[llvm-commits] [llvm] r52459 - in /llvm/trunk: lib/Transforms/IPO/DeadArgumentElimination.cpp test/Transforms/DeadArgElim/multdeadretval.ll
Owen Anderson
resistor at mac.com
Wed Jun 18 10:30:10 PDT 2008
Matthijs,
This patch causes either an infinite loop or a massive slowdown when
optimizing MultiSource/Applications/SPASS, and possibly others as
well. I'm reverting it for now. In the future, please run llvm-test
on at least MultiSource/ before committing a large change like this.
--Owen
On Jun 18, 2008, at 4:13 AM, Matthijs Kooijman wrote:
> Author: matthijs
> Date: Wed Jun 18 06:12:53 2008
> New Revision: 52459
>
> URL: http://llvm.org/viewvc/llvm-project?rev=52459&view=rev
> Log:
> Rewrite the DeadArgumentElimination pass, to use a more explicit
> tracking of
> dependencies between return values and/or arguments. Also make the
> handling of
> arguments and return values the same.
>
> The pass now looks properly inside returned structs, but only at the
> first
> level (ie, not inside nested structs).
>
> Also add a testcase for testing various variations of (multiple)
> dead rerturn
> values.
>
> Added:
> llvm/trunk/test/Transforms/DeadArgElim/multdeadretval.ll
> Modified:
> llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp
>
> Modified: llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp?rev=52459&r1=52458&r2=52459&view=diff
>
> =
> =
> =
> =
> =
> =
> =
> =
> ======================================================================
> --- llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp
> (original)
> +++ llvm/trunk/lib/Transforms/IPO/DeadArgumentElimination.cpp Wed
> Jun 18 06:12:53 2008
> @@ -10,10 +10,10 @@
> // This pass deletes dead arguments from internal functions. Dead
> argument
> // elimination removes arguments which are directly dead, as well as
> arguments
> // only passed into function calls as dead arguments of other
> functions. This
> -// pass also deletes dead arguments in a similar way.
> +// pass also deletes dead return values in a similar way.
> //
> // This pass is often useful as a cleanup pass to run after aggressive
> -// interprocedural passes, which add possibly-dead arguments.
> +// interprocedural passes, which add possibly-dead arguments or
> return values.
> //
> //
> =
> =
> =
> ----------------------------------------------------------------------=
> ==//
>
> @@ -42,40 +42,66 @@
> /// DAE - The dead argument elimination pass.
> ///
> class VISIBILITY_HIDDEN DAE : public ModulePass {
> + public:
> +
> + /// Struct that represent either a (part of 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) {}
> + const Function *F;
> + unsigned Idx;
> + bool IsArg;
> +
> + /// 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;
> + else if (Idx != O.Idx)
> + return Idx < O.Idx;
> + else
> + return IsArg < O.IsArg;
> + }
> + };
> +
> /// 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 };
>
> - /// LiveArguments, MaybeLiveArguments, DeadArguments - These
> sets contain
> - /// all of the arguments in the program. The Dead set contains
> arguments
> - /// which are completely dead (never used in the function).
> The MaybeLive
> - /// set contains arguments which are only passed into other
> function calls,
> - /// thus may be live and may be dead. The Live set contains
> arguments which
> - /// are known to be alive.
> - ///
> - std::set<Argument*> DeadArguments, MaybeLiveArguments,
> LiveArguments;
> -
> - /// DeadRetVal, MaybeLiveRetVal, LifeRetVal - These sets
> contain all of the
> - /// functions in the program. The Dead set contains functions
> whose return
> - /// value is known to be dead. The MaybeLive set contains
> functions whose
> - /// return values are only used by return instructions, and the
> Live set
> - /// contains functions whose return values are used, functions
> that are
> - /// external, and functions that already return void.
> - ///
> - std::set<Function*> DeadRetVal, MaybeLiveRetVal, LiveRetVal;
> -
> - /// InstructionsToInspect - As we mark arguments and return
> values
> - /// MaybeLive, we keep track of which instructions could make
> the values
> - /// live here. Once the entire program has had the return
> value and
> - /// arguments analyzed, this set is scanned to promote the
> MaybeLive objects
> - /// to be Live if they really are used.
