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262 lines
10 KiB
C++
262 lines
10 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 "llvm/ADT/SmallVector.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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class MRegisterInfo;
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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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inline bool operator<(const LiveRange &LR, unsigned V) {
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return LR.start < V;
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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 SmallVector<LiveRange,4> 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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private:
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/// ValueNumberInfo - If this value number is not defined by a copy, this
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/// holds ~0,x. If the value number is not in use, it contains ~1,x to
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/// indicate that the value # is not used. If the val# is defined by a
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/// copy, the first entry is the instruction # of the copy, and the second
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/// is the register number copied from.
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SmallVector<std::pair<unsigned,unsigned>, 4> ValueNumberInfo;
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public:
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LiveInterval(unsigned Reg, float Weight)
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: reg(Reg), weight(Weight) {
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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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std::swap(ranges, other.ranges);
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std::swap(ValueNumberInfo, other.ValueNumberInfo);
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}
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bool containsOneValue() const { return ValueNumberInfo.size() == 1; }
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unsigned getNumValNums() const { return ValueNumberInfo.size(); }
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/// getNextValue - Create a new value number and return it. MIIdx specifies
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/// the instruction that defines the value number.
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unsigned getNextValue(unsigned MIIdx, unsigned SrcReg) {
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ValueNumberInfo.push_back(std::make_pair(MIIdx, SrcReg));
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return ValueNumberInfo.size()-1;
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}
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/// getInstForValNum - Return the machine instruction index that defines the
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/// specified value number.
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unsigned getInstForValNum(unsigned ValNo) const {
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//assert(ValNo < ValueNumberInfo.size());
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return ValueNumberInfo[ValNo].first;
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}
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unsigned getSrcRegForValNum(unsigned ValNo) const {
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//assert(ValNo < ValueNumberInfo.size());
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if (ValueNumberInfo[ValNo].first < ~2U)
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return ValueNumberInfo[ValNo].second;
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return 0;
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}
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std::pair<unsigned, unsigned> getValNumInfo(unsigned ValNo) const {
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//assert(ValNo < ValueNumberInfo.size());
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return ValueNumberInfo[ValNo];
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}
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/// setValueNumberInfo - Change the value number info for the specified
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/// value number.
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void setValueNumberInfo(unsigned ValNo,
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const std::pair<unsigned, unsigned> &I){
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ValueNumberInfo[ValNo] = I;
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}
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/// MergeValueNumberInto - This method is called when two value nubmers
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/// are found to be equivalent. This eliminates V1, replacing all
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/// LiveRanges with the V1 value number with the V2 value number. This can
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/// cause merging of V1/V2 values numbers and compaction of the value space.
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void MergeValueNumberInto(unsigned V1, unsigned V2);
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/// MergeInClobberRanges - For any live ranges that are not defined in the
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/// current interval, but are defined in the Clobbers interval, mark them
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/// used with an unknown definition value.
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void MergeInClobberRanges(const LiveInterval &Clobbers);
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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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const_iterator I = FindLiveRangeContaining(Idx);
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return I == end() ? 0 : &*I;
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}
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/// FindLiveRangeContaining - Return an iterator to the live range that
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/// contains the specified index, or end() if there is none.
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const_iterator FindLiveRangeContaining(unsigned Idx) const;
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/// FindLiveRangeContaining - Return an iterator to the live range that
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/// contains the specified index, or end() if there is none.
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iterator FindLiveRangeContaining(unsigned Idx);
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/// getOverlapingRanges - Given another live interval which is defined as a
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/// copy from this one, return a list of all of the live ranges where the
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/// two overlap and have different value numbers.
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void getOverlapingRanges(const LiveInterval &Other, unsigned CopyIdx,
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std::vector<LiveRange*> &Ranges);
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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 applies
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/// mappings to the value numbers in the LHS/RHS intervals as specified. If
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/// the intervals are not joinable, this aborts.
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void join(LiveInterval &Other, int *ValNoAssignments,
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int *RHSValNoAssignments,
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SmallVector<std::pair<unsigned,unsigned>,16> &NewValueNumberInfo);
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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 print(std::ostream &OS, const MRegisterInfo *MRI = 0) const;
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void dump() const;
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private:
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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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inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) {
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LI.print(OS);
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return OS;
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}
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}
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#endif
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