| /* | |
| * Copyright (C) 2015 The Android Open Source Project | |
| * | |
| * Licensed under the Apache License, Version 2.0 (the "License"); | |
| * you may not use this file except in compliance with the License. | |
| * You may obtain a copy of the License at | |
| * | |
| * http://www.apache.org/licenses/LICENSE-2.0 | |
| * | |
| * Unless required by applicable law or agreed to in writing, software | |
| * distributed under the License is distributed on an "AS IS" BASIS, | |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| * See the License for the specific language governing permissions and | |
| * limitations under the License. | |
| */ | |
| #include "induction_var_range.h" | |
| #include <limits> | |
| #include "optimizing/nodes.h" | |
| namespace art HIDDEN { | |
| /** Returns true if 64-bit constant fits in 32-bit constant. */ | |
| static bool CanLongValueFitIntoInt(int64_t c) { | |
| return std::numeric_limits<int32_t>::min() <= c && c <= std::numeric_limits<int32_t>::max(); | |
| } | |
| /** Returns true if 32-bit addition can be done safely. */ | |
| static bool IsSafeAdd(int32_t c1, int32_t c2) { | |
| return CanLongValueFitIntoInt(static_cast<int64_t>(c1) + static_cast<int64_t>(c2)); | |
| } | |
| /** Returns true if 32-bit subtraction can be done safely. */ | |
| static bool IsSafeSub(int32_t c1, int32_t c2) { | |
| return CanLongValueFitIntoInt(static_cast<int64_t>(c1) - static_cast<int64_t>(c2)); | |
| } | |
| /** Returns true if 32-bit multiplication can be done safely. */ | |
| static bool IsSafeMul(int32_t c1, int32_t c2) { | |
| return CanLongValueFitIntoInt(static_cast<int64_t>(c1) * static_cast<int64_t>(c2)); | |
| } | |
| /** Returns true if 32-bit division can be done safely. */ | |
| static bool IsSafeDiv(int32_t c1, int32_t c2) { | |
| return c2 != 0 && CanLongValueFitIntoInt(static_cast<int64_t>(c1) / static_cast<int64_t>(c2)); | |
| } | |
| /** Computes a * b for a,b > 0 (at least until first overflow happens). */ | |
| static int64_t SafeMul(int64_t a, int64_t b, /*out*/ bool* overflow) { | |
| int64_t result; | |
| if (__builtin_mul_overflow(a, b, &result)) { | |
| *overflow = true; | |
| } | |
| return result; | |
| } | |
| /** Returns b^e for b,e > 0. Sets overflow if arithmetic wrap-around occurred. */ | |
| static int64_t IntPow(int64_t b, int64_t e, /*out*/ bool* overflow) { | |
| DCHECK_LT(0, b); | |
| DCHECK_LT(0, e); | |
| int64_t pow = 1; | |
| while (e) { | |
| if (e & 1) { | |
| pow = SafeMul(pow, b, overflow); | |
| } | |
| e >>= 1; | |
| if (e) { | |
| b = SafeMul(b, b, overflow); | |
| } | |
| } | |
| return pow; | |
| } | |
| /** Hunts "under the hood" for a suitable instruction at the hint. */ | |
| static bool IsMaxAtHint( | |
| HInstruction* instruction, HInstruction* hint, /*out*/HInstruction** suitable) { | |
| if (instruction->IsMin()) { | |
| // For MIN(x, y), return most suitable x or y as maximum. | |
| return IsMaxAtHint(instruction->InputAt(0), hint, suitable) || | |
| IsMaxAtHint(instruction->InputAt(1), hint, suitable); | |
| } else { | |
| *suitable = instruction; | |
| return HuntForDeclaration(instruction) == hint; | |
| } | |
| } | |
| /** Post-analysis simplification of a minimum value that makes the bound more useful to clients. */ | |
| static InductionVarRange::Value SimplifyMin(InductionVarRange::Value v) { | |
| if (v.is_known && v.a_constant == 1 && v.b_constant <= 0) { | |
| // If a == 1, instruction >= 0 and b <= 0, just return the constant b. | |
| // No arithmetic wrap-around can occur. | |
| if (IsGEZero(v.instruction)) { | |
| return InductionVarRange::Value(v.b_constant); | |
| } | |
| } | |
| return v; | |
| } | |
| /** Post-analysis simplification of a maximum value that makes the bound more useful to clients. */ | |
| static InductionVarRange::Value SimplifyMax(InductionVarRange::Value v, HInstruction* hint) { | |
| if (v.is_known && v.a_constant >= 1) { | |
| // An upper bound a * (length / a) + b, where a >= 1, can be conservatively rewritten as | |
| // length + b because length >= 0 is true. | |
| int64_t value; | |
| if (v.instruction->IsDiv() && | |
| v.instruction->InputAt(0)->IsArrayLength() && | |
| IsInt64AndGet(v.instruction->InputAt(1), &value) && v.a_constant == value) { | |
| return InductionVarRange::Value(v.instruction->InputAt(0), 1, v.b_constant); | |
| } | |
| // If a == 1, the most suitable one suffices as maximum value. | |
| HInstruction* suitable = nullptr; | |
| if (v.a_constant == 1 && IsMaxAtHint(v.instruction, hint, &suitable)) { | |
| return InductionVarRange::Value(suitable, 1, v.b_constant); | |
| } | |
| } | |
| return v; | |
| } | |
| /** Tests for a constant value. */ | |
| static bool IsConstantValue(InductionVarRange::Value v) { | |
| return v.is_known && v.a_constant == 0; | |
| } | |
| /** Corrects a value for type to account for arithmetic wrap-around in lower precision. */ | |
| static InductionVarRange::Value CorrectForType(InductionVarRange::Value v, DataType::Type type) { | |
| switch (type) { | |
| case DataType::Type::kUint8: | |
| case DataType::Type::kInt8: | |
| case DataType::Type::kUint16: | |
| case DataType::Type::kInt16: { | |
| // Constants within range only. | |
| // TODO: maybe some room for improvement, like allowing widening conversions | |
| int32_t min = DataType::MinValueOfIntegralType(type); | |
| int32_t max = DataType::MaxValueOfIntegralType(type); | |
| return (IsConstantValue(v) && min <= v.b_constant && v.b_constant <= max) | |
| ? v | |
| : InductionVarRange::Value(); | |
| } | |
| default: | |
| return v; | |
| } | |
| } | |
| /** Inserts an instruction. */ | |
| static HInstruction* Insert(HBasicBlock* block, HInstruction* instruction) { | |
| DCHECK(block != nullptr); | |
| DCHECK(block->GetLastInstruction() != nullptr) << block->GetBlockId(); | |
| DCHECK(instruction != nullptr); | |
| block->InsertInstructionBefore(instruction, block->GetLastInstruction()); | |
| return instruction; | |
| } | |
| /** Obtains loop's control instruction. */ | |
| static HInstruction* GetLoopControl(const HLoopInformation* loop) { | |
| DCHECK(loop != nullptr); | |
| return loop->GetHeader()->GetLastInstruction(); | |
| } | |
| /** Determines whether the `context` is in the body of the `loop`. */ | |
| static bool IsContextInBody(const HBasicBlock* context, const HLoopInformation* loop) { | |
| DCHECK(loop != nullptr); | |
| // We're currently classifying trip count only for the exit condition from loop header. | |
| // All other blocks in the loop are considered loop body. | |
| return context != loop->GetHeader() && loop->Contains(*context); | |
| } | |
| /** Determines whether to use the full trip count for given `context`, `loop` and `is_min`. */ | |
| bool UseFullTripCount(const HBasicBlock* context, const HLoopInformation* loop, bool is_min) { | |
| // We're currently classifying trip count only for the exit condition from loop header. | |
| // So, we should call this helper function only if the loop control is an `HIf` with | |
| // one edge leaving the loop. The loop header is the only block that's both inside | |
| // the loop and not in the loop body. | |
| DCHECK(GetLoopControl(loop)->IsIf()); | |
| DCHECK_NE(loop->Contains(*GetLoopControl(loop)->AsIf()->IfTrueSuccessor()), | |
| loop->Contains(*GetLoopControl(loop)->AsIf()->IfFalseSuccessor())); | |
| if (loop->Contains(*context)) { | |
| // Use the full trip count if determining the maximum and context is not in the loop body. | |
| DCHECK_NE(context == loop->GetHeader(), IsContextInBody(context, loop)); | |
| return !is_min && context == loop->GetHeader(); | |
| } else { | |
| // Trip count after the loop is always the maximum (ignoring `is_min`), | |
| // as long as the `context` is dominated by the loop control exit block. | |
| // If there are additional exit edges, the value is unknown on those paths. | |
| HInstruction* loop_control = GetLoopControl(loop); | |
| HBasicBlock* then_block = loop_control->AsIf()->IfTrueSuccessor(); | |
| HBasicBlock* else_block = loop_control->AsIf()->IfFalseSuccessor(); | |
| HBasicBlock* loop_exit_block = loop->Contains(*then_block) ? else_block : then_block; | |
| return loop_exit_block->Dominates(context); | |
| } | |
| } | |
| // | |
| // Public class methods. | |
| // | |
| InductionVarRange::InductionVarRange(HInductionVarAnalysis* induction_analysis) | |
| : induction_analysis_(induction_analysis), | |
| chase_hint_(nullptr) { | |
| DCHECK(induction_analysis != nullptr); | |