> - std::vector<Instruction*> InstructionsToInspect;
> -
> - /// CallSites - Keep track of the call sites of functions that
> have
> - /// MaybeLive arguments or return values.
> - std::multimap<Function*, CallSite> CallSites;
> + /// Convenience wrapper
> + 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); }
> +
> + typedef std::multimap<RetOrArg, RetOrArg> UseMap;
> + /// This map maps a return value or argument to all return
> values or
> + /// arguments it uses.
> + /// 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.
> + /// - Uses[arg F] = ret G
> + /// This means that some function calls G and passes its
> result as an
> + /// argument to F.
> + /// - Uses[ret F] = arg F
> + /// This means that F returns one of its own arguments.
> + /// - Uses[arg F] = arg G
> + /// This means that G calls F and passes one of its own
> (G's) arguments
> + /// directly to F.
> + UseMap Uses;
> +
> + typedef std::set<RetOrArg> LiveSet;
> +
> + /// This set contains all values that have been determined to
> be live
> + LiveSet LiveValues;
> +
> + typedef SmallVector<RetOrArg, 5> UseVector;
> +
> + /// This is the set of functions that have been inspected.
> Since LiveValues
> + /// keeps a list of live values for inspected functions only,
> this way we
> + /// can prevent uninspected functions becoming completely dead.
> + std::set<Function*> InspectedFunctions;
>
> public:
> static char ID; // Pass identification, replacement for typeid
> @@ -85,20 +111,19 @@
> virtual bool ShouldHackArguments() const { return false; }
>
> private:
> - Liveness getArgumentLiveness(const Argument &A);
> - bool isMaybeLiveArgumentNowLive(Argument *Arg);
> -
> + 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);
> + bool RemoveDeadStuffFromFunction(Function *F);
> bool DeleteDeadVarargs(Function &Fn);
> - void SurveyFunction(Function &Fn);
> -
> - void MarkArgumentLive(Argument *Arg);
> - void MarkRetValLive(Function *F);
> - void MarkReturnInstArgumentLive(ReturnInst *RI);
> -
> - void RemoveDeadArgumentsFromFunction(Function *F);
> };
> }
>
> +
> char DAE::ID = 0;
> static RegisterPass<DAE>
> X("deadargelim", "Dead Argument Elimination");
> @@ -155,7 +180,7 @@
> // 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.
> + // the old function, but doesn't have isVarArg set.
> const FunctionType *FTy = Fn.getFunctionType();
> std::vector<const Type*> Params(FTy->param_begin(), FTy-
> >param_end());
> FunctionType *NFTy = FunctionType::get(FTy->getReturnType(),
> Params, false);
> @@ -233,57 +258,110 @@
> return true;
> }
>
> +/// Convenience function that returns the number of return values.
> It returns 0
> +/// 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)
> + return 0;
> + else if (const StructType *STy = dyn_cast<StructType>(F-
> >getReturnType()))
> + return STy->getNumElements();
> + else
> + return 1;
> +}
>
> -static inline bool CallPassesValueThoughVararg(Instruction *Call,
> - const Value *Arg) {
> - CallSite CS = CallSite::get(Call);
> - const Type *CalledValueTy = CS.getCalledValue()->getType();
> - const Type *FTy = cast<PointerType>(CalledValueTy)-
> >getElementType();
> - unsigned NumFixedArgs = cast<FunctionType>(FTy)->getNumParams();
> - for (CallSite::arg_iterator AI = CS.arg_begin()+NumFixedArgs;
> - AI != CS.arg_end(); ++AI)
> - if (AI->get() == Arg)
> - return true;
> - return false;
> -}
> -
> -// getArgumentLiveness - Inspect an argument, determining if is
> known Live
> -// (used in a computation), MaybeLive (only passed as an argument
> to a call), or
> -// Dead (not used).
> -DAE::Liveness DAE::getArgumentLiveness(const Argument &A) {
> - const Function *F = A.getParent();
> -
> - // If this is the return value of a struct function, it's not
> really dead.
> - if (F->hasStructRetAttr() && &*(F->arg_begin()) == &A)
> +/// 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))
> 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) {
> - // Return instructions do not immediately effect liveness.
