mirror of
https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224807 91177308-0d34-0410-b5e6-96231b3b80d8
1226 lines
39 KiB
C++
1226 lines
39 KiB
C++
//===-- LiveInterval.cpp - Live Interval Representation -------------------===//
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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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#include "llvm/CodeGen/LiveInterval.h"
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#include "RegisterCoalescer.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include <algorithm>
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using namespace llvm;
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LiveRange::iterator LiveRange::find(SlotIndex Pos) {
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// This algorithm is basically std::upper_bound.
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// Unfortunately, std::upper_bound cannot be used with mixed types until we
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// adopt C++0x. Many libraries can do it, but not all.
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if (empty() || Pos >= endIndex())
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return end();
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iterator I = begin();
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size_t Len = size();
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do {
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size_t Mid = Len >> 1;
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if (Pos < I[Mid].end)
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Len = Mid;
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else
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I += Mid + 1, Len -= Mid + 1;
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} while (Len);
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return I;
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}
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VNInfo *LiveRange::createDeadDef(SlotIndex Def,
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VNInfo::Allocator &VNInfoAllocator) {
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assert(!Def.isDead() && "Cannot define a value at the dead slot");
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iterator I = find(Def);
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if (I == end()) {
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VNInfo *VNI = getNextValue(Def, VNInfoAllocator);
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segments.push_back(Segment(Def, Def.getDeadSlot(), VNI));
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return VNI;
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}
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if (SlotIndex::isSameInstr(Def, I->start)) {
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assert(I->valno->def == I->start && "Inconsistent existing value def");
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// It is possible to have both normal and early-clobber defs of the same
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// register on an instruction. It doesn't make a lot of sense, but it is
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// possible to specify in inline assembly.
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//
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// Just convert everything to early-clobber.
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Def = std::min(Def, I->start);
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if (Def != I->start)
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I->start = I->valno->def = Def;
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return I->valno;
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}
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assert(SlotIndex::isEarlierInstr(Def, I->start) && "Already live at def");
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VNInfo *VNI = getNextValue(Def, VNInfoAllocator);
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segments.insert(I, Segment(Def, Def.getDeadSlot(), VNI));
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return VNI;
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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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//
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// An example for overlaps():
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//
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// 0: A = ...
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// 4: B = ...
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// 8: C = A + B ;; last use of A
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//
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// The live ranges should look like:
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//
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// A = [3, 11)
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// B = [7, x)
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// C = [11, y)
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//
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// A->overlaps(C) should return false since we want to be able to join
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// A and C.
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//
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bool LiveRange::overlapsFrom(const LiveRange& other,
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const_iterator StartPos) const {
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assert(!empty() && "empty range");
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const_iterator i = begin();
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const_iterator ie = end();
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const_iterator j = StartPos;
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const_iterator je = other.end();
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assert((StartPos->start <= i->start || StartPos == other.begin()) &&
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StartPos != other.end() && "Bogus start position hint!");
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if (i->start < j->start) {
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i = std::upper_bound(i, ie, j->start);
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if (i != begin()) --i;
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} else if (j->start < i->start) {
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++StartPos;
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if (StartPos != other.end() && StartPos->start <= i->start) {
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assert(StartPos < other.end() && i < end());
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j = std::upper_bound(j, je, i->start);
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if (j != other.begin()) --j;
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}
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} else {
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return true;
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}
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if (j == je) return false;
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while (i != ie) {
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if (i->start > j->start) {
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std::swap(i, j);
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std::swap(ie, je);
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}
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if (i->end > j->start)
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return true;
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++i;
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}
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return false;
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}
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bool LiveRange::overlaps(const LiveRange &Other, const CoalescerPair &CP,
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const SlotIndexes &Indexes) const {
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assert(!empty() && "empty range");
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if (Other.empty())
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return false;
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// Use binary searches to find initial positions.
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const_iterator I = find(Other.beginIndex());
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const_iterator IE = end();
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if (I == IE)
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return false;
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const_iterator J = Other.find(I->start);
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const_iterator JE = Other.end();
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if (J == JE)
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return false;
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for (;;) {
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// J has just been advanced to satisfy:
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assert(J->end >= I->start);
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// Check for an overlap.
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if (J->start < I->end) {
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// I and J are overlapping. Find the later start.
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SlotIndex Def = std::max(I->start, J->start);
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// Allow the overlap if Def is a coalescable copy.
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if (Def.isBlock() ||
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!CP.isCoalescable(Indexes.getInstructionFromIndex(Def)))
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return true;
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}
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// Advance the iterator that ends first to check for more overlaps.
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if (J->end > I->end) {
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std::swap(I, J);
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std::swap(IE, JE);
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}
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// Advance J until J->end >= I->start.
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do
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if (++J == JE)
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return false;
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while (J->end < I->start);
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}
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}
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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 LiveRange::overlaps(SlotIndex Start, SlotIndex End) const {
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assert(Start < End && "Invalid range");
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const_iterator I = std::lower_bound(begin(), end(), End);
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return I != begin() && (--I)->end > Start;
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}
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bool LiveRange::covers(const LiveRange &Other) const {
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if (empty())
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return Other.empty();
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const_iterator I = begin();
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for (const Segment &O : Other.segments) {
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I = advanceTo(I, O.start);
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if (I == end() || I->start > O.start)
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return false;
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// Check adjacent live segments and see if we can get behind O.end.
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while (I->end < O.end) {
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const_iterator Last = I;
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// Get next segment and abort if it was not adjacent.
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++I;
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if (I == end() || Last->end != I->start)
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return false;
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}
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}
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return true;
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}
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/// ValNo is dead, remove it. If it is the largest value number, just nuke it
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/// (and any other deleted values neighboring it), otherwise mark it as ~1U so
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/// it can be nuked later.