| } | |
| bool InductionVarRange::GetInductionRange(const HBasicBlock* context, | |
| HInstruction* instruction, | |
| HInstruction* chase_hint, | |
| /*out*/Value* min_val, | |
| /*out*/Value* max_val, | |
| /*out*/bool* needs_finite_test) { | |
| const HLoopInformation* loop = nullptr; | |
| HInductionVarAnalysis::InductionInfo* info = nullptr; | |
| HInductionVarAnalysis::InductionInfo* trip = nullptr; | |
| if (!HasInductionInfo(context, instruction, &loop, &info, &trip)) { | |
| return false; | |
| } | |
| // Type int or lower (this is not too restrictive since intended clients, like | |
| // bounds check elimination, will have truncated higher precision induction | |
| // at their use point already). | |
| switch (info->type) { | |
| case DataType::Type::kUint8: | |
| case DataType::Type::kInt8: | |
| case DataType::Type::kUint16: | |
| case DataType::Type::kInt16: | |
| case DataType::Type::kInt32: | |
| break; | |
| default: | |
| return false; | |
| } | |
| // Find range. | |
| chase_hint_ = chase_hint; | |
| int64_t stride_value = 0; | |
| *min_val = SimplifyMin(GetVal(context, loop, info, trip, /*is_min=*/ true)); | |
| *max_val = SimplifyMax(GetVal(context, loop, info, trip, /*is_min=*/ false), chase_hint); | |
| *needs_finite_test = | |
| NeedsTripCount(context, loop, info, &stride_value) && IsUnsafeTripCount(trip); | |
| chase_hint_ = nullptr; | |
| // Retry chasing constants for wrap-around (merge sensitive). | |
| if (!min_val->is_known && info->induction_class == HInductionVarAnalysis::kWrapAround) { | |
| *min_val = SimplifyMin(GetVal(context, loop, info, trip, /*is_min=*/ true)); | |
| } | |
| return true; | |
| } | |
| bool InductionVarRange::CanGenerateRange(const HBasicBlock* context, | |
| HInstruction* instruction, | |
| /*out*/bool* needs_finite_test, | |
| /*out*/bool* needs_taken_test) { | |
| bool is_last_value = false; | |
| int64_t stride_value = 0; | |
| return GenerateRangeOrLastValue(context, | |
| instruction, | |
| is_last_value, | |
| nullptr, | |
| nullptr, | |
| nullptr, | |
| nullptr, | |
| nullptr, // nothing generated yet | |
| &stride_value, | |
| needs_finite_test, | |
| needs_taken_test) && | |
| (stride_value == -1 || | |
| stride_value == 0 || | |
| stride_value == 1); // avoid arithmetic wrap-around anomalies. | |
| } | |
| void InductionVarRange::GenerateRange(const HBasicBlock* context, | |
| HInstruction* instruction, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| /*out*/HInstruction** lower, | |
| /*out*/HInstruction** upper) { | |
| bool is_last_value = false; | |
| int64_t stride_value = 0; | |
| bool b1, b2; // unused | |
| if (!GenerateRangeOrLastValue(context, | |
| instruction, | |
| is_last_value, | |
| graph, | |
| block, | |
| lower, | |
| upper, | |
| nullptr, | |
| &stride_value, | |
| &b1, | |
| &b2) || | |
| (stride_value != -1 && | |
| stride_value != 0 && | |
| stride_value != 1)) { | |
| LOG(FATAL) << "Failed precondition: CanGenerateRange()"; | |
| } | |
| } | |
| HInstruction* InductionVarRange::GenerateTakenTest(HInstruction* loop_control, | |
| HGraph* graph, | |
| HBasicBlock* block) { | |
| const HBasicBlock* context = loop_control->GetBlock(); | |
| HInstruction* taken_test = nullptr; | |
| bool is_last_value = false; | |
| int64_t stride_value = 0; | |
| bool b1, b2; // unused | |
| if (!GenerateRangeOrLastValue(context, | |
| loop_control, | |
| is_last_value, | |
| graph, | |
| block, | |
| nullptr, | |
| nullptr, | |
| &taken_test, | |
| &stride_value, | |
| &b1, | |
| &b2) || | |
| (stride_value != -1 && | |
| stride_value != 0 && | |
| stride_value != 1)) { | |
| LOG(FATAL) << "Failed precondition: CanGenerateRange()"; | |
| } | |
| return taken_test; | |
| } | |
| bool InductionVarRange::CanGenerateLastValue(HInstruction* instruction) { | |
| const HBasicBlock* context = instruction->GetBlock(); | |
| bool is_last_value = true; | |
| int64_t stride_value = 0; | |
| bool needs_finite_test = false; | |
| bool needs_taken_test = false; | |
| return GenerateRangeOrLastValue(context, | |
| instruction, | |
| is_last_value, | |
| nullptr, | |
| nullptr, | |
| nullptr, | |
| nullptr, | |
| nullptr, // nothing generated yet | |
| &stride_value, | |
| &needs_finite_test, | |
| &needs_taken_test) | |
| && !needs_finite_test && !needs_taken_test; | |
| } | |
| HInstruction* InductionVarRange::GenerateLastValue(HInstruction* instruction, | |
| HGraph* graph, | |
| HBasicBlock* block) { | |
| const HBasicBlock* context = instruction->GetBlock(); | |
| HInstruction* last_value = nullptr; | |
| bool is_last_value = true; | |
| int64_t stride_value = 0; | |
| bool needs_finite_test = false; | |
| bool needs_taken_test = false; | |
| if (!GenerateRangeOrLastValue(context, | |
| instruction, | |
| is_last_value, | |
| graph, | |
| block, | |
| &last_value, | |
| &last_value, | |
| nullptr, | |
| &stride_value, | |
| &needs_finite_test, | |
| &needs_taken_test) || | |
| needs_finite_test || | |
| needs_taken_test) { | |
| LOG(FATAL) << "Failed precondition: CanGenerateLastValue()"; | |
| } | |
| return last_value; | |
| } | |
| void InductionVarRange::Replace(HInstruction* instruction, | |
| HInstruction* fetch, | |
| HInstruction* replacement) { | |
| for (HLoopInformation* lp = instruction->GetBlock()->GetLoopInformation(); // closest enveloping loop | |
| lp != nullptr; | |
| lp = lp->GetPreHeader()->GetLoopInformation()) { | |
| // Update loop's InductionInfo about fetch. | |
| ReplaceInduction(induction_analysis_->LookupInfo(lp, fetch), fetch, replacement); | |
| // Update loop's trip-count information. | |
| ReplaceInduction(induction_analysis_->LookupInfo(lp, GetLoopControl(lp)), fetch, replacement); | |
| } | |
| } | |
| bool InductionVarRange::IsFinite(const HLoopInformation* loop, /*out*/ int64_t* trip_count) const { | |
| bool is_constant_unused = false; | |
| return CheckForFiniteAndConstantProps(loop, &is_constant_unused, trip_count); | |
| } | |
| bool InductionVarRange::HasKnownTripCount(const HLoopInformation* loop, | |
| /*out*/ int64_t* trip_count) const { | |
| bool is_constant = false; | |
| CheckForFiniteAndConstantProps(loop, &is_constant, trip_count); | |
| // Set negative trip counts as 0, since it means that no trips would happen. Note that if the | |
| // `is_constant` value is false, `trip_count` would be disregareded. | |
| if (*trip_count < 0) { | |
| *trip_count = 0; | |
| } | |
| return is_constant; | |
| } | |
| bool InductionVarRange::IsUnitStride(const HBasicBlock* context, | |
| HInstruction* instruction, | |
| HGraph* graph, | |
| /*out*/ HInstruction** offset) const { | |
| const HLoopInformation* loop = nullptr; | |
| HInductionVarAnalysis::InductionInfo* info = nullptr; | |
| HInductionVarAnalysis::InductionInfo* trip = nullptr; | |
| if (HasInductionInfo(context, instruction, &loop, &info, &trip)) { | |
| if (info->induction_class == HInductionVarAnalysis::kLinear && | |
| !HInductionVarAnalysis::IsNarrowingLinear(info)) { | |
| int64_t stride_value = 0; | |
| if (IsConstant(context, loop, info->op_a, kExact, &stride_value) && stride_value == 1) { | |
| int64_t off_value = 0; | |
| if (IsConstant(context, loop, info->op_b, kExact, &off_value)) { | |
| *offset = graph->GetConstant(info->op_b->type, off_value); | |
| } else if (info->op_b->operation == HInductionVarAnalysis::kFetch) { | |
| *offset = info->op_b->fetch; | |
| } else { | |
| return false; | |
| } | |
| return true; | |
| } | |
| } | |
| } | |
| return false; | |
| } | |
| HInstruction* InductionVarRange::GenerateTripCount(const HLoopInformation* loop, | |
| HGraph* graph, | |
| HBasicBlock* block) { | |
| HInstruction* loop_control = GetLoopControl(loop); | |
| HInductionVarAnalysis::InductionInfo *trip = induction_analysis_->LookupInfo(loop, loop_control); | |
| if (trip != nullptr && !IsUnsafeTripCount(trip)) { | |
| const HBasicBlock* context = loop_control->GetBlock(); | |
| HInstruction* taken_test = nullptr; | |
| HInstruction* trip_expr = nullptr; | |
| if (IsBodyTripCount(trip)) { | |
| if (!GenerateCode(context, | |
| loop, | |
| trip->op_b, | |
| /*trip=*/ nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/ false, | |
| &taken_test)) { | |
| return nullptr; | |
| } | |
| } | |
| if (GenerateCode(context, | |
| loop, | |
| trip->op_a, | |
| /*trip=*/ nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/ false, | |
| &trip_expr)) { | |
| if (taken_test != nullptr) { | |
| HInstruction* zero = graph->GetConstant(trip->type, 0); | |