> - if (isa<ReturnInst>(*I))
> - continue;
> -
> - CallSite CS = CallSite::get(const_cast<User*>(*I));
> - if (!CS.getInstruction()) {
> - // If its used by something that is not a call or invoke,
> it's alive!
> - return Live;
> - }
> - // If it's an indirect call, mark it alive...
> - Function *Callee = CS.getCalledFunction();
> - if (!Callee) return Live;
> -
> - // Check to see if it's passed through a va_arg area: if so, we
> cannot
> - // remove it.
> - if (CallPassesValueThoughVararg(CS.getInstruction(), &A))
> - return Live; // If passed through va_arg area, we cannot
> remove it
> - }
> + // We're maybe live otherwise, but remember that we must become
> live if
> + // Use becomes live.
> + MaybeLiveUses.push_back(Use);
> + return MaybeLive;
> +}
> +
>
> - return MaybeLive; // It must be used, but only as argument to a
> function
> +/// 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.
> +///
> +/// 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<ReturnInst>(V)) {
> + // The value is returned from another function. It's only
> live when the
> + // caller's return value is live
> + 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<InsertValueInst>(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.
> + RetValNum = *IV->idx_begin();
> +
> + // 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(),
> + E = V->use_end(); I != E; ++I) {
> + Result = SurveyUse(I, MaybeLiveUses, RetValNum);
> + if (Result == Live)
> + break;
> + }
> + return Result;
> + }
> + CallSite CS = CallSite::get(V);
> + if (CS.getInstruction()) {
> + 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())
> + // The value is passed in through a vararg! Must be live.
> + return Live;
> +
> + // 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;
> + }
> + }
> + // 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).
> +/// 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(),
> + E = V->use_end(); I != E; ++I) {
> + Result = SurveyUse(I, MaybeLiveUses);
> + if (Result == Live)
> + break;
> + }
> + return Result;
> +}
>
> // SurveyFunction - This performs the initial survey of the
> specified function,
> // checking out whether or not it uses any of its incoming arguments
> or whether
> @@ -294,13 +372,36 @@
> // well as arguments to functions which have their "address taken".
> //
> void DAE::SurveyFunction(Function &F) {
> + InspectedFunctions.insert(&F);
> bool FunctionIntrinsicallyLive = false;
> - Liveness RetValLiveness = F.getReturnType() == Type::VoidTy ?
> Live : Dead;
> -
> - if (!F.hasInternalLinkage() &&
> - (!ShouldHackArguments() || F.isIntrinsic()))
> + unsigned RetCount = NumRetVals(&F);
> + // Assume all return values are dead
> + typedef SmallVector<Liveness, 5> RetVals;
> + RetVals RetValLiveness(RetCount, Dead);
> +
> + // 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<UseVector, 5> RetUses;
> + // Intialized 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<ReturnInst>(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;
> - else
> + 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<StructType>(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) {
> @@ -315,191 +416,138 @@
> FunctionIntrinsicallyLive = true;
> break;
> }
> -
> - // Check to see if the return value is used...
> - if (RetValLiveness != Live)
> - for (Value::use_iterator I = TheCall->use_begin(),
> - E = TheCall->use_end(); I != E; ++I)
> - if (isa<ReturnInst>(cast<Instruction>(*I))) {
> - RetValLiveness = MaybeLive;
> - } else if (isa<CallInst>(cast<Instruction>(*I)) ||
> - isa<InvokeInst>(cast<Instruction>(*I))) {
> - if (CallPassesValueThoughVararg(cast<Instruction>(*I),
> TheCall) ||
> - !