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void LiveRange::markValNoForDeletion(VNInfo *ValNo) {
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if (ValNo->id == getNumValNums()-1) {
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do {
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valnos.pop_back();
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} while (!valnos.empty() && valnos.back()->isUnused());
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} else {
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ValNo->markUnused();
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}
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}
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/// RenumberValues - Renumber all values in order of appearance and delete the
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/// remaining unused values.
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void LiveRange::RenumberValues() {
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SmallPtrSet<VNInfo*, 8> Seen;
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valnos.clear();
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for (const Segment &S : segments) {
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VNInfo *VNI = S.valno;
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if (!Seen.insert(VNI).second)
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continue;
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assert(!VNI->isUnused() && "Unused valno used by live segment");
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VNI->id = (unsigned)valnos.size();
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valnos.push_back(VNI);
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}
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}
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/// This method is used when we want to extend the segment specified by I to end
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/// at the specified endpoint. To do this, we should merge and eliminate all
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/// segments that this will overlap with. The iterator is not invalidated.
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void LiveRange::extendSegmentEndTo(iterator I, SlotIndex NewEnd) {
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assert(I != end() && "Not a valid segment!");
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VNInfo *ValNo = I->valno;
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// Search for the first segment that we can't merge with.
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iterator MergeTo = std::next(I);
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for (; MergeTo != end() && NewEnd >= MergeTo->end; ++MergeTo) {
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assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
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}
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// If NewEnd was in the middle of a segment, make sure to get its endpoint.
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I->end = std::max(NewEnd, std::prev(MergeTo)->end);
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// If the newly formed segment now touches the segment after it and if they
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// have the same value number, merge the two segments into one segment.
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if (MergeTo != end() && MergeTo->start <= I->end &&
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MergeTo->valno == ValNo) {
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I->end = MergeTo->end;
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++MergeTo;
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}
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// Erase any dead segments.
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segments.erase(std::next(I), MergeTo);
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}
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/// This method is used when we want to extend the segment specified by I to
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/// start at the specified endpoint. To do this, we should merge and eliminate
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/// all segments that this will overlap with.
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LiveRange::iterator
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LiveRange::extendSegmentStartTo(iterator I, SlotIndex NewStart) {
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assert(I != end() && "Not a valid segment!");
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VNInfo *ValNo = I->valno;
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// Search for the first segment that we can't merge with.
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iterator MergeTo = I;
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do {
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if (MergeTo == begin()) {
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I->start = NewStart;
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segments.erase(MergeTo, I);
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return I;
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}
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assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
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--MergeTo;
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} while (NewStart <= MergeTo->start);
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// If we start in the middle of another segment, just delete a range and
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// extend that segment.
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if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) {
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MergeTo->end = I->end;
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} else {
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// Otherwise, extend the segment right after.
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++MergeTo;
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MergeTo->start = NewStart;
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MergeTo->end = I->end;
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}
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segments.erase(std::next(MergeTo), std::next(I));
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return MergeTo;
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}
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void LiveRange::append(const Segment S) {
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// Check that the segment belongs to the back of the list.
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assert(segments.empty() || segments.back().end <= S.start);
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segments.push_back(S);
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}
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LiveRange::iterator LiveRange::addSegmentFrom(Segment S, iterator From) {
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SlotIndex Start = S.start, End = S.end;
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iterator it = std::upper_bound(From, end(), Start);
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// If the inserted segment starts in the middle or right at the end of
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// another segment, just extend that segment to contain the segment of S.
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if (it != begin()) {
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iterator B = std::prev(it);
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if (S.valno == B->valno) {
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if (B->start <= Start && B->end >= Start) {
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extendSegmentEndTo(B, End);
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return B;
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}
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} else {
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// Check to make sure that we are not overlapping two live segments with
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// different valno's.
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assert(B->end <= Start &&
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"Cannot overlap two segments with differing ValID's"
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" (did you def the same reg twice in a MachineInstr?)");
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}
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}
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// Otherwise, if this segment ends in the middle of, or right next to, another
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// segment, merge it into that segment.
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if (it != end()) {
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if (S.valno == it->valno) {
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if (it->start <= End) {
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it = extendSegmentStartTo(it, Start);
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// If S is a complete superset of a segment, we may need to grow its
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// endpoint as well.
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if (End > it->end)
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extendSegmentEndTo(it, End);
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return it;
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}
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} else {
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// Check to make sure that we are not overlapping two live segments with
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// different valno's.
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assert(it->start >= End &&
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"Cannot overlap two segments with differing ValID's");
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}
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}
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// Otherwise, this is just a new segment that doesn't interact with anything.
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// Insert it.
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return segments.insert(it, S);
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}
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/// extendInBlock - If this range is live before Kill in the basic
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/// block that starts at StartIdx, extend it to be live up to Kill and return
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/// the value. If there is no live range before Kill, return NULL.
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VNInfo *LiveRange::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) {
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if (empty())
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return nullptr;
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iterator I = std::upper_bound(begin(), end(), Kill.getPrevSlot());
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if (I == begin())
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return nullptr;
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--I;
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if (I->end <= StartIdx)
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return nullptr;
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if (I->end < Kill)
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extendSegmentEndTo(I, Kill);
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return I->valno;
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}
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/// Remove the specified segment from this range. Note that the segment must
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/// be in a single Segment in its entirety.
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void LiveRange::removeSegment(SlotIndex Start, SlotIndex End,
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bool RemoveDeadValNo) {
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// Find the Segment containing this span.
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iterator I = find(Start);
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assert(I != end() && "Segment is not in range!");
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assert(I->containsInterval(Start, End)
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&& "Segment is not entirely in range!");
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// If the span we are removing is at the start of the Segment, adjust it.
