+ /// SDep - Scheduling dependency. This represents one direction of an
+ /// edge in the scheduling DAG.
+ class SDep {
+ public:
+ /// Kind - These are the different kinds of scheduling dependencies.
+ enum Kind {
+ Data, ///< Regular data dependence (aka true-dependence).
+ Anti, ///< A register anti-dependedence (aka WAR).
+ Output, ///< A register output-dependence (aka WAW).
+ Order ///< Any other ordering dependency.
+ };
+
+ // Strong dependencies must be respected by the scheduler. Artificial
+ // dependencies may be removed only if they are redundant with another
+ // strong depedence.
+ //
+ // Weak dependencies may be violated by the scheduling strategy, but only if
+ // the strategy can prove it is correct to do so.
+ //
+ // Strong OrderKinds must occur before "Weak".
+ // Weak OrderKinds must occur after "Weak".
+ enum OrderKind {
+ Barrier, ///< An unknown scheduling barrier.
+ MayAliasMem, ///< Nonvolatile load/Store instructions that may alias.
+ MustAliasMem, ///< Nonvolatile load/Store instructions that must alias.
+ Artificial, ///< Arbitrary strong DAG edge (no real dependence).
+ Weak, ///< Arbitrary weak DAG edge.
+ Cluster ///< Weak DAG edge linking a chain of clustered instrs.
+ };
+
+ private:
+ /// Dep - A pointer to the depending/depended-on SUnit, and an enum
+ /// indicating the kind of the dependency.
+ PointerIntPair<SUnit *, 2, Kind> Dep;
+
+ /// Contents - A union discriminated by the dependence kind.
+ union {
+ /// Reg - For Data, Anti, and Output dependencies, the associated
+ /// register. For Data dependencies that don't currently have a register
+ /// assigned, this is set to zero.
+ unsigned Reg;
+
+ /// Order - Additional information about Order dependencies.
+ unsigned OrdKind; // enum OrderKind
+ } Contents;
+
+ /// Latency - The time associated with this edge. Often this is just
+ /// the value of the Latency field of the predecessor, however advanced
+ /// models may provide additional information about specific edges.
+ unsigned Latency;
+
+ public:
+ /// SDep - Construct a null SDep. This is only for use by container
+ /// classes which require default constructors. SUnits may not
+ /// have null SDep edges.
+ SDep() : Dep(0, Data) {}
+
+ /// SDep - Construct an SDep with the specified values.
+ SDep(SUnit *S, Kind kind, unsigned Reg)
+ : Dep(S, kind), Contents() {
+ switch (kind) {
+ default:
+ llvm_unreachable("Reg given for non-register dependence!");
+ case Anti:
+ case Output:
+ assert(Reg != 0 &&
+ "SDep::Anti and SDep::Output must use a non-zero Reg!");
+ Contents.Reg = Reg;
+ Latency = 0;
+ break;
+ case Data:
+ Contents.Reg = Reg;
+ Latency = 1;
+ break;
+ }
+ }
+ SDep(SUnit *S, OrderKind kind)
+ : Dep(S, Order), Contents(), Latency(0) {
+ Contents.OrdKind = kind;
+ }
+
+ /// Return true if the specified SDep is equivalent except for latency.
+ bool overlaps(const SDep &Other) const {
+ if (Dep != Other.Dep) return false;
+ switch (Dep.getInt()) {
+ case Data:
+ case Anti:
+ case Output:
+ return Contents.Reg == Other.Contents.Reg;
+ case Order:
+ return Contents.OrdKind == Other.Contents.OrdKind;
+ }
+ llvm_unreachable("Invalid dependency kind!");
+ }
+
+ bool operator==(const SDep &Other) const {
+ return overlaps(Other) && Latency == Other.Latency;
+ }
+
+ bool operator!=(const SDep &Other) const {
+ return !operator==(Other);
+ }
+
+ /// getLatency - Return the latency value for this edge, which roughly
+ /// means the minimum number of cycles that must elapse between the
+ /// predecessor and the successor, given that they have this edge
+ /// between them.
+ unsigned getLatency() const {
+ return Latency;
+ }
+
+ /// setLatency - Set the latency for this edge.
+ void setLatency(unsigned Lat) {
+ Latency = Lat;
+ }
+
+ //// getSUnit - Return the SUnit to which this edge points.
+ SUnit *getSUnit() const {
+ return Dep.getPointer();
+ }
+
+ //// setSUnit - Assign the SUnit to which this edge points.
+ void setSUnit(SUnit *SU) {
+ Dep.setPointer(SU);
+ }
+
+ /// getKind - Return an enum value representing the kind of the dependence.
+ Kind getKind() const {
+ return Dep.getInt();
+ }
+
+ /// isCtrl - Shorthand for getKind() != SDep::Data.
+ bool isCtrl() const {
+ return getKind() != Data;
+ }
+
+ /// isNormalMemory - Test if this is an Order dependence between two
+ /// memory accesses where both sides of the dependence access memory
+ /// in non-volatile and fully modeled ways.
+ bool isNormalMemory() const {
+ return getKind() == Order && (Contents.OrdKind == MayAliasMem
+ || Contents.OrdKind == MustAliasMem);
+ }
+
+ /// isMustAlias - Test if this is an Order dependence that is marked
+ /// as "must alias", meaning that the SUnits at either end of the edge
+ /// have a memory dependence on a known memory location.
+ bool isMustAlias() const {
+ return getKind() == Order && Contents.OrdKind == MustAliasMem;
+ }
+
+ /// isWeak - Test if this a weak dependence. Weak dependencies are
+ /// considered DAG edges for height computation and other heuristics, but do
+ /// not force ordering. Breaking a weak edge may require the scheduler to
+ /// compensate, for example by inserting a copy.
+ bool isWeak() const {
+ return getKind() == Order && Contents.OrdKind >= Weak;
+ }
+
+ /// isArtificial - Test if this is an Order dependence that is marked
+ /// as "artificial", meaning it isn't necessary for correctness.
+ bool isArtificial() const {
+ return getKind() == Order && Contents.OrdKind == Artificial;
+ }
+
+ /// isCluster - Test if this is an Order dependence that is marked
+ /// as "cluster", meaning it is artificial and wants to be adjacent.
+ bool isCluster() const {
+ return getKind() == Order && Contents.OrdKind == Cluster;
+ }
+
+ /// isAssignedRegDep - Test if this is a Data dependence that is
+ /// associated with a register.
+ bool isAssignedRegDep() const {
+ return getKind() == Data && Contents.Reg != 0;
+ }
+
+ /// getReg - Return the register associated with this edge. This is
+ /// only valid on Data, Anti, and Output edges. On Data edges, this
+ /// value may be zero, meaning there is no associated register.
+ unsigned getReg() const {
+ assert((getKind() == Data || getKind() == Anti || getKind() == Output) &&
+ "getReg called on non-register dependence edge!");
+ return Contents.Reg;
+ }
+
+ /// setReg - Assign the associated register for this edge. This is
+ /// only valid on Data, Anti, and Output edges. On Anti and Output
+ /// edges, this value must not be zero. On Data edges, the value may
+ /// be zero, which would mean that no specific register is associated
+ /// with this edge.
+ void setReg(unsigned Reg) {
+ assert((getKind() == Data || getKind() == Anti || getKind() == Output) &&
+ "setReg called on non-register dependence edge!");
+ assert((getKind() != Anti || Reg != 0) &&
+ "SDep::Anti edge cannot use the zero register!");
+ assert((getKind() != Output || Reg != 0) &&
+ "SDep::Output edge cannot use the zero register!");
+ Contents.Reg = Reg;
+ }