Line data Source code
1 : //===- LiveIntervalUnion.cpp - Live interval union data structure ---------===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 : //
10 : // LiveIntervalUnion represents a coalesced set of live intervals. This may be
11 : // used during coalescing to represent a congruence class, or during register
12 : // allocation to model liveness of a physical register.
13 : //
14 : //===----------------------------------------------------------------------===//
15 :
16 : #include "llvm/CodeGen/LiveIntervalUnion.h"
17 : #include "llvm/ADT/STLExtras.h"
18 : #include "llvm/ADT/SparseBitVector.h"
19 : #include "llvm/CodeGen/LiveInterval.h"
20 : #include "llvm/CodeGen/TargetRegisterInfo.h"
21 : #include "llvm/Support/raw_ostream.h"
22 : #include <cassert>
23 : #include <cstdlib>
24 :
25 : using namespace llvm;
26 :
27 : #define DEBUG_TYPE "regalloc"
28 :
29 : // Merge a LiveInterval's segments. Guarantee no overlaps.
30 2576532 : void LiveIntervalUnion::unify(LiveInterval &VirtReg, const LiveRange &Range) {
31 2576532 : if (Range.empty())
32 716955 : return;
33 2565447 : ++Tag;
34 :
35 : // Insert each of the virtual register's live segments into the map.
36 : LiveRange::const_iterator RegPos = Range.begin();
37 : LiveRange::const_iterator RegEnd = Range.end();
38 2565447 : SegmentIter SegPos = Segments.find(RegPos->start);
39 :
40 676532 : while (SegPos.valid()) {
41 1382402 : SegPos.insert(RegPos->start, RegPos->end, &VirtReg);
42 1382402 : if (++RegPos == RegEnd)
43 : return;
44 676532 : SegPos.advanceTo(RegPos->start);
45 : }
46 :
47 : // We have reached the end of Segments, so it is no longer necessary to search
48 : // for the insertion position.
49 : // It is faster to insert the end first.
50 1859577 : --RegEnd;
51 1859577 : SegPos.insert(RegEnd->start, RegEnd->end, &VirtReg);
52 2862826 : for (; RegPos != RegEnd; ++RegPos, ++SegPos)
53 1003249 : SegPos.insert(RegPos->start, RegPos->end, &VirtReg);
54 : }
55 :
56 : // Remove a live virtual register's segments from this union.
57 175354 : void LiveIntervalUnion::extract(LiveInterval &VirtReg, const LiveRange &Range) {
58 175354 : if (Range.empty())
59 : return;
60 175354 : ++Tag;
61 :
62 : // Remove each of the virtual register's live segments from the map.
63 : LiveRange::const_iterator RegPos = Range.begin();
64 : LiveRange::const_iterator RegEnd = Range.end();
65 175354 : SegmentIter SegPos = Segments.find(RegPos->start);
66 :
67 : while (true) {
68 325903 : assert(SegPos.value() == &VirtReg && "Inconsistent LiveInterval");
69 501257 : SegPos.erase();
70 : if (!SegPos.valid())
71 : return;
72 :
73 : // Skip all segments that may have been coalesced.
74 368007 : RegPos = Range.advanceTo(RegPos, SegPos.start());
75 368007 : if (RegPos == RegEnd)
76 : return;
77 :
78 325903 : SegPos.advanceTo(RegPos->start);
79 : }
80 : }
81 :
82 : void
83 0 : LiveIntervalUnion::print(raw_ostream &OS, const TargetRegisterInfo *TRI) const {
84 0 : if (empty()) {
85 0 : OS << " empty\n";
86 0 : return;
87 : }
88 0 : for (LiveSegments::const_iterator SI = Segments.begin(); SI.valid(); ++SI) {
89 0 : OS << " [" << SI.start() << ' ' << SI.stop() << "):"
90 0 : << printReg(SI.value()->reg, TRI);
91 : }
92 : OS << '\n';
93 : }
94 :
95 : #ifndef NDEBUG
96 : // Verify the live intervals in this union and add them to the visited set.
97 : void LiveIntervalUnion::verify(LiveVirtRegBitSet& VisitedVRegs) {
98 : for (SegmentIter SI = Segments.begin(); SI.valid(); ++SI)
99 : VisitedVRegs.set(SI.value()->reg);
100 : }
101 : #endif //!NDEBUG
102 :
103 : // Scan the vector of interfering virtual registers in this union. Assume it's
104 : // quite small.