| ArenaAllocator* allocator = graph->GetAllocator(); | |
| trip_expr = Insert(block, new (allocator) HSelect(taken_test, trip_expr, zero, kNoDexPc)); | |
| } | |
| return trip_expr; | |
| } | |
| } | |
| return nullptr; | |
| } | |
| // | |
| // Private class methods. | |
| // | |
| bool InductionVarRange::CheckForFiniteAndConstantProps(const HLoopInformation* loop, | |
| /*out*/ bool* is_constant, | |
| /*out*/ int64_t* trip_count) const { | |
| HInstruction* loop_control = GetLoopControl(loop); | |
| HInductionVarAnalysis::InductionInfo *trip = induction_analysis_->LookupInfo(loop, loop_control); | |
| if (trip != nullptr && !IsUnsafeTripCount(trip)) { | |
| const HBasicBlock* context = loop_control->GetBlock(); | |
| *is_constant = IsConstant(context, loop, trip->op_a, kExact, trip_count); | |
| return true; | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::IsConstant(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| ConstantRequest request, | |
| /*out*/ int64_t* value) const { | |
| if (info != nullptr) { | |
| // A direct 32-bit or 64-bit constant fetch. This immediately satisfies | |
| // any of the three requests (kExact, kAtMost, and KAtLeast). | |
| if (info->induction_class == HInductionVarAnalysis::kInvariant && | |
| info->operation == HInductionVarAnalysis::kFetch) { | |
| if (IsInt64AndGet(info->fetch, value)) { | |
| return true; | |
| } | |
| } | |
| // Try range analysis on the invariant, only accept a proper range | |
| // to avoid arithmetic wrap-around anomalies. | |
| Value min_val = GetVal(context, loop, info, /*trip=*/ nullptr, /*is_min=*/ true); | |
| Value max_val = GetVal(context, loop, info, /*trip=*/ nullptr, /*is_min=*/ false); | |
| if (IsConstantValue(min_val) && | |
| IsConstantValue(max_val) && min_val.b_constant <= max_val.b_constant) { | |
| if ((request == kExact && min_val.b_constant == max_val.b_constant) || request == kAtMost) { | |
| *value = max_val.b_constant; | |
| return true; | |
| } else if (request == kAtLeast) { | |
| *value = min_val.b_constant; | |
| return true; | |
| } | |
| } | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::HasInductionInfo( | |
| const HBasicBlock* context, | |
| HInstruction* instruction, | |
| /*out*/ const HLoopInformation** loop, | |
| /*out*/ HInductionVarAnalysis::InductionInfo** info, | |
| /*out*/ HInductionVarAnalysis::InductionInfo** trip) const { | |
| DCHECK(context != nullptr); | |
| HLoopInformation* lp = context->GetLoopInformation(); // closest enveloping loop | |
| if (lp != nullptr) { | |
| HInductionVarAnalysis::InductionInfo* i = induction_analysis_->LookupInfo(lp, instruction); | |
| if (i != nullptr) { | |
| *loop = lp; | |
| *info = i; | |
| *trip = induction_analysis_->LookupInfo(lp, GetLoopControl(lp)); | |
| return true; | |
| } | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::IsWellBehavedTripCount(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* trip) const { | |
| if (trip != nullptr) { | |
| // Both bounds that define a trip-count are well-behaved if they either are not defined | |
| // in any loop, or are contained in a proper interval. This allows finding the min/max | |
| // of an expression by chasing outward. | |
| InductionVarRange range(induction_analysis_); | |
| HInductionVarAnalysis::InductionInfo* lower = trip->op_b->op_a; | |
| HInductionVarAnalysis::InductionInfo* upper = trip->op_b->op_b; | |
| int64_t not_used = 0; | |
| return | |
| (!HasFetchInLoop(lower) || range.IsConstant(context, loop, lower, kAtLeast, ¬_used)) && | |
| (!HasFetchInLoop(upper) || range.IsConstant(context, loop, upper, kAtLeast, ¬_used)); | |
| } | |
| return true; | |
| } | |
| bool InductionVarRange::HasFetchInLoop(HInductionVarAnalysis::InductionInfo* info) const { | |
| if (info != nullptr) { | |
| if (info->induction_class == HInductionVarAnalysis::kInvariant && | |
| info->operation == HInductionVarAnalysis::kFetch) { | |
| return info->fetch->GetBlock()->GetLoopInformation() != nullptr; | |
| } | |
| return HasFetchInLoop(info->op_a) || HasFetchInLoop(info->op_b); | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::NeedsTripCount(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| int64_t* stride_value) const { | |
| if (info != nullptr) { | |
| if (info->induction_class == HInductionVarAnalysis::kLinear) { | |
| return IsConstant(context, loop, info->op_a, kExact, stride_value); | |
| } else if (info->induction_class == HInductionVarAnalysis::kPolynomial) { | |
| return NeedsTripCount(context, loop, info->op_a, stride_value); | |
| } else if (info->induction_class == HInductionVarAnalysis::kWrapAround) { | |
| return NeedsTripCount(context, loop, info->op_b, stride_value); | |
| } | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::IsBodyTripCount(HInductionVarAnalysis::InductionInfo* trip) const { | |
| if (trip != nullptr) { | |
| if (trip->induction_class == HInductionVarAnalysis::kInvariant) { | |
| return trip->operation == HInductionVarAnalysis::kTripCountInBody || | |
| trip->operation == HInductionVarAnalysis::kTripCountInBodyUnsafe; | |
| } | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::IsUnsafeTripCount(HInductionVarAnalysis::InductionInfo* trip) const { | |
| if (trip != nullptr) { | |
| if (trip->induction_class == HInductionVarAnalysis::kInvariant) { | |
| return trip->operation == HInductionVarAnalysis::kTripCountInBodyUnsafe || | |
| trip->operation == HInductionVarAnalysis::kTripCountInLoopUnsafe; | |
| } | |
| } | |
| return false; | |
| } | |
| InductionVarRange::Value InductionVarRange::GetLinear(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| DCHECK(info != nullptr); | |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kLinear); | |
| // Detect common situation where an offset inside the trip-count cancels out during range | |
| // analysis (finding max a * (TC - 1) + OFFSET for a == 1 and TC = UPPER - OFFSET or finding | |
| // min a * (TC - 1) + OFFSET for a == -1 and TC = OFFSET - UPPER) to avoid losing information | |
| // with intermediate results that only incorporate single instructions. | |
| if (trip != nullptr) { | |
| HInductionVarAnalysis::InductionInfo* trip_expr = trip->op_a; | |
| if (trip_expr->type == info->type && trip_expr->operation == HInductionVarAnalysis::kSub) { | |
| int64_t stride_value = 0; | |
| if (IsConstant(context, loop, info->op_a, kExact, &stride_value)) { | |
| if (!is_min && stride_value == 1) { | |
| // Test original trip's negative operand (trip_expr->op_b) against offset of induction. | |
| if (HInductionVarAnalysis::InductionEqual(trip_expr->op_b, info->op_b)) { | |
| // Analyze cancelled trip with just the positive operand (trip_expr->op_a). | |
| HInductionVarAnalysis::InductionInfo cancelled_trip( | |
| trip->induction_class, | |
| trip->operation, | |
| trip_expr->op_a, | |
| trip->op_b, | |
| nullptr, | |
| trip->type); | |
| return GetVal(context, loop, &cancelled_trip, trip, is_min); | |
| } | |
| } else if (is_min && stride_value == -1) { | |
| // Test original trip's positive operand (trip_expr->op_a) against offset of induction. | |
| if (HInductionVarAnalysis::InductionEqual(trip_expr->op_a, info->op_b)) { | |
| // Analyze cancelled trip with just the negative operand (trip_expr->op_b). | |
| HInductionVarAnalysis::InductionInfo neg( | |
| HInductionVarAnalysis::kInvariant, | |
| HInductionVarAnalysis::kNeg, | |
| nullptr, | |
| trip_expr->op_b, | |
| nullptr, | |
| trip->type); | |
| HInductionVarAnalysis::InductionInfo cancelled_trip( | |
| trip->induction_class, trip->operation, &neg, trip->op_b, nullptr, trip->type); | |
| return SubValue(Value(0), GetVal(context, loop, &cancelled_trip, trip, !is_min)); | |
| } | |
| } | |
| } | |
| } | |
| } | |
| // General rule of linear induction a * i + b, for normalized 0 <= i < TC. | |
| return AddValue(GetMul(context, loop, info->op_a, trip, trip, is_min), | |
| GetVal(context, loop, info->op_b, trip, is_min)); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetPolynomial( | |
| const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| DCHECK(info != nullptr); | |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kPolynomial); | |
| int64_t a = 0; | |
| int64_t b = 0; | |
| if (IsConstant(context, loop, info->op_a->op_a, kExact, &a) && | |
| CanLongValueFitIntoInt(a) && | |
| a >= 0 && | |
| IsConstant(context, loop, info->op_a->op_b, kExact, &b) && | |
| CanLongValueFitIntoInt(b) && | |
| b >= 0) { | |
