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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206142 91177308-0d34-0410-b5e6-96231b3b80d8
683 lines
24 KiB
C++
683 lines
24 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 is distributed under the University of Illinois Open Source
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// 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 range 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 ranges can have holes,
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// i.e. a range might look like [1,20), [50,65), [1000,1001). Each
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// individual segment is represented as an instance of LiveRange::Segment,
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// and the whole range is represented as an instance of LiveRange.
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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/IntEqClasses.h"
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#include "llvm/CodeGen/SlotIndexes.h"
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#include "llvm/Support/AlignOf.h"
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#include "llvm/Support/Allocator.h"
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#include <cassert>
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#include <climits>
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namespace llvm {
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class CoalescerPair;
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class LiveIntervals;
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class MachineInstr;
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class MachineRegisterInfo;
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class TargetRegisterInfo;
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class raw_ostream;
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template <typename T, unsigned Small> class SmallPtrSet;
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/// VNInfo - Value Number Information.
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/// This class holds information about a machine level values, including
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/// definition and use points.
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///
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class VNInfo {
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public:
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typedef BumpPtrAllocator Allocator;
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/// The ID number of this value.
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unsigned id;
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/// The index of the defining instruction.
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SlotIndex def;
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/// VNInfo constructor.
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VNInfo(unsigned i, SlotIndex d)
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: id(i), def(d)
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{ }
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/// VNInfo construtor, copies values from orig, except for the value number.
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VNInfo(unsigned i, const VNInfo &orig)
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: id(i), def(orig.def)
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{ }
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/// Copy from the parameter into this VNInfo.
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void copyFrom(VNInfo &src) {
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def = src.def;
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}
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/// Returns true if this value is defined by a PHI instruction (or was,
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/// PHI instructions may have been eliminated).
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/// PHI-defs begin at a block boundary, all other defs begin at register or
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/// EC slots.
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bool isPHIDef() const { return def.isBlock(); }
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/// Returns true if this value is unused.
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bool isUnused() const { return !def.isValid(); }
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/// Mark this value as unused.
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void markUnused() { def = SlotIndex(); }
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};
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/// Result of a LiveRange query. This class hides the implementation details
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/// of live ranges, and it should be used as the primary interface for
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/// examining live ranges around instructions.
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class LiveQueryResult {
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VNInfo *const EarlyVal;
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VNInfo *const LateVal;
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const SlotIndex EndPoint;
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const bool Kill;
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public:
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LiveQueryResult(VNInfo *EarlyVal, VNInfo *LateVal, SlotIndex EndPoint,
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bool Kill)
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: EarlyVal(EarlyVal), LateVal(LateVal), EndPoint(EndPoint), Kill(Kill)
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{}
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/// Return the value that is live-in to the instruction. This is the value
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/// that will be read by the instruction's use operands. Return NULL if no
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/// value is live-in.
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VNInfo *valueIn() const {
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return EarlyVal;
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}
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/// Return true if the live-in value is killed by this instruction. This
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/// means that either the live range ends at the instruction, or it changes
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/// value.
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bool isKill() const {
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return Kill;
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}
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/// Return true if this instruction has a dead def.
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bool isDeadDef() const {
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return EndPoint.isDead();
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}
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/// Return the value leaving the instruction, if any. This can be a
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/// live-through value, or a live def. A dead def returns NULL.
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VNInfo *valueOut() const {
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return isDeadDef() ? nullptr : LateVal;
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}
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/// Return the value defined by this instruction, if any. This includes
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/// dead defs, it is the value created by the instruction's def operands.
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VNInfo *valueDefined() const {
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return EarlyVal == LateVal ? nullptr : LateVal;
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}
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/// Return the end point of the last live range segment to interact with
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/// the instruction, if any.
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///
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/// The end point is an invalid SlotIndex only if the live range doesn't
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/// intersect the instruction at all.
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///
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/// The end point may be at or past the end of the instruction's basic
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/// block. That means the value was live out of the block.
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SlotIndex endPoint() const {
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return EndPoint;
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}
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};
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/// This class represents the liveness of a register, stack slot, etc.
