| /* |
| * 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> |
| |
| namespace art { |
| |
| /** 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) { |
| if (a > 0 && b > 0 && a > (std::numeric_limits<int64_t>::max() / b)) { |
| *overflow = true; |
| } |
| return a * b; |
| } |
| |
| /** 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; |
| } |
| |
| /** |
| * Detects an instruction that is >= 0. As long as the value is carried by |
| * a single instruction, arithmetic wrap-around cannot occur. |
| */ |
| static bool IsGEZero(HInstruction* instruction) { |
| DCHECK(instruction != nullptr); |
| if (instruction->IsArrayLength()) { |
| return true; |
| } else if (instruction->IsMin()) { |
| // Instruction MIN(>=0, >=0) is >= 0. |
| return IsGEZero(instruction->InputAt(0)) && |
| IsGEZero(instruction->InputAt(1)); |
| } else if (instruction->IsAbs()) { |
| // Instruction ABS(>=0) is >= 0. |
| // NOTE: ABS(minint) = minint prevents assuming |
| // >= 0 without looking at the argument. |
| return IsGEZero(instruction->InputAt(0)); |
| } |
| int64_t value = -1; |
| return IsInt64AndGet(instruction, &value) && value >= 0; |
| } |
| |
| /** 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(HLoopInformation* loop) { |
| DCHECK(loop != nullptr); |
| return loop->GetHeader()->GetLastInstruction(); |
| } |
| |
| // |
| // Public class methods. |
| // |
| |
| InductionVarRange::InductionVarRange(HInductionVarAnalysis* induction_analysis) |
| : induction_analysis_(induction_analysis), |
| chase_hint_(nullptr) { |
| DCHECK(induction_analysis != nullptr); |
| } |
| |
| bool InductionVarRange::GetInductionRange(HInstruction* context, |
| HInstruction* instruction, |
| HInstruction* chase_hint, |
| /*out*/Value* min_val, |
| /*out*/Value* max_val, |
| /*out*/bool* needs_finite_test) { |
| 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; |
| bool in_body = context->GetBlock() != loop->GetHeader(); |
| int64_t stride_value = 0; |
| *min_val = SimplifyMin(GetVal(info, trip, in_body, /* is_min= */ true)); |
| *max_val = SimplifyMax(GetVal(info, trip, in_body, /* is_min= */ false), chase_hint); |
| *needs_finite_test = NeedsTripCount(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(info, trip, in_body, /* is_min= */ true)); |
| } |
| return true; |
| } |
| |
| bool InductionVarRange::CanGenerateRange(HInstruction* 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(HInstruction* 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)) { |
| LOG(FATAL) << "Failed precondition: CanGenerateRange()"; |
| } |
| } |
| |
| HInstruction* InductionVarRange::GenerateTakenTest(HInstruction* context, |
| HGraph* graph, |
| HBasicBlock* block) { |
| HInstruction* taken_test = nullptr; |
| bool is_last_value = false; |
| int64_t stride_value = 0; |
| bool b1, b2; // unused |
| if (!GenerateRangeOrLastValue(context, |
| context, |
| is_last_value, |
| graph, |
| block, |
| nullptr, |
| nullptr, |
| &taken_test, |
| &stride_value, |
| &b1, |
| &b2)) { |
| LOG(FATAL) << "Failed precondition: CanGenerateRange()"; |
| } |
| return taken_test; |
| } |
| |
| bool InductionVarRange::CanGenerateLastValue(HInstruction* instruction) { |
| bool is_last_value = true; |
| int64_t stride_value = 0; |
| bool needs_finite_test = false; |
| bool needs_taken_test = false; |
| return GenerateRangeOrLastValue(instruction, |
| 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) { |
| HInstruction* last_value = nullptr; |
| bool is_last_value = true; |
| int64_t stride_value = 0; |
| bool b1, b2; // unused |
| if (!GenerateRangeOrLastValue(instruction, |
| instruction, |
| is_last_value, |
| graph, |
| block, |
| &last_value, |
| &last_value, |
| nullptr, |
| &stride_value, |
| &b1, |
| &b2)) { |
| 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 instruction's information. |
| ReplaceInduction(induction_analysis_->LookupInfo(lp, instruction), fetch, replacement); |
| // Update loop's trip-count information. |
| ReplaceInduction(induction_analysis_->LookupInfo(lp, GetLoopControl(lp)), fetch, replacement); |
| } |
| } |
| |
| bool InductionVarRange::IsFinite(HLoopInformation* loop, /*out*/ int64_t* trip_count) const { |
| bool is_constant_unused = false; |
| return CheckForFiniteAndConstantProps(loop, &is_constant_unused, trip_count); |