> CallSite::get(cast<Instruction>(*I)).getCalledFunction()) {
> - RetValLiveness = Live;
> - 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<ExtractValueInst>(*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 {
> - RetValLiveness = MaybeLive;
> + // 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 {
> - RetValLiveness = Live;
> - break;
> }
> + } else {
> + // Single return value
> + RetValLiveness[0] = SurveyUses(TheCall,
> MaybeLiveRetUses[0]);
> + if (RetValLiveness[0] == Live)
> + NumLiveRetVals = RetCount;
> + }
> + }
> }
> -
> + }
> if (FunctionIntrinsicallyLive) {
> - DOUT << " Intrinsically live fn: " << F.getName() << "\n";
> + 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)
> - LiveArguments.insert(AI);
> - LiveRetVal.insert(&F);
> + 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;
> }
> -
> - switch (RetValLiveness) {
> - case Live: LiveRetVal.insert(&F); break;
> - case MaybeLive: MaybeLiveRetVal.insert(&F); break;
> - case Dead: DeadRetVal.insert(&F); break;
> +
> + // 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";
> +
> + // Now, check all of our arguments
> + unsigned i = 0;
> + UseVector MaybeLiveArgUses;
> + for (Function::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)
> + 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
> + MaybeLiveArgUses.clear();
> }
> +}
>
> - 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
> - // directly used, and keep track of all of the call sites of this
> function
> - // if there are any arguments we assume that are dead.
> - //
> - bool AnyMaybeLiveArgs = false;
> - for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
> - AI != E; ++AI)
> - switch (getArgumentLiveness(*AI)) {
> - case Live:
> - DOUT << " Arg live by use: " << AI->getName() << "\n";
> - LiveArguments.insert(AI);
> - break;
> - case Dead:
> - DOUT << " Arg definitely dead: " << AI->getName() <<"\n";
> - DeadArguments.insert(AI);
> - break;
> +/// 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) {
> + switch (L) {
> + case Live: MarkLive(RA); break;
> case MaybeLive:
> - DOUT << " Arg only passed to calls: " << AI->getName() <<
> "\n";
> - AnyMaybeLiveArgs = true;
> - MaybeLiveArguments.insert(AI);
> + {
> + // 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(),
> + UE = MaybeLiveUses.end(); UI != UE; ++UI)
> + Where = Uses.insert(Where, UseMap::value_type(*UI, RA));
> break;
> }
> -
> - // If there are any "MaybeLive" arguments, we need to check
> callees of
> - // this function when/if they become alive. Record which
> functions are
> - // callees...
> - if (AnyMaybeLiveArgs || RetValLiveness == MaybeLive)
> - for (Value::use_iterator I = F.use_begin(), E = F.use_end();
> - I != E; ++I) {
> - if (AnyMaybeLiveArgs)
> - CallSites.insert(std::make_pair(&F, CallSite::get(*I)));
> -
> - if (RetValLiveness == MaybeLive)
> - for (Value::use_iterator UI = I->use_begin(), E = I-
> >use_end();
> - UI != E; ++UI)
> - InstructionsToInspect.push_back(cast<Instruction>(*UI));
> - }
> -}
> -
> -// isMaybeLiveArgumentNowLive - Check to see if Arg is alive. At
> this point, we
> -// know that the only uses of Arg are to be passed in as an
> argument to a
> -// function call or return. Check to see if the formal argument
> passed in is in
> -// the LiveArguments set. If so, return true.
> -//
> -bool DAE::isMaybeLiveArgumentNowLive(Argument *Arg) {
> - for (Value::use_iterator I = Arg->use_begin(), E = Arg-
> >use_end(); I!=E; ++I){
> - if (isa<ReturnInst>(*I)) {
> - if (LiveRetVal.count(Arg->getParent())) return true;
> - continue;
> - }
> -
> - CallSite CS = CallSite::get(*I);
> -
> - // We know that this can only be used for direct calls...
> - Function *Callee = CS.getCalledFunction();
> -
> - // 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::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))
> - return true;
> - }
> - return false;
> -}
> -
> -/// MarkArgumentLive - The MaybeLive argument 'Arg' is now known to
> be alive.
> -/// Mark it live in the specified sets and recursively mark
> arguments in callers
> -/// live that are needed to pass in a value.
> -///
> -void DAE::MarkArgumentLive(Argument *Arg) {
> - std::set<Argument*>::iterator It =
> MaybeLiveArguments.lower_bound(Arg);
> - if (It == MaybeLiveArguments.end() || *It != Arg) return;
> -
> - 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->arg_begin(),
> Function::arg_iterator(Arg));
> -
> - std::multimap<Function*, CallSite>::iterator I =
> CallSites.lower_bound(Fn);
> - for (; I != CallSites.end() && I->first == Fn; ++I) {
> - CallSite CS = I->second;
> - Value *ArgVal = *(CS.arg_begin()+ArgNo);
> - if (Argument *ActualArg = dyn_cast<Argument>(ArgVal)) {
> - MarkArgumentLive(ActualArg);
> - } else {
> - // If the value passed in at this call site is a return value
> computed by
> - // some other call site, make sure to mark the return value
> at the other
> - // call site as being needed.
