| /* |
| * 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)); |
| } |
| |
| /** Returns true for 32/64-bit constant instruction. */ |
| static bool IsIntAndGet(HInstruction* instruction, int64_t* value) { |
| if (instruction->IsIntConstant()) { |
| *value = instruction->AsIntConstant()->GetValue(); |
| return true; |
| } else if (instruction->IsLongConstant()) { |
| *value = instruction->AsLongConstant()->GetValue(); |
| return true; |
| } |
| return false; |
| } |
| |
| /** |
| * An upper bound a * (length / a) + b, where a >= 1, can be conservatively rewritten as length + b |
| * because length >= 0 is true. This makes it more likely the bound is useful to clients. |
| */ |
| static InductionVarRange::Value SimplifyMax(InductionVarRange::Value v) { |
| int64_t value; |
| if (v.is_known && |
| v.a_constant >= 1 && |
| v.instruction->IsDiv() && |
| v.instruction->InputAt(0)->IsArrayLength() && |
| IsIntAndGet(v.instruction->InputAt(1), &value) && v.a_constant == value) { |
| return InductionVarRange::Value(v.instruction->InputAt(0), 1, v.b_constant); |
| } |
| return v; |
| } |
| |
| /** |
| * Corrects a value for type to account for arithmetic wrap-around in lower precision. |
| */ |
| static InductionVarRange::Value CorrectForType(InductionVarRange::Value v, Primitive::Type type) { |
| switch (type) { |
| case Primitive::kPrimShort: |
| case Primitive::kPrimChar: |
| case Primitive::kPrimByte: { |
| // Constants within range only. |
| // TODO: maybe some room for improvement, like allowing widening conversions |
| const int32_t min = Primitive::MinValueOfIntegralType(type); |
| const int32_t max = Primitive::MaxValueOfIntegralType(type); |
| return (v.is_known && v.a_constant == 0 && min <= v.b_constant && v.b_constant <= max) |
| ? v |
| : InductionVarRange::Value(); |
| } |
| default: |
| // At int or higher. |
| return v; |
| } |
| } |
| |
| /** Helper method to test for a constant value. */ |
| static bool IsConstantValue(InductionVarRange::Value v) { |
| return v.is_known && v.a_constant == 0; |
| } |
| |
| /** Helper method to test for same constant value. */ |
| static bool IsSameConstantValue(InductionVarRange::Value v1, InductionVarRange::Value v2) { |
| return IsConstantValue(v1) && IsConstantValue(v2) && v1.b_constant == v2.b_constant; |
| } |
| |
| /** Helper method to insert 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; |
| } |
| |
| // |
| // Public class methods. |
| // |
| |
| InductionVarRange::InductionVarRange(HInductionVarAnalysis* induction_analysis) |
| : induction_analysis_(induction_analysis) { |
| DCHECK(induction_analysis != nullptr); |
| } |
| |
| bool InductionVarRange::GetInductionRange(HInstruction* context, |
| HInstruction* instruction, |
| /*out*/Value* min_val, |
| /*out*/Value* max_val, |
| /*out*/bool* needs_finite_test) { |
| HLoopInformation* loop = context->GetBlock()->GetLoopInformation(); // closest enveloping loop |
| if (loop == nullptr) { |
| return false; // no loop |
| } |
| HInductionVarAnalysis::InductionInfo* info = induction_analysis_->LookupInfo(loop, instruction); |
| if (info == nullptr) { |
| return false; // no induction information |
| } |
| // 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 Primitive::kPrimInt: |
| case Primitive::kPrimShort: |
| case Primitive::kPrimChar: |
| case Primitive::kPrimByte: |
| break; |
| default: |
| return false; |
| } |
| // Set up loop information. |
| HBasicBlock* header = loop->GetHeader(); |
| bool in_body = context->GetBlock() != header; |
| HInductionVarAnalysis::InductionInfo* trip = |
| induction_analysis_->LookupInfo(loop, header->GetLastInstruction()); |
| // Find range. |
| *min_val = GetVal(info, trip, in_body, /* is_min */ true); |
| *max_val = SimplifyMax(GetVal(info, trip, in_body, /* is_min */ false)); |
| *needs_finite_test = NeedsTripCount(info) && IsUnsafeTripCount(trip); |
| return true; |
| } |
| |
| bool InductionVarRange::RefineOuter(/*in-out*/ Value* min_val, |
| /*in-out*/ Value* max_val) const { |