105 22432313 : bool LiveIntervalUnion::Query::isSeenInterference(LiveInterval *VirtReg) const {
106 22432313 : return is_contained(InterferingVRegs, VirtReg);
107 : }
108 :
109 : // Collect virtual registers in this union that interfere with this
110 : // query's live virtual register.
111 : //
112 : // The query state is one of:
113 : //
114 : // 1. CheckedFirstInterference == false: Iterators are uninitialized.
115 : // 2. SeenAllInterferences == true: InterferingVRegs complete, iterators unused.
116 : // 3. Iterators left at the last seen intersection.
117 : //
118 24274733 : unsigned LiveIntervalUnion::Query::
119 : collectInterferingVRegs(unsigned MaxInterferingRegs) {
120 : // Fast path return if we already have the desired information.
121 24274733 : if (SeenAllInterferences || InterferingVRegs.size() >= MaxInterferingRegs)
122 905754 : return InterferingVRegs.size();
123 :
124 : // Set up iterators on the first call.
125 23368979 : if (!CheckedFirstInterference) {
126 22731181 : CheckedFirstInterference = true;
127 :
128 : // Quickly skip interference check for empty sets.
129 45462362 : if (LR->empty() || LiveUnion->empty()) {
130 1258654 : SeenAllInterferences = true;
131 1258654 : return 0;
132 : }
133 :
134 : // In most cases, the union will start before LR.
135 21472527 : LRI = LR->begin();
136 : LiveUnionI.setMap(LiveUnion->getMap());
137 21472527 : LiveUnionI.find(LRI->start);
138 : }
139 :
140 22110325 : LiveRange::const_iterator LREnd = LR->end();
141 : LiveInterval *RecentReg = nullptr;
142 : while (LiveUnionI.valid()) {
143 : assert(LRI != LREnd && "Reached end of LR");
144 :
145 : // Check for overlapping interference.
146 83980626 : while (LRI->start < LiveUnionI.stop() && LRI->end > LiveUnionI.start()) {
147 : // This is an overlap, record the interfering register.
148 22654510 : LiveInterval *VReg = LiveUnionI.value();
149 22654510 : if (VReg != RecentReg && !isSeenInterference(VReg)) {
150 20908451 : RecentReg = VReg;
151 20908451 : InterferingVRegs.push_back(VReg);
152 20908451 : if (InterferingVRegs.size() >= MaxInterferingRegs)
153 20533450 : return InterferingVRegs.size();
154 : }
155 : // This LiveUnion segment is no longer interesting.
156 2785523 : if (!(++LiveUnionI).valid()) {
157 664463 : SeenAllInterferences = true;
158 664463 : return InterferingVRegs.size();
159 : }
160 : }
161 :
162 : // The iterators are now not overlapping, LiveUnionI has been advanced
163 : // beyond LRI.
164 : assert(LRI->end <= LiveUnionI.start() && "Expected non-overlap");
165 :
166 : // Advance the iterator that ends first.
167 9264024 : LRI = LR->advanceTo(LRI, LiveUnionI.start());
168 4632012 : if (LRI == LREnd)
169 : break;
170 :
171 : // Detect overlap, handle above.
172 3711973 : if (LRI->start < LiveUnionI.stop())
173 : continue;
174 :
175 : // Still not overlapping. Catch up LiveUnionI.
176 333904 : LiveUnionI.advanceTo(LRI->start);
177 : }
178 1576875 : SeenAllInterferences = true;
179 1576875 : return InterferingVRegs.size();
180 : }
181 :
182 193992 : void LiveIntervalUnion::Array::init(LiveIntervalUnion::Allocator &Alloc,
183 : unsigned NSize) {
184 : // Reuse existing allocation.
185 193992 : if (NSize == Size)
186 : return;
187 18827 : clear();
188 18827 : Size = NSize;
189 18827 : LIUs = static_cast<LiveIntervalUnion*>(
190 18827 : safe_malloc(sizeof(LiveIntervalUnion)*NSize));
191 3761707 : for (unsigned i = 0; i != Size; ++i)
192 3742880 : new(LIUs + i) LiveIntervalUnion(Alloc);
193 : }
194 :
195 38232 : void LiveIntervalUnion::Array::clear() {
196 38232 : if (!LIUs)
197 : return;
198 3759486 : for (unsigned i = 0; i != Size; ++i)
199 3740677 : LIUs[i].~LiveIntervalUnion();
200 18809 : free(LIUs);
201 18809 : Size = 0;
202 18809 : LIUs = nullptr;
203 : }
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