> - CallSite ArgCS = CallSite::get(ArgVal);
> - if (ArgCS.getInstruction())
> - if (Function *Fn = ArgCS.getCalledFunction())
> - MarkRetValLive(Fn);
> - }
> + case Dead: break;
> }
> }
>
> -/// MarkArgumentLive - The MaybeLive return value for the specified
> function is
> -/// now known to be alive. Propagate this fact to the return
> instructions which
> -/// produce it.
> -void DAE::MarkRetValLive(Function *F) {
> - assert(F && "Shame shame, we can't have null pointers here!");
> -
> - // Check to see if we already knew it was live
> - std::set<Function*>::iterator I = MaybeLiveRetVal.lower_bound(F);
> - if (I == MaybeLiveRetVal.end() || *I != F) return; // It's
> already alive!
> -
> - DOUT << " MaybeLive retval now live: " << F->getName() << "\n";
> +/// 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) {
> + if (!LiveValues.insert(RA).second)
> + return; // We were already marked Live
>
> - MaybeLiveRetVal.erase(I);
> - LiveRetVal.insert(F); // It is now known to be 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";
>
> - // Loop over all of the functions, noticing that the return value
> is now live.
> - for (Function::iterator BB = F->begin(), E = F->end(); BB != E; +
> +BB)
> - if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
> - MarkReturnInstArgumentLive(RI);
> + std::pair<UseMap::iterator, UseMap::iterator> Range =
> Uses.equal_range(RA);
> + UseMap::iterator E = Range.second;
> + UseMap::iterator I = Range.first;
> + for (; I != E; ++I)
> + MarkLive(I->second);
> + // Erase RA from the Uses map (from the lower bound to wherever
> we ended up
> + // after the loop).
> + Uses.erase(Range.first, Range.second);
> }
>
> -void DAE::MarkReturnInstArgumentLive(ReturnInst *RI) {
> - Value *Op = RI->getOperand(0);
> - if (Argument *A = dyn_cast<Argument>(Op)) {
> - MarkArgumentLive(A);
> - } else if (CallInst *CI = dyn_cast<CallInst>(Op)) {
> - if (Function *F = CI->getCalledFunction())
> - MarkRetValLive(F);
> - } else if (InvokeInst *II = dyn_cast<InvokeInst>(Op)) {
> - if (Function *F = II->getCalledFunction())
> - MarkRetValLive(F);
> - }
> -}
> -
> -// RemoveDeadArgumentsFromFunction - We know that F has dead
> arguments, as
> +// 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.
> //
> -void DAE::RemoveDeadArgumentsFromFunction(Function *F) {
> +bool DAE::RemoveDeadStuffFromFunction(Function *F) {
> + // Don't process functions we didn't inspect (such as external
> functions, or
> + // functions that we've newly created).
> + if (!InspectedFunctions.count(F))
> + return false;
> +
> // Start by computing a new prototype for the function, which is
> the same as
> - // the old function, but has fewer arguments.
> + // the old function, but has fewer arguments and a different
> return type.
> const FunctionType *FTy = F->getFunctionType();
> std::vector<const Type*> Params;
>
> @@ -510,28 +558,78 @@
> // The existing function return attributes.
> ParameterAttributes RAttrs = PAL.getParamAttrs(0);
>
> - // Make the function return void if the return value is dead.
