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https://github.com/RPCS3/llvm.git
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Revert r52459, which was causing an infinite loop or massive slowdown on MultiSource/Applications/SPASS, and possibly others as well.
Please reapply once this is fixed. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52465 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
parent
e24fa64d52
commit
bb3761c9e5
@ -10,10 +10,10 @@
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// This pass deletes dead arguments from internal functions. Dead argument
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// elimination removes arguments which are directly dead, as well as arguments
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// only passed into function calls as dead arguments of other functions. This
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// pass also deletes dead return values in a similar way.
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// pass also deletes dead arguments in a similar way.
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//
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// This pass is often useful as a cleanup pass to run after aggressive
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// interprocedural passes, which add possibly-dead arguments or return values.
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// interprocedural passes, which add possibly-dead arguments.
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//
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//===----------------------------------------------------------------------===//
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@ -42,66 +42,40 @@ namespace {
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/// DAE - The dead argument elimination pass.
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///
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class VISIBILITY_HIDDEN DAE : public ModulePass {
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public:
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/// Struct that represent either a (part of a) return value or a function
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/// argument. Used so that arguments and return values can be used
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/// interchangably.
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struct RetOrArg {
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RetOrArg(const Function* F, unsigned Idx, bool IsArg) : F(F), Idx(Idx), IsArg(IsArg) {}
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const Function *F;
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unsigned Idx;
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bool IsArg;
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/// Make RetOrArg comparable, so we can put it into a map
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bool operator<(const RetOrArg &O) const {
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if (F != O.F)
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return F < O.F;
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else if (Idx != O.Idx)
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return Idx < O.Idx;
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else
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return IsArg < O.IsArg;
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}
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};
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/// Liveness enum - During our initial pass over the program, we determine
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/// that things are either definately alive, definately dead, or in need of
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/// interprocedural analysis (MaybeLive).
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///
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enum Liveness { Live, MaybeLive, Dead };
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/// Convenience wrapper
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RetOrArg CreateRet(const Function *F, unsigned Idx) { return RetOrArg(F, Idx, false); }
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/// Convenience wrapper
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RetOrArg CreateArg(const Function *F, unsigned Idx) { return RetOrArg(F, Idx, true); }
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/// LiveArguments, MaybeLiveArguments, DeadArguments - These sets contain
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/// all of the arguments in the program. The Dead set contains arguments
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/// which are completely dead (never used in the function). The MaybeLive
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/// set contains arguments which are only passed into other function calls,
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/// thus may be live and may be dead. The Live set contains arguments which
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/// are known to be alive.
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///
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std::set<Argument*> DeadArguments, MaybeLiveArguments, LiveArguments;
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typedef std::multimap<RetOrArg, RetOrArg> UseMap;
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/// This map maps a return value or argument to all return values or
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/// arguments it uses.
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/// For example (indices are left out for clarity):
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/// - Uses[ret F] = ret G
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/// This means that F calls G, and F returns the value returned by G.
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/// - Uses[arg F] = ret G
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/// This means that some function calls G and passes its result as an
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/// argument to F.
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/// - Uses[ret F] = arg F
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/// This means that F returns one of its own arguments.
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/// - Uses[arg F] = arg G
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/// This means that G calls F and passes one of its own (G's) arguments
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/// directly to F.
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UseMap Uses;
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/// DeadRetVal, MaybeLiveRetVal, LifeRetVal - These sets contain all of the
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/// functions in the program. The Dead set contains functions whose return
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/// value is known to be dead. The MaybeLive set contains functions whose
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/// return values are only used by return instructions, and the Live set
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/// contains functions whose return values are used, functions that are
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/// external, and functions that already return void.
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///
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std::set<Function*> DeadRetVal, MaybeLiveRetVal, LiveRetVal;
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typedef std::set<RetOrArg> LiveSet;
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/// InstructionsToInspect - As we mark arguments and return values
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/// MaybeLive, we keep track of which instructions could make the values
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/// live here. Once the entire program has had the return value and
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/// arguments analyzed, this set is scanned to promote the MaybeLive objects
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/// to be Live if they really are used.
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std::vector<Instruction*> InstructionsToInspect;
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/// This set contains all values that have been determined to be live
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LiveSet LiveValues;
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typedef SmallVector<RetOrArg, 5> UseVector;
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/// This is the set of functions that have been inspected. Since LiveValues
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/// keeps a list of live values for inspected functions only, this way we
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/// can prevent uninspected functions becoming completely dead.
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std::set<Function*> InspectedFunctions;
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/// CallSites - Keep track of the call sites of functions that have
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/// MaybeLive arguments or return values.