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/// It manages an ordered list of Segment objects.
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/// The Segments are organized in a static single assignment form: At places
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/// where a new value is defined or different values reach a CFG join a new
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/// segment with a new value number is used.
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class LiveRange {
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public:
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/// This represents a simple continuous liveness interval for a value.
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/// The start point is inclusive, the end point exclusive. These intervals
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/// are rendered as [start,end).
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struct Segment {
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SlotIndex start; // Start point of the interval (inclusive)
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SlotIndex end; // End point of the interval (exclusive)
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VNInfo *valno; // identifier for the value contained in this segment.
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Segment() : valno(nullptr) {}
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Segment(SlotIndex S, SlotIndex E, VNInfo *V)
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: start(S), end(E), valno(V) {
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assert(S < E && "Cannot create empty or backwards segment");
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}
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/// Return true if the index is covered by this segment.
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bool contains(SlotIndex I) const {
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return start <= I && I < end;
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}
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/// Return true if the given interval, [S, E), is covered by this segment.
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bool containsInterval(SlotIndex S, SlotIndex E) const {
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assert((S < E) && "Backwards interval?");
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return (start <= S && S < end) && (start < E && E <= end);
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}
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bool operator<(const Segment &Other) const {
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return std::tie(start, end) < std::tie(Other.start, Other.end);
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}
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bool operator==(const Segment &Other) const {
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return start == Other.start && end == Other.end;
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}
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void dump() const;
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};
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typedef SmallVector<Segment,4> Segments;
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typedef SmallVector<VNInfo*,4> VNInfoList;
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Segments segments; // the liveness segments
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VNInfoList valnos; // value#'s
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typedef Segments::iterator iterator;
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iterator begin() { return segments.begin(); }
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iterator end() { return segments.end(); }
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typedef Segments::const_iterator const_iterator;
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const_iterator begin() const { return segments.begin(); }
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const_iterator end() const { return segments.end(); }
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typedef VNInfoList::iterator vni_iterator;
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vni_iterator vni_begin() { return valnos.begin(); }
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vni_iterator vni_end() { return valnos.end(); }
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typedef VNInfoList::const_iterator const_vni_iterator;
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const_vni_iterator vni_begin() const { return valnos.begin(); }
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const_vni_iterator vni_end() const { return valnos.end(); }
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/// advanceTo - Advance the specified iterator to point to the Segment
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/// containing the specified position, or end() if the position is past the
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/// end of the range. If no Segment contains this position, but the
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/// position is in a hole, this method returns an iterator pointing to the
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/// Segment immediately after the hole.
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iterator advanceTo(iterator I, SlotIndex Pos) {
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assert(I != end());
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if (Pos >= endIndex())
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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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/// find - Return an iterator pointing to the first segment that ends after
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/// Pos, or end(). This is the same as advanceTo(begin(), Pos), but faster
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/// when searching large ranges.
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///
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/// If Pos is contained in a Segment, that segment is returned.
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/// If Pos is in a hole, the following Segment is returned.
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/// If Pos is beyond endIndex, end() is returned.
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iterator find(SlotIndex Pos);
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const_iterator find(SlotIndex Pos) const {
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return const_cast<LiveRange*>(this)->find(Pos);
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}
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void clear() {
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valnos.clear();
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segments.clear();
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}
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size_t size() const {
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return segments.size();
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}
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bool hasAtLeastOneValue() const { return !valnos.empty(); }
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bool containsOneValue() const { return valnos.size() == 1; }
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unsigned getNumValNums() const { return (unsigned)valnos.size(); }
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/// getValNumInfo - Returns pointer to the specified val#.
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///
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inline VNInfo *getValNumInfo(unsigned ValNo) {
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return valnos[ValNo];
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}
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inline const VNInfo *getValNumInfo(unsigned ValNo) const {
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return valnos[ValNo];
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}
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/// containsValue - Returns true if VNI belongs to this range.