| if (min_val->instruction != nullptr || max_val->instruction != nullptr) { |
| Value v1_min = RefineOuter(*min_val, /* is_min */ true); |
| Value v2_max = RefineOuter(*max_val, /* is_min */ false); |
| // The refined range is safe if both sides refine the same instruction. Otherwise, since two |
| // different ranges are combined, the new refined range is safe to pass back to the client if |
| // the extremes of the computed ranges ensure no arithmetic wrap-around anomalies occur. |
| if (min_val->instruction != max_val->instruction) { |
| Value v1_max = RefineOuter(*min_val, /* is_min */ false); |
| Value v2_min = RefineOuter(*max_val, /* is_min */ true); |
| if (!IsConstantValue(v1_max) || |
| !IsConstantValue(v2_min) || |
| v1_max.b_constant > v2_min.b_constant) { |
| return false; |
| } |
| } |
| // Did something change? |
| if (v1_min.instruction != min_val->instruction || v2_max.instruction != max_val->instruction) { |
| *min_val = v1_min; |
| *max_val = v2_max; |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| bool InductionVarRange::CanGenerateCode(HInstruction* context, |
| HInstruction* instruction, |
| /*out*/bool* needs_finite_test, |
| /*out*/bool* needs_taken_test) { |
| return GenerateCode(context, |
| instruction, |
| nullptr, nullptr, nullptr, nullptr, nullptr, // nothing generated yet |
| needs_finite_test, |
| needs_taken_test); |
| } |
| |
| void InductionVarRange::GenerateRangeCode(HInstruction* context, |
| HInstruction* instruction, |
| HGraph* graph, |
| HBasicBlock* block, |
| /*out*/HInstruction** lower, |
| /*out*/HInstruction** upper) { |
| bool b1, b2; // unused |
| if (!GenerateCode(context, instruction, graph, block, lower, upper, nullptr, &b1, &b2)) { |
| LOG(FATAL) << "Failed precondition: GenerateCode()"; |
| } |
| } |
| |
| void InductionVarRange::GenerateTakenTest(HInstruction* context, |
| HGraph* graph, |
| HBasicBlock* block, |
| /*out*/HInstruction** taken_test) { |
| bool b1, b2; // unused |
| if (!GenerateCode(context, context, graph, block, nullptr, nullptr, taken_test, &b1, &b2)) { |
| LOG(FATAL) << "Failed precondition: GenerateCode()"; |
| } |
| } |
| |
| // |
| // Private class methods. |
| // |
| |
| 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 (IsIntAndGet(info->fetch, value)) { |
| return true; |
| } |
| } |
| // Try range analysis while traversing outward on loops. |
| bool in_body = true; // no known trip count |
| Value v_min = GetVal(info, nullptr, in_body, /* is_min */ true); |
| Value v_max = GetVal(info, nullptr, in_body, /* is_min */ false); |
| do { |
| // Make sure *both* extremes are known to avoid arithmetic wrap-around anomalies. |
| if (IsConstantValue(v_min) && IsConstantValue(v_max) && v_min.b_constant <= v_max.b_constant) { |
| if ((request == kExact && v_min.b_constant == v_max.b_constant) || request == kAtMost) { |
| *value = v_max.b_constant; |
| return true; |
| } else if (request == kAtLeast) { |
| *value = v_min.b_constant; |
| return true; |
| } |
| } |
| } while (RefineOuter(&v_min, &v_max)); |
| // Exploit array length + c >= c, with c <= 0 to avoid arithmetic wrap-around anomalies |
| // (e.g. array length == maxint and c == 1 would yield minint). |
| if (request == kAtLeast) { |
| if (v_min.a_constant == 1 && v_min.b_constant <= 0 && v_min.instruction->IsArrayLength()) { |
| *value = v_min.b_constant; |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| bool InductionVarRange::NeedsTripCount(HInductionVarAnalysis::InductionInfo* info) const { |
| if (info != nullptr) { |
| if (info->induction_class == HInductionVarAnalysis::kLinear) { |
| return true; |
| } else if (info->induction_class == HInductionVarAnalysis::kWrapAround) { |
| return NeedsTripCount(info->op_b); |
| } |
| } |
| 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 { |
| // 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->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::GetFetch(HInstruction* instruction, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) const { |