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std::multimap<Function*, CallSite> CallSites;
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public:
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static char ID; // Pass identification, replacement for typeid
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@ -111,19 +85,20 @@ namespace {
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virtual bool ShouldHackArguments() const { return false; }
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private:
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Liveness IsMaybeLive(RetOrArg Use, UseVector &MaybeLiveUses);
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Liveness SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses, unsigned RetValNum = 0);
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Liveness SurveyUses(Value *V, UseVector &MaybeLiveUses);
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Liveness getArgumentLiveness(const Argument &A);
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bool isMaybeLiveArgumentNowLive(Argument *Arg);
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void SurveyFunction(Function &F);
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void MarkValue(const RetOrArg &RA, Liveness L, const UseVector &MaybeLiveUses);
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void MarkLive(RetOrArg RA);
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bool RemoveDeadStuffFromFunction(Function *F);
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bool DeleteDeadVarargs(Function &Fn);
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void SurveyFunction(Function &Fn);
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void MarkArgumentLive(Argument *Arg);
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void MarkRetValLive(Function *F);
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void MarkReturnInstArgumentLive(ReturnInst *RI);
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void RemoveDeadArgumentsFromFunction(Function *F);
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};
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}
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char DAE::ID = 0;
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static RegisterPass<DAE>
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X("deadargelim", "Dead Argument Elimination");
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@ -180,7 +155,7 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
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// remove the "..." and adjust all the calls.
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// Start by computing a new prototype for the function, which is the same as
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// the old function, but doesn't have isVarArg set.
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// the old function, but has fewer arguments.
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const FunctionType *FTy = Fn.getFunctionType();
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std::vector<const Type*> Params(FTy->param_begin(), FTy->param_end());
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FunctionType *NFTy = FunctionType::get(FTy->getReturnType(), Params, false);
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@ -258,111 +233,58 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
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return true;
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}
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/// Convenience function that returns the number of return values. It returns 0
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/// for void functions and 1 for functions not returning a struct. It returns
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/// the number of struct elements for functions returning a struct.
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static unsigned NumRetVals(const Function *F) {
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if (F->getReturnType() == Type::VoidTy)
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return 0;
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else if (const StructType *STy = dyn_cast<StructType>(F->getReturnType()))
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return STy->getNumElements();
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else
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return 1;
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static inline bool CallPassesValueThoughVararg(Instruction *Call,
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const Value *Arg) {
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CallSite CS = CallSite::get(Call);
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const Type *CalledValueTy = CS.getCalledValue()->getType();
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const Type *FTy = cast<PointerType>(CalledValueTy)->getElementType();
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unsigned NumFixedArgs = cast<FunctionType>(FTy)->getNumParams();
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for (CallSite::arg_iterator AI = CS.arg_begin()+NumFixedArgs;
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AI != CS.arg_end(); ++AI)
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if (AI->get() == Arg)
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return true;
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return false;
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}
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/// IsMaybeAlive - This checks Use for liveness. If Use is live, returns Live,
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/// else returns MaybeLive. Also, adds Use to MaybeLiveUses in the latter case.
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DAE::Liveness DAE::IsMaybeLive(RetOrArg Use, UseVector &MaybeLiveUses) {
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// We're live if our use is already marked as live
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if (LiveValues.count(Use))
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// getArgumentLiveness - Inspect an argument, determining if is known Live
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// (used in a computation), MaybeLive (only passed as an argument to a call), or
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// Dead (not used).
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DAE::Liveness DAE::getArgumentLiveness(const Argument &A) {
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const Function *F = A.getParent();
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// If this is the return value of a struct function, it's not really dead.
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if (F->hasStructRetAttr() && &*(F->arg_begin()) == &A)
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return Live;
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if (A.use_empty()) // First check, directly dead?
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return Dead;
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// We're maybe live otherwise, but remember that we must become live if
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// Use becomes live.
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MaybeLiveUses.push_back(Use);
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return MaybeLive;
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}
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// Scan through all of the uses, looking for non-argument passing uses.
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for (Value::use_const_iterator I = A.use_begin(), E = A.use_end(); I!=E;++I) {
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// Return instructions do not immediately effect liveness.
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if (isa<ReturnInst>(*I))
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continue;
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/// SurveyUse - This looks at a single use of an argument or return value
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/// and determines if it should be alive or not. Adds this use to MaybeLiveUses
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/// if it causes the used value to become MaybeAlive.
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///
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/// RetValNum is the return value number to use when this use is used in a
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/// return instruction. This is used in the recursion, you should always leave
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/// it at 0.