| } |
| |
| bool InductionVarRange::HasKnownTripCount(HLoopInformation* loop, |
| /*out*/ int64_t* trip_count) const { |
| bool is_constant = false; |
| CheckForFiniteAndConstantProps(loop, &is_constant, trip_count); |
| return is_constant; |
| } |
| |
| bool InductionVarRange::IsUnitStride(HInstruction* context, |
| HInstruction* instruction, |
| HGraph* graph, |
| /*out*/ HInstruction** offset) 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(info->op_a, kExact, &stride_value) && stride_value == 1) { |
| int64_t off_value = 0; |
| if (IsConstant(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(HLoopInformation* loop, |
| HGraph* graph, |
| HBasicBlock* block) { |
| HInductionVarAnalysis::InductionInfo *trip = |
| induction_analysis_->LookupInfo(loop, GetLoopControl(loop)); |
| if (trip != nullptr && !IsUnsafeTripCount(trip)) { |
| HInstruction* taken_test = nullptr; |
| HInstruction* trip_expr = nullptr; |
| if (IsBodyTripCount(trip)) { |
| if (!GenerateCode(trip->op_b, nullptr, graph, block, &taken_test, false, false)) { |
| return nullptr; |
| } |
| } |
| if (GenerateCode(trip->op_a, nullptr, graph, block, &trip_expr, false, false)) { |
| 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(HLoopInformation* loop, |
| /*out*/ bool* is_constant, |
| /*out*/ int64_t* trip_count) const { |
| HInductionVarAnalysis::InductionInfo *trip = |
| induction_analysis_->LookupInfo(loop, GetLoopControl(loop)); |
| if (trip != nullptr && !IsUnsafeTripCount(trip)) { |
| *is_constant = IsConstant(trip->op_a, kExact, trip_count); |
| return true; |
| } |
| return false; |
| } |
| |
| bool InductionVarRange::IsConstant(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(info, nullptr, /* in_body= */ true, /* is_min= */ true); |
| Value max_val = GetVal(info, nullptr, /* in_body= */ true, /* 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( |
| HInstruction* context, |
| HInstruction* instruction, |
| /*out*/ HLoopInformation** loop, |
| /*out*/ HInductionVarAnalysis::InductionInfo** info, |
| /*out*/ HInductionVarAnalysis::InductionInfo** trip) const { |
| DCHECK(context != nullptr); |
| DCHECK(context->GetBlock() != nullptr); |
| HLoopInformation* lp = context->GetBlock()->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(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(lower, kAtLeast, ¬_used)) && |
| (!HasFetchInLoop(upper) || range.IsConstant(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(HInductionVarAnalysis::InductionInfo* info, |
| int64_t* stride_value) const { |
| if (info != nullptr) { |
| if (info->induction_class == HInductionVarAnalysis::kLinear) { |
| return IsConstant(info->op_a, kExact, stride_value); |
| } else if (info->induction_class == HInductionVarAnalysis::kPolynomial) { |
| return NeedsTripCount(info->op_a, stride_value); |
| } else if (info->induction_class == HInductionVarAnalysis::kWrapAround) { |
| return NeedsTripCount(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(HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| 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(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(&cancelled_trip, trip, in_body, 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(&cancelled_trip, trip, in_body, !is_min)); |
| } |
| } |
| } |
| } |
| } |
| // General rule of linear induction a * i + b, for normalized 0 <= i < TC. |
| return AddValue(GetMul(info->op_a, trip, trip, in_body, is_min), |
| GetVal(info->op_b, trip, in_body, is_min)); |
| } |
| |
| InductionVarRange::Value InductionVarRange::GetPolynomial(HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| DCHECK(info != nullptr); |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kPolynomial); |
| int64_t a = 0; |
| int64_t b = 0; |
| if (IsConstant(info->op_a->op_a, kExact, &a) && CanLongValueFitIntoInt(a) && a >= 0 && |
| IsConstant(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. |
| Value c = GetVal(info->op_b, trip, in_body, is_min); |
| if (is_min) { |
| return c; |
| } else { |
| Value m = GetVal(trip, trip, in_body, 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(HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| DCHECK(info != nullptr); |
| DCHECK_EQ(info->induction_class, HInductionVarAnalysis::kGeometric); |
| int64_t a = 0; |
