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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17938 91177308-0d34-0410-b5e6-96231b3b80d8
192 lines
6.9 KiB
C++
192 lines
6.9 KiB
C++
//===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the LiveRange and LiveInterval classes. Given some
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// numbering of each the machine instructions an interval [i, j) is said to be a
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// live interval for register v if there is no instruction with number j' > j
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// such that v is live at j' and there is no instruction with number i' < i such
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// that v is live at i'. In this implementation intervals can have holes,
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// i.e. an interval might look like [1,20), [50,65), [1000,1001). Each
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// individual range is represented as an instance of LiveRange, and the whole
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// interval is represented as an instance of LiveInterval.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_LIVEINTERVAL_H
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#define LLVM_CODEGEN_LIVEINTERVAL_H
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#include <iosfwd>
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#include <vector>
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#include <cassert>
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namespace llvm {
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/// LiveRange structure - This represents a simple register range in the
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/// program, with an inclusive start point and an exclusive end point.
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/// These ranges are rendered as [start,end).
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struct LiveRange {
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unsigned start; // Start point of the interval (inclusive)
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unsigned end; // End point of the interval (exclusive)
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unsigned ValId; // identifier for the value contained in this interval.
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LiveRange(unsigned S, unsigned E, unsigned V) : start(S), end(E), ValId(V) {
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assert(S < E && "Cannot create empty or backwards range");
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}
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/// contains - Return true if the index is covered by this range.
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///
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bool contains(unsigned I) const {
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return start <= I && I < end;
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}
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bool operator<(const LiveRange &LR) const {
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return start < LR.start || (start == LR.start && end < LR.end);
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}
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bool operator==(const LiveRange &LR) const {
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return start == LR.start && end == LR.end;
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}
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void dump() const;
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private:
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LiveRange(); // DO NOT IMPLEMENT
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};
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std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
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inline bool operator<(unsigned V, const LiveRange &LR) {
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return V < LR.start;
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}
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/// LiveInterval - This class represents some number of live ranges for a
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/// register or value. This class also contains a bit of register allocator
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/// state.
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struct LiveInterval {
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typedef std::vector<LiveRange> Ranges;
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unsigned reg; // the register of this interval
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float weight; // weight of this interval
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Ranges ranges; // the ranges in which this register is live
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LiveInterval(unsigned Reg, float Weight)
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: reg(Reg), weight(Weight), NumValues(0) {
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}
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typedef Ranges::iterator iterator;
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iterator begin() { return ranges.begin(); }
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iterator end() { return ranges.end(); }
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typedef Ranges::const_iterator const_iterator;
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const_iterator begin() const { return ranges.begin(); }
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const_iterator end() const { return ranges.end(); }
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/// advanceTo - Advance the specified iterator to point to the LiveRange
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/// containing the specified position, or end() if the position is past the
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/// end of the interval. If no LiveRange contains this position, but the
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/// position is in a hole, this method returns an iterator pointing the the
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/// LiveRange immediately after the hole.
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iterator advanceTo(iterator I, unsigned Pos) {
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if (Pos >= endNumber())
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return end();
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while (I->end <= Pos) ++I;
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return I;
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}
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void swap(LiveInterval& other) {
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std::swap(reg, other.reg);
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std::swap(weight, other.weight);
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ranges.swap(other.ranges);
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std::swap(NumValues, other.NumValues);
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}
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bool containsOneValue() const { return NumValues == 1; }
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unsigned getNextValue() {
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return NumValues++;
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}
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bool empty() const { return ranges.empty(); }
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/// beginNumber - Return the lowest numbered slot covered by interval.
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unsigned beginNumber() const {
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assert(!empty() && "empty interval for register");
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return ranges.front().start;
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}
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/// endNumber - return the maximum point of the interval of the whole,
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/// exclusive.
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unsigned endNumber() const {
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assert(!empty() && "empty interval for register");
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return ranges.back().end;
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}
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bool expiredAt(unsigned index) const {
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return index >= endNumber();
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}
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bool liveAt(unsigned index) const;
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/// getLiveRangeContaining - Return the live range that contains the
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/// specified index, or null if there is none.
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const LiveRange *getLiveRangeContaining(unsigned Idx) const;
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/// joinable - Two intervals are joinable if the either don't overlap at all
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/// or if the destination of the copy is a single assignment value, and it
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/// only overlaps with one value in the source interval.
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bool joinable(const LiveInterval& other, unsigned CopyIdx) const;
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/// overlaps - Return true if the intersection of the two live intervals is
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/// not empty.
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bool overlaps(const LiveInterval& other) const {
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return overlapsFrom(other, other.begin());
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}
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/// overlapsFrom - Return true if the intersection of the two live intervals
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/// is not empty. The specified iterator is a hint that we can begin
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/// scanning the Other interval starting at I.
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bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
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/// addRange - Add the specified LiveRange to this interval, merging
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/// intervals as appropriate. This returns an iterator to the inserted live
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/// range (which may have grown since it was inserted.
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void addRange(LiveRange LR) {
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addRangeFrom(LR, ranges.begin());
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}
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/// join - Join two live intervals (this, and other) together. This
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/// operation is the result of a copy instruction in the source program,
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/// that occurs at index 'CopyIdx' that copies from 'other' to 'this'. This
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/// destroys 'other'.
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void join(LiveInterval& other, unsigned CopyIdx);
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/// removeRange - Remove the specified range from this interval. Note that
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/// the range must already be in this interval in its entirety.
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void removeRange(unsigned Start, unsigned End);
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bool operator<(const LiveInterval& other) const {
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return beginNumber() < other.beginNumber();
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}
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void dump() const;
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private:
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unsigned NumValues; // the number of distinct values in this interval.
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Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
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void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
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Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
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LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
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};
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std::ostream& operator<<(std::ostream& os, const LiveInterval& li);
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}
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#endif
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