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DAE::Liveness DAE::SurveyUse(Value::use_iterator U, UseVector &MaybeLiveUses, unsigned RetValNum) {
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Value *V = *U;
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if (ReturnInst *RI = dyn_cast<ReturnInst>(V)) {
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// The value is returned from another function. It's only live when the
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// caller's return value is live
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RetOrArg Use = CreateRet(RI->getParent()->getParent(), RetValNum);
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// We might be live, depending on the liveness of Use
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return IsMaybeLive(Use, MaybeLiveUses);
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}
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if (InsertValueInst *IV = dyn_cast<InsertValueInst>(V)) {
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if (U.getOperandNo() != InsertValueInst::getAggregateOperandIndex() && IV->hasIndices())
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// The use we are examining is inserted into an aggregate. Our liveness
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// depends on all uses of that aggregate, but if it is used as a return
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// value, only index at which we were inserted counts.
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RetValNum = *IV->idx_begin();
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// Note that if we are used as the aggregate operand to the insertvalue,
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// we don't change RetValNum, but do survey all our uses.
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Liveness Result = Dead;
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for (Value::use_iterator I = IV->use_begin(),
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E = V->use_end(); I != E; ++I) {
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Result = SurveyUse(I, MaybeLiveUses, RetValNum);
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if (Result == Live)
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break;
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}
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return Result;
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CallSite CS = CallSite::get(const_cast<User*>(*I));
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if (!CS.getInstruction()) {
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// If its used by something that is not a call or invoke, it's alive!
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return Live;
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}
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CallSite CS = CallSite::get(V);
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if (CS.getInstruction()) {
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Function *F = CS.getCalledFunction();
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if (F) {
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// Used in a direct call
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// Check for vararg. Do - 1 to skip the first operand to call (the
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// function itself).
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if (U.getOperandNo() - 1 >= F->getFunctionType()->getNumParams())
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// The value is passed in through a vararg! Must be live.
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return Live;
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// If it's an indirect call, mark it alive...
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Function *Callee = CS.getCalledFunction();
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if (!Callee) return Live;
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// Value passed to a normal call. It's only live when the corresponding
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// argument (operand number - 1 to skip the function pointer operand) to
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// the called function turns out live
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RetOrArg Use = CreateArg(F, U.getOperandNo() - 1);
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return IsMaybeLive(Use, MaybeLiveUses);
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} else {
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// Used in any other way? Value must be live.
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return Live;
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}
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}
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// Used in any other way? Value must be live.
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return Live;
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}
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/// SurveyUses - This looks at all the uses of the given return value
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/// (possibly a partial return value from a function returning a struct).
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/// Returns the Liveness deduced from the uses of this value.
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///
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/// Adds all uses that cause the result to be MaybeLive to MaybeLiveRetUses.
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DAE::Liveness DAE::SurveyUses(Value *V, UseVector &MaybeLiveUses) {
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// Assume it's dead (which will only hold if there are no uses at all..)
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Liveness Result = Dead;
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// Check each use
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for (Value::use_iterator I = V->use_begin(),
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E = V->use_end(); I != E; ++I) {
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Result = SurveyUse(I, MaybeLiveUses);
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if (Result == Live)
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break;
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// Check to see if it's passed through a va_arg area: if so, we cannot
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// remove it.
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if (CallPassesValueThoughVararg(CS.getInstruction(), &A))
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return Live; // If passed through va_arg area, we cannot remove it
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}
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return Result;
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return MaybeLive; // It must be used, but only as argument to a function
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}
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// SurveyFunction - This performs the initial survey of the specified function,
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// checking out whether or not it uses any of its incoming arguments or whether
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// any callers use the return value. This fills in the
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@ -372,36 +294,13 @@ DAE::Liveness DAE::SurveyUses(Value *V, UseVector &MaybeLiveUses) {
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// well as arguments to functions which have their "address taken".