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VNInfo *ValNo = I->valno;
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if (I->start == Start) {
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if (I->end == End) {
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if (RemoveDeadValNo) {
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// Check if val# is dead.
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bool isDead = true;
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for (const_iterator II = begin(), EE = end(); II != EE; ++II)
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if (II != I && II->valno == ValNo) {
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isDead = false;
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break;
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}
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if (isDead) {
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// Now that ValNo is dead, remove it.
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markValNoForDeletion(ValNo);
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}
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}
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segments.erase(I); // Removed the whole Segment.
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} else
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I->start = End;
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return;
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}
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// Otherwise if the span we are removing is at the end of the Segment,
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// adjust the other way.
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if (I->end == End) {
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I->end = Start;
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return;
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}
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// Otherwise, we are splitting the Segment into two pieces.
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SlotIndex OldEnd = I->end;
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I->end = Start; // Trim the old segment.
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// Insert the new one.
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segments.insert(std::next(I), Segment(End, OldEnd, ValNo));
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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 LiveRange::removeValNo(VNInfo *ValNo) {
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if (empty()) return;
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iterator I = end();
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iterator E = begin();
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do {
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--I;
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if (I->valno == ValNo)
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segments.erase(I);
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} while (I != E);
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// Now that ValNo is dead, remove it.
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markValNoForDeletion(ValNo);
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}
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void LiveRange::join(LiveRange &Other,
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const int *LHSValNoAssignments,
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const int *RHSValNoAssignments,
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SmallVectorImpl<VNInfo *> &NewVNInfo) {
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verify();
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// Determine if any of our values are mapped. This is uncommon, so we want
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// to avoid the range scan if not.
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bool MustMapCurValNos = false;
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unsigned NumVals = getNumValNums();
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unsigned NumNewVals = NewVNInfo.size();
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for (unsigned i = 0; i != NumVals; ++i) {
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unsigned LHSValID = LHSValNoAssignments[i];
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if (i != LHSValID ||
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(NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(i))) {
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MustMapCurValNos = true;
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break;
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}
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}
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// If we have to apply a mapping to our base range assignment, rewrite it now.
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if (MustMapCurValNos && !empty()) {
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// Map the first live range.
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iterator OutIt = begin();
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OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]];
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for (iterator I = std::next(OutIt), E = end(); I != E; ++I) {
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VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]];
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assert(nextValNo && "Huh?");
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// If this live range has the same value # as its immediate predecessor,
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// and if they are neighbors, remove one Segment. This happens when we
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// have [0,4:0)[4,7:1) and map 0/1 onto the same value #.
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if (OutIt->valno == nextValNo && OutIt->end == I->start) {
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OutIt->end = I->end;
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} else {
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// Didn't merge. Move OutIt to the next segment,
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++OutIt;
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OutIt->valno = nextValNo;
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if (OutIt != I) {
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OutIt->start = I->start;
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OutIt->end = I->end;
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}
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}
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}
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// If we merge some segments, chop off the end.
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++OutIt;
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segments.erase(OutIt, end());
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}
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// Rewrite Other values before changing the VNInfo ids.
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// This can leave Other in an invalid state because we're not coalescing
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// touching segments that now have identical values. That's OK since Other is
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// not supposed to be valid after calling join();
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for (Segment &S : Other.segments)
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S.valno = NewVNInfo[RHSValNoAssignments[S.valno->id]];
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|
|
// Update val# info. Renumber them and make sure they all belong to this
|
|
// LiveRange now. Also remove dead val#'s.
|
|
unsigned NumValNos = 0;
|
|
for (unsigned i = 0; i < NumNewVals; ++i) {
|
|
VNInfo *VNI = NewVNInfo[i];
|
|
if (VNI) {
|
|
if (NumValNos >= NumVals)
|
|
valnos.push_back(VNI);
|
|
else
|
|
valnos[NumValNos] = VNI;
|
|
VNI->id = NumValNos++; // Renumber val#.
|
|
}
|
|
}
|
|
if (NumNewVals < NumVals)
|
|
valnos.resize(NumNewVals); // shrinkify
|
|
|
|
// Okay, now insert the RHS live segments into the LHS.
|
|
LiveRangeUpdater Updater(this);
|
|
for (Segment &S : Other.segments)
|
|
Updater.add(S);
|
|
}
|
|
|
|
/// Merge all of the segments in RHS into this live range as the specified
|
|
/// value number. The segments in RHS are allowed to overlap with segments in
|
|
/// the current range, but only if the overlapping segments have the
|
|
/// specified value number.
|
|
void LiveRange::MergeSegmentsInAsValue(const LiveRange &RHS,
|
|
VNInfo *LHSValNo) {
|
|
LiveRangeUpdater Updater(this);
|
|
for (const Segment &S : RHS.segments)
|
|
Updater.add(S.start, S.end, LHSValNo);
|
|
}
|
|
|
|
/// MergeValueInAsValue - Merge all of the live segments of a specific val#
|
|
/// in RHS into this live range as the specified value number.
|
|
/// The segments in RHS are allowed to overlap with segments in the
|
|
/// current range, it will replace the value numbers of the overlaped
|
|
/// segments with the specified value number.
|
|
void LiveRange::MergeValueInAsValue(const LiveRange &RHS,
|
|
const VNInfo *RHSValNo,
|
|
VNInfo *LHSValNo) {
|
|
LiveRangeUpdater Updater(this);
|
|
for (const Segment &S : RHS.segments)
|
|
if (S.valno == RHSValNo)
|
|
Updater.add(S.start, S.end, LHSValNo);
|
|
}
|
|
|
|
/// MergeValueNumberInto - This method is called when two value nubmers
|
|
/// are found to be equivalent. This eliminates V1, replacing all
|
|
/// segments with the V1 value number with the V2 value number. This can
|
|
/// cause merging of V1/V2 values numbers and compaction of the value space.
