13842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// Copyright 2013 the V8 project authors. All rights reserved. 23842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// Use of this source code is governed by a BSD-style license that can be 33842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// found in the LICENSE file. 43842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 53842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz#include "src/hydrogen-uint32-analysis.h" 63842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 73842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitznamespace v8 { 83842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitznamespace internal { 93842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 103842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 113842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitzstatic bool IsUnsignedLoad(HLoadKeyed* instr) { 123842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz switch (instr->elements_kind()) { 133842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case EXTERNAL_UINT8_ELEMENTS: 143842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case EXTERNAL_UINT16_ELEMENTS: 153842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case EXTERNAL_UINT32_ELEMENTS: 163842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case EXTERNAL_UINT8_CLAMPED_ELEMENTS: 173842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case UINT8_ELEMENTS: 183842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case UINT16_ELEMENTS: 193842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case UINT32_ELEMENTS: 203842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz case UINT8_CLAMPED_ELEMENTS: 213842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return true; 223842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz default: 233842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return false; 243842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } 253842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz} 263842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 273842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 283842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitzstatic bool IsUint32Operation(HValue* instr) { 293842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return instr->IsShr() || 303842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz (instr->IsLoadKeyed() && IsUnsignedLoad(HLoadKeyed::cast(instr))) || 313842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz (instr->IsInteger32Constant() && instr->GetInteger32Constant() >= 0); 323842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz} 333842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 343842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 353842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitzbool HUint32AnalysisPhase::IsSafeUint32Use(HValue* val, HValue* use) { 363842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // Operations that operate on bits are safe. 373842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz if (use->IsBitwise() || use->IsShl() || use->IsSar() || use->IsShr()) { 383842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return true; 393842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } else if (use->IsSimulate()) { 403842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // Deoptimization has special support for uint32. 413842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return true; 423842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } else if (use->IsChange()) { 433842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // Conversions have special support for uint32. 443842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // This DCHECK guards that the conversion in question is actually 453842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // implemented. Do not extend the whitelist without adding 463842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // support to LChunkBuilder::DoChange(). 473842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz DCHECK(HChange::cast(use)->to().IsDouble() || 483842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz HChange::cast(use)->to().IsSmi() || 493842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz HChange::cast(use)->to().IsTagged()); 503842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return true; 513842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } else if (use->IsStoreKeyed()) { 523842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz HStoreKeyed* store = HStoreKeyed::cast(use); 530f9937485ea8c52cebd4512885d9e2decd5a3dddKen Werner if (store->is_external()) { 543842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // Storing a value into an external integer array is a bit level 553842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // operation. 563842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz if (store->value() == val) { 573842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz // Clamping or a conversion to double should have beed inserted. 583842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz DCHECK(store->elements_kind() != EXTERNAL_UINT8_CLAMPED_ELEMENTS); 593842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz DCHECK(store->elements_kind() != EXTERNAL_FLOAT32_ELEMENTS); 603842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz DCHECK(store->elements_kind() != EXTERNAL_FLOAT64_ELEMENTS); 613842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return true; 623842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } 633842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } 643842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } else if (use->IsCompareNumericAndBranch()) { 653842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz HCompareNumericAndBranch* c = HCompareNumericAndBranch::cast(use); 663842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return IsUint32Operation(c->left()) && IsUint32Operation(c->right()); 673842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz } 683842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 693842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz return false; 703842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz} 713842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 723842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz 733842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// Iterate over all uses and verify that they are uint32 safe: either don't 743842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// distinguish between int32 and uint32 due to their bitwise nature or 753842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// have special support for uint32 values. 