| /* |
| * 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 integral constant. */ |
| static bool IsIntAndGet(HInstruction* instruction, int32_t* value) { |
| if (instruction->IsIntConstant()) { |
| *value = instruction->AsIntConstant()->GetValue(); |
| return true; |
| } else if (instruction->IsLongConstant()) { |
| const int64_t c = instruction->AsLongConstant()->GetValue(); |
| if (CanLongValueFitIntoInt(c)) { |
| *value = static_cast<int32_t>(c); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /** |
| * An upper bound a * (length / a) + b, where a > 0, 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) { |
| int32_t value; |
| if (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; |
| } |
| |
| // |
| // Public class methods. |
| // |
| |
| InductionVarRange::InductionVarRange(HInductionVarAnalysis* induction_analysis) |
| : induction_analysis_(induction_analysis) { |
| DCHECK(induction_analysis != nullptr); |
| } |
| |
| InductionVarRange::Value InductionVarRange::GetMinInduction(HInstruction* context, |
| HInstruction* instruction) { |
| return GetInduction(context, instruction, /* is_min */ true); |
| } |
| |
| InductionVarRange::Value InductionVarRange::GetMaxInduction(HInstruction* context, |
| HInstruction* instruction) { |
| return SimplifyMax(GetInduction(context, instruction, /* is_min */ false)); |
| } |
| |
| // |
| // Private class methods. |
| // |
| |
| InductionVarRange::Value InductionVarRange::GetInduction(HInstruction* context, |
| HInstruction* instruction, |
| bool is_min) { |
| HLoopInformation* loop = context->GetBlock()->GetLoopInformation(); // closest enveloping loop |
| if (loop != nullptr) { |
| HBasicBlock* header = loop->GetHeader(); |
| bool in_body = context->GetBlock() != header; |
| return GetVal(induction_analysis_->LookupInfo(loop, instruction), |
| induction_analysis_->LookupInfo(loop, header->GetLastInstruction()), |
| in_body, |
| is_min); |
| } |
| return Value(); |
| } |
| |
| InductionVarRange::Value InductionVarRange::GetFetch(HInstruction* instruction, |
| HInductionVarAnalysis::InductionInfo* trip, |
| bool in_body, |
| bool is_min) { |
| // 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. |
| int32_t value; |
| if (IsIntAndGet(instruction, &value)) { |
| return Value(value); |
| } else if (instruction->IsAdd()) { |
| if (IsIntAndGet(instruction->InputAt(0), &value)) { |
| return AddValue(Value(value), GetFetch(instruction->InputAt(1), trip, in_body, is_min)); |
| } else if (IsIntAndGet(instruction->InputAt(1), &value)) { |
| return AddValue(GetFetch(instruction->InputAt(0), trip, in_body, is_min), Value(value)); |
| } |
| } 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_b->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) { |
| 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: |
| if (!in_body) { |
| return is_min ? Value(0) |
| : GetVal(info->op_b, trip, in_body, is_min); // one extra! |
| } |
| FALLTHROUGH_INTENDED; |
| case HInductionVarAnalysis::kTripCountInBody: |
| if (in_body) { |
| return is_min ? Value(0) |
| : SubValue(GetVal(info->op_b, trip, in_body, is_min), Value(1)); |
| } |
| break; |
| default: |
| break; |
| } |
| break; |
| case HInductionVarAnalysis::kLinear: |
| // 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)); |
| case HInductionVarAnalysis::kWrapAround: |
| case HInductionVarAnalysis::kPeriodic: |
| // Merge values in the wrap-around/periodic. |
| 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) { |
| 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); |
| if (v1_min.is_known && v1_min.a_constant == 0 && v1_min.b_constant >= 0) { |
| // Positive range vs. positive or negative range. |
| if (v2_min.is_known && v2_min.a_constant == 0 && v2_min.b_constant >= 0) { |
| return is_min ? MulValue(v1_min, v2_min) |
| : MulValue(v1_max, v2_max); |
| } else if (v2_max.is_known && v2_max.a_constant == 0 && v2_max.b_constant <= 0) { |
| return is_min ? MulValue(v1_max, v2_min) |
| : MulValue(v1_min, v2_max); |
| } |
| } else if (v1_min.is_known && v1_min.a_constant == 0 && v1_min.b_constant <= 0) { |
| // Negative range vs. positive or negative range. |
| if (v2_min.is_known && v2_min.a_constant == 0 && v2_min.b_constant >= 0) { |
| return is_min ? MulValue(v1_min, v2_max) |
| : MulValue(v1_max, v2_min); |
| } else if (v2_max.is_known && v2_max.a_constant == 0 && 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) { |
| 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); |
| if (v1_min.is_known && v1_min.a_constant == 0 && v1_min.b_constant >= 0) { |
| // Positive range vs. positive or negative range. |
| if (v2_min.is_known && v2_min.a_constant == 0 && v2_min.b_constant >= 0) { |
| return is_min ? DivValue(v1_min, v2_max) |
| : DivValue(v1_max, v2_min); |
| } else if (v2_max.is_known && v2_max.a_constant == 0 && v2_max.b_constant <= 0) { |
| return is_min ? DivValue(v1_max, v2_max) |
| : DivValue(v1_min, v2_min); |
| } |
| } else if (v1_min.is_known && v1_min.a_constant == 0 && v1_min.b_constant <= 0) { |
| // Negative range vs. positive or negative range. |
| if (v2_min.is_known && v2_min.a_constant == 0 && v2_min.b_constant >= 0) { |
| return is_min ? DivValue(v1_min, v2_min) |
| : DivValue(v1_max, v2_max); |
| } else if (v2_max.is_known && v2_max.a_constant == 0 && v2_max.b_constant <= 0) { |
| return is_min ? DivValue(v1_max, v2_min) |
| : DivValue(v1_min, v2_max); |
| } |
| } |
| return Value(); |
| } |
| |
| bool InductionVarRange::GetConstant(HInductionVarAnalysis::InductionInfo* info, int32_t *value) { |
| Value v_min = GetVal(info, nullptr, false, /* is_min */ true); |
| Value v_max = GetVal(info, nullptr, false, /* is_min */ false); |
| if (v_min.a_constant == 0 && v_max.a_constant == 0 && v_min.b_constant == v_max.b_constant) { |
| *value = v_min.b_constant; |
| return true; |
| } |
| return false; |
| } |
| |
| InductionVarRange::Value InductionVarRange::AddValue(Value v1, Value v2) { |
| 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) { |
| 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) { |
| 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) { |
| 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) { |
| 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(); |
| } |
| |
| } // namespace art |