| int64_t f = 0; |
| if (IsConstant(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(info->op_b, trip, in_body, is_min); |
| return is_min_a ? b : AddValue(Value(a), b); |
| } |
| } |
| return Value(); |
| } |
| |
| InductionVarRange::Value InductionVarRange::GetFetch(HInstruction* instruction, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| 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 && in_body && 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(instruction->InputAt(1), trip, in_body, is_min)); |
| } else if (IsInt64AndGet(instruction->InputAt(1), &value) && CanLongValueFitIntoInt(value)) { |
| return AddValue(GetFetch(instruction->InputAt(0), trip, in_body, 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(instruction->InputAt(1), trip, in_body, !is_min)); |
| } else if (IsInt64AndGet(instruction->InputAt(1), &value) && CanLongValueFitIntoInt(value)) { |
| return SubValue(GetFetch(instruction->InputAt(0), trip, in_body, 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(instruction->InputAt(0)->AsNewArray()->GetLength(), trip, in_body, 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(instruction->InputAt(0), trip, in_body, is_min); |
| } |
| } |
| // Chase an invariant fetch that is defined by an outer 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) |
| HLoopInformation* next_loop = nullptr; |
| HInductionVarAnalysis::InductionInfo* next_info = nullptr; |
| HInductionVarAnalysis::InductionInfo* next_trip = nullptr; |
| bool next_in_body = true; // inner loop is always in body of outer loop |
| if (HasInductionInfo(instruction, instruction, &next_loop, &next_info, &next_trip) && |
| IsWellBehavedTripCount(trip) && |
| !IsUnsafeTripCount(next_trip)) { |
| return GetVal(next_info, next_trip, next_in_body, is_min); |
| } |
| // Fetch is represented by itself. |
| return Value(instruction, 1, 0); |
| } |
| |
| InductionVarRange::Value InductionVarRange::GetVal(HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| if (info != nullptr) { |
| switch (info->induction_class) { |
| case HInductionVarAnalysis::kInvariant: |
| // Invariants. |
| switch (info->operation) { |
| case HInductionVarAnalysis::kAdd: |
| return AddValue(GetVal(info->op_a, trip, in_body, is_min), |
| GetVal(info->op_b, trip, in_body, is_min)); |
| case HInductionVarAnalysis::kSub: // second reversed! |
| return SubValue(GetVal(info->op_a, trip, in_body, is_min), |
| GetVal(info->op_b, trip, in_body, !is_min)); |
| case HInductionVarAnalysis::kNeg: // second reversed! |
| return SubValue(Value(0), |
| GetVal(info->op_b, trip, in_body, !is_min)); |
| case HInductionVarAnalysis::kMul: |
| return GetMul(info->op_a, info->op_b, trip, in_body, is_min); |
| case HInductionVarAnalysis::kDiv: |
| return GetDiv(info->op_a, info->op_b, trip, in_body, is_min); |
| case HInductionVarAnalysis::kRem: |
| return GetRem(info->op_a, info->op_b); |
| case HInductionVarAnalysis::kXor: |
| return GetXor(info->op_a, info->op_b); |
| case HInductionVarAnalysis::kFetch: |
| return GetFetch(info->fetch, trip, in_body, is_min); |
| case HInductionVarAnalysis::kTripCountInLoop: |
| case HInductionVarAnalysis::kTripCountInLoopUnsafe: |
| if (!in_body && !is_min) { // one extra! |
| return GetVal(info->op_a, trip, in_body, is_min); |
| } |
| FALLTHROUGH_INTENDED; |
| case HInductionVarAnalysis::kTripCountInBody: |
| case HInductionVarAnalysis::kTripCountInBodyUnsafe: |
| if (is_min) { |
| return Value(0); |
| } else if (in_body) { |
| return SubValue(GetVal(info->op_a, trip, in_body, is_min), Value(1)); |
| } |
| break; |
| default: |
| break; |
| } |
| break; |
| case HInductionVarAnalysis::kLinear: |
| return CorrectForType(GetLinear(info, trip, in_body, is_min), info->type); |
| case HInductionVarAnalysis::kPolynomial: |
| return GetPolynomial(info, trip, in_body, is_min); |
| case HInductionVarAnalysis::kGeometric: |
| return GetGeometric(info, trip, in_body, is_min); |
| case HInductionVarAnalysis::kWrapAround: |
| case HInductionVarAnalysis::kPeriodic: |
| return MergeVal(GetVal(info->op_a, trip, in_body, is_min), |
| GetVal(info->op_b, trip, in_body, is_min), is_min); |
| } |
| } |
| return Value(); |
| } |
| |
| InductionVarRange::Value InductionVarRange::GetMul(HInductionVarAnalysis::InductionInfo* info1, |
