// 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");
}
+ /// contains - Return true if the index is covered by this range.
+ ///
+ bool contains(unsigned I) const {
+ return start <= I && I < end;
+ }
+
bool operator<(const LiveRange &LR) const {
return start < LR.start || (start == LR.start && end < LR.end);
}
bool operator==(const LiveRange &LR) const {
return start == LR.start && end == LR.end;
}
- private:
+
+ void dump() const;
+
+ private:
LiveRange(); // DO NOT IMPLEMENT
};
std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
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) {
+ }
+
+ 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 isDefinedOnce; }
+ bool containsOneValue() const { return NumValues == 1; }
+
+ unsigned getNextValue() {
+ return NumValues++;
+ }
bool empty() const { return ranges.empty(); }
bool liveAt(unsigned index) const;
+ /// getLiveRangeContaining - Return the live range that contains the
+ /// specified index, or null if there is none.
+ const LiveRange *getLiveRangeContaining(unsigned Idx) const;
+
+
+ /// 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 overlaps(const LiveInterval& other) const;
- void addRange(LiveRange R);
+ /// 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);
- void join(const LiveInterval& other);
+
+ /// 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 start() < other.start();
}
- bool operator==(const LiveInterval& other) const {
- return reg == other.reg;
- }
+ 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);