| // Evaluate bounds on sum_i=0^m-1(a * i + b) + c with a,b >= 0 for | |
| // maximum index value m as a * (m * (m-1)) / 2 + b * m + c. | |
| // Do not simply return `c` as minimum because the trip count may be non-zero | |
| // if the `context` is after the `loop` (and therefore ignoring `is_min`). | |
| Value c = GetVal(context, loop, info->op_b, trip, is_min); | |
| Value m = GetVal(context, loop, trip, trip, is_min); | |
| Value t = DivValue(MulValue(m, SubValue(m, Value(1))), Value(2)); | |
| Value x = MulValue(Value(a), t); | |
| Value y = MulValue(Value(b), m); | |
| return AddValue(AddValue(x, y), c); | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetGeometric(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| DCHECK(info != nullptr); | |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kGeometric); | |
| int64_t a = 0; | |
| int64_t f = 0; | |
| if (IsConstant(context, loop, info->op_a, kExact, &a) && | |
| CanLongValueFitIntoInt(a) && | |
| IsInt64AndGet(info->fetch, &f) && f >= 1) { | |
| // Conservative bounds on a * f^-i + b with f >= 1 can be computed without | |
| // trip count. Other forms would require a much more elaborate evaluation. | |
| const bool is_min_a = a >= 0 ? is_min : !is_min; | |
| if (info->operation == HInductionVarAnalysis::kDiv) { | |
| Value b = GetVal(context, loop, info->op_b, trip, is_min); | |
| return is_min_a ? b : AddValue(Value(a), b); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetFetch(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInstruction* instruction, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| // Special case when chasing constants: single instruction that denotes trip count in the | |
| // loop-body is minimal 1 and maximal, with safe trip-count, max int, | |
| if (chase_hint_ == nullptr && | |
| IsContextInBody(context, loop) && | |
| trip != nullptr && | |
| instruction == trip->op_a->fetch) { | |
| if (is_min) { | |
| return Value(1); | |
| } else if (!instruction->IsConstant() && !IsUnsafeTripCount(trip)) { | |
| return Value(std::numeric_limits<int32_t>::max()); | |
| } | |
| } | |
| // Unless at a constant or hint, chase the instruction a bit deeper into the HIR tree, so that | |
| // it becomes more likely range analysis will compare the same instructions as terminal nodes. | |
| int64_t value; | |
| if (IsInt64AndGet(instruction, &value) && CanLongValueFitIntoInt(value)) { | |
| // Proper constant reveals best information. | |
| return Value(static_cast<int32_t>(value)); | |
| } else if (instruction == chase_hint_) { | |
| // At hint, fetch is represented by itself. | |
| return Value(instruction, 1, 0); | |
| } else if (instruction->IsAdd()) { | |
| // Incorporate suitable constants in the chased value. | |
| if (IsInt64AndGet(instruction->InputAt(0), &value) && CanLongValueFitIntoInt(value)) { | |
| return AddValue(Value(static_cast<int32_t>(value)), | |
| GetFetch(context, loop, instruction->InputAt(1), trip, is_min)); | |
| } else if (IsInt64AndGet(instruction->InputAt(1), &value) && CanLongValueFitIntoInt(value)) { | |
| return AddValue(GetFetch(context, loop, instruction->InputAt(0), trip, is_min), | |
| Value(static_cast<int32_t>(value))); | |
| } | |
| } else if (instruction->IsSub()) { | |
| // Incorporate suitable constants in the chased value. | |
| if (IsInt64AndGet(instruction->InputAt(0), &value) && CanLongValueFitIntoInt(value)) { | |
| return SubValue(Value(static_cast<int32_t>(value)), | |
| GetFetch(context, loop, instruction->InputAt(1), trip, !is_min)); | |
| } else if (IsInt64AndGet(instruction->InputAt(1), &value) && CanLongValueFitIntoInt(value)) { | |
| return SubValue(GetFetch(context, loop, instruction->InputAt(0), trip, is_min), | |
| Value(static_cast<int32_t>(value))); | |
| } | |
| } else if (instruction->IsArrayLength()) { | |
| // Exploit length properties when chasing constants or chase into a new array declaration. | |
| if (chase_hint_ == nullptr) { | |
| return is_min ? Value(0) : Value(std::numeric_limits<int32_t>::max()); | |
| } else if (instruction->InputAt(0)->IsNewArray()) { | |
| return GetFetch( | |
| context, loop, instruction->InputAt(0)->AsNewArray()->GetLength(), trip, is_min); | |
| } | |
| } else if (instruction->IsTypeConversion()) { | |
| // Since analysis is 32-bit (or narrower), chase beyond widening along the path. | |
| // For example, this discovers the length in: for (long i = 0; i < a.length; i++); | |
| if (instruction->AsTypeConversion()->GetInputType() == DataType::Type::kInt32 && | |
| instruction->AsTypeConversion()->GetResultType() == DataType::Type::kInt64) { | |
| return GetFetch(context, loop, instruction->InputAt(0), trip, is_min); | |
| } | |
| } | |
| // Chase an invariant fetch that is defined by another loop if the trip-count used | |
| // so far is well-behaved in both bounds and the next trip-count is safe. | |
| // Example: | |
| // for (int i = 0; i <= 100; i++) // safe | |
| // for (int j = 0; j <= i; j++) // well-behaved | |
| // j is in range [0, i ] (if i is chase hint) | |
| // or in range [0, 100] (otherwise) | |
| // Example: | |
| // for (i = 0; i < 100; ++i) | |
| // <some-code> | |
| // for (j = 0; j < 10; ++j) | |
| // sum += i; // The `i` is a "fetch" of a loop Phi from the previous loop. | |
| const HLoopInformation* next_loop = nullptr; | |
| HInductionVarAnalysis::InductionInfo* next_info = nullptr; | |
| HInductionVarAnalysis::InductionInfo* next_trip = nullptr; | |
| if (HasInductionInfo(instruction->GetBlock(), instruction, &next_loop, &next_info, &next_trip) && | |
| IsWellBehavedTripCount(context, next_loop, trip) && | |
| !IsUnsafeTripCount(next_trip)) { | |
| return GetVal(context, next_loop, next_info, next_trip, is_min); | |
| } | |
| // Fetch is represented by itself. | |
| return Value(instruction, 1, 0); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetVal(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| if (info != nullptr) { | |
| switch (info->induction_class) { | |
| case HInductionVarAnalysis::kInvariant: | |
| // Invariants. | |
| switch (info->operation) { | |
| case HInductionVarAnalysis::kAdd: | |
| return AddValue(GetVal(context, loop, info->op_a, trip, is_min), | |
| GetVal(context, loop, info->op_b, trip, is_min)); | |
| case HInductionVarAnalysis::kSub: // second reversed! | |
| return SubValue(GetVal(context, loop, info->op_a, trip, is_min), | |
| GetVal(context, loop, info->op_b, trip, !is_min)); | |
| case HInductionVarAnalysis::kNeg: // second reversed! | |
| return SubValue(Value(0), | |
| GetVal(context, loop, info->op_b, trip, !is_min)); | |
| case HInductionVarAnalysis::kMul: | |
| return GetMul(context, loop, info->op_a, info->op_b, trip, is_min); | |
| case HInductionVarAnalysis::kDiv: | |
| return GetDiv(context, loop, info->op_a, info->op_b, trip, is_min); | |
| case HInductionVarAnalysis::kRem: | |
| return GetRem(context, loop, info->op_a, info->op_b); | |
| case HInductionVarAnalysis::kXor: | |
| return GetXor(context, loop, info->op_a, info->op_b); | |
| case HInductionVarAnalysis::kFetch: | |
| return GetFetch(context, loop, info->fetch, trip, is_min); | |
| case HInductionVarAnalysis::kTripCountInLoop: | |
| case HInductionVarAnalysis::kTripCountInLoopUnsafe: | |
| if (UseFullTripCount(context, loop, is_min)) { | |
| // Return the full trip count (do not subtract 1 as we do in loop body). | |
| return GetVal(context, loop, info->op_a, trip, is_min); | |
| } | |
| FALLTHROUGH_INTENDED; | |
| case HInductionVarAnalysis::kTripCountInBody: | |
| case HInductionVarAnalysis::kTripCountInBodyUnsafe: | |
| if (is_min) { | |
| return Value(0); | |
| } else if (IsContextInBody(context, loop)) { | |
| return SubValue(GetVal(context, loop, info->op_a, trip, is_min), Value(1)); | |
| } | |
| break; | |
| default: | |
| break; | |
| } | |
| break; | |
| case HInductionVarAnalysis::kLinear: | |
| return CorrectForType(GetLinear(context, loop, info, trip, is_min), info->type); | |
| case HInductionVarAnalysis::kPolynomial: | |
| return GetPolynomial(context, loop, info, trip, is_min); | |
| case HInductionVarAnalysis::kGeometric: | |
| return GetGeometric(context, loop, info, trip, is_min); | |
| case HInductionVarAnalysis::kWrapAround: | |
| case HInductionVarAnalysis::kPeriodic: | |
| return MergeVal(GetVal(context, loop, info->op_a, trip, is_min), | |
| GetVal(context, loop, info->op_b, trip, is_min), | |
| is_min); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetMul(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info1, | |
