Line data Source code
1 : // Copyright 2015 the V8 project authors. All rights reserved.
2 : // Use of this source code is governed by a BSD-style license that can be
3 : // found in the LICENSE file.
4 :
5 : #include "src/compiler/live-range-separator.h"
6 : #include "src/compiler/register-allocator.h"
7 :
8 : namespace v8 {
9 : namespace internal {
10 : namespace compiler {
11 :
12 :
13 : #define TRACE(...) \
14 : do { \
15 : if (FLAG_trace_alloc) PrintF(__VA_ARGS__); \
16 : } while (false)
17 :
18 :
19 : namespace {
20 :
21 :
22 30644696 : void CreateSplinter(TopLevelLiveRange *range, RegisterAllocationData *data,
23 : LifetimePosition first_cut, LifetimePosition last_cut) {
24 : DCHECK(!range->IsSplinter());
25 : // We can ignore ranges that live solely in deferred blocks.
26 : // If a range ends right at the end of a deferred block, it is marked by
27 : // the range builder as ending at gap start of the next block - since the
28 : // end is a position where the variable isn't live. We need to take that
29 : // into consideration.
30 : LifetimePosition max_allowed_end = last_cut.NextFullStart();
31 :
32 25423733 : if (first_cut <= range->Start() && max_allowed_end >= range->End()) {
33 11069758 : return;
34 : }
35 :
36 : LifetimePosition start = Max(first_cut, range->Start());
37 : LifetimePosition end = Min(last_cut, range->End());
38 :
39 11069778 : if (start < end) {
40 : // Ensure the original range has a spill range associated, before it gets
41 : // splintered. Splinters will point to it. This way, when attempting to
42 : // reuse spill slots of splinters, during allocation, we avoid clobbering
43 : // such slots.
44 9787491 : if (range->MayRequireSpillRange()) {
45 866277 : data->CreateSpillRangeForLiveRange(range);
46 : }
47 9787477 : if (range->splinter() == nullptr) {
48 3284200 : TopLevelLiveRange *splinter =
49 3284202 : data->NextLiveRange(range->representation());
50 : DCHECK_NULL(data->live_ranges()[splinter->vreg()]);
51 6568400 : data->live_ranges()[splinter->vreg()] = splinter;
52 3284200 : range->SetSplinter(splinter);
53 : }
54 : Zone *zone = data->allocation_zone();
55 9787466 : TRACE("creating splinter for range %d between %d and %d\n", range->vreg(),
56 : start.ToInstructionIndex(), end.ToInstructionIndex());
57 9787466 : range->Splinter(start, end, zone);
58 : }
59 : }
60 :
61 10995279 : void SetSlotUse(TopLevelLiveRange *range) {
62 : range->set_has_slot_use(false);
63 16812716 : for (const UsePosition *pos = range->first_pos();
64 8406358 : !range->has_slot_use() && pos != nullptr; pos = pos->next()) {
65 5817437 : if (pos->type() == UsePositionType::kRequiresSlot) {
66 : range->set_has_slot_use(true);
67 : }
68 : }
69 2588921 : }
70 :
71 39886228 : void SplinterLiveRange(TopLevelLiveRange *range, RegisterAllocationData *data) {
72 103665982 : const InstructionSequence *code = data->code();
73 41612802 : UseInterval *interval = range->first_interval();
74 :
75 : LifetimePosition first_cut = LifetimePosition::Invalid();
76 18206012 : LifetimePosition last_cut = LifetimePosition::Invalid();
77 :
78 59818844 : while (interval != nullptr) {
79 : UseInterval *next_interval = interval->next();
80 : const InstructionBlock *first_block =
81 23406790 : code->GetInstructionBlock(interval->FirstGapIndex());
82 : const InstructionBlock *last_block =
83 23406795 : code->GetInstructionBlock(interval->LastGapIndex());
84 : int first_block_nr = first_block->rpo_number().ToInt();
85 : int last_block_nr = last_block->rpo_number().ToInt();
86 127072802 : for (int block_id = first_block_nr; block_id <= last_block_nr; ++block_id) {
87 136553706 : const InstructionBlock *current_block =
88 103665982 : code->InstructionBlockAt(RpoNumber::FromInt(block_id));
89 103666012 : if (current_block->IsDeferred()) {
90 21817889 : if (!first_cut.IsValid()) {
91 : first_cut = LifetimePosition::GapFromInstructionIndex(
92 : current_block->first_instruction_index());
93 : }
94 : last_cut = LifetimePosition::GapFromInstructionIndex(
95 21817889 : current_block->last_instruction_index());
96 : } else {
97 81848123 : if (first_cut.IsValid()) {
98 10249819 : CreateSplinter(range, data, first_cut, last_cut);
99 : first_cut = LifetimePosition::Invalid();
100 10249823 : last_cut = LifetimePosition::Invalid();
101 : }
102 : }
103 : }
104 : interval = next_interval;
105 : }
106 : // When the range ends in deferred blocks, first_cut will be valid here.