> +
> + // Find out the new return value
> +
> const Type *RetTy = FTy->getReturnType();
> - if (DeadRetVal.count(F)) {
> - RetTy = Type::VoidTy;
> - RAttrs &= ~ParamAttr::typeIncompatible(RetTy);
> - DeadRetVal.erase(F);
> - }
> -
> + const Type *NRetTy;
> + unsigned RetCount = NumRetVals(F);
> + // -1 means unused, other numbers are the new index
> + SmallVector<int, 5> NewRetIdxs(RetCount, -1);
> + std::vector<const Type*> RetTypes;
> + if (RetTy != Type::VoidTy) {
> + const StructType *STy = dyn_cast<StructType>(RetTy);
> + if (STy)
> + // 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)) {
> + RetTypes.push_back(STy->getElementType(i));
> + NewRetIdxs[i] = RetTypes.size() - 1;
> + } else {
> + ++NumRetValsEliminated;
> + DOUT << "DAE - Removing return value " << i << " from " <<
> F->getNameStart() << "\n";
> + }
> + }
> + else
> + // 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";
> + ++NumRetValsEliminated;
> + }
> + if (RetTypes.size() == 0)
> + // No return types? Make it void
> + NRetTy = Type::VoidTy;
> + else if (RetTypes.size() == 1)
> + // One return type? Just a simple value then
> + NRetTy = RetTypes.front();
> + else
> + // More return types? Return a struct with them
> + NRetTy = StructType::get(RetTypes);
> + } else {
> + NRetTy = Type::VoidTy;
> + }
> +
> + // Remove any incompatible attributes
> + RAttrs &= ~ParamAttr::typeIncompatible(NRetTy);
> if (RAttrs)
> ParamAttrsVec.push_back(ParamAttrsWithIndex::get(0, RAttrs));
> -
> +
> + // Remember which arguments are still alive
> + SmallVector<bool, 10> ArgAlive(FTy->getNumParams(), false);
> // Construct the new parameter list from non-dead arguments. Also
> construct
> - // a new set of parameter attributes to correspond.
> - unsigned index = 1;
> - for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
> I != E;
> - ++I, ++index)
> - if (!DeadArguments.count(I)) {
> + // a new set of parameter attributes to correspond. Skip the
> first parameter
> + // attribute, since that belongs to the return value.
> + unsigned i = 0;
> + for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
> + I != E; ++I, ++i) {
> + RetOrArg Arg = CreateArg(F, i);
> + if (LiveValues.erase(Arg)) {
> Params.push_back(I->getType());
> + ArgAlive[i] = true;
>
> - if (ParameterAttributes Attrs = PAL.getParamAttrs(index))
> + // 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));
> + } else {
> + ++NumArgumentsEliminated;
> + DOUT << "DAE - Removing argument " << i << " (" << I-
> >getNameStart() << ") from " << F->getNameStart() << "\n";
> }
> + }
>
> // Reconstruct the ParamAttrsList based on the vector we
> constructed.
> PAListPtr NewPAL = PAListPtr::get(ParamAttrsVec.begin(),
> ParamAttrsVec.end());
> @@ -546,7 +644,11 @@
> }
>
> // Create the new function type based on the recomputed parameters.
> - FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy-
> >isVarArg());
> + FunctionType *NFTy = FunctionType::get(NRetTy, Params, FTy-
> >isVarArg());
> +
> + // No change?
> + if (NFTy == FTy)
> + return false;
>
> // Create the new function body and insert it into the module...
> Function *NF = Function::Create(NFTy, F->getLinkage());
> @@ -572,14 +674,17 @@
> if (RAttrs)
> ParamAttrsVec.push_back(ParamAttrsWithIndex::get(0, RAttrs));
>
> - // Loop over the operands, deleting dead ones...
> - CallSite::arg_iterator AI = CS.arg_begin();
> - index = 1;
> - for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
> - I != E; ++I, ++AI, ++index)
> - if (!DeadArguments.count(I)) { // Remove operands for dead
> arguments
> - Args.push_back(*AI);
> - if (ParameterAttributes Attrs = CallPAL.getParamAttrs(index))
> + // Declare these outside of the loops, so we can reuse them for
> the second
> + // loop, which loops the varargs
> + CallSite::arg_iterator I = CS.arg_begin();
> + 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));
> }
>
> @@ -587,9 +692,9 @@
> Args.push_back(UndefValue::get(Type::Int32Ty));
>
> // Push any varargs arguments on the list. Don't forget their
> attributes.