|
|
VNInfo *LiveRange::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) {
|
|
assert(V1 != V2 && "Identical value#'s are always equivalent!");
|
|
|
|
// This code actually merges the (numerically) larger value number into the
|
|
// smaller value number, which is likely to allow us to compactify the value
|
|
// space. The only thing we have to be careful of is to preserve the
|
|
// instruction that defines the result value.
|
|
|
|
// Make sure V2 is smaller than V1.
|
|
if (V1->id < V2->id) {
|
|
V1->copyFrom(*V2);
|
|
std::swap(V1, V2);
|
|
}
|
|
|
|
// Merge V1 segments into V2.
|
|
for (iterator I = begin(); I != end(); ) {
|
|
iterator S = I++;
|
|
if (S->valno != V1) continue; // Not a V1 Segment.
|
|
|
|
// Okay, we found a V1 live range. If it had a previous, touching, V2 live
|
|
// range, extend it.
|
|
if (S != begin()) {
|
|
iterator Prev = S-1;
|
|
if (Prev->valno == V2 && Prev->end == S->start) {
|
|
Prev->end = S->end;
|
|
|
|
// Erase this live-range.
|
|
segments.erase(S);
|
|
I = Prev+1;
|
|
S = Prev;
|
|
}
|
|
}
|
|
|
|
// Okay, now we have a V1 or V2 live range that is maximally merged forward.
|
|
// Ensure that it is a V2 live-range.
|
|
S->valno = V2;
|
|
|
|
// If we can merge it into later V2 segments, do so now. We ignore any
|
|
// following V1 segments, as they will be merged in subsequent iterations
|
|
// of the loop.
|
|
if (I != end()) {
|
|
if (I->start == S->end && I->valno == V2) {
|
|
S->end = I->end;
|
|
segments.erase(I);
|
|
I = S+1;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Now that V1 is dead, remove it.
|
|
markValNoForDeletion(V1);
|
|
|
|
return V2;
|
|
}
|
|
|
|
void LiveInterval::removeEmptySubRanges() {
|
|
SubRange **NextPtr = &SubRanges;
|
|
SubRange *I = *NextPtr;
|
|
while (I != nullptr) {
|
|
if (!I->empty()) {
|
|
NextPtr = &I->Next;
|
|
I = *NextPtr;
|
|
continue;
|
|
}
|
|
// Skip empty subranges until we find the first nonempty one.
|
|
do {
|
|
I = I->Next;
|
|
} while (I != nullptr && I->empty());
|
|
*NextPtr = I;
|
|
}
|
|
}
|
|
|
|
/// Helper function for constructMainRangeFromSubranges(): Search the CFG
|
|
/// backwards until we find a place covered by a LiveRange segment that actually
|
|
/// has a valno set.
|
|
static VNInfo *searchForVNI(const SlotIndexes &Indexes, LiveRange &LR,
|
|
const MachineBasicBlock *MBB,
|
|
SmallPtrSetImpl<const MachineBasicBlock*> &Visited) {
|
|
// We start the search at the end of MBB.
|
|
SlotIndex EndIdx = Indexes.getMBBEndIdx(MBB);
|
|
// In our use case we can't live the area covered by the live segments without
|
|
// finding an actual VNI def.
|
|
LiveRange::iterator I = LR.find(EndIdx.getPrevSlot());
|
|
assert(I != LR.end());
|
|
LiveRange::Segment &S = *I;
|
|
if (S.valno != nullptr)
|
|
return S.valno;
|
|
|
|
VNInfo *VNI = nullptr;
|
|
// Continue at predecessors (we could even go to idom with domtree available).
|
|
for (const MachineBasicBlock *Pred : MBB->predecessors()) {
|
|
// Avoid going in circles.
|
|
if (Visited.count(Pred))
|
|
continue;
|
|
Visited.insert(Pred);
|
|
|
|
VNI = searchForVNI(Indexes, LR, Pred, Visited);
|
|
if (VNI != nullptr) {
|
|
S.valno = VNI;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return VNI;
|
|
}
|
|
|
|
void LiveInterval::constructMainRangeFromSubranges(
|
|
const SlotIndexes &Indexes, VNInfo::Allocator &VNIAllocator) {
|
|
// The basic observations on which this algorithm is based:
|
|
// - Each Def/ValNo in a subrange must have a corresponding def on the main
|
|
// range, but not further defs/valnos are necessary.
|
|
// - If any of the subranges is live at a point the main liverange has to be
|
|
// live too, conversily if no subrange is live the main range mustn't be
|
|
// live either.
|
|
// We do this by scannig through all the subranges simultaneously creating new
|
|
// segments in the main range as segments start/ends come up in the subranges.
|
|
assert(hasSubRanges());
|
|
assert(segments.empty() && valnos.empty() && "expected empty main range");
|
|
|
|
// Collect subrange, iterator pairs for the walk and determine first and last
|
|
// SlotIndex involved.
|
|
SmallVector<std::pair<const SubRange*, const_iterator>, 4> SRs;
|
|
SlotIndex First;
|
|
SlotIndex Last;
|
|
for (const SubRange &SR : subranges()) {
|
|
if (SR.empty())
|
|
continue;
|
|
SRs.push_back(std::make_pair(&SR, SR.begin()));
|
|
if (!First.isValid() || SR.segments.front().start < First)
|
|
First = SR.segments.front().start;
|
|
if (!Last.isValid() || SR.segments.back().end > Last)
|
|
Last = SR.segments.back().end;
|
|
}
|
|
|
|
// Walk over all subranges simultaneously.