107 : // Splinter from there to the last instruction that was in a deferred block.
108 18206042 : if (first_cut.IsValid()) {
109 819998 : CreateSplinter(range, data, first_cut, last_cut);
110 : }
111 :
112 : // Redo has_slot_use
113 20385748 : if (range->has_slot_use() && range->splinter() != nullptr) {
114 1294468 : SetSlotUse(range);
115 1294468 : SetSlotUse(range->splinter());
116 : }
117 18206068 : }
118 :
119 : } // namespace
120 :
121 :
122 66293427 : void LiveRangeSeparator::Splinter() {
123 915120 : size_t virt_reg_count = data()->live_ranges().size();
124 48087375 : for (size_t vreg = 0; vreg < virt_reg_count; ++vreg) {
125 119923543 : TopLevelLiveRange *range = data()->live_ranges()[vreg];
126 99385254 : if (range == nullptr || range->IsEmpty() || range->IsSplinter()) {
127 : continue;
128 : }
129 : int first_instr = range->first_interval()->FirstGapIndex();
130 22294830 : if (!data()->code()->GetInstructionBlock(first_instr)->IsDeferred()) {
131 18206032 : SplinterLiveRange(range, data());
132 : }
133 : }
134 915100 : }
135 :
136 :
137 1545660 : void LiveRangeMerger::MarkRangesSpilledInDeferredBlocks() {
138 1545660 : const InstructionSequence *code = data()->code();
139 74581614 : for (TopLevelLiveRange *top : data()->live_ranges()) {
140 102669970 : if (top == nullptr || top->IsEmpty() || top->splinter() == nullptr ||
141 48750629 : top->HasSpillOperand() || !top->splinter()->HasSpillRange()) {
142 : continue;
143 : }
144 :
145 2499492 : LiveRange *child = top;
146 2228514 : for (; child != nullptr; child = child->next()) {
147 2499722 : if (child->spilled() ||
148 901925 : child->NextSlotPosition(child->Start()) != nullptr) {
149 : break;
150 : }
151 : }
152 1326819 : if (child == nullptr) {
153 : top->TreatAsSpilledInDeferredBlock(data()->allocation_zone(),
154 630718 : code->InstructionBlockCount());
155 : }
156 : }
157 915104 : }
158 :
159 :
160 52287155 : void LiveRangeMerger::Merge() {
161 915096 : MarkRangesSpilledInDeferredBlocks();
162 :
163 1830236 : int live_range_count = static_cast<int>(data()->live_ranges().size());
164 48087817 : for (int i = 0; i < live_range_count; ++i) {
165 170381599 : TopLevelLiveRange *range = data()->live_ranges()[i];
166 99386166 : if (range == nullptr || range->IsEmpty() || !range->IsSplinter()) {
167 : continue;
168 : }
169 : TopLevelLiveRange *splinter_parent = range->splintered_from();
170 :
171 : int to_remove = range->vreg();
172 3284242 : splinter_parent->Merge(range, data()->allocation_zone());
173 9852690 : data()->live_ranges()[to_remove] = nullptr;
174 : }
175 915106 : }
176 :
177 :
178 : } // namespace compiler
179 : } // namespace internal
180 : } // namespace v8
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