| // Detect constants and chase the fetch 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 (IsIntAndGet(instruction, &value) && CanLongValueFitIntoInt(value)) { |
| return Value(static_cast<int32_t>(value)); |
| } else if (instruction->IsAdd()) { |
| if (IsIntAndGet(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 (IsIntAndGet(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->IsArrayLength() && instruction->InputAt(0)->IsNewArray()) { |
| return GetFetch(instruction->InputAt(0)->InputAt(0), trip, in_body, is_min); |
| } else if (instruction->IsTypeConversion()) { |
| // Since analysis is 32-bit (or narrower) we allow a widening along the path. |
| if (instruction->AsTypeConversion()->GetInputType() == Primitive::kPrimInt && |
| instruction->AsTypeConversion()->GetResultType() == Primitive::kPrimLong) { |
| return GetFetch(instruction->InputAt(0), trip, in_body, is_min); |
| } |
| } else if (is_min) { |
| // Special case for finding minimum: minimum of trip-count in loop-body is 1. |
| if (trip != nullptr && in_body && instruction == trip->op_a->fetch) { |
| return Value(1); |
| } |
| } |
| 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::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::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 { |
| 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); |
| // Try to refine first operand. |
| if (!IsConstantValue(v1_min) && !IsConstantValue(v1_max)) { |
| RefineOuter(&v1_min, &v1_max); |
| } |
| // Constant times range. |
| if (IsSameConstantValue(v1_min, v1_max)) { |
| return MulRangeAndConstant(v2_min, v2_max, v1_min, is_min); |
| } else if (IsSameConstantValue(v2_min, v2_max)) { |
| return MulRangeAndConstant(v1_min, v1_max, v2_min, is_min); |
| } |
| // 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 { |
| 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); |
| // Range divided by constant. |
| if (IsSameConstantValue(v2_min, v2_max)) { |
| return DivRangeAndConstant(v1_min, v1_max, v2_min, is_min); |
| } |
| // 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::MulRangeAndConstant(Value v_min, |
| Value v_max, |
| Value c, |
| bool is_min) const { |
| return is_min == (c.b_constant >= 0) ? MulValue(v_min, c) : MulValue(v_max, c); |
| } |
| |
| InductionVarRange::Value InductionVarRange::DivRangeAndConstant(Value v_min, |
| Value v_max, |
| Value c, |
| bool is_min) const { |
| return is_min == (c.b_constant >= 0) ? DivValue(v_min, c) : DivValue(v_max, c); |
| } |
| |
| InductionVarRange::Value InductionVarRange::AddValue(Value v1, Value v2) const { |
| if (v1.is_known && v2.is_known && IsSafeAdd(v1.b_constant, v2.b_constant)) { |
| const 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)) { |
| const 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(); |
| } |
| |
| InductionVarRange::Value InductionVarRange::RefineOuter(Value v, bool is_min) const { |
| if (v.instruction == nullptr) { |
| return v; // nothing to refine |
| } |
| HLoopInformation* loop = |
| v.instruction->GetBlock()->GetLoopInformation(); // closest enveloping loop |
| if (loop == nullptr) { |
| return v; // no loop |
| } |
| HInductionVarAnalysis::InductionInfo* info = induction_analysis_->LookupInfo(loop, v.instruction); |
| if (info == nullptr) { |
| return v; // no induction information |
| } |
| // Set up loop information. |
| HBasicBlock* header = loop->GetHeader(); |
| bool in_body = true; // inner always in more outer |
| HInductionVarAnalysis::InductionInfo* trip = |
| induction_analysis_->LookupInfo(loop, header->GetLastInstruction()); |
| // Try to refine "a x instruction + b" with outer loop range information on instruction. |
| return AddValue(MulValue(Value(v.a_constant), GetVal(info, trip, in_body, is_min)), Value(v.b_constant)); |
| } |
| |
| bool InductionVarRange::GenerateCode(HInstruction* context, |
| HInstruction* instruction, |
| HGraph* graph, |
| HBasicBlock* block, |
| /*out*/HInstruction** lower, |