> - for (; AI != CS.arg_end(); ++AI) {
> - Args.push_back(*AI);
> - if (ParameterAttributes Attrs = CallPAL.getParamAttrs(index++))
> + 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));
> }
>
> @@ -614,8 +719,45 @@
>
> 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 {
> + else if (isa<StructType>(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<ExtractValueInst>(*I) && "Return value not
> only used by extractvalue?");
> + ExtractValueInst *EV = cast<ExtractValueInst>(*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<unsigned> 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();
> + }
> + }
> + New->takeName(Call);
> + } else {
> + // The original function had a single return value
> Call->replaceAllUsesWith(New);
> New->takeName(Call);
> }
> @@ -632,13 +774,11 @@
> NF->getBasicBlockList().splice(NF->begin(), F->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.
> - //
> + // the new arguments, also transfering over the names as well.
> + i = 0;
> for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(),
> - I2 = NF->arg_begin();
> - I != E; ++I)
> - if (!DeadArguments.count(I)) {
> + I2 = NF->arg_begin(); I != E; ++I, ++i)
> + if (ArgAlive[i]) {
> // If this is a live argument, move the name and users over to
> the new
> // version.
> I->replaceAllUsesWith(I2);
> @@ -646,10 +786,8 @@
> ++I2;
> } else {
> // If this argument is dead, replace any uses of it with null
> constants
> - // (these are guaranteed to only be operands to call
> instructions which
> - // will later be simplified).
> + // (these are guaranteed to become unused later on)
> I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
> - DeadArguments.erase(I);
> }
>
> // If we change the return value of the function we must rewrite
> any return
> @@ -657,12 +795,45 @@
> if (F->getReturnType() != NF->getReturnType())
> for (Function::iterator BB = NF->begin(), E = NF->end(); BB !=
> E; ++BB)
> if (ReturnInst *RI = dyn_cast<ReturnInst>(BB-
> >getTerminator())) {
> - ReturnInst::Create(0, RI);
> + Value *RetVal;
> +
> + if (NFTy->getReturnType() == Type::VoidTy) {
> + RetVal = 0;
> + } else {
> + assert (isa<StructType>(RetTy));
> + // 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
> + Value *OldRet = RI->getOperand(0);
> + // Start out building up our return value from undef
> + RetVal = llvm::UndefValue::get(NRetTy);
> + for (unsigned i = 0; i != RetCount; ++i)
> + if (NewRetIdxs[i] != -1) {
> + ExtractValueInst *EV =
> ExtractValueInst::Create(OldRet, i, "newret", 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");
> + } else {
> + // We are now only returning a simple value, so
> just return the
> + // 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);
> BB->getInstList().erase(RI);
> }
>
> // Now that the old function is dead, delete it.
> F->eraseFromParent();
> +
> + return true;
> }
>
> bool DAE::runOnModule(Module &M) {
> @@ -677,7 +848,7 @@
> if (F.getFunctionType()->isVarArg())
> Changed |= DeleteDeadVarargs(F);
> }
> -
> +
> // Second 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).
> @@ -686,85 +857,14 @@
> for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
> SurveyFunction(*I);
>
> - // Loop over the instructions to inspect, propagating liveness
> among arguments
> - // and return values which are MaybeLive.
> - while (!InstructionsToInspect.empty()) {
> - Instruction *I = InstructionsToInspect.back();
> - InstructionsToInspect.pop_back();
> -
> - if (ReturnInst *RI = dyn_cast<ReturnInst>(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
> - // arguments used by it are now alive, and any call
> instruction return
> - // value is alive as well.
> - if (LiveRetVal.count(RI->getParent()->getParent()))
> - MarkReturnInstArgumentLive(RI);
> -
> - } else {
> - CallSite CS = CallSite::get(I);
> - 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::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))
> - if (Function *Callee = ArgCS.getCalledFunction())
> - MarkRetValLive(Callee);
> - }
> - }
> + // Now, remove all dead arguments and return values from each
> function in
> + // 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)
> + Function *F = I++;
> + Changed |= RemoveDeadStuffFromFunction(F);
> }
>
> - // Now we loop over all of the MaybeLive arguments, promoting
> them to be live
> - // arguments if one of the calls that uses the arguments to the
> calls they are
> - // passed into requires them to be live. Of course this could
> make other
> - // arguments live, so process callers recursively.
> - //
> - // Because elements can be removed from the MaybeLiveArguments
> set, copy it to
> - // a temporary vector.