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bool containsValue(const VNInfo *VNI) const {
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return VNI && VNI->id < getNumValNums() && VNI == getValNumInfo(VNI->id);
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}
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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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VNInfo *getNextValue(SlotIndex def, VNInfo::Allocator &VNInfoAllocator) {
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VNInfo *VNI =
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new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def);
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valnos.push_back(VNI);
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return VNI;
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}
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/// createDeadDef - Make sure the range has a value defined at Def.
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/// If one already exists, return it. Otherwise allocate a new value and
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/// add liveness for a dead def.
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VNInfo *createDeadDef(SlotIndex Def, VNInfo::Allocator &VNInfoAllocator);
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/// Create a copy of the given value. The new value will be identical except
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/// for the Value number.
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VNInfo *createValueCopy(const VNInfo *orig,
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VNInfo::Allocator &VNInfoAllocator) {
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VNInfo *VNI =
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new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig);
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valnos.push_back(VNI);
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return VNI;
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}
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/// RenumberValues - Renumber all values in order of appearance and remove
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/// unused values.
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void RenumberValues();
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/// MergeValueNumberInto - This method is called when two value numbers
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/// are found to be equivalent. This eliminates V1, replacing all
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/// segments 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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VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
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/// Merge all of the live segments of a specific val# in RHS into this live
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/// range as the specified value number. The segments in RHS are allowed
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/// to overlap with segments in the current range, it will replace the
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/// value numbers of the overlaped live segments with the specified value
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/// number.
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void MergeSegmentsInAsValue(const LiveRange &RHS, VNInfo *LHSValNo);
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/// MergeValueInAsValue - Merge all of the segments of a specific val#
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/// in RHS into this live range as the specified value number.
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/// The segments in RHS are allowed to overlap with segments in the
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/// current range, but only if the overlapping segments have the
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/// specified value number.
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void MergeValueInAsValue(const LiveRange &RHS,
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const VNInfo *RHSValNo, VNInfo *LHSValNo);
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bool empty() const { return segments.empty(); }
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/// beginIndex - Return the lowest numbered slot covered.
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SlotIndex beginIndex() const {
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assert(!empty() && "Call to beginIndex() on empty range.");
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return segments.front().start;
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}
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/// endNumber - return the maximum point of the range of the whole,
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/// exclusive.
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SlotIndex endIndex() const {
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assert(!empty() && "Call to endIndex() on empty range.");
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return segments.back().end;
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}
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bool expiredAt(SlotIndex index) const {
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return index >= endIndex();
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}
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bool liveAt(SlotIndex index) const {
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const_iterator r = find(index);
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return r != end() && r->start <= index;
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}
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/// Return the segment that contains the specified index, or null if there
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/// is none.
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const Segment *getSegmentContaining(SlotIndex Idx) const {
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const_iterator I = FindSegmentContaining(Idx);
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return I == end() ? nullptr : &*I;
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}
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/// Return the live segment that contains the specified index, or null if
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/// there is none.
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Segment *getSegmentContaining(SlotIndex Idx) {
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iterator I = FindSegmentContaining(Idx);
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return I == end() ? nullptr : &*I;
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}
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/// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL.
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VNInfo *getVNInfoAt(SlotIndex Idx) const {
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const_iterator I = FindSegmentContaining(Idx);
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return I == end() ? nullptr : I->valno;
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}
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/// getVNInfoBefore - Return the VNInfo that is live up to but not
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/// necessarilly including Idx, or NULL. Use this to find the reaching def
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/// used by an instruction at this SlotIndex position.
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VNInfo *getVNInfoBefore(SlotIndex Idx) const {
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const_iterator I = FindSegmentContaining(Idx.getPrevSlot());
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return I == end() ? nullptr : I->valno;
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}
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/// Return an iterator to the segment that contains the specified index, or
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/// end() if there is none.
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iterator FindSegmentContaining(SlotIndex Idx) {
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iterator I = find(Idx);
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return I != end() && I->start <= Idx ? I : end();
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}
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const_iterator FindSegmentContaining(SlotIndex Idx) const {
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const_iterator I = find(Idx);
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return I != end() && I->start <= Idx ? I : end();
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}
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/// overlaps - Return true if the intersection of the two live ranges is
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/// not empty.