|
|
Segment CurrentSegment;
|
|
bool ConstructingSegment = false;
|
|
bool NeedVNIFixup = false;
|
|
unsigned ActiveMask = 0;
|
|
SlotIndex Pos = First;
|
|
while (true) {
|
|
SlotIndex NextPos = Last;
|
|
enum {
|
|
NOTHING,
|
|
BEGIN_SEGMENT,
|
|
END_SEGMENT,
|
|
} Event = NOTHING;
|
|
unsigned EventMask = 0;
|
|
bool IsDef = false;
|
|
// Find the next begin or end of a subrange segment. Combine masks if we
|
|
// have multiple begins/ends at the same position. Ends take precedence over
|
|
// Begins.
|
|
for (auto &SRP : SRs) {
|
|
const SubRange &SR = *SRP.first;
|
|
const_iterator &I = SRP.second;
|
|
while (I != SR.end() &&
|
|
(I->end < Pos ||
|
|
(I->end == Pos && (ActiveMask & SR.LaneMask) == 0)))
|
|
++I;
|
|
if (I == SR.end())
|
|
continue;
|
|
if ((ActiveMask & SR.LaneMask) == 0 &&
|
|
Pos <= I->start && I->start <= NextPos) {
|
|
// Merge multiple begins at the same position
|
|
if (I->start == NextPos && Event == BEGIN_SEGMENT) {
|
|
EventMask |= SR.LaneMask;
|
|
IsDef |= I->valno->def == I->start;
|
|
} else if (I->start < NextPos || Event != END_SEGMENT) {
|
|
Event = BEGIN_SEGMENT;
|
|
NextPos = I->start;
|
|
EventMask = SR.LaneMask;
|
|
IsDef = I->valno->def == I->start;
|
|
}
|
|
}
|
|
if ((ActiveMask & SR.LaneMask) != 0 &&
|
|
Pos <= I->end && I->end <= NextPos) {
|
|
// Merge multiple ends at the same position.
|
|
if (I->end == NextPos && Event == END_SEGMENT)
|
|
EventMask |= SR.LaneMask;
|
|
else {
|
|
Event = END_SEGMENT;
|
|
NextPos = I->end;
|
|
EventMask = SR.LaneMask;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Advance scan position.
|
|
Pos = NextPos;
|
|
if (Event == BEGIN_SEGMENT) {
|
|
if (ConstructingSegment && IsDef) {
|
|
// Finish previous segment because we have to start a new one.
|
|
CurrentSegment.end = Pos;
|
|
append(CurrentSegment);
|
|
ConstructingSegment = false;
|
|
}
|
|
|
|
// Start a new segment if necessary.
|
|
if (!ConstructingSegment) {
|
|
// Determine value number for the segment.
|
|
VNInfo *VNI;
|
|
if (IsDef) {
|
|
VNI = getNextValue(Pos, VNIAllocator);
|
|
} else {
|
|
// We have to reuse an existing value number, if we are lucky
|
|
// then we already passed one of the predecessor blocks and determined
|
|
// its value number (with blocks in reverse postorder this would be
|
|
// always true but we have no such guarantee).
|
|
assert(Pos.isBlock());
|
|
const MachineBasicBlock *MBB = Indexes.getMBBFromIndex(Pos);
|
|
// See if any of the predecessor blocks has a lower number and a VNI
|
|
for (const MachineBasicBlock *Pred : MBB->predecessors()) {
|
|
SlotIndex PredEnd = Indexes.getMBBEndIdx(Pred);
|
|
VNI = getVNInfoBefore(PredEnd);
|
|
if (VNI != nullptr)
|
|
break;
|
|
}
|
|
// Def will come later: We have to do an extra fixup pass.
|
|
if (VNI == nullptr)
|
|
NeedVNIFixup = true;
|
|
}
|
|
|
|
CurrentSegment.start = Pos;
|
|
CurrentSegment.valno = VNI;
|
|
ConstructingSegment = true;
|
|
}
|
|
ActiveMask |= EventMask;
|
|
} else if (Event == END_SEGMENT) {
|
|
assert(ConstructingSegment);
|
|
// Finish segment if no lane is active anymore.
|
|
ActiveMask &= ~EventMask;
|
|
if (ActiveMask == 0) {
|
|
CurrentSegment.end = Pos;
|
|
append(CurrentSegment);
|
|
ConstructingSegment = false;
|
|
}
|
|
} else {
|
|
// We reached the end of the last subranges and can stop.
|
|
assert(Event == NOTHING);
|
|
break;
|
|
}
|
|
}
|
|
|
|
// We might not be able to assign new valnos for all segments if the basic
|
|
// block containing the definition comes after a segment using the valno.
|
|
// Do a fixup pass for this uncommon case.
|
|
if (NeedVNIFixup) {
|
|
SmallPtrSet<const MachineBasicBlock*, 5> Visited;
|
|
for (Segment &S : segments) {
|
|
if (S.valno != nullptr)
|
|
continue;
|
|
// This can only happen at the begin of a basic block.