> - //
> - std::vector<Argument*> TmpArgList(MaybeLiveArguments.begin(),
> - MaybeLiveArguments.end());
> - for (unsigned i = 0, e = TmpArgList.size(); i != e; ++i) {
> - Argument *MLA = TmpArgList[i];
> - if (MaybeLiveArguments.count(MLA) &&
> - isMaybeLiveArgumentNowLive(MLA))
> - MarkArgumentLive(MLA);
> - }
> -
> - // Recover memory early...
> - CallSites.clear();
> -
> - // At this point, we know that all arguments in DeadArguments and
> - // MaybeLiveArguments are dead. If the two sets are empty, there
> is nothing
> - // to do.
> - if (MaybeLiveArguments.empty() && DeadArguments.empty() &&
> - MaybeLiveRetVal.empty() && DeadRetVal.empty())
> - return Changed;
> -
> - // Otherwise, compact into one set, and start eliminating the
> arguments from
> - // the functions.
> - DeadArguments.insert(MaybeLiveArguments.begin(),
> MaybeLiveArguments.end());
> - MaybeLiveArguments.clear();
> - DeadRetVal.insert(MaybeLiveRetVal.begin(), MaybeLiveRetVal.end());
> - MaybeLiveRetVal.clear();
> -
> - LiveArguments.clear();
> - LiveRetVal.clear();
> -
> - NumArgumentsEliminated += DeadArguments.size();
> - NumRetValsEliminated += DeadRetVal.size();
> - while (!DeadArguments.empty())
> - RemoveDeadArgumentsFromFunction((*DeadArguments.begin())-
> >getParent());
> -
> - while (!DeadRetVal.empty())
> - RemoveDeadArgumentsFromFunction(*DeadRetVal.begin());
> - return true;
> + return Changed;
> }
>
> Added: llvm/trunk/test/Transforms/DeadArgElim/multdeadretval.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/DeadArgElim/multdeadretval.ll?rev=52459&view=auto
>
> =
> =
> =
> =
> =
> =
> =
> =
> ======================================================================
> --- llvm/trunk/test/Transforms/DeadArgElim/multdeadretval.ll (added)
> +++ llvm/trunk/test/Transforms/DeadArgElim/multdeadretval.ll Wed Jun
> 18 06:12:53 2008
> @@ -0,0 +1,39 @@
> +; This test sees if return values (and arguments) are properly
> removed when they
> +; are unused. All unused values are typed i16, so we can easily
> check. We also
> +; run instcombine to fold insert/extractvalue chains and we run dce
> to clean up
> +; any remaining dead stuff.
> +; RUN: llvm-as < %s | opt -deadargelim -instcombine -dce | llvm-dis
> | not grep i16
> +
> +define internal {i16, i32} @test(i16 %DEADARG) {
> + %A = insertvalue {i16,i32} undef, i16 1, 0
> + %B = insertvalue {i16,i32} %A, i32 1001, 1
> + ret {i16,i32} %B
> +}
> +
> +define internal {i32, i16} @test2() {
> + %DEAD = call i16 @test4()
> + %A = insertvalue {i32,i16} undef, i32 1, 0
> + %B = insertvalue {i32,i16} %A, i16 %DEAD, 1
> + ret {i32,i16} %B
> +}
> +
> +define internal i32 @test3(i16 %A) {
> + %ret = call {i16, i32} @test( i16 %A ) ;
> <i32> [#uses=0]
> + %DEAD = extractvalue {i16, i32} %ret, 0
> + %LIVE = extractvalue {i16, i32} %ret, 1
> + ret i32 %LIVE
> +}
> +
> +define internal i16 @test4() {
> + ret i16 0
> +}
> +
> +define i32 @main() {
> + %ret = call {i32, i16} @test2() ; <i32>
> [#uses=1]
> + %LIVE = extractvalue {i32, i16} %ret, 0
> + %DEAD = extractvalue {i32, i16} %ret, 1
> + %Y = add i32 %LIVE, -123 ; <i32> [#uses=1]
> + %LIVE2 = call i32 @test3(i16 %DEAD) ; <i32>
> [#uses=1]
> + %Z = add i32 %LIVE2, %Y ; <i32> [#uses=1]
> + ret i32 %Z
> +}
>
>
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