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//
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void DAE::SurveyFunction(Function &F) {
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InspectedFunctions.insert(&F);
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bool FunctionIntrinsicallyLive = false;
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unsigned RetCount = NumRetVals(&F);
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// Assume all return values are dead
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typedef SmallVector<Liveness, 5> RetVals;
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RetVals RetValLiveness(RetCount, Dead);
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Liveness RetValLiveness = F.getReturnType() == Type::VoidTy ? Live : Dead;
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// These vectors maps each return value to the uses that make it MaybeLive, so
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// we can add those to the MaybeLiveRetVals list if the return value
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// really turns out to be MaybeLive. Initializes to RetCount empty vectors
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typedef SmallVector<UseVector, 5> RetUses;
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// Intialized to a list of RetCount empty lists
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RetUses MaybeLiveRetUses(RetCount);
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
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if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
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if (RI->getNumOperands() != 0 && RI->getOperand(0)->getType() != F.getFunctionType()->getReturnType()) {
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// We don't support old style multiple return values
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FunctionIntrinsicallyLive = true;
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break;
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}
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if (!F.hasInternalLinkage() && (!ShouldHackArguments() || F.isIntrinsic()))
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if (!F.hasInternalLinkage() &&
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(!ShouldHackArguments() || F.isIntrinsic()))
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FunctionIntrinsicallyLive = true;
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if (!FunctionIntrinsicallyLive) {
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DOUT << "DAE - Inspecting callers for fn: " << F.getName() << "\n";
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// Keep track of the number of live retvals, so we can skip checks once all
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// of them turn out to be live.
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unsigned NumLiveRetVals = 0;
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const Type *STy = dyn_cast<StructType>(F.getReturnType());
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// Loop all uses of the function
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else
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for (Value::use_iterator I = F.use_begin(), E = F.use_end(); I != E; ++I) {
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// If the function is PASSED IN as an argument, its address has been taken
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if (I.getOperandNo() != 0) {
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@ -416,138 +315,191 @@ void DAE::SurveyFunction(Function &F) {
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FunctionIntrinsicallyLive = true;
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break;
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}
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// If we end up here, we are looking at a direct call to our function.
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// Now, check how our return value(s) is/are used in this caller. Don't
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// bother checking return values if all of them are live already
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if (NumLiveRetVals != RetCount) {
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if (STy) {
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// Check all uses of the return value
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for (Value::use_iterator I = TheCall->use_begin(),
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E = TheCall->use_end(); I != E; ++I) {
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ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(*I);
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if (Ext && Ext->hasIndices()) {
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// This use uses a part of our return value, survey the uses of that
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// part and store the results for this index only.
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unsigned Idx = *Ext->idx_begin();
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if (RetValLiveness[Idx] != Live) {
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RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]);
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if (RetValLiveness[Idx] == Live)
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NumLiveRetVals++;
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}
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} else {
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// Used by something else than extractvalue. Mark all
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// return values as live.
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for (unsigned i = 0; i != RetCount; ++i )
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RetValLiveness[i] = Live;
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NumLiveRetVals = RetCount;
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// Check to see if the return value is used...
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if (RetValLiveness != Live)
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for (Value::use_iterator I = TheCall->use_begin(),
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E = TheCall->use_end(); I != E; ++I)
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if (isa<ReturnInst>(cast<Instruction>(*I))) {
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RetValLiveness = MaybeLive;
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} else if (isa<CallInst>(cast<Instruction>(*I)) ||
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isa<InvokeInst>(cast<Instruction>(*I))) {
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if (CallPassesValueThoughVararg(cast<Instruction>(*I), TheCall) ||
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!CallSite::get(cast<Instruction>(*I)).getCalledFunction()) {
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RetValLiveness = Live;
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break;
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} else {
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RetValLiveness = MaybeLive;
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}
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} else {
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RetValLiveness = Live;
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break;
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}
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} else {
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// Single return value
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RetValLiveness[0] = SurveyUses(TheCall, MaybeLiveRetUses[0]);
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if (RetValLiveness[0] == Live)
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NumLiveRetVals = RetCount;
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}
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}
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}
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}
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if (FunctionIntrinsicallyLive) {
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DOUT << "DAE - Intrinsically live fn: " << F.getName() << "\n";
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// Mark all arguments as live
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unsigned i = 0;
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DOUT << " Intrinsically live fn: " << F.getName() << "\n";
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for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
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AI != E; ++AI, ++i)
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MarkLive(CreateArg(&F, i));
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// Mark all return values as live
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i = 0;
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for (unsigned i = 0, e = RetValLiveness.size(); i != e; ++i)
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MarkLive(CreateRet(&F, i));
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AI != E; ++AI)
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LiveArguments.insert(AI);
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LiveRetVal.insert(&F);
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return;
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}
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// 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();
|
||||
switch (RetValLiveness) {
|
||||
case Live: LiveRetVal.insert(&F); break;
|
||||
case MaybeLive: MaybeLiveRetVal.insert(&F); break;
|
||||
case Dead: DeadRetVal.insert(&F); 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;
|
||||
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;
|
||||
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(),
|
||||
UE = MaybeLiveUses.end(); UI != UE; ++UI)
|
||||
Where = Uses.insert(Where, UseMap::value_type(*UI, RA));
|
||||
DOUT << " Arg only passed to calls: " << AI->getName() << "\n";
|
||||
AnyMaybeLiveArgs = true;
|
||||
MaybeLiveArguments.insert(AI);
|
||||
break;
|
||||
}
|
||||
case Dead: 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);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// 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
|
||||
/// 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!");
|
||||
|
||||
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";
|
||||
// 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!