763842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// Encountered phis are optimistically treated as safe uint32 uses, 773842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// marked with kUint32 flag and collected in the phis_ list. A separate 783842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// pass will be performed later by UnmarkUnsafePhis to clear kUint32 from 793842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz// phis that are not actually uint32-safe (it requires fix point iteration). 803842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitzbool HUint32AnalysisPhase::Uint32UsesAreSafe(HValue* uint32val) { 813842dac7333e42aa44531eda34ba55200b99ccf8Daniel Jacobowitz bool collect_phi_uses = false; 82 for (HUseIterator it(uint32val->uses()); !it.Done(); it.Advance()) { 83 HValue* use = it.value(); 84 85 if (use->IsPhi()) { 86 if (!use->CheckFlag(HInstruction::kUint32)) { 87 // There is a phi use of this value from a phi that is not yet 88 // collected in phis_ array. Separate pass is required. 89 collect_phi_uses = true; 90 } 91 92 // Optimistically treat phis as uint32 safe. 93 continue; 94 } 95 96 if (!IsSafeUint32Use(uint32val, use)) { 97 return false; 98 } 99 } 100 101 if (collect_phi_uses) { 102 for (HUseIterator it(uint32val->uses()); !it.Done(); it.Advance()) { 103 HValue* use = it.value(); 104 105 // There is a phi use of this value from a phi that is not yet 106 // collected in phis_ array. Separate pass is required. 107 if (use->IsPhi() && !use->CheckFlag(HInstruction::kUint32)) { 108 use->SetFlag(HInstruction::kUint32); 109 phis_.Add(HPhi::cast(use), zone()); 110 } 111 } 112 } 113 114 return true; 115} 116 117 118// Check if all operands to the given phi are marked with kUint32 flag. 119bool HUint32AnalysisPhase::CheckPhiOperands(HPhi* phi) { 120 if (!phi->CheckFlag(HInstruction::kUint32)) { 121 // This phi is not uint32 safe. No need to check operands. 122 return false; 123 } 124 125 for (int j = 0; j < phi->OperandCount(); j++) { 126 HValue* operand = phi->OperandAt(j); 127 if (!operand->CheckFlag(HInstruction::kUint32)) { 128 // Lazily mark constants that fit into uint32 range with kUint32 flag. 129 if (operand->IsInteger32Constant() && 130 operand->GetInteger32Constant() >= 0) { 131 operand->SetFlag(HInstruction::kUint32); 132 continue; 133 } 134 135 // This phi is not safe, some operands are not uint32 values. 136 return false; 137 } 138 } 139 140 return true; 141} 142 143 144// Remove kUint32 flag from the phi itself and its operands. If any operand 145// was a phi marked with kUint32 place it into a worklist for 146// transitive clearing of kUint32 flag. 147void HUint32AnalysisPhase::UnmarkPhi(HPhi* phi, ZoneList<HPhi*>* worklist) { 148 phi->ClearFlag(HInstruction::kUint32); 149 for (int j = 0; j < phi->OperandCount(); j++) { 150 HValue* operand = phi->OperandAt(j); 151 if (operand->CheckFlag(HInstruction::kUint32)) { 152 operand->ClearFlag(HInstruction::kUint32); 153 if (operand->IsPhi()) { 154 worklist->Add(HPhi::cast(operand), zone()); 155 } 156 } 157 } 158} 159 160 161void HUint32AnalysisPhase::UnmarkUnsafePhis() { 162 // No phis were collected. Nothing to do. 163 if (phis_.length() == 0) return; 164 165 // Worklist used to transitively clear kUint32 from phis that 166 // are used as arguments to other phis. 167 ZoneList<HPhi*> worklist(phis_.length(), zone()); 168 169 // Phi can be used as a uint32 value if and only if 170 // all its operands are uint32 values and all its 171 // uses are uint32 safe. 172 173 // Iterate over collected phis and unmark those that 174 // are unsafe. When unmarking phi unmark its operands 175 // and add it to the worklist if it is a phi as well. 176 // Phis that are still marked as safe are shifted down 177 // so that all safe phis form a prefix of the phis_ array. 178 int phi_count = 0; 179 for (int i = 0; i < phis_.length(); i++) { 180 HPhi* phi = phis_[i]; 181 182 if (CheckPhiOperands(phi) && Uint32UsesAreSafe(phi)) { 183 phis_[phi_count++] = phi; 184 } else { 185 UnmarkPhi(phi, &worklist); 186 } 187 } 188 189 // Now phis array contains only those phis that have safe 190 // non-phi uses. Start transitively clearing kUint32 flag 191 // from phi operands of discovered non-safe phis until 192 // only safe phis are left. 193 while (!worklist.is_empty()) { 194 while (!worklist.is_empty()) { 195 HPhi* phi = worklist.RemoveLast(); 196 UnmarkPhi(phi, &worklist); 197 } 198 199 // Check if any operands to safe phis were unmarked 200 // turning a safe phi into unsafe. The same value 201 // can flow into several phis. 202 int new_phi_count = 0; 203 for (int i = 0; i < phi_count; i++) { 204 HPhi* phi = phis_[i]; 205 206 if (CheckPhiOperands(phi)) { 207 phis_[new_phi_count++] = phi; 208 } else { 209 UnmarkPhi(phi, &worklist); 210 } 211 } 212 phi_count = new_phi_count; 213 } 214} 215 216 217void HUint32AnalysisPhase::Run() { 218 if (!graph()->has_uint32_instructions()) return; 219 220 ZoneList<HInstruction*>* uint32_instructions = graph()->uint32_instructions(); 221 for (int i = 0; i < uint32_instructions->length(); ++i) { 222 // Analyze instruction and mark it with kUint32 if all 223 // its uses are uint32 safe. 224 HInstruction* current = uint32_instructions->at(i); 225 if (current->IsLinked() && 226 current->representation().IsInteger32() && 227 Uint32UsesAreSafe(current)) { 228 current->SetFlag(HInstruction::kUint32); 229 } 230 } 231 232 // Some phis might have been optimistically marked with kUint32 flag. 233 // Remove this flag from those phis that are unsafe and propagate 234 // this information transitively potentially clearing kUint32 flag 235 // from some non-phi operations that are used as operands to unsafe phis. 236 UnmarkUnsafePhis(); 237} 238 239 240} } // namespace v8::internal 241