| HInductionVarAnalysis::InductionInfo* info2, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| // Constant times range. |
| int64_t value = 0; |
| if (IsConstant(info1, kExact, &value)) { |
| return MulRangeAndConstant(value, info2, trip, in_body, is_min); |
| } else if (IsConstant(info2, kExact, &value)) { |
| return MulRangeAndConstant(value, info1, trip, in_body, is_min); |
| } |
| // Interval ranges. |
| Value v1_min = GetVal(info1, trip, in_body, /* is_min= */ true); |
| Value v1_max = GetVal(info1, trip, in_body, /* is_min= */ false); |
| Value v2_min = GetVal(info2, trip, in_body, /* is_min= */ true); |
| Value v2_max = GetVal(info2, trip, in_body, /* 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(HInductionVarAnalysis::InductionInfo* info1, |
| HInductionVarAnalysis::InductionInfo* info2, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| // Range divided by constant. |
| int64_t value = 0; |
| if (IsConstant(info2, kExact, &value)) { |
| return DivRangeAndConstant(value, info1, trip, in_body, is_min); |
| } |
| // Interval ranges. |
| Value v1_min = GetVal(info1, trip, in_body, /* is_min= */ true); |
| Value v1_max = GetVal(info1, trip, in_body, /* is_min= */ false); |
| Value v2_min = GetVal(info2, trip, in_body, /* is_min= */ true); |
| Value v2_max = GetVal(info2, trip, in_body, /* 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( |
| HInductionVarAnalysis::InductionInfo* info1, |
| HInductionVarAnalysis::InductionInfo* info2) const { |
| int64_t v1 = 0; |
| int64_t v2 = 0; |
| // Only accept exact values. |
| if (IsConstant(info1, kExact, &v1) && IsConstant(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( |
| HInductionVarAnalysis::InductionInfo* info1, |
| HInductionVarAnalysis::InductionInfo* info2) const { |
| int64_t v1 = 0; |
| int64_t v2 = 0; |
| // Only accept exact values. |
| if (IsConstant(info1, kExact, &v1) && IsConstant(info2, kExact, &v2)) { |
| int64_t value = v1 ^ v2; |
| if (CanLongValueFitIntoInt(value)) { |
| return Value(static_cast<int32_t>(value)); |
| } |
| } |
| return Value(); |
| } |
| |
| InductionVarRange::Value InductionVarRange::MulRangeAndConstant( |
| int64_t value, |
| HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| if (CanLongValueFitIntoInt(value)) { |
| Value c(static_cast<int32_t>(value)); |
| return MulValue(GetVal(info, trip, in_body, is_min == value >= 0), c); |
| } |
| return Value(); |
| } |
| |
| InductionVarRange::Value InductionVarRange::DivRangeAndConstant( |
| int64_t value, |
| HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| if (CanLongValueFitIntoInt(value)) { |
| Value c(static_cast<int32_t>(value)); |
| return DivValue(GetVal(info, trip, in_body, 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(HInstruction* 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 { |
| 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). |
| bool in_body = context->GetBlock() != loop->GetHeader(); |
| *stride_value = 0; |
| *needs_finite_test = NeedsTripCount(info, stride_value) && IsUnsafeTripCount(trip); |
| *needs_taken_test = IsBodyTripCount(trip); |
| // Handle last value request. |
| if (is_last_value) { |
| DCHECK(!in_body); |
| switch (info->induction_class) { |
| case HInductionVarAnalysis::kLinear: |
| if (*stride_value > 0) { |
| lower = nullptr; |
| } else { |
| upper = nullptr; |
| } |
| break; |
| case HInductionVarAnalysis::kPolynomial: |
| return GenerateLastValuePolynomial(info, trip, graph, block, lower); |
| case HInductionVarAnalysis::kGeometric: |
| return GenerateLastValueGeometric(info, trip, graph, block, lower); |
| case HInductionVarAnalysis::kWrapAround: |
| return GenerateLastValueWrapAround(info, trip, graph, block, lower); |
| case HInductionVarAnalysis::kPeriodic: |
| return GenerateLastValuePeriodic(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(trip->op_b, nullptr, graph, block, taken_test, in_body, /* is_min= */ false); |
| } else if (*needs_taken_test) { |
| if (!GenerateCode( |
| trip->op_b, nullptr, nullptr, nullptr, nullptr, in_body, /* is_min= */ false)) { |
| 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(info, trip, graph, block, lower, in_body, /* is_min= */ true)) && |
| // And success on upper. |
| GenerateCode(info, trip, graph, block, upper, in_body, /* is_min= */ false); |
| } |