|
|
assert(S.start.isBlock());
|
|
|
|
Visited.clear();
|
|
const MachineBasicBlock *MBB = Indexes.getMBBFromIndex(S.start);
|
|
for (const MachineBasicBlock *Pred : MBB->predecessors()) {
|
|
VNInfo *VNI = searchForVNI(Indexes, *this, Pred, Visited);
|
|
if (VNI != nullptr) {
|
|
S.valno = VNI;
|
|
break;
|
|
}
|
|
}
|
|
assert(S.valno != nullptr);
|
|
}
|
|
}
|
|
assert(ActiveMask == 0 && !ConstructingSegment);
|
|
verify();
|
|
}
|
|
|
|
unsigned LiveInterval::getSize() const {
|
|
unsigned Sum = 0;
|
|
for (const Segment &S : segments)
|
|
Sum += S.start.distance(S.end);
|
|
return Sum;
|
|
}
|
|
|
|
raw_ostream& llvm::operator<<(raw_ostream& os, const LiveRange::Segment &S) {
|
|
return os << '[' << S.start << ',' << S.end << ':' << S.valno->id << ")";
|
|
}
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
void LiveRange::Segment::dump() const {
|
|
dbgs() << *this << "\n";
|
|
}
|
|
#endif
|
|
|
|
void LiveRange::print(raw_ostream &OS) const {
|
|
if (empty())
|
|
OS << "EMPTY";
|
|
else {
|
|
for (const Segment &S : segments) {
|
|
OS << S;
|
|
assert(S.valno == getValNumInfo(S.valno->id) && "Bad VNInfo");
|
|
}
|
|
}
|
|
|
|
// Print value number info.
|
|
if (getNumValNums()) {
|
|
OS << " ";
|
|
unsigned vnum = 0;
|
|
for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e;
|
|
++i, ++vnum) {
|
|
const VNInfo *vni = *i;
|
|
if (vnum) OS << " ";
|
|
OS << vnum << "@";
|
|
if (vni->isUnused()) {
|
|
OS << "x";
|
|
} else {
|
|
OS << vni->def;
|
|
if (vni->isPHIDef())
|
|
OS << "-phi";
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void LiveInterval::print(raw_ostream &OS) const {
|
|
OS << PrintReg(reg) << ' ';
|
|
super::print(OS);
|
|
// Print subranges
|
|
for (const SubRange &SR : subranges()) {
|
|
OS << format(" L%04X ", SR.LaneMask) << SR;
|
|
}
|
|
}
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
void LiveRange::dump() const {
|
|
dbgs() << *this << "\n";
|
|
}
|
|
|
|
void LiveInterval::dump() const {
|
|
dbgs() << *this << "\n";
|
|
}
|
|
#endif
|
|
|
|
#ifndef NDEBUG
|
|
void LiveRange::verify() const {
|
|
for (const_iterator I = begin(), E = end(); I != E; ++I) {
|
|
assert(I->start.isValid());
|
|
assert(I->end.isValid());
|
|
assert(I->start < I->end);
|
|
assert(I->valno != nullptr);
|
|
assert(I->valno->id < valnos.size());
|
|
assert(I->valno == valnos[I->valno->id]);
|
|
if (std::next(I) != E) {
|
|
assert(I->end <= std::next(I)->start);
|
|
if (I->end == std::next(I)->start)
|
|
assert(I->valno != std::next(I)->valno);
|
|
}
|
|
}
|
|
}
|
|
|
|
void LiveInterval::verify(const MachineRegisterInfo *MRI) const {
|
|
super::verify();
|
|
|
|
// Make sure SubRanges are fine and LaneMasks are disjunct.
|
|
unsigned Mask = 0;
|
|
unsigned MaxMask = MRI != nullptr ? MRI->getMaxLaneMaskForVReg(reg) : ~0u;
|
|
for (const SubRange &SR : subranges()) {
|
|
// Subrange lanemask should be disjunct to any previous subrange masks.
|
|
assert((Mask & SR.LaneMask) == 0);
|
|
Mask |= SR.LaneMask;
|
|
|
|
// subrange mask should not contained in maximum lane mask for the vreg.
|
|
assert((Mask & ~MaxMask) == 0);
|
|
|
|
SR.verify();
|
|
// Main liverange should cover subrange.
|
|
assert(covers(SR));
|
|
}
|
|
}
|
|
#endif
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// LiveRangeUpdater class
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// The LiveRangeUpdater class always maintains these invariants:
|
|
//
|
|
// - When LastStart is invalid, Spills is empty and the iterators are invalid.
|
|
// This is the initial state, and the state created by flush().
|
|
// In this state, isDirty() returns false.
|
|
//
|
|
// Otherwise, segments are kept in three separate areas:
|
|
//
|
|
// 1. [begin; WriteI) at the front of LR.
|
|
// 2. [ReadI; end) at the back of LR.
|
|
// 3. Spills.
|
|
//
|
|
// - LR.begin() <= WriteI <= ReadI <= LR.end().
|
|
// - Segments in all three areas are fully ordered and coalesced.
|
|
// - Segments in area 1 precede and can't coalesce with segments in area 2.
|
|
// - Segments in Spills precede and can't coalesce with segments in area 2.
|
|
// - No coalescing is possible between segments in Spills and segments in area
|
|
// 1, and there are no overlapping segments.
|
|
//
|
|
// The segments in Spills are not ordered with respect to the segments in area
|
|
// 1. They need to be merged.
|
|
//
|
|
// When they exist, Spills.back().start <= LastStart,
|
|
// and WriteI[-1].start <= LastStart.
|
|
|
|
void LiveRangeUpdater::print(raw_ostream &OS) const {
|
|
if (!isDirty()) {
|
|
if (LR)
|
|
OS << "Clean updater: " << *LR << '\n';
|
|
else
|
|
OS << "Null updater.\n";
|
|
return;
|
|
}
|
|
assert(LR && "Can't have null LR in dirty updater.");
|
|
OS << " updater with gap = " << (ReadI - WriteI)
|
|
<< ", last start = " << LastStart
|
|
<< ":\n Area 1:";
|
|
for (const auto &S : make_range(LR->begin(), WriteI))
|
|
OS << ' ' << S;
|
|
OS << "\n Spills:";
|
|
for (unsigned I = 0, E = Spills.size(); I != E; ++I)
|
|
OS << ' ' << Spills[I];
|
|
OS << "\n Area 2:";
|
|
for (const auto &S : make_range(ReadI, LR->end()))
|
|
OS << ' ' << S;
|
|
OS << '\n';
|
|
}
|
|
|
|
void LiveRangeUpdater::dump() const
|
|
{
|
|
print(errs());
|
|
}
|
|
|
|
// Determine if A and B should be coalesced.