| HInductionVarAnalysis::InductionInfo* info2, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| // Constant times range. | |
| int64_t value = 0; | |
| if (IsConstant(context, loop, info1, kExact, &value)) { | |
| return MulRangeAndConstant(context, loop, value, info2, trip, is_min); | |
| } else if (IsConstant(context, loop, info2, kExact, &value)) { | |
| return MulRangeAndConstant(context, loop, value, info1, trip, is_min); | |
| } | |
| // Interval ranges. | |
| Value v1_min = GetVal(context, loop, info1, trip, /*is_min=*/ true); | |
| Value v1_max = GetVal(context, loop, info1, trip, /*is_min=*/ false); | |
| Value v2_min = GetVal(context, loop, info2, trip, /*is_min=*/ true); | |
| Value v2_max = GetVal(context, loop, info2, trip, /*is_min=*/ false); | |
| // Positive range vs. positive or negative range. | |
| if (IsConstantValue(v1_min) && v1_min.b_constant >= 0) { | |
| if (IsConstantValue(v2_min) && v2_min.b_constant >= 0) { | |
| return is_min ? MulValue(v1_min, v2_min) : MulValue(v1_max, v2_max); | |
| } else if (IsConstantValue(v2_max) && v2_max.b_constant <= 0) { | |
| return is_min ? MulValue(v1_max, v2_min) : MulValue(v1_min, v2_max); | |
| } | |
| } | |
| // Negative range vs. positive or negative range. | |
| if (IsConstantValue(v1_max) && v1_max.b_constant <= 0) { | |
| if (IsConstantValue(v2_min) && v2_min.b_constant >= 0) { | |
| return is_min ? MulValue(v1_min, v2_max) : MulValue(v1_max, v2_min); | |
| } else if (IsConstantValue(v2_max) && v2_max.b_constant <= 0) { | |
| return is_min ? MulValue(v1_max, v2_max) : MulValue(v1_min, v2_min); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetDiv(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info1, | |
| HInductionVarAnalysis::InductionInfo* info2, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| // Range divided by constant. | |
| int64_t value = 0; | |
| if (IsConstant(context, loop, info2, kExact, &value)) { | |
| return DivRangeAndConstant(context, loop, value, info1, trip, is_min); | |
| } | |
| // Interval ranges. | |
| Value v1_min = GetVal(context, loop, info1, trip, /*is_min=*/ true); | |
| Value v1_max = GetVal(context, loop, info1, trip, /*is_min=*/ false); | |
| Value v2_min = GetVal(context, loop, info2, trip, /*is_min=*/ true); | |
| Value v2_max = GetVal(context, loop, info2, trip, /*is_min=*/ false); | |
| // Positive range vs. positive or negative range. | |
| if (IsConstantValue(v1_min) && v1_min.b_constant >= 0) { | |
| if (IsConstantValue(v2_min) && v2_min.b_constant >= 0) { | |
| return is_min ? DivValue(v1_min, v2_max) : DivValue(v1_max, v2_min); | |
| } else if (IsConstantValue(v2_max) && v2_max.b_constant <= 0) { | |
| return is_min ? DivValue(v1_max, v2_max) : DivValue(v1_min, v2_min); | |
| } | |
| } | |
| // Negative range vs. positive or negative range. | |
| if (IsConstantValue(v1_max) && v1_max.b_constant <= 0) { | |
| if (IsConstantValue(v2_min) && v2_min.b_constant >= 0) { | |
| return is_min ? DivValue(v1_min, v2_min) : DivValue(v1_max, v2_max); | |
| } else if (IsConstantValue(v2_max) && v2_max.b_constant <= 0) { | |
| return is_min ? DivValue(v1_max, v2_min) : DivValue(v1_min, v2_max); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetRem( | |
| const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info1, | |
| HInductionVarAnalysis::InductionInfo* info2) const { | |
| int64_t v1 = 0; | |
| int64_t v2 = 0; | |
| // Only accept exact values. | |
| if (IsConstant(context, loop, info1, kExact, &v1) && | |
| IsConstant(context, loop, info2, kExact, &v2) && | |
| v2 != 0) { | |
| int64_t value = v1 % v2; | |
| if (CanLongValueFitIntoInt(value)) { | |
| return Value(static_cast<int32_t>(value)); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::GetXor( | |
| const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info1, | |
| HInductionVarAnalysis::InductionInfo* info2) const { | |
| int64_t v1 = 0; | |
| int64_t v2 = 0; | |
| // Only accept exact values. | |
| if (IsConstant(context, loop, info1, kExact, &v1) && | |
| IsConstant(context, loop, info2, kExact, &v2)) { | |
| int64_t value = v1 ^ v2; | |
| if (CanLongValueFitIntoInt(value)) { | |
| return Value(static_cast<int32_t>(value)); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::MulRangeAndConstant( | |
| const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| int64_t value, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| if (CanLongValueFitIntoInt(value)) { | |
| Value c(static_cast<int32_t>(value)); | |
| return MulValue(GetVal(context, loop, info, trip, is_min == value >= 0), c); | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::DivRangeAndConstant( | |
| const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| int64_t value, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| bool is_min) const { | |
| if (CanLongValueFitIntoInt(value)) { | |
| Value c(static_cast<int32_t>(value)); | |
| return DivValue(GetVal(context, loop, info, trip, is_min == value >= 0), c); | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::AddValue(Value v1, Value v2) const { | |
| if (v1.is_known && v2.is_known && IsSafeAdd(v1.b_constant, v2.b_constant)) { | |
| int32_t b = v1.b_constant + v2.b_constant; | |
| if (v1.a_constant == 0) { | |
| return Value(v2.instruction, v2.a_constant, b); | |
| } else if (v2.a_constant == 0) { | |
| return Value(v1.instruction, v1.a_constant, b); | |
| } else if (v1.instruction == v2.instruction && IsSafeAdd(v1.a_constant, v2.a_constant)) { | |
| return Value(v1.instruction, v1.a_constant + v2.a_constant, b); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::SubValue(Value v1, Value v2) const { | |
| if (v1.is_known && v2.is_known && IsSafeSub(v1.b_constant, v2.b_constant)) { | |
| int32_t b = v1.b_constant - v2.b_constant; | |
| if (v1.a_constant == 0 && IsSafeSub(0, v2.a_constant)) { | |
| return Value(v2.instruction, -v2.a_constant, b); | |
| } else if (v2.a_constant == 0) { | |
| return Value(v1.instruction, v1.a_constant, b); | |
| } else if (v1.instruction == v2.instruction && IsSafeSub(v1.a_constant, v2.a_constant)) { | |
| return Value(v1.instruction, v1.a_constant - v2.a_constant, b); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::MulValue(Value v1, Value v2) const { | |
| if (v1.is_known && v2.is_known) { | |
| if (v1.a_constant == 0) { | |
| if (IsSafeMul(v1.b_constant, v2.a_constant) && IsSafeMul(v1.b_constant, v2.b_constant)) { | |
| return Value(v2.instruction, v1.b_constant * v2.a_constant, v1.b_constant * v2.b_constant); | |
| } | |
| } else if (v2.a_constant == 0) { | |
| if (IsSafeMul(v1.a_constant, v2.b_constant) && IsSafeMul(v1.b_constant, v2.b_constant)) { | |
| return Value(v1.instruction, v1.a_constant * v2.b_constant, v1.b_constant * v2.b_constant); | |
| } | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::DivValue(Value v1, Value v2) const { | |
| if (v1.is_known && v2.is_known && v1.a_constant == 0 && v2.a_constant == 0) { | |
| if (IsSafeDiv(v1.b_constant, v2.b_constant)) { | |
| return Value(v1.b_constant / v2.b_constant); | |
| } | |
| } | |
| return Value(); | |
| } | |
| InductionVarRange::Value InductionVarRange::MergeVal(Value v1, Value v2, bool is_min) const { | |
| if (v1.is_known && v2.is_known) { | |
| if (v1.instruction == v2.instruction && v1.a_constant == v2.a_constant) { | |
| return Value(v1.instruction, v1.a_constant, | |
| is_min ? std::min(v1.b_constant, v2.b_constant) | |
| : std::max(v1.b_constant, v2.b_constant)); | |
| } | |
| } | |
| return Value(); | |
| } | |
| bool InductionVarRange::GenerateRangeOrLastValue(const HBasicBlock* context, | |
| HInstruction* instruction, | |
| bool is_last_value, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| /*out*/HInstruction** lower, | |
| /*out*/HInstruction** upper, | |
| /*out*/HInstruction** taken_test, | |
| /*out*/int64_t* stride_value, | |
| /*out*/bool* needs_finite_test, | |
| /*out*/bool* needs_taken_test) const { | |
| const HLoopInformation* loop = nullptr; | |
| HInductionVarAnalysis::InductionInfo* info = nullptr; | |
| HInductionVarAnalysis::InductionInfo* trip = nullptr; | |
| if (!HasInductionInfo(context, instruction, &loop, &info, &trip) || trip == nullptr) { | |
| return false; // codegen needs all information, including tripcount | |
| } | |
| // Determine what tests are needed. A finite test is needed if the evaluation code uses the | |
| // trip-count and the loop maybe unsafe (because in such cases, the index could "overshoot" | |
