Line data Source code
1 : // Copyright 2013 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/crankshaft/hydrogen-representation-changes.h"
6 : #include "src/objects-inl.h"
7 :
8 : namespace v8 {
9 : namespace internal {
10 :
11 1981604 : void HRepresentationChangesPhase::InsertRepresentationChangeForUse(
12 2070922 : HValue* value, HValue* use_value, int use_index, Representation to) {
13 : // Insert the representation change right before its use. For phi-uses we
14 : // insert at the end of the corresponding predecessor.
15 : HInstruction* next = NULL;
16 1981608 : if (use_value->IsPhi()) {
17 89314 : next = use_value->block()->predecessors()->at(use_index)->end();
18 : } else {
19 : next = HInstruction::cast(use_value);
20 : }
21 : // For constants we try to make the representation change at compile
22 : // time. When a representation change is not possible without loss of
23 : // information we treat constants like normal instructions and insert the
24 : // change instructions for them.
25 : HInstruction* new_value = NULL;
26 : bool is_truncating_to_smi = use_value->CheckFlag(HValue::kTruncatingToSmi);
27 : bool is_truncating_to_int = use_value->CheckFlag(HValue::kTruncatingToInt32);
28 : bool is_truncating_to_number =
29 : use_value->CheckFlag(HValue::kTruncatingToNumber);
30 1981606 : if (value->IsConstant()) {
31 : HConstant* constant = HConstant::cast(value);
32 : // Try to create a new copy of the constant with the new representation.
33 1484262 : if (is_truncating_to_int && to.IsInteger32()) {
34 1982686 : Maybe<HConstant*> res = constant->CopyToTruncatedInt32(graph()->zone());
35 3902 : if (res.IsJust()) new_value = res.FromJust();
36 : } else {
37 1469677 : new_value = constant->CopyToRepresentation(to, graph()->zone());
38 : }
39 : }
40 :
41 1981606 : if (new_value == NULL) {
42 509107 : new_value = new (graph()->zone())
43 : HChange(value, to, is_truncating_to_smi, is_truncating_to_int,
44 1018215 : is_truncating_to_number);
45 : }
46 :
47 1981604 : new_value->InsertBefore(next);
48 1981605 : use_value->SetOperandAt(use_index, new_value);
49 1981603 : }
50 :
51 :
52 : static bool IsNonDeoptingIntToSmiChange(HChange* change) {
53 : Representation from_rep = change->from();
54 : Representation to_rep = change->to();
55 : // Flags indicating Uint32 operations are set in a later Hydrogen phase.
56 : DCHECK(!change->CheckFlag(HValue::kUint32));
57 2037 : return from_rep.IsInteger32() && to_rep.IsSmi() && SmiValuesAre32Bits();
58 : }
59 :
60 :
61 30333519 : void HRepresentationChangesPhase::InsertRepresentationChangesForValue(
62 27370113 : HValue* value) {
63 : Representation r = value->representation();
64 30333519 : if (r.IsNone()) {
65 : #ifdef DEBUG
66 : for (HUseIterator it(value->uses()); !it.Done(); it.Advance()) {
67 : HValue* use_value = it.value();
68 : int use_index = it.index();
69 : Representation req = use_value->RequiredInputRepresentation(use_index);
70 : DCHECK(req.IsNone());
71 : }
72 : #endif
73 : return;
74 : }
75 15268994 : if (value->HasNoUses()) {
76 3167836 : if (value->IsForceRepresentation()) value->DeleteAndReplaceWith(NULL);
77 : return;
78 : }
79 :
80 23536055 : for (HUseIterator it(value->uses()); !it.Done(); it.Advance()) {
81 23536095 : HValue* use_value = it.value();
82 23536095 : int use_index = it.index();
83 23536095 : Representation req = use_value->RequiredInputRepresentation(use_index);
84 23536057 : if (req.IsNone() || req.Equals(r)) continue;
85 :
86 : // If this is an HForceRepresentation instruction, and an HChange has been
87 : // inserted above it, examine the input representation of the HChange. If
88 : // that's int32, and this HForceRepresentation use is int32, and int32 to
89 : // smi changes can't cause deoptimisation, set the input of the use to the
90 : // input of the HChange.
