- /// HasOtherReachingDefs - Return true if there are definitions of IntB
- /// other than BValNo val# that can reach uses of AValno val# of IntA.
- bool HasOtherReachingDefs(LiveInterval &IntA, LiveInterval &IntB,
- VNInfo *AValNo, VNInfo *BValNo);
-
- /// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy.
- /// If the source value number is defined by a commutable instruction and
- /// its other operand is coalesced to the copy dest register, see if we
- /// can transform the copy into a noop by commuting the definition.
- bool RemoveCopyByCommutingDef(const CoalescerPair &CP,MachineInstr *CopyMI);
-
- /// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
- /// computation, replace the copy by rematerialize the definition.
- /// If PreserveSrcInt is true, make sure SrcInt is valid after the call.
- bool ReMaterializeTrivialDef(LiveInterval &SrcInt, bool PreserveSrcInt,
- unsigned DstReg, unsigned DstSubIdx,
- MachineInstr *CopyMI);
-
- /// shouldJoinPhys - Return true if a physreg copy should be joined.
- bool shouldJoinPhys(CoalescerPair &CP);
-
- /// isWinToJoinCrossClass - Return true if it's profitable to coalesce
- /// two virtual registers from different register classes.
- bool isWinToJoinCrossClass(unsigned SrcReg,
- unsigned DstReg,
- const TargetRegisterClass *SrcRC,
- const TargetRegisterClass *DstRC,
- const TargetRegisterClass *NewRC);
-
- /// UpdateRegDefsUses - Replace all defs and uses of SrcReg to DstReg and
- /// update the subregister number if it is not zero. If DstReg is a
- /// physical register and the existing subregister number of the def / use
- /// being updated is not zero, make sure to set it to the correct physical
- /// subregister.
- void UpdateRegDefsUses(const CoalescerPair &CP);
-
- /// RemoveDeadDef - If a def of a live interval is now determined dead,
- /// remove the val# it defines. If the live interval becomes empty, remove
- /// it as well.
- bool RemoveDeadDef(LiveInterval &li, MachineInstr *DefMI);
-
- /// RemoveCopyFlag - If DstReg is no longer defined by CopyMI, clear the
- /// VNInfo copy flag for DstReg and all aliases.
- void RemoveCopyFlag(unsigned DstReg, const MachineInstr *CopyMI);
-
- /// markAsJoined - Remember that CopyMI has already been joined.
- void markAsJoined(MachineInstr *CopyMI);
-
- public:
- static char ID; // Class identification, replacement for typeinfo
- RegisterCoalescer() : MachineFunctionPass(ID) {
- initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry());
- }
-
- /// Run the coalescer on this function, providing interference
- /// data to query. Return whether we removed any copies.
- virtual bool coalesceFunction(MachineFunction &mf,
- RegallocQuery &ifd) {
- // This runs as an independent pass, so don't do anything.
- return false;
- }
-
- /// Reset state. Can be used to allow a coalescer run by
- /// PassManager to be run again by the register allocator.
- virtual void reset(MachineFunction &mf) {}
-
- /// Register allocators must call this from their own
- /// getAnalysisUsage to cover the case where the coalescer is not
- /// a Pass in the proper sense and isn't managed by PassManager.
- /// PassManager needs to know which analyses to make available and
- /// which to invalidate when running the register allocator or any
- /// pass that might call coalescing. The long-term solution is to
- /// allow hierarchies of PassManagers.
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
-
- virtual void releaseMemory();
-
- /// runOnMachineFunction - pass entry point
- virtual bool runOnMachineFunction(MachineFunction&);
-
- /// print - Implement the dump method.
- virtual void print(raw_ostream &O, const Module* = 0) const;
- };
-
- /// An abstract interface for register allocators to interact with
- /// coalescers
- ///
- /// Example:
- ///
- /// This is simply an example of how to use the RegallocQuery
- /// interface. It is not meant to be used in production.
- ///
- /// class LinearScanRegallocQuery : public RegallocQuery {
- /// private:
- /// const LiveIntervals \&li;
- ///
- /// public:
- /// LinearScanRegallocQuery(LiveIntervals &intervals)
- /// : li(intervals) {}
- ///
- /// /// This is pretty slow and conservative, but since linear scan
- /// /// allocation doesn't pre-compute interference information it's
- /// /// the best we can do. Coalescers are always free to ignore this
- /// /// and implement their own discovery strategy. See
- /// /// RegisterCoalescer for an example.
- /// void getInterferences(IntervalSet &interferences,
- /// const LiveInterval &a) const {
- /// for(LiveIntervals::const_iterator iv = li.begin(),
- /// ivend = li.end();
- /// iv != ivend;
- /// ++iv) {
- /// if (interfere(a, iv->second)) {
- /// interferences.insert(&iv->second);
- /// }
- /// }
- /// }
- ///
- /// /// This is *really* slow and stupid. See above.
- /// int getNumberOfInterferences(const LiveInterval &a) const {
- /// IntervalSet intervals;
- /// getInterferences(intervals, a);
- /// return intervals.size();
- /// }
- /// };
- ///
- /// In the allocator:
- ///
- /// RegisterCoalescer &coalescer = getAnalysis<RegisterCoalescer>();
- ///
- /// // We don't reset the coalescer so if it's already been run this
- /// // takes almost no time.
- /// LinearScanRegallocQuery ifd(*li_);
- /// coalescer.coalesceFunction(fn, ifd);
- ///
- class RegallocQuery {
- public:
- typedef SmallPtrSet<const LiveInterval *, 8> IntervalSet;
-
- virtual ~RegallocQuery() {}
-
- /// Return whether two live ranges interfere.
- virtual bool interfere(const LiveInterval &a,
- const LiveInterval &b) const {
- // A naive test
- return a.overlaps(b);
- }
-
- /// Return the set of intervals that interfere with this one.
- virtual void getInterferences(IntervalSet &interferences,
- const LiveInterval &a) const = 0;
-
- /// This can often be cheaper than actually returning the
- /// interferences.
- virtual int getNumberOfInterferences(const LiveInterval &a) const = 0;
-
- /// Make any data structure updates necessary to reflect
- /// coalescing or other modifications.
- virtual void updateDataForMerge(const LiveInterval &a,
- const LiveInterval &b,
- const MachineInstr ©) {}
-
- /// Allow the register allocator to communicate when it doesn't
- /// want a copy coalesced. This may be due to assumptions made by
- /// the allocator about various invariants and so this question is
- /// a matter of legality, not performance. Performance decisions
- /// about which copies to coalesce should be made by the
- /// coalescer.
- virtual bool isLegalToCoalesce(const MachineInstr &inst) const {
- return true;
- }
- };
-
-
- /// CoalescerPair - A helper class for register coalescers. When deciding if