| // the computed range). A taken test is needed for any unknown trip-count, even if evaluation | |
| // code does not use the trip-count explicitly (since there could be an implicit relation | |
| // between e.g. an invariant subscript and a not-taken condition). | |
| *stride_value = 0; | |
| *needs_finite_test = NeedsTripCount(context, loop, info, stride_value) && IsUnsafeTripCount(trip); | |
| *needs_taken_test = IsBodyTripCount(trip); | |
| // Handle last value request. | |
| if (is_last_value) { | |
| DCHECK(!IsContextInBody(context, loop)); | |
| switch (info->induction_class) { | |
| case HInductionVarAnalysis::kLinear: | |
| if (*stride_value > 0) { | |
| lower = nullptr; | |
| return GenerateLastValueLinear( | |
| context, loop, info, trip, graph, block, /*is_min=*/false, upper, needs_taken_test); | |
| } else { | |
| upper = nullptr; | |
| return GenerateLastValueLinear( | |
| context, loop, info, trip, graph, block, /*is_min=*/true, lower, needs_taken_test); | |
| } | |
| case HInductionVarAnalysis::kPolynomial: | |
| return GenerateLastValuePolynomial(context, loop, info, trip, graph, block, lower); | |
| case HInductionVarAnalysis::kGeometric: | |
| return GenerateLastValueGeometric(context, loop, info, trip, graph, block, lower); | |
| case HInductionVarAnalysis::kWrapAround: | |
| return GenerateLastValueWrapAround(context, loop, info, trip, graph, block, lower); | |
| case HInductionVarAnalysis::kPeriodic: | |
| return GenerateLastValuePeriodic( | |
| context, loop, info, trip, graph, block, lower, needs_taken_test); | |
| default: | |
| return false; | |
| } | |
| } | |
| // Code generation for taken test: generate the code when requested or otherwise analyze | |
| // if code generation is feasible when taken test is needed. | |
| if (taken_test != nullptr) { | |
| return GenerateCode(context, | |
| loop, | |
| trip->op_b, | |
| /*trip=*/ nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/ false, | |
| taken_test); | |
| } else if (*needs_taken_test) { | |
| if (!GenerateCode(context, | |
| loop, | |
| trip->op_b, | |
| /*trip=*/ nullptr, | |
| /*graph=*/ nullptr, | |
| /*block=*/ nullptr, | |
| /*is_min=*/ false, | |
| /*result=*/ nullptr)) { | |
| return false; | |
| } | |
| } | |
| // Code generation for lower and upper. | |
| return | |
| // Success on lower if invariant (not set), or code can be generated. | |
| ((info->induction_class == HInductionVarAnalysis::kInvariant) || | |
| GenerateCode(context, loop, info, trip, graph, block, /*is_min=*/ true, lower)) && | |
| // And success on upper. | |
| GenerateCode(context, loop, info, trip, graph, block, /*is_min=*/ false, upper); | |
| } | |
| bool InductionVarRange::GenerateLastValueLinear(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| bool is_min, | |
| /*out*/ HInstruction** result, | |
| /*inout*/ bool* needs_taken_test) const { | |
| DataType::Type type = info->type; | |
| // Avoid any narrowing linear induction or any type mismatch between the linear induction and the | |
| // trip count expression. | |
| if (HInductionVarAnalysis::IsNarrowingLinear(info) || trip->type != type) { | |
| return false; | |
| } | |
| // Stride value must be a known constant that fits into int32. The stride will be the `i` in `a * | |
| // i + b`. | |
| int64_t stride_value = 0; | |
| if (!IsConstant(context, loop, info->op_a, kExact, &stride_value) || | |
| !CanLongValueFitIntoInt(stride_value)) { | |
| return false; | |
| } | |
| // We require the calculation of `a` to not overflow. | |
| const bool is_min_a = stride_value >= 0 ? is_min : !is_min; | |
| HInstruction* opa; | |
| HInstruction* opb; | |
| if (!GenerateCode(context, | |
| loop, | |
| trip, | |
| trip, | |
| graph, | |
| block, | |
| is_min_a, | |
| &opa, | |
| /*allow_potential_overflow=*/false) || | |
| !GenerateCode(context, loop, info->op_b, trip, graph, block, is_min, &opb)) { | |
| return false; | |
| } | |
| if (graph != nullptr) { | |
| ArenaAllocator* allocator = graph->GetAllocator(); | |
| HInstruction* oper; | |
| // Emit instructions for `a * i + b`. These are fine to overflow as they would have overflown | |
| // also if we had kept the loop. | |
| if (stride_value == 1) { | |
| oper = new (allocator) HAdd(type, opa, opb); | |
| } else if (stride_value == -1) { | |
| oper = new (graph->GetAllocator()) HSub(type, opb, opa); | |
| } else { | |
| HInstruction* mul = new (allocator) HMul(type, graph->GetConstant(type, stride_value), opa); | |
| oper = new (allocator) HAdd(type, Insert(block, mul), opb); | |
| } | |
| *result = Insert(block, oper); | |
| } | |
| if (*needs_taken_test) { | |
| if (TryGenerateTakenTest(context, loop, trip->op_b, graph, block, result, opb)) { | |
| *needs_taken_test = false; // taken care of | |
| } else { | |
| return false; | |
| } | |
| } | |
| return true; | |
| } | |
| bool InductionVarRange::GenerateLastValuePolynomial(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| /*out*/HInstruction** result) const { | |
| DCHECK(info != nullptr); | |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kPolynomial); | |
| // Detect known coefficients and trip count (always taken). | |
| int64_t a = 0; | |
| int64_t b = 0; | |
| int64_t m = 0; | |
| if (IsConstant(context, loop, info->op_a->op_a, kExact, &a) && | |
| IsConstant(context, loop, info->op_a->op_b, kExact, &b) && | |
| IsConstant(context, loop, trip->op_a, kExact, &m) && | |
| m >= 1) { | |
| // Evaluate bounds on sum_i=0^m-1(a * i + b) + c for known | |
| // maximum index value m as a * (m * (m-1)) / 2 + b * m + c. | |
| HInstruction* c = nullptr; | |
| if (GenerateCode(context, | |
| loop, | |
| info->op_b, | |
| /*trip=*/ nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/ false, | |
| graph ? &c : nullptr)) { | |
| if (graph != nullptr) { | |
| DataType::Type type = info->type; | |
| int64_t sum = a * ((m * (m - 1)) / 2) + b * m; | |
| if (type != DataType::Type::kInt64) { | |
| sum = static_cast<int32_t>(sum); // okay to truncate | |
| } | |
| *result = | |
| Insert(block, new (graph->GetAllocator()) HAdd(type, graph->GetConstant(type, sum), c)); | |
| } | |
| return true; | |
| } | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::GenerateLastValueGeometric(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| /*out*/HInstruction** result) const { | |
| DCHECK(info != nullptr); | |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kGeometric); | |
| // Detect known base and trip count (always taken). | |
| int64_t f = 0; | |
| int64_t m = 0; | |
| if (IsInt64AndGet(info->fetch, &f) && | |
| f >= 1 && | |
| IsConstant(context, loop, trip->op_a, kExact, &m) && | |
| m >= 1) { | |
| HInstruction* opa = nullptr; | |
| HInstruction* opb = nullptr; | |
| if (GenerateCode( | |
| context, loop, info->op_a, /*trip=*/ nullptr, graph, block, /*is_min=*/ false, &opa) && | |
| GenerateCode( | |
| context, loop, info->op_b, /*trip=*/ nullptr, graph, block, /*is_min=*/ false, &opb)) { | |
| if (graph != nullptr) { | |
| DataType::Type type = info->type; | |
| // Compute f ^ m for known maximum index value m. | |
| bool overflow = false; | |
| int64_t fpow = IntPow(f, m, &overflow); | |
| if (info->operation == HInductionVarAnalysis::kDiv) { | |
| // For division, any overflow truncates to zero. | |
| if (overflow || (type != DataType::Type::kInt64 && !CanLongValueFitIntoInt(fpow))) { | |
| fpow = 0; | |
| } | |
| } else if (type != DataType::Type::kInt64) { | |
| // For multiplication, okay to truncate to required precision. | |
| DCHECK(info->operation == HInductionVarAnalysis::kMul); | |
| fpow = static_cast<int32_t>(fpow); | |
| } | |
| // Generate code. | |
| if (fpow == 0) { | |
| // Special case: repeated mul/div always yields zero. | |
| *result = graph->GetConstant(type, 0); | |
| } else { | |
| // Last value: a * f ^ m + b or a * f ^ -m + b. | |
| HInstruction* e = nullptr; | |
| ArenaAllocator* allocator = graph->GetAllocator(); | |
| if (info->operation == HInductionVarAnalysis::kMul) { | |
| e = new (allocator) HMul(type, opa, graph->GetConstant(type, fpow)); | |
| } else { | |
| e = new (allocator) HDiv(type, opa, graph->GetConstant(type, fpow), kNoDexPc); | |
| } | |
| *result = Insert(block, new (allocator) HAdd(type, Insert(block, e), opb)); | |
| } | |
| } | |
| return true; | |
| } | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::GenerateLastValueWrapAround(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| /*out*/HInstruction** result) const { | |