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bool overlaps(const LiveRange &other) const {
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if (other.empty())
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return false;
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return overlapsFrom(other, other.begin());
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}
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/// overlaps - Return true if the two ranges have overlapping segments
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/// that are not coalescable according to CP.
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///
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/// Overlapping segments where one range is defined by a coalescable
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/// copy are allowed.
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bool overlaps(const LiveRange &Other, const CoalescerPair &CP,
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const SlotIndexes&) const;
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/// overlaps - Return true if the live range overlaps an interval specified
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/// by [Start, End).
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bool overlaps(SlotIndex Start, SlotIndex End) const;
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/// overlapsFrom - Return true if the intersection of the two live ranges
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/// is not empty. The specified iterator is a hint that we can begin
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/// scanning the Other range starting at I.
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bool overlapsFrom(const LiveRange &Other, const_iterator I) const;
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/// Add the specified Segment to this range, merging segments as
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/// appropriate. This returns an iterator to the inserted segment (which
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/// may have grown since it was inserted).
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iterator addSegment(Segment S) {
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return addSegmentFrom(S, segments.begin());
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}
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/// extendInBlock - If this range is live before Kill in the basic block
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/// that starts at StartIdx, extend it to be live up to Kill, and return
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/// the value. If there is no segment before Kill, return NULL.
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VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex Kill);
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/// join - Join two live ranges (this, and other) together. This applies
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/// mappings to the value numbers in the LHS/RHS ranges as specified. If
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/// the ranges are not joinable, this aborts.
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void join(LiveRange &Other,
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const int *ValNoAssignments,
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const int *RHSValNoAssignments,
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SmallVectorImpl<VNInfo *> &NewVNInfo);
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/// True iff this segment is a single segment that lies between the
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/// specified boundaries, exclusively. Vregs live across a backedge are not
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/// considered local. The boundaries are expected to lie within an extended
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/// basic block, so vregs that are not live out should contain no holes.
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bool isLocal(SlotIndex Start, SlotIndex End) const {
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return beginIndex() > Start.getBaseIndex() &&
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endIndex() < End.getBoundaryIndex();
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}
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/// Remove the specified segment from this range. Note that the segment
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/// must be a single Segment in its entirety.
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void removeSegment(SlotIndex Start, SlotIndex End,
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bool RemoveDeadValNo = false);
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void removeSegment(Segment S, bool RemoveDeadValNo = false) {
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removeSegment(S.start, S.end, RemoveDeadValNo);
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}
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/// Query Liveness at Idx.
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/// The sub-instruction slot of Idx doesn't matter, only the instruction
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/// it refers to is considered.
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LiveQueryResult Query(SlotIndex Idx) const {
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// Find the segment that enters the instruction.
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const_iterator I = find(Idx.getBaseIndex());
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const_iterator E = end();
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if (I == E)
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return LiveQueryResult(nullptr, nullptr, SlotIndex(), false);
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// Is this an instruction live-in segment?
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// If Idx is the start index of a basic block, include live-in segments
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// that start at Idx.getBaseIndex().
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VNInfo *EarlyVal = nullptr;
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VNInfo *LateVal = nullptr;
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SlotIndex EndPoint;
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bool Kill = false;
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if (I->start <= Idx.getBaseIndex()) {
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EarlyVal = I->valno;
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EndPoint = I->end;
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// Move to the potentially live-out segment.
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if (SlotIndex::isSameInstr(Idx, I->end)) {
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Kill = true;
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if (++I == E)
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return LiveQueryResult(EarlyVal, LateVal, EndPoint, Kill);
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}
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// Special case: A PHIDef value can have its def in the middle of a
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// segment if the value happens to be live out of the layout
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// predecessor.
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// Such a value is not live-in.
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if (EarlyVal->def == Idx.getBaseIndex())
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EarlyVal = nullptr;
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}
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// I now points to the segment that may be live-through, or defined by
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// this instr. Ignore segments starting after the current instr.