| |
| bool InductionVarRange::GenerateLastValuePolynomial(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(info->op_a->op_a, kExact, &a) && |
| IsConstant(info->op_a->op_b, kExact, &b) && |
| IsConstant(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(info->op_b, nullptr, graph, block, graph ? &c : nullptr, false, false)) { |
| 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(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(trip->op_a, kExact, &m) && m >= 1) { |
| HInstruction* opa = nullptr; |
| HInstruction* opb = nullptr; |
| if (GenerateCode(info->op_a, nullptr, graph, block, &opa, false, false) && |
| GenerateCode(info->op_b, nullptr, graph, block, &opb, false, false)) { |
| 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(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(trip->op_a, kExact, &m) && m >= depth) { |
| return GenerateCode(info, nullptr, graph, block, result, false, false); |
| } |
| return false; |
| } |
| |
| bool InductionVarRange::GenerateLastValuePeriodic(HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| HGraph* graph, |
| HBasicBlock* block, |
| /*out*/HInstruction** result, |
| /*out*/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(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(info, nullptr, graph, block, result, false, false); |
| } |
| // 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; |
| if (period == 2 && |
| GenerateCode(info->op_a, nullptr, graph, block, graph ? &x : nullptr, false, false) && |
| GenerateCode(info->op_b, nullptr, graph, block, graph ? &y : nullptr, false, false) && |
| GenerateCode(trip->op_a, nullptr, graph, block, graph ? &t : nullptr, false, false)) { |
| // 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)); |
| } |
| // Guard select with taken test if needed. |
| if (*needs_taken_test) { |
| HInstruction* is_taken = nullptr; |
| if (GenerateCode(trip->op_b, nullptr, graph, block, graph ? &is_taken : nullptr, false, false)) { |
| if (graph != nullptr) { |
| ArenaAllocator* allocator = graph->GetAllocator(); |
| *result = Insert(block, new (allocator) HSelect(is_taken, *result, x, kNoDexPc)); |
| } |
| *needs_taken_test = false; // taken care of |
| } else { |
| return false; |
| } |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| bool InductionVarRange::GenerateCode(HInductionVarAnalysis::InductionInfo* info, |
| HInductionVarAnalysis::InductionInfo* trip, |
| HGraph* graph, // when set, code is generated |
| HBasicBlock* block, |
| /*out*/HInstruction** result, |
| bool in_body, |
| bool is_min) 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(info->op_a, trip, graph, block, &opa, in_body, is_min) && |
| GenerateCode(info->op_b, trip, graph, block, &opb, in_body, is_min)) { |
| 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(info->op_b, trip, graph, block, &opb, in_body, !is_min)) { |
| 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 (!in_body && !is_min) { // one extra! |
| return GenerateCode(info->op_a, trip, graph, block, result, in_body, is_min); |
| } |
| FALLTHROUGH_INTENDED; |
| case HInductionVarAnalysis::kTripCountInBody: |
| case HInductionVarAnalysis::kTripCountInBodyUnsafe: |
| if (is_min) { |
| if (graph != nullptr) { |
| *result = graph->GetConstant(type, 0); |
| } |
| return true; |
| } else if (in_body) { |
| if (GenerateCode(info->op_a, trip, graph, block, &opb, in_body, is_min)) { |
| if (graph != nullptr) { |
| ArenaAllocator* allocator = graph->GetAllocator(); |
| *result = |
| Insert(block, new (allocator) HSub(type, opb, graph->GetConstant(type, 1))); |
| } |
| 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(info->op_a, kExact, &stride_value) && |
| CanLongValueFitIntoInt(stride_value)) { |
| const bool is_min_a = stride_value >= 0 ? is_min : !is_min; |
| if (GenerateCode(trip, trip, graph, block, &opa, in_body, is_min_a) && |
| GenerateCode(info->op_b, trip, graph, block, &opb, in_body, is_min)) { |
| 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(info, trip, in_body, is_min); |
| if (IsConstantValue(extreme)) { |
| if (graph != nullptr) { |
| *result = graph->GetConstant(type, extreme.b_constant); |
| } |
| return true; |
| } |
| break; |
| } |
| } // switch induction class |
| } |
| 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 |