| DCHECK(info != nullptr); | |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kWrapAround); | |
| // Count depth. | |
| int32_t depth = 0; | |
| for (; info->induction_class == HInductionVarAnalysis::kWrapAround; | |
| info = info->op_b, ++depth) {} | |
| // Handle wrap(x, wrap(.., y)) if trip count reaches an invariant at end. | |
| // TODO: generalize, but be careful to adjust the terminal. | |
| int64_t m = 0; | |
| if (info->induction_class == HInductionVarAnalysis::kInvariant && | |
| IsConstant(context, loop, trip->op_a, kExact, &m) && | |
| m >= depth) { | |
| return GenerateCode( | |
| context, loop, info, /*trip=*/ nullptr, graph, block, /*is_min=*/ false, result); | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::GenerateLastValuePeriodic(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| /*out*/ HInstruction** result, | |
| /*inout*/ bool* needs_taken_test) const { | |
| DCHECK(info != nullptr); | |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kPeriodic); | |
| // Count period and detect all-invariants. | |
| int64_t period = 1; | |
| bool all_invariants = true; | |
| HInductionVarAnalysis::InductionInfo* p = info; | |
| for (; p->induction_class == HInductionVarAnalysis::kPeriodic; p = p->op_b, ++period) { | |
| DCHECK_EQ(p->op_a->induction_class, HInductionVarAnalysis::kInvariant); | |
| if (p->op_a->operation != HInductionVarAnalysis::kFetch) { | |
| all_invariants = false; | |
| } | |
| } | |
| DCHECK_EQ(p->induction_class, HInductionVarAnalysis::kInvariant); | |
| if (p->operation != HInductionVarAnalysis::kFetch) { | |
| all_invariants = false; | |
| } | |
| // Don't rely on FP arithmetic to be precise, unless the full period | |
| // consist of pre-computed expressions only. | |
| if (info->type == DataType::Type::kFloat32 || info->type == DataType::Type::kFloat64) { | |
| if (!all_invariants) { | |
| return false; | |
| } | |
| } | |
| // Handle any periodic(x, periodic(.., y)) for known maximum index value m. | |
| int64_t m = 0; | |
| if (IsConstant(context, loop, trip->op_a, kExact, &m) && m >= 1) { | |
| int64_t li = m % period; | |
| for (int64_t i = 0; i < li; info = info->op_b, i++) {} | |
| if (info->induction_class == HInductionVarAnalysis::kPeriodic) { | |
| info = info->op_a; | |
| } | |
| return GenerateCode( | |
| context, loop, info, /*trip=*/ nullptr, graph, block, /*is_min=*/ false, result); | |
| } | |
| // Handle periodic(x, y) using even/odd-select on trip count. Enter trip count expression | |
| // directly to obtain the maximum index value t even if taken test is needed. | |
| HInstruction* x = nullptr; | |
| HInstruction* y = nullptr; | |
| HInstruction* t = nullptr; | |
| // Overflows when the stride is equal to `1` are fine since the periodicity is | |
| // `2` and the lowest bit is the same. Similar with `-1`. | |
| auto allow_potential_overflow = [&]() { | |
| int64_t stride_value = 0; | |
| return IsConstant(context, loop, trip->op_a->op_b, kExact, &stride_value) && | |
| (stride_value == 1 || stride_value == -1); | |
| }; | |
| if (period == 2 && | |
| GenerateCode(context, | |
| loop, | |
| info->op_a, | |
| /*trip=*/ nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/ false, | |
| graph ? &x : nullptr) && | |
| GenerateCode(context, | |
| loop, | |
| info->op_b, | |
| /*trip=*/ nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/ false, | |
| graph ? &y : nullptr) && | |
| GenerateCode(context, | |
| loop, | |
| trip->op_a, | |
| /*trip=*/ nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/ false, | |
| graph ? &t : nullptr, | |
| allow_potential_overflow())) { | |
| // During actual code generation (graph != nullptr), generate is_even ? x : y. | |
| if (graph != nullptr) { | |
| DataType::Type type = trip->type; | |
| ArenaAllocator* allocator = graph->GetAllocator(); | |
| HInstruction* msk = | |
| Insert(block, new (allocator) HAnd(type, t, graph->GetConstant(type, 1))); | |
| HInstruction* is_even = | |
| Insert(block, new (allocator) HEqual(msk, graph->GetConstant(type, 0), kNoDexPc)); | |
| *result = Insert(block, new (graph->GetAllocator()) HSelect(is_even, x, y, kNoDexPc)); | |
| } | |
| if (*needs_taken_test) { | |
| if (TryGenerateTakenTest(context, loop, trip->op_b, graph, block, result, x)) { | |
| *needs_taken_test = false; // taken care of | |
| } else { | |
| return false; | |
| } | |
| } | |
| return true; | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::GenerateCode(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HInductionVarAnalysis::InductionInfo* trip, | |
| HGraph* graph, // when set, code is generated | |
| HBasicBlock* block, | |
| bool is_min, | |
| /*out*/ HInstruction** result, | |
| bool allow_potential_overflow) const { | |
| if (info != nullptr) { | |
| // If during codegen, the result is not needed (nullptr), simply return success. | |
| if (graph != nullptr && result == nullptr) { | |
| return true; | |
| } | |
| // Handle current operation. | |
| DataType::Type type = info->type; | |
| HInstruction* opa = nullptr; | |
| HInstruction* opb = nullptr; | |
| switch (info->induction_class) { | |
| case HInductionVarAnalysis::kInvariant: | |
| // Invariants (note that since invariants only have other invariants as | |
| // sub expressions, viz. no induction, there is no need to adjust is_min). | |
| switch (info->operation) { | |
| case HInductionVarAnalysis::kAdd: | |
| case HInductionVarAnalysis::kSub: | |
| case HInductionVarAnalysis::kMul: | |
| case HInductionVarAnalysis::kDiv: | |
| case HInductionVarAnalysis::kRem: | |
| case HInductionVarAnalysis::kXor: | |
| case HInductionVarAnalysis::kLT: | |
| case HInductionVarAnalysis::kLE: | |
| case HInductionVarAnalysis::kGT: | |
| case HInductionVarAnalysis::kGE: | |
| if (GenerateCode(context, | |
| loop, | |
| info->op_a, | |
| trip, | |
| graph, | |
| block, | |
| is_min, | |
| &opa, | |
| allow_potential_overflow) && | |
| GenerateCode(context, | |
| loop, | |
| info->op_b, | |
| trip, | |
| graph, | |
| block, | |
| is_min, | |
| &opb, | |
| allow_potential_overflow)) { | |
| // Check for potentially invalid operations. | |
| if (!allow_potential_overflow) { | |
| switch (info->operation) { | |
| case HInductionVarAnalysis::kAdd: | |
| return TryGenerateAddWithoutOverflow( | |
| context, loop, info, graph, opa, opb, result); | |
| case HInductionVarAnalysis::kSub: | |
| return TryGenerateSubWithoutOverflow(context, loop, info, graph, opa, result); | |
| default: | |
| // The rest of the operations are not relevant in the cases where | |
| // `allow_potential_overflow` is false. Fall through to the allowed overflow | |
| // case. | |
| break; | |
| } | |
| } | |
| // Overflows here are accepted. | |
| if (graph != nullptr) { | |
| HInstruction* operation = nullptr; | |
| switch (info->operation) { | |
| case HInductionVarAnalysis::kAdd: | |
| operation = new (graph->GetAllocator()) HAdd(type, opa, opb); break; | |
| case HInductionVarAnalysis::kSub: | |
| operation = new (graph->GetAllocator()) HSub(type, opa, opb); break; | |
| case HInductionVarAnalysis::kMul: | |
| operation = new (graph->GetAllocator()) HMul(type, opa, opb, kNoDexPc); break; | |
| case HInductionVarAnalysis::kDiv: | |
| operation = new (graph->GetAllocator()) HDiv(type, opa, opb, kNoDexPc); break; | |
| case HInductionVarAnalysis::kRem: | |
| operation = new (graph->GetAllocator()) HRem(type, opa, opb, kNoDexPc); break; | |
| case HInductionVarAnalysis::kXor: | |
| operation = new (graph->GetAllocator()) HXor(type, opa, opb); break; | |
| case HInductionVarAnalysis::kLT: | |
| operation = new (graph->GetAllocator()) HLessThan(opa, opb); break; | |
| case HInductionVarAnalysis::kLE: | |
| operation = new (graph->GetAllocator()) HLessThanOrEqual(opa, opb); break; | |
| case HInductionVarAnalysis::kGT: | |
| operation = new (graph->GetAllocator()) HGreaterThan(opa, opb); break; | |
| case HInductionVarAnalysis::kGE: | |
| operation = new (graph->GetAllocator()) HGreaterThanOrEqual(opa, opb); break; | |
| default: | |
| LOG(FATAL) << "unknown operation"; | |
| } | |
| *result = Insert(block, operation); | |
| } | |
| return true; | |
| } | |
| break; | |
| case HInductionVarAnalysis::kNeg: | |
| if (GenerateCode(context, | |
| loop, | |
| info->op_b, | |
| trip, | |
| graph, | |
| block, | |
| !is_min, | |
| &opb, | |
| allow_potential_overflow)) { | |
| if (graph != nullptr) { | |
| *result = Insert(block, new (graph->GetAllocator()) HNeg(type, opb)); | |