91 1982075 : if (value->IsForceRepresentation()) {
92 : HValue* input = HForceRepresentation::cast(value)->value();
93 16107 : if (input->IsChange()) {
94 : HChange* change = HChange::cast(input);
95 11474 : if (change->from().Equals(req) && IsNonDeoptingIntToSmiChange(change)) {
96 469 : use_value->SetOperandAt(use_index, change->value());
97 469 : continue;
98 : }
99 : }
100 : }
101 1981606 : InsertRepresentationChangeForUse(value, use_value, use_index, req);
102 : }
103 12101119 : if (value->HasNoUses()) {
104 : DCHECK(value->IsConstant() || value->IsForceRepresentation());
105 1309184 : value->DeleteAndReplaceWith(NULL);
106 : } else {
107 : // The only purpose of a HForceRepresentation is to represent the value
108 : // after the (possible) HChange instruction. We make it disappear.
109 10791937 : if (value->IsForceRepresentation()) {
110 61156 : value->DeleteAndReplaceWith(HForceRepresentation::cast(value)->value());
111 : }
112 : }
113 : }
114 :
115 :
116 283729 : void HRepresentationChangesPhase::Run() {
117 : // Compute truncation flag for phis:
118 : //
119 : // - Initially assume that all phis allow truncation to number and iteratively
120 : // remove the ones that are used in an operation that not do an implicit
121 : // ToNumber conversion.
122 : // - Also assume that all Integer32 phis allow ToInt32 truncation and all
123 : // Smi phis allow truncation to Smi.
124 : //
125 283729 : ZoneList<HPhi*> number_worklist(8, zone());
126 283730 : ZoneList<HPhi*> int_worklist(8, zone());
127 283730 : ZoneList<HPhi*> smi_worklist(8, zone());
128 :
129 567458 : const ZoneList<HPhi*>* phi_list(graph()->phi_list());
130 1201112 : for (int i = 0; i < phi_list->length(); i++) {
131 1517938 : HPhi* phi = phi_list->at(i);
132 316826 : if (phi->representation().IsInteger32()) {
133 : phi->SetFlag(HValue::kTruncatingToInt32);
134 264319 : } else if (phi->representation().IsSmi()) {
135 : phi->SetFlag(HValue::kTruncatingToSmi);
136 : phi->SetFlag(HValue::kTruncatingToInt32);
137 : }
138 : phi->SetFlag(HValue::kTruncatingToNumber);
139 : }
140 :
141 917382 : for (int i = 0; i < phi_list->length(); i++) {
142 316826 : HPhi* phi = phi_list->at(i);
143 316826 : HValue* value = NULL;
144 :
145 950478 : if (phi->CheckFlag(HValue::kTruncatingToNumber) &&
146 316826 : !phi->CheckUsesForFlag(HValue::kTruncatingToNumber, &value)) {
147 : number_worklist.Add(phi, zone());
148 : phi->ClearFlag(HValue::kTruncatingToNumber);
149 : phi->ClearFlag(HValue::kTruncatingToInt32);
150 : phi->ClearFlag(HValue::kTruncatingToSmi);
151 210168 : if (FLAG_trace_representation) {
152 : PrintF("#%d Phi is not truncating Number because of #%d %s\n",
153 0 : phi->id(), value->id(), value->Mnemonic());
154 : }
155 118259 : } else if (phi->representation().IsSmiOrInteger32() &&
156 11601 : !phi->CheckUsesForFlag(HValue::kTruncatingToInt32, &value)) {
157 : int_worklist.Add(phi, zone());
158 : phi->ClearFlag(HValue::kTruncatingToInt32);
159 : phi->ClearFlag(HValue::kTruncatingToSmi);
160 5036 : if (FLAG_trace_representation) {
161 : PrintF("#%d Phi is not truncating Int32 because of #%d %s\n",
162 0 : phi->id(), value->id(), value->Mnemonic());
163 : }