| /*out*/HInstruction** upper, |
| /*out*/HInstruction** taken_test, |
| /*out*/bool* needs_finite_test, |
| /*out*/bool* needs_taken_test) const { |
| HLoopInformation* loop = context->GetBlock()->GetLoopInformation(); // closest enveloping loop |
| if (loop == nullptr) { |
| return false; // no loop |
| } |
| HInductionVarAnalysis::InductionInfo* info = induction_analysis_->LookupInfo(loop, instruction); |
| if (info == nullptr) { |
| return false; // no induction information |
| } |
| // Set up loop information. |
| HBasicBlock* header = loop->GetHeader(); |
| bool in_body = context->GetBlock() != header; |
| HInductionVarAnalysis::InductionInfo* trip = |
| induction_analysis_->LookupInfo(loop, header->GetLastInstruction()); |
| if (trip == nullptr) { |
| return false; // codegen relies on trip count |
| } |
| // 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). |
| *needs_finite_test = NeedsTripCount(info) && IsUnsafeTripCount(trip); |
| *needs_taken_test = IsBodyTripCount(trip); |
| // 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::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) { |
| // Verify type safety. |
| Primitive::Type type = Primitive::kPrimInt; |
| if (info->type != type) { |
| return false; |
| } |
| // Handle current operation. |
| HInstruction* opa = nullptr; |
| HInstruction* opb = nullptr; |
| switch (info->induction_class) { |
| case HInductionVarAnalysis::kInvariant: |
| // Invariants. |
| switch (info->operation) { |
| case HInductionVarAnalysis::kAdd: |
| 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->GetArena()) HAdd(type, opa, opb); break; |
| case HInductionVarAnalysis::kLT: |
| operation = new (graph->GetArena()) HLessThan(opa, opb); break; |
| case HInductionVarAnalysis::kLE: |
| operation = new (graph->GetArena()) HLessThanOrEqual(opa, opb); break; |
| case HInductionVarAnalysis::kGT: |
| operation = new (graph->GetArena()) HGreaterThan(opa, opb); break; |
| case HInductionVarAnalysis::kGE: |
| operation = new (graph->GetArena()) HGreaterThanOrEqual(opa, opb); break; |
| default: |
| LOG(FATAL) << "unknown operation"; |
| } |
| *result = Insert(block, operation); |
| } |
| return true; |
| } |
| break; |
| case HInductionVarAnalysis::kSub: // second reversed! |
| 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) { |
| *result = Insert(block, new (graph->GetArena()) HSub(type, opa, opb)); |
| } |
| return true; |
| } |
| break; |
| case HInductionVarAnalysis::kNeg: // reversed! |
| if (GenerateCode(info->op_b, trip, graph, block, &opb, in_body, !is_min)) { |
| if (graph != nullptr) { |
| *result = Insert(block, new (graph->GetArena()) 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->GetIntConstant(0); |
| } |
| return true; |
| } else if (in_body) { |
| if (GenerateCode(info->op_a, trip, graph, block, &opb, in_body, is_min)) { |
| if (graph != nullptr) { |
| *result = Insert(block, |
| new (graph->GetArena()) |
| HSub(type, opb, graph->GetIntConstant(1))); |
| } |
| return true; |
| } |
| } |
| break; |
| default: |
| break; |
| } |
| break; |
| case HInductionVarAnalysis::kLinear: { |
| // Linear induction a * i + b, for normalized 0 <= i < TC. Restrict to unit stride only |
| // to avoid arithmetic wrap-around situations that are hard to guard against. |
| int64_t stride_value = 0; |
| if (IsConstant(info->op_a, kExact, &stride_value)) { |
| if (stride_value == 1 || stride_value == -1) { |
| const bool is_min_a = stride_value == 1 ? 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) { |
| HInstruction* oper; |
| if (stride_value == 1) { |
| oper = new (graph->GetArena()) HAdd(type, opa, opb); |
| } else { |
| oper = new (graph->GetArena()) HSub(type, opb, opa); |
| } |
| *result = Insert(block, oper); |
| } |
| return true; |
| } |
| } |
| } |
| 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->GetIntConstant(extreme.b_constant); |
| } |
| return true; |
| } |
| break; |
| } |
| default: |
| break; |
| } |
| } |
| return false; |
| } |
| |
| } // namespace art |