| } | |
| return true; | |
| } | |
| break; | |
| case HInductionVarAnalysis::kFetch: | |
| if (graph != nullptr) { | |
| *result = info->fetch; // already in HIR | |
| } | |
| return true; | |
| case HInductionVarAnalysis::kTripCountInLoop: | |
| case HInductionVarAnalysis::kTripCountInLoopUnsafe: | |
| if (UseFullTripCount(context, loop, is_min)) { | |
| // Generate the full trip count (do not subtract 1 as we do in loop body). | |
| return GenerateCode(context, | |
| loop, | |
| info->op_a, | |
| trip, | |
| graph, | |
| block, | |
| is_min, | |
| result, | |
| allow_potential_overflow); | |
| } | |
| FALLTHROUGH_INTENDED; | |
| case HInductionVarAnalysis::kTripCountInBody: | |
| case HInductionVarAnalysis::kTripCountInBodyUnsafe: | |
| if (is_min) { | |
| if (graph != nullptr) { | |
| *result = graph->GetConstant(type, 0); | |
| } | |
| return true; | |
| } else if (IsContextInBody(context, loop) || | |
| (context == loop->GetHeader() && !allow_potential_overflow)) { | |
| if (GenerateCode(context, | |
| loop, | |
| info->op_a, | |
| trip, | |
| graph, | |
| block, | |
| is_min, | |
| &opb, | |
| allow_potential_overflow)) { | |
| if (graph != nullptr) { | |
| if (IsContextInBody(context, loop)) { | |
| ArenaAllocator* allocator = graph->GetAllocator(); | |
| *result = | |
| Insert(block, new (allocator) HSub(type, opb, graph->GetConstant(type, 1))); | |
| } else { | |
| // We want to generate the full trip count since we want the last value. This | |
| // will be combined with an `is_taken` test so we don't want to subtract one. | |
| DCHECK(context == loop->GetHeader()); | |
| // TODO(solanes): Remove the !allow_potential_overflow restriction and allow | |
| // other parts e.g. BCE to take advantage of this. | |
| DCHECK(!allow_potential_overflow); | |
| *result = opb; | |
| } | |
| } | |
| return true; | |
| } | |
| } | |
| break; | |
| case HInductionVarAnalysis::kNop: | |
| LOG(FATAL) << "unexpected invariant nop"; | |
| } // switch invariant operation | |
| break; | |
| case HInductionVarAnalysis::kLinear: { | |
| // Linear induction a * i + b, for normalized 0 <= i < TC. For ranges, this should | |
| // be restricted to a unit stride to avoid arithmetic wrap-around situations that | |
| // are harder to guard against. For a last value, requesting min/max based on any | |
| // known stride yields right value. Always avoid any narrowing linear induction or | |
| // any type mismatch between the linear induction and the trip count expression. | |
| // TODO: careful runtime type conversions could generalize this latter restriction. | |
| if (!HInductionVarAnalysis::IsNarrowingLinear(info) && trip->type == type) { | |
| int64_t stride_value = 0; | |
| if (IsConstant(context, loop, info->op_a, kExact, &stride_value) && | |
| CanLongValueFitIntoInt(stride_value)) { | |
| const bool is_min_a = stride_value >= 0 ? is_min : !is_min; | |
| if (GenerateCode(context, | |
| loop, | |
| trip, | |
| trip, | |
| graph, | |
| block, | |
| is_min_a, | |
| &opa, | |
| allow_potential_overflow) && | |
| GenerateCode(context, | |
| loop, | |
| info->op_b, | |
| trip, | |
| graph, | |
| block, | |
| is_min, | |
| &opb, | |
| allow_potential_overflow)) { | |
| if (graph != nullptr) { | |
| ArenaAllocator* allocator = graph->GetAllocator(); | |
| HInstruction* oper; | |
| if (stride_value == 1) { | |
| oper = new (allocator) HAdd(type, opa, opb); | |
| } else if (stride_value == -1) { | |
| oper = new (graph->GetAllocator()) HSub(type, opb, opa); | |
| } else { | |
| HInstruction* mul = | |
| new (allocator) HMul(type, graph->GetConstant(type, stride_value), opa); | |
| oper = new (allocator) HAdd(type, Insert(block, mul), opb); | |
| } | |
| *result = Insert(block, oper); | |
| } | |
| return true; | |
| } | |
| } | |
| } | |
| break; | |
| } | |
| case HInductionVarAnalysis::kPolynomial: | |
| case HInductionVarAnalysis::kGeometric: | |
| break; | |
| case HInductionVarAnalysis::kWrapAround: | |
| case HInductionVarAnalysis::kPeriodic: { | |
| // Wrap-around and periodic inductions are restricted to constants only, so that extreme | |
| // values are easy to test at runtime without complications of arithmetic wrap-around. | |
| Value extreme = GetVal(context, loop, info, trip, is_min); | |
| if (IsConstantValue(extreme)) { | |
| if (graph != nullptr) { | |
| *result = graph->GetConstant(type, extreme.b_constant); | |
| } | |
| return true; | |
| } | |
| break; | |
| } | |
| } // switch induction class | |
| } | |
| return false; | |
| } | |
| bool InductionVarRange::TryGenerateAddWithoutOverflow(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HGraph* graph, | |
| /*in*/ HInstruction* opa, | |
| /*in*/ HInstruction* opb, | |
| /*out*/ HInstruction** result) const { | |
| // Calculate `a + b` making sure we can't overflow. | |
| int64_t val_a; | |
| const bool a_is_const = IsConstant(context, loop, info->op_a, kExact, &val_a); | |
| int64_t val_b; | |
| const bool b_is_const = IsConstant(context, loop, info->op_b, kExact, &val_b); | |
| if (a_is_const && b_is_const) { | |
| // Calculate `a + b` and use that. Note that even when the values are known, | |
| // their addition can still overflow. | |
| Value add_val = AddValue(Value(val_a), Value(val_b)); | |
| if (add_val.is_known) { | |
| DCHECK(IsConstantValue(add_val)); | |
| // Known value not overflowing. | |
| if (graph != nullptr) { | |
| *result = graph->GetConstant(info->type, add_val.b_constant); | |
| } | |
| return true; | |
| } | |
| } | |
| // When `a` is `0`, we can just use `b`. | |
| if (a_is_const && val_a == 0) { | |
| if (graph != nullptr) { | |
| *result = opb; | |
| } | |
| return true; | |
| } | |
| if (b_is_const && val_b == 0) { | |
| if (graph != nullptr) { | |
| *result = opa; | |
| } | |
| return true; | |
| } | |
| // Couldn't safely calculate the addition. | |
| return false; | |
| } | |
| bool InductionVarRange::TryGenerateSubWithoutOverflow(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HGraph* graph, | |
| /*in*/ HInstruction* opa, | |
| /*out*/ HInstruction** result) const { | |
| // Calculate `a - b` making sure we can't overflow. | |
| int64_t val_b; | |
| if (!IsConstant(context, loop, info->op_b, kExact, &val_b)) { | |
| // If b is unknown, a - b can potentially overflow for any value of a since b | |
| // can be Integer.MIN_VALUE. | |
| return false; | |
| } | |
| int64_t val_a; | |
| if (IsConstant(context, loop, info->op_a, kExact, &val_a)) { | |
| // Calculate `a - b` and use that. Note that even when the values are known, | |
| // their subtraction can still overflow. | |
| Value sub_val = SubValue(Value(val_a), Value(val_b)); | |
| if (sub_val.is_known) { | |
| DCHECK(IsConstantValue(sub_val)); | |
| // Known value not overflowing. | |
| if (graph != nullptr) { | |
| *result = graph->GetConstant(info->type, sub_val.b_constant); | |
| } | |
| return true; | |
| } | |
| } | |
| // When `b` is `0`, we can just use `a`. | |
| if (val_b == 0) { | |
| if (graph != nullptr) { | |
| *result = opa; | |
| } | |
| return true; | |
| } | |
| // Couldn't safely calculate the subtraction. | |
| return false; | |
| } | |
| bool InductionVarRange::TryGenerateTakenTest(const HBasicBlock* context, | |
| const HLoopInformation* loop, | |
| HInductionVarAnalysis::InductionInfo* info, | |
| HGraph* graph, | |
| HBasicBlock* block, | |
| /*inout*/ HInstruction** result, | |
| /*inout*/ HInstruction* not_taken_result) const { | |
| HInstruction* is_taken = nullptr; | |
| if (GenerateCode(context, | |
| loop, | |
| info, | |
| /*trip=*/nullptr, | |
| graph, | |
| block, | |
| /*is_min=*/false, | |
| graph != nullptr ? &is_taken : nullptr)) { | |
| if (graph != nullptr) { | |
| ArenaAllocator* allocator = graph->GetAllocator(); | |
| *result = | |
| Insert(block, new (allocator) HSelect(is_taken, *result, not_taken_result, kNoDexPc)); | |
| } | |
| return true; | |
| } else { | |
| return false; | |
| } | |
| } | |
| void InductionVarRange::ReplaceInduction(HInductionVarAnalysis::InductionInfo* info, | |
| HInstruction* fetch, | |
| HInstruction* replacement) { | |
| if (info != nullptr) { | |
| if (info->induction_class == HInductionVarAnalysis::kInvariant && | |
| info->operation == HInductionVarAnalysis::kFetch && | |
| info->fetch == fetch) { | |
| info->fetch = replacement; | |
| } | |
| ReplaceInduction(info->op_a, fetch, replacement); | |
| ReplaceInduction(info->op_b, fetch, replacement); | |
| } | |
| } | |
| } // namespace art |