164 101782 : } else if (phi->representation().IsSmi() &&
165 160 : !phi->CheckUsesForFlag(HValue::kTruncatingToSmi, &value)) {
166 : smi_worklist.Add(phi, zone());
167 : phi->ClearFlag(HValue::kTruncatingToSmi);
168 0 : if (FLAG_trace_representation) {
169 : PrintF("#%d Phi is not truncating Smi because of #%d %s\n",
170 0 : phi->id(), value->id(), value->Mnemonic());
171 : }
172 : }
173 : }
174 :
175 547738 : while (!number_worklist.is_empty()) {
176 : HPhi* current = number_worklist.RemoveLast();
177 887379 : for (int i = current->OperandCount() - 1; i >= 0; --i) {
178 229835 : HValue* input = current->OperandAt(i);
179 853206 : if (input->IsPhi() && input->CheckFlag(HValue::kTruncatingToNumber)) {
180 53842 : if (FLAG_trace_representation) {
181 : PrintF("#%d Phi is not truncating Number because of #%d %s\n",
182 0 : input->id(), current->id(), current->Mnemonic());
183 : }
184 : input->ClearFlag(HValue::kTruncatingToNumber);
185 : input->ClearFlag(HValue::kTruncatingToInt32);
186 : input->ClearFlag(HValue::kTruncatingToSmi);
187 : number_worklist.Add(HPhi::cast(input), zone());
188 : }
189 : }
190 : }
191 :
192 288794 : while (!int_worklist.is_empty()) {
193 : HPhi* current = int_worklist.RemoveLast();
194 30404 : for (int i = 0; i < current->OperandCount(); ++i) {
195 375 : HValue* input = current->OperandAt(i);
196 10511 : if (input->IsPhi() &&
197 10511 : input->representation().IsSmiOrInteger32() &&
198 : input->CheckFlag(HValue::kTruncatingToInt32)) {
199 31 : if (FLAG_trace_representation) {
200 : PrintF("#%d Phi is not truncating Int32 because of #%d %s\n",
201 0 : input->id(), current->id(), current->Mnemonic());
202 : }
203 : input->ClearFlag(HValue::kTruncatingToInt32);
204 : int_worklist.Add(HPhi::cast(input), zone());
205 : }
206 : }
207 : }
208 :
209 283728 : while (!smi_worklist.is_empty()) {
210 : HPhi* current = smi_worklist.RemoveLast();
211 2 : for (int i = 0; i < current->OperandCount(); ++i) {
212 0 : HValue* input = current->OperandAt(i);
213 0 : if (input->IsPhi() &&
214 0 : input->representation().IsSmi() &&
215 : input->CheckFlag(HValue::kTruncatingToSmi)) {
216 0 : if (FLAG_trace_representation) {
217 : PrintF("#%d Phi is not truncating Smi because of #%d %s\n",
218 0 : input->id(), current->id(), current->Mnemonic());
219 : }
220 : input->ClearFlag(HValue::kTruncatingToSmi);
221 : smi_worklist.Add(HPhi::cast(input), zone());
222 : }
223 : }
224 : }
225 :
226 : const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
227 9590744 : for (int i = 0; i < blocks->length(); ++i) {
228 : // Process phi instructions first.
229 13818661 : const HBasicBlock* block(blocks->at(i));
230 : const ZoneList<HPhi*>* phis = block->phis();
231 9656928 : for (int j = 0; j < phis->length(); j++) {
232 5145281 : InsertRepresentationChangesForValue(phis->at(j));
233 : }
234 :
235 : // Process normal instructions.
236 39040052 : for (HInstruction* current = block->first(); current != NULL; ) {
237 : HInstruction* next = current->next();
238 30016761 : InsertRepresentationChangesForValue(current);
239 : current = next;
240 : }
241 : }
242 283730 : }
243 :
244 : } // namespace internal
245 : } // namespace v8
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