|
||||
|
||||
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);
|
||||
DOUT << " MaybeLive retval now live: " << F->getName() << "\n";
|
||||
|
||||
MaybeLiveRetVal.erase(I);
|
||||
LiveRetVal.insert(F); // It is now known to be live!
|
||||
|
||||
// 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);
|
||||
}
|
||||
|
||||
// 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.
|
||||
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
|
||||
// specified by the DeadArguments list. Transform the function and all of the
|
||||
// callees of the function to not have these arguments.
|
||||
//
|
||||
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;
|
||||
|
||||
void DAE::RemoveDeadArgumentsFromFunction(Function *F) {
|
||||
// Start by computing a new prototype for the function, which is the same as
|
||||
// the old function, but has fewer arguments and a different return type.
|
||||
// the old function, but has fewer arguments.
|
||||
const FunctionType *FTy = F->getFunctionType();
|
||||
std::vector<const Type*> Params;
|
||||
|
||||
@ -558,78 +510,28 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
|
||||
// The existing function return attributes.
|
||||
ParameterAttributes RAttrs = PAL.getParamAttrs(0);
|
||||
|
||||
|
||||
// Find out the new return value
|
||||
|
||||
// Make the function return void if the return value is dead.
|
||||
const Type *RetTy = FTy->getReturnType();
|
||||
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;
|
||||
if (DeadRetVal.count(F)) {
|
||||
RetTy = Type::VoidTy;
|
||||
RAttrs &= ~ParamAttr::typeIncompatible(RetTy);
|
||||
DeadRetVal.erase(F);
|
||||
}
|
||||
|
||||
// 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. 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)) {
|
||||
// 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)) {
|
||||
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))
|
||||
if (ParameterAttributes Attrs = PAL.getParamAttrs(index))
|
||||
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());
|
||||
@ -644,11 +546,7 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
|
||||
}
|
||||
|
||||
// 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;
|
||||
FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg());
|
||||
|
||||
// Create the new function body and insert it into the module...
|
||||
Function *NF = Function::Create(NFTy, F->getLinkage());
|
||||
@ -674,17 +572,14 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
|
||||
if (RAttrs)
|
||||
ParamAttrsVec.push_back(ParamAttrsWithIndex::get(0, RAttrs));
|
||||
|
||||
// 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))
|
||||
// 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))
|
||||
ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Args.size(), Attrs));
|
||||
}
|
||||
|
||||
@ -692,9 +587,9 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
|
||||
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))
|
||||
for (; AI != CS.arg_end(); ++AI) {
|
||||
Args.push_back(*AI);
|
||||
if (ParameterAttributes Attrs = CallPAL.getParamAttrs(index++))
|
||||
ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Args.size(), Attrs));
|
||||
}
|
||||
|
||||
@ -719,45 +614,8 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
|
||||
|
||||
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<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
|
||||
else {
|
||||
Call->replaceAllUsesWith(New);
|
||||
New->takeName(Call);
|
||||
}
|
||||
@ -774,11 +632,13 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
|
||||
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.
|
||||
i = 0;
|
||||
// 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 = F->arg_begin(), E = F->arg_end(),
|
||||
I2 = NF->arg_begin(); I != E; ++I, ++i)
|
||||
if (ArgAlive[i]) {
|
||||
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
|
||||
// version.
|
||||
I->replaceAllUsesWith(I2);
|
||||
@ -786,8 +646,10 @@ 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 only be operands to call instructions which
|
||||
// will later be simplified).
|
||||
I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
|
||||
DeadArguments.erase(I);
|
||||
}
|
||||
|
||||
// If we change the return value of the function we must rewrite any return
|
||||
@ -795,45 +657,12 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
|
||||
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())) {
|
||||
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);
|
||||
ReturnInst::Create(0, RI);
|
||||
BB->getInstList().erase(RI);
|
||||
}
|
||||
|
||||
// Now that the old function is dead, delete it.
|
||||
F->eraseFromParent();
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
bool DAE::runOnModule(Module &M) {
|
||||
@ -848,7 +677,7 @@ bool DAE::runOnModule(Module &M) {
|
||||
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).
|
||||
@ -857,14 +686,85 @@ bool DAE::runOnModule(Module &M) {
|
||||
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
|
||||
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);
|
||||
// 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);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return Changed;
|
||||
// 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;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user