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if (!SlotIndex::isEarlierInstr(Idx, I->start)) {
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LateVal = I->valno;
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EndPoint = I->end;
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}
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return LiveQueryResult(EarlyVal, LateVal, EndPoint, Kill);
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}
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/// removeValNo - Remove all the segments defined by the specified value#.
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/// Also remove the value# from value# list.
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void removeValNo(VNInfo *ValNo);
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/// Returns true if the live range is zero length, i.e. no live segments
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/// span instructions. It doesn't pay to spill such a range.
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bool isZeroLength(SlotIndexes *Indexes) const {
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for (const_iterator i = begin(), e = end(); i != e; ++i)
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if (Indexes->getNextNonNullIndex(i->start).getBaseIndex() <
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i->end.getBaseIndex())
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return false;
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return true;
|
|
}
|
|
|
|
bool operator<(const LiveRange& other) const {
|
|
const SlotIndex &thisIndex = beginIndex();
|
|
const SlotIndex &otherIndex = other.beginIndex();
|
|
return thisIndex < otherIndex;
|
|
}
|
|
|
|
void print(raw_ostream &OS) const;
|
|
void dump() const;
|
|
|
|
/// \brief Walk the range and assert if any invariants fail to hold.
|
|
///
|
|
/// Note that this is a no-op when asserts are disabled.
|
|
#ifdef NDEBUG
|
|
void verify() const {}
|
|
#else
|
|
void verify() const;
|
|
#endif
|
|
|
|
private:
|
|
|
|
iterator addSegmentFrom(Segment S, iterator From);
|
|
void extendSegmentEndTo(iterator I, SlotIndex NewEnd);
|
|
iterator extendSegmentStartTo(iterator I, SlotIndex NewStr);
|
|
void markValNoForDeletion(VNInfo *V);
|
|
|
|
};
|
|
|
|
inline raw_ostream &operator<<(raw_ostream &OS, const LiveRange &LR) {
|
|
LR.print(OS);
|
|
return OS;
|
|
}
|
|
|
|
/// LiveInterval - This class represents the liveness of a register,
|
|
/// or stack slot.
|
|
class LiveInterval : public LiveRange {
|
|
public:
|
|
typedef LiveRange super;
|
|
|
|
const unsigned reg; // the register or stack slot of this interval.
|
|
float weight; // weight of this interval
|
|
|
|
LiveInterval(unsigned Reg, float Weight)
|
|
: reg(Reg), weight(Weight) {}
|
|
|
|
/// getSize - Returns the sum of sizes of all the LiveRange's.
|
|
///
|
|
unsigned getSize() const;
|
|
|
|
/// isSpillable - Can this interval be spilled?
|
|
bool isSpillable() const {
|
|
return weight != llvm::huge_valf;
|
|
}
|
|
|
|
/// markNotSpillable - Mark interval as not spillable
|
|
void markNotSpillable() {
|
|
weight = llvm::huge_valf;
|
|
}
|
|
|
|
bool operator<(const LiveInterval& other) const {
|
|
const SlotIndex &thisIndex = beginIndex();
|
|
const SlotIndex &otherIndex = other.beginIndex();
|
|
return std::tie(thisIndex, reg) < std::tie(otherIndex, other.reg);
|
|
}
|
|
|
|
void print(raw_ostream &OS) const;
|
|
void dump() const;
|
|
|
|
private:
|
|
LiveInterval& operator=(const LiveInterval& rhs) LLVM_DELETED_FUNCTION;
|
|
|
|
};
|
|
|
|
inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {
|
|
LI.print(OS);
|
|
return OS;
|
|
}
|
|
|
|
raw_ostream &operator<<(raw_ostream &OS, const LiveRange::Segment &S);
|
|
|
|
inline bool operator<(SlotIndex V, const LiveRange::Segment &S) {
|
|
return V < S.start;
|
|
}
|
|
|
|
inline bool operator<(const LiveRange::Segment &S, SlotIndex V) {
|
|
return S.start < V;
|
|
}
|
|
|
|
/// Helper class for performant LiveRange bulk updates.
|
|
///
|
|
/// Calling LiveRange::addSegment() repeatedly can be expensive on large
|
|
/// live ranges because segments after the insertion point may need to be
|
|
/// shifted. The LiveRangeUpdater class can defer the shifting when adding
|
|
/// many segments in order.
