()); + Args.clear(); if (!Call->use_empty()) { - if (New->getType() == Type::VoidTy) - // Our return value was unused, replace by null for now, uses will get - // removed later on - Call->replaceAllUsesWith(Constant::getNullValue(Call->getType())); - else if (isa(RetTy)) { - // The original return value was a struct, update all uses (which are - // all extractvalue instructions). - for (Value::use_iterator I = Call->use_begin(), E = Call->use_end(); - I != E;) { - assert(isa(*I) && "Return value not only used by extractvalue?"); - ExtractValueInst *EV = cast(*I); - // Increment now, since we're about to throw away this use. - ++I; - assert(EV->hasIndices() && "Return value used by extractvalue without indices?"); - unsigned Idx = *EV->idx_begin(); - if (NewRetIdxs[Idx] != -1) { - if (RetTypes.size() > 1) { - // We're still returning a struct, create a new extractvalue - // instruction with the first index updated - std::vector NewIdxs(EV->idx_begin(), EV->idx_end()); - NewIdxs[0] = NewRetIdxs[Idx]; - Value *NEV = ExtractValueInst::Create(New, NewIdxs.begin(), NewIdxs.end(), "retval", EV); - EV->replaceAllUsesWith(NEV); - EV->eraseFromParent(); - } else { - // We are now only returning a simple value, remove the - // extractvalue - EV->replaceAllUsesWith(New); - EV->eraseFromParent(); - } - } else { - // Value unused, replace uses by null for now, they will get removed - // later on - EV->replaceAllUsesWith(Constant::getNullValue(EV->getType())); - EV->eraseFromParent(); - } - } + if (New->getType() == Call->getType()) { + // Return type not changed? Just replace users then. + Call->replaceAllUsesWith(New); New->takeName(Call); + } else if (New->getType()->isVoidTy()) { + // Our return value has uses, but they will get removed later on. + // Replace by null for now. + Call->replaceAllUsesWith(Constant::getNullValue(Call->getType())); } else { - // The original function had a single return value - Call->replaceAllUsesWith(New); + assert(RetTy->isStructTy() && + "Return type changed, but not into a void. The old return type" + " must have been a struct!"); + Instruction *InsertPt = Call; + if (InvokeInst *II = dyn_cast(Call)) { + BasicBlock::iterator IP = II->getNormalDest()->begin(); + while (isa(IP)) ++IP; + InsertPt = IP; + } + + // We used to return a struct. Instead of doing smart stuff with all the + // uses of this struct, we will just rebuild it using + // extract/insertvalue chaining and let instcombine clean that up. + // + // Start out building up our return value from undef + Value *RetVal = UndefValue::get(RetTy); + for (unsigned i = 0; i != RetCount; ++i) + if (NewRetIdxs[i] != -1) { + Value *V; + if (RetTypes.size() > 1) + // We are still returning a struct, so extract the value from our + // return value + V = ExtractValueInst::Create(New, NewRetIdxs[i], "newret", + InsertPt); + else + // We are now returning a single element, so just insert that + V = New; + // Insert the value at the old position + RetVal = InsertValueInst::Create(RetVal, V, i, "oldret", InsertPt); + } + // Now, replace all uses of the old call instruction with the return + // struct we built + Call->replaceAllUsesWith(RetVal); New->takeName(Call); } } @@ -811,7 +853,7 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) { ++I2; } else { // If this argument is dead, replace any uses of it with null constants - // (these are guaranteed to become unused later on) + // (these are guaranteed to become unused later on). I->replaceAllUsesWith(Constant::getNullValue(I->getType())); } @@ -822,36 +864,38 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) { if (ReturnInst *RI = dyn_cast(BB->getTerminator())) { Value *RetVal; - if (NFTy->getReturnType() == Type::VoidTy) { + if (NFTy->getReturnType()->isVoidTy()) { RetVal = 0; } else { - assert (isa(RetTy)); + assert (RetTy->isStructTy()); // The original return value was a struct, insert // extractvalue/insertvalue chains to extract only the values we need // to return and insert them into our new result. // This does generate messy code, but we'll let it to instcombine to - // clean that up + // clean that up. Value *OldRet = RI->getOperand(0); // Start out building up our return value from undef - RetVal = llvm::UndefValue::get(NRetTy); + RetVal = UndefValue::get(NRetTy); for (unsigned i = 0; i != RetCount; ++i) if (NewRetIdxs[i] != -1) { - ExtractValueInst *EV = ExtractValueInst::Create(OldRet, i, "newret", RI); + ExtractValueInst *EV = ExtractValueInst::Create(OldRet, i, + "oldret", RI); if (RetTypes.size() > 1) { // We're still returning a struct, so reinsert the value into // our new return value at the new index - RetVal = InsertValueInst::Create(RetVal, EV, NewRetIdxs[i], "oldret"); + RetVal = InsertValueInst::Create(RetVal, EV, NewRetIdxs[i], + "newret", RI); } else { // We are now only returning a simple value, so just return the - // extracted value + // extracted value. RetVal = EV; } - } - } + } + } // Replace the return instruction with one returning the new return // value (possibly 0 if we became void). - ReturnInst::Create(RetVal, RI); + ReturnInst::Create(F->getContext(), RetVal, RI); BB->getInstList().erase(RI); } @@ -863,11 +907,12 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) { bool DAE::runOnModule(Module &M) { bool Changed = false; + // First pass: Do a simple check to see if any functions can have their "..." // removed. We can do this if they never call va_start. This loop cannot be // fused with the next loop, because deleting a function invalidates // information computed while surveying other functions. - DOUT << "DAE - Deleting dead varargs\n"; + DEBUG(dbgs() << "DAE - Deleting dead varargs\n"); for (Module::iterator I = M.begin(), E = M.end(); I != E; ) { Function &F = *I++; if (F.getFunctionType()->isVarArg()) @@ -878,18 +923,17 @@ bool DAE::runOnModule(Module &M) { // We assume all arguments are dead unless proven otherwise (allowing us to // determine that dead arguments passed into recursive functions are dead). // - DOUT << "DAE - Determining liveness\n"; + DEBUG(dbgs() << "DAE - Determining liveness\n"); for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) SurveyFunction(*I); // Now, remove all dead arguments and return values from each function in - // turn + // turn. for (Module::iterator I = M.begin(), E = M.end(); I != E; ) { - // Increment now, because the function will probably get removed (ie - // replaced by a new one) + // Increment now, because the function will probably get removed (ie. + // replaced by a new one). Function *F = I++; Changed |= RemoveDeadStuffFromFunction(F); } - return Changed; }