|
|
static inline bool coalescable(const LiveRange::Segment &A,
|
|
const LiveRange::Segment &B) {
|
|
assert(A.start <= B.start && "Unordered live segments.");
|
|
if (A.end == B.start)
|
|
return A.valno == B.valno;
|
|
if (A.end < B.start)
|
|
return false;
|
|
assert(A.valno == B.valno && "Cannot overlap different values");
|
|
return true;
|
|
}
|
|
|
|
void LiveRangeUpdater::add(LiveRange::Segment Seg) {
|
|
assert(LR && "Cannot add to a null destination");
|
|
|
|
// Flush the state if Start moves backwards.
|
|
if (!LastStart.isValid() || LastStart > Seg.start) {
|
|
if (isDirty())
|
|
flush();
|
|
// This brings us to an uninitialized state. Reinitialize.
|
|
assert(Spills.empty() && "Leftover spilled segments");
|
|
WriteI = ReadI = LR->begin();
|
|
}
|
|
|
|
// Remember start for next time.
|
|
LastStart = Seg.start;
|
|
|
|
// Advance ReadI until it ends after Seg.start.
|
|
LiveRange::iterator E = LR->end();
|
|
if (ReadI != E && ReadI->end <= Seg.start) {
|
|
// First try to close the gap between WriteI and ReadI with spills.
|
|
if (ReadI != WriteI)
|
|
mergeSpills();
|
|
// Then advance ReadI.
|
|
if (ReadI == WriteI)
|
|
ReadI = WriteI = LR->find(Seg.start);
|
|
else
|
|
while (ReadI != E && ReadI->end <= Seg.start)
|
|
*WriteI++ = *ReadI++;
|
|
}
|
|
|
|
assert(ReadI == E || ReadI->end > Seg.start);
|
|
|
|
// Check if the ReadI segment begins early.
|
|
if (ReadI != E && ReadI->start <= Seg.start) {
|
|
assert(ReadI->valno == Seg.valno && "Cannot overlap different values");
|
|
// Bail if Seg is completely contained in ReadI.
|
|
if (ReadI->end >= Seg.end)
|
|
return;
|
|
// Coalesce into Seg.
|
|
Seg.start = ReadI->start;
|
|
++ReadI;
|
|
}
|
|
|
|
// Coalesce as much as possible from ReadI into Seg.
|
|
while (ReadI != E && coalescable(Seg, *ReadI)) {
|
|
Seg.end = std::max(Seg.end, ReadI->end);
|
|
++ReadI;
|
|
}
|
|
|
|
// Try coalescing Spills.back() into Seg.
|
|
if (!Spills.empty() && coalescable(Spills.back(), Seg)) {
|
|
Seg.start = Spills.back().start;
|
|
Seg.end = std::max(Spills.back().end, Seg.end);
|
|
Spills.pop_back();
|
|
}
|
|
|
|
// Try coalescing Seg into WriteI[-1].
|
|
if (WriteI != LR->begin() && coalescable(WriteI[-1], Seg)) {
|
|
WriteI[-1].end = std::max(WriteI[-1].end, Seg.end);
|
|
return;
|
|
}
|
|
|
|
// Seg doesn't coalesce with anything, and needs to be inserted somewhere.
|
|
if (WriteI != ReadI) {
|
|
*WriteI++ = Seg;
|
|
return;
|
|
}
|
|
|
|
// Finally, append to LR or Spills.
|
|
if (WriteI == E) {
|
|
LR->segments.push_back(Seg);
|
|
WriteI = ReadI = LR->end();
|
|
} else
|
|
Spills.push_back(Seg);
|
|
}
|
|
|
|
// Merge as many spilled segments as possible into the gap between WriteI
|
|
// and ReadI. Advance WriteI to reflect the inserted instructions.
|
|
void LiveRangeUpdater::mergeSpills() {
|
|
// Perform a backwards merge of Spills and [SpillI;WriteI).
|
|
size_t GapSize = ReadI - WriteI;
|
|
size_t NumMoved = std::min(Spills.size(), GapSize);
|
|
LiveRange::iterator Src = WriteI;
|
|
LiveRange::iterator Dst = Src + NumMoved;
|
|
LiveRange::iterator SpillSrc = Spills.end();
|
|
LiveRange::iterator B = LR->begin();
|
|
|
|
// This is the new WriteI position after merging spills.
|
|
WriteI = Dst;
|
|
|
|
// Now merge Src and Spills backwards.
|
|
while (Src != Dst) {
|
|
if (Src != B && Src[-1].start > SpillSrc[-1].start)
|
|
*--Dst = *--Src;
|
|
else
|
|
*--Dst = *--SpillSrc;
|
|
}
|
|
assert(NumMoved == size_t(Spills.end() - SpillSrc));
|
|
Spills.erase(SpillSrc, Spills.end());
|
|
}
|
|
|
|
void LiveRangeUpdater::flush() {
|
|
if (!isDirty())
|
|
return;
|
|
// Clear the dirty state.
|
|
LastStart = SlotIndex();
|
|
|
|
assert(LR && "Cannot add to a null destination");
|
|
|
|
// Nothing to merge?
