// This file implements the LiveRange and LiveInterval classes. Given some
// numbering of each the machine instructions an interval [i, j) is said to be a
// live interval for register v if there is no instruction with number j' > j
-// such that v is live at j' abd there is no instruction with number i' < i such
+// such that v is live at j' and there is no instruction with number i' < i such
// that v is live at i'. In this implementation intervals can have holes,
// i.e. an interval might look like [1,20), [50,65), [1000,1001). Each
// individual range is represented as an instance of LiveRange, and the whole
/// These ranges are rendered as [start,end).
struct LiveRange {
unsigned start; // Start point of the interval (inclusive)
- unsigned end; // End point of the interval (exclusive)
- LiveRange(unsigned S, unsigned E) : start(S), end(E) {
+ unsigned end; // End point of the interval (exclusive)
+ unsigned ValId; // identifier for the value contained in this interval.
+
+ LiveRange(unsigned S, unsigned E, unsigned V) : start(S), end(E), ValId(V) {
assert(S < E && "Cannot create empty or backwards range");
}
bool operator==(const LiveRange &LR) const {
return start == LR.start && end == LR.end;
}
+
+ void dump() const;
+
private:
LiveRange(); // DO NOT IMPLEMENT
};
unsigned reg; // the register of this interval
float weight; // weight of this interval
Ranges ranges; // the ranges in which this register is live
- bool isDefinedOnce; // True if this interval contains one value.
LiveInterval(unsigned Reg, float Weight)
- : reg(Reg), weight(Weight), isDefinedOnce(false) {
+ : reg(Reg), weight(Weight), NumValues(0) {
+ }
+
+ typedef Ranges::iterator iterator;
+ iterator begin() { return ranges.begin(); }
+ iterator end() { return ranges.end(); }
+
+ typedef Ranges::const_iterator const_iterator;
+ const_iterator begin() const { return ranges.begin(); }
+ const_iterator end() const { return ranges.end(); }
+
+
+ /// advanceTo - Advance the specified iterator to point to the LiveRange
+ /// containing the specified position, or end() if the position is past the
+ /// end of the interval. If no LiveRange contains this position, but the
+ /// position is in a hole, this method returns an iterator pointing the the
+ /// LiveRange immediately after the hole.
+ iterator advanceTo(iterator I, unsigned Pos) {
+ if (Pos >= endNumber())
+ return end();
+ while (I->end <= Pos) ++I;
+ return I;
}
- bool containsOneValue() const { return isDefinedOnce; }
+ void swap(LiveInterval& other) {
+ std::swap(reg, other.reg);
+ std::swap(weight, other.weight);
+ ranges.swap(other.ranges);
+ std::swap(NumValues, other.NumValues);
+ }
+
+ bool containsOneValue() const { return NumValues == 1; }
+
+ unsigned getNextValue() {
+ return NumValues++;
+ }
bool empty() const { return ranges.empty(); }
- /// start - Return the lowest numbered slot covered by interval.
- unsigned start() const {
+ /// beginNumber - Return the lowest numbered slot covered by interval.
+ unsigned beginNumber() const {
assert(!empty() && "empty interval for register");
return ranges.front().start;
}
- /// end - return the maximum point of the interval of the whole,
+ /// endNumber - return the maximum point of the interval of the whole,
/// exclusive.
- unsigned end() const {
+ unsigned endNumber() const {
assert(!empty() && "empty interval for register");
return ranges.back().end;
}
bool expiredAt(unsigned index) const {
- return end() <= (index + 1);
+ return index >= endNumber();
}
bool liveAt(unsigned index) const;
- bool overlaps(const LiveInterval& other) const;
+ /// getLiveRangeContaining - Return the live range that contains the
+ /// specified index, or null if there is none.
+ const LiveRange *getLiveRangeContaining(unsigned Idx) const;
- void addRange(LiveRange R);
- void join(const LiveInterval& other);
+ /// joinable - Two intervals are joinable if the either don't overlap at all
+ /// or if the destination of the copy is a single assignment value, and it
+ /// only overlaps with one value in the source interval.
+ bool joinable(const LiveInterval& other, unsigned CopyIdx) const;
- bool operator<(const LiveInterval& other) const {
- return start() < other.start();
+
+ /// overlaps - Return true if the intersection of the two live intervals is
+ /// not empty.
+ bool overlaps(const LiveInterval& other) const {
+ return overlapsFrom(other, other.begin());
}
- bool operator==(const LiveInterval& other) const {
- return reg == other.reg;
+ /// overlapsFrom - Return true if the intersection of the two live intervals
+ /// is not empty. The specified iterator is a hint that we can begin
+ /// scanning the Other interval starting at I.
+ bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
+
+ /// addRange - Add the specified LiveRange to this interval, merging
+ /// intervals as appropriate. This returns an iterator to the inserted live
+ /// range (which may have grown since it was inserted.
+ void addRange(LiveRange LR) {
+ addRangeFrom(LR, ranges.begin());
}
+ /// join - Join two live intervals (this, and other) together. This
+ /// operation is the result of a copy instruction in the source program,
+ /// that occurs at index 'CopyIdx' that copies from 'other' to 'this'. This
+ /// destroys 'other'.
+ void join(LiveInterval& other, unsigned CopyIdx);
+
+
+ /// removeRange - Remove the specified range from this interval. Note that
+ /// the range must already be in this interval in its entirety.
+ void removeRange(unsigned Start, unsigned End);
+
+ bool operator<(const LiveInterval& other) const {
+ return beginNumber() < other.beginNumber();
+ }
+
+ void dump() const;
+
private:
- Ranges::iterator mergeRangesForward(Ranges::iterator it);
- Ranges::iterator mergeRangesBackward(Ranges::iterator it);
+ unsigned NumValues; // the number of distinct values in this interval.
+ Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
+ void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
+ Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
+ LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
};
std::ostream& operator<<(std::ostream& os, const LiveInterval& li);
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