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Remove dead code.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134148 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2011-06-30 13:17:24 +00:00
parent eb7fe5df1b
commit ef17e01725
1 changed files with 0 additions and 88 deletions
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88
lib/CodeGen/RegisterCoalescer.h
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@ -160,94 +160,6 @@ namespace llvm {
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_);
///
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 &copy) {}
/// 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
/// two registers can be coalesced, CoalescerPair can determine if a copy
/// instruction would become an identity copy after coalescing.