|
|
if (Spills.empty()) {
|
|
LR->segments.erase(WriteI, ReadI);
|
|
LR->verify();
|
|
return;
|
|
}
|
|
|
|
// Resize the WriteI - ReadI gap to match Spills.
|
|
size_t GapSize = ReadI - WriteI;
|
|
if (GapSize < Spills.size()) {
|
|
// The gap is too small. Make some room.
|
|
size_t WritePos = WriteI - LR->begin();
|
|
LR->segments.insert(ReadI, Spills.size() - GapSize, LiveRange::Segment());
|
|
// This also invalidated ReadI, but it is recomputed below.
|
|
WriteI = LR->begin() + WritePos;
|
|
} else {
|
|
// Shrink the gap if necessary.
|
|
LR->segments.erase(WriteI + Spills.size(), ReadI);
|
|
}
|
|
ReadI = WriteI + Spills.size();
|
|
mergeSpills();
|
|
LR->verify();
|
|
}
|
|
|
|
unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
|
|
// Create initial equivalence classes.
|
|
EqClass.clear();
|
|
EqClass.grow(LI->getNumValNums());
|
|
|
|
const VNInfo *used = nullptr, *unused = nullptr;
|
|
|
|
// Determine connections.
|
|
for (const VNInfo *VNI : LI->valnos) {
|
|
// Group all unused values into one class.
|
|
if (VNI->isUnused()) {
|
|
if (unused)
|
|
EqClass.join(unused->id, VNI->id);
|
|
unused = VNI;
|
|
continue;
|
|
}
|
|
used = VNI;
|
|
if (VNI->isPHIDef()) {
|
|
const MachineBasicBlock *MBB = LIS.getMBBFromIndex(VNI->def);
|
|
assert(MBB && "Phi-def has no defining MBB");
|
|
// Connect to values live out of predecessors.
|
|
for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
|
|
PE = MBB->pred_end(); PI != PE; ++PI)
|
|
if (const VNInfo *PVNI = LI->getVNInfoBefore(LIS.getMBBEndIdx(*PI)))
|
|
EqClass.join(VNI->id, PVNI->id);
|
|
} else {
|
|
// Normal value defined by an instruction. Check for two-addr redef.
|
|
// FIXME: This could be coincidental. Should we really check for a tied
|
|
// operand constraint?
|
|
// Note that VNI->def may be a use slot for an early clobber def.
|
|
if (const VNInfo *UVNI = LI->getVNInfoBefore(VNI->def))
|
|
EqClass.join(VNI->id, UVNI->id);
|
|
}
|
|
}
|
|
|
|
// Lump all the unused values in with the last used value.
|
|
if (used && unused)
|
|
EqClass.join(used->id, unused->id);
|
|
|
|
EqClass.compress();
|
|
return EqClass.getNumClasses();
|
|
}
|
|
|
|
void ConnectedVNInfoEqClasses::Distribute(LiveInterval *LIV[],
|
|
MachineRegisterInfo &MRI) {
|
|
assert(LIV[0] && "LIV[0] must be set");
|
|
LiveInterval &LI = *LIV[0];
|
|
|
|
// Rewrite instructions.
|
|
for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg),
|
|
RE = MRI.reg_end(); RI != RE;) {
|
|
MachineOperand &MO = *RI;
|
|
MachineInstr *MI = RI->getParent();
|
|
++RI;
|
|
// DBG_VALUE instructions don't have slot indexes, so get the index of the
|
|
// instruction before them.
|
|
// Normally, DBG_VALUE instructions are removed before this function is
|
|
// called, but it is not a requirement.
|
|
SlotIndex Idx;
|
|
if (MI->isDebugValue())
|
|
Idx = LIS.getSlotIndexes()->getIndexBefore(MI);
|
|
else
|
|
Idx = LIS.getInstructionIndex(MI);
|
|
LiveQueryResult LRQ = LI.Query(Idx);
|
|
const VNInfo *VNI = MO.readsReg() ? LRQ.valueIn() : LRQ.valueDefined();
|
|
// In the case of an <undef> use that isn't tied to any def, VNI will be
|
|
// NULL. If the use is tied to a def, VNI will be the defined value.
|
|
if (!VNI)
|
|
continue;
|
|
MO.setReg(LIV[getEqClass(VNI)]->reg);
|
|
}
|
|
|
|
// Move runs to new intervals.
|
|
LiveInterval::iterator J = LI.begin(), E = LI.end();
|
|
while (J != E && EqClass[J->valno->id] == 0)
|
|
++J;
|
|
for (LiveInterval::iterator I = J; I != E; ++I) {
|
|
if (unsigned eq = EqClass[I->valno->id]) {
|
|
assert((LIV[eq]->empty() || LIV[eq]->expiredAt(I->start)) &&
|
|
"New intervals should be empty");
|
|
LIV[eq]->segments.push_back(*I);
|
|
} else
|
|
*J++ = *I;
|
|
}
|
|
// TODO: do not cheat anymore by simply cleaning all subranges
|
|
LI.clearSubRanges();
|
|
LI.segments.erase(J, E);
|
|
|
|
// Transfer VNInfos to their new owners and renumber them.
|
|
unsigned j = 0, e = LI.getNumValNums();
|
|
while (j != e && EqClass[j] == 0)
|
|
++j;
|
|
for (unsigned i = j; i != e; ++i) {
|
|
VNInfo *VNI = LI.getValNumInfo(i);
|
|
if (unsigned eq = EqClass[i]) {
|
|
VNI->id = LIV[eq]->getNumValNums();
|
|
LIV[eq]->valnos.push_back(VNI);
|
|
} else {
|
|
VNI->id = j;
|
|
LI.valnos[j++] = VNI;
|
|
}
|
|
}
|
|
LI.valnos.resize(j);
|
|
}
|