|
|
///
|
|
/// The LiveRange will be in an invalid state until flush() is called.
|
|
class LiveRangeUpdater {
|
|
LiveRange *LR;
|
|
SlotIndex LastStart;
|
|
LiveRange::iterator WriteI;
|
|
LiveRange::iterator ReadI;
|
|
SmallVector<LiveRange::Segment, 16> Spills;
|
|
void mergeSpills();
|
|
|
|
public:
|
|
/// Create a LiveRangeUpdater for adding segments to LR.
|
|
/// LR will temporarily be in an invalid state until flush() is called.
|
|
LiveRangeUpdater(LiveRange *lr = nullptr) : LR(lr) {}
|
|
|
|
~LiveRangeUpdater() { flush(); }
|
|
|
|
/// Add a segment to LR and coalesce when possible, just like
|
|
/// LR.addSegment(). Segments should be added in increasing start order for
|
|
/// best performance.
|
|
void add(LiveRange::Segment);
|
|
|
|
void add(SlotIndex Start, SlotIndex End, VNInfo *VNI) {
|
|
add(LiveRange::Segment(Start, End, VNI));
|
|
}
|
|
|
|
/// Return true if the LR is currently in an invalid state, and flush()
|
|
/// needs to be called.
|
|
bool isDirty() const { return LastStart.isValid(); }
|
|
|
|
/// Flush the updater state to LR so it is valid and contains all added
|
|
/// segments.
|
|
void flush();
|
|
|
|
/// Select a different destination live range.
|
|
void setDest(LiveRange *lr) {
|
|
if (LR != lr && isDirty())
|
|
flush();
|
|
LR = lr;
|
|
}
|
|
|
|
/// Get the current destination live range.
|
|
LiveRange *getDest() const { return LR; }
|
|
|
|
void dump() const;
|
|
void print(raw_ostream&) const;
|
|
};
|
|
|
|
inline raw_ostream &operator<<(raw_ostream &OS, const LiveRangeUpdater &X) {
|
|
X.print(OS);
|
|
return OS;
|
|
}
|
|
|
|
/// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a
|
|
/// LiveInterval into equivalence clases of connected components. A
|
|
/// LiveInterval that has multiple connected components can be broken into
|
|
/// multiple LiveIntervals.
|
|
///
|
|
/// Given a LiveInterval that may have multiple connected components, run:
|
|
///
|
|
/// unsigned numComps = ConEQ.Classify(LI);
|
|
/// if (numComps > 1) {
|
|
/// // allocate numComps-1 new LiveIntervals into LIS[1..]
|
|
/// ConEQ.Distribute(LIS);
|
|
/// }
|
|
|
|
class ConnectedVNInfoEqClasses {
|
|
LiveIntervals &LIS;
|
|
IntEqClasses EqClass;
|
|
|
|
// Note that values a and b are connected.
|
|
void Connect(unsigned a, unsigned b);
|
|
|
|
unsigned Renumber();
|
|
|
|
public:
|
|
explicit ConnectedVNInfoEqClasses(LiveIntervals &lis) : LIS(lis) {}
|
|
|
|
/// Classify - Classify the values in LI into connected components.
|
|
/// Return the number of connected components.
|
|
unsigned Classify(const LiveInterval *LI);
|
|
|
|
/// getEqClass - Classify creates equivalence classes numbered 0..N. Return
|
|
/// the equivalence class assigned the VNI.
|
|
unsigned getEqClass(const VNInfo *VNI) const { return EqClass[VNI->id]; }
|
|
|
|
/// Distribute - Distribute values in LIV[0] into a separate LiveInterval
|
|
/// for each connected component. LIV must have a LiveInterval for each
|
|
/// connected component. The LiveIntervals in Liv[1..] must be empty.
|
|
/// Instructions using LIV[0] are rewritten.
|
|
void Distribute(LiveInterval *LIV[], MachineRegisterInfo &MRI);
|
|
|
|
};
|
|
|
|
}
|
|
#endif
|