798 lines
34 KiB
C++
798 lines
34 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "induction_var_range.h"
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#include <limits>
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namespace art {
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/** Returns true if 64-bit constant fits in 32-bit constant. */
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static bool CanLongValueFitIntoInt(int64_t c) {
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return std::numeric_limits<int32_t>::min() <= c && c <= std::numeric_limits<int32_t>::max();
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}
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/** Returns true if 32-bit addition can be done safely. */
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static bool IsSafeAdd(int32_t c1, int32_t c2) {
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return CanLongValueFitIntoInt(static_cast<int64_t>(c1) + static_cast<int64_t>(c2));
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}
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/** Returns true if 32-bit subtraction can be done safely. */
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static bool IsSafeSub(int32_t c1, int32_t c2) {
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return CanLongValueFitIntoInt(static_cast<int64_t>(c1) - static_cast<int64_t>(c2));
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}
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/** Returns true if 32-bit multiplication can be done safely. */
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static bool IsSafeMul(int32_t c1, int32_t c2) {
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return CanLongValueFitIntoInt(static_cast<int64_t>(c1) * static_cast<int64_t>(c2));
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}
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/** Returns true if 32-bit division can be done safely. */
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static bool IsSafeDiv(int32_t c1, int32_t c2) {
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return c2 != 0 && CanLongValueFitIntoInt(static_cast<int64_t>(c1) / static_cast<int64_t>(c2));
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}
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/** Returns true for 32/64-bit constant instruction. */
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static bool IsIntAndGet(HInstruction* instruction, int64_t* value) {
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if (instruction->IsIntConstant()) {
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*value = instruction->AsIntConstant()->GetValue();
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return true;
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} else if (instruction->IsLongConstant()) {
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*value = instruction->AsLongConstant()->GetValue();
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return true;
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}
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return false;
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}
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/**
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* An upper bound a * (length / a) + b, where a >= 1, can be conservatively rewritten as length + b
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* because length >= 0 is true. This makes it more likely the bound is useful to clients.
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*/
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static InductionVarRange::Value SimplifyMax(InductionVarRange::Value v) {
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int64_t value;
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if (v.is_known &&
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v.a_constant >= 1 &&
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v.instruction->IsDiv() &&
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v.instruction->InputAt(0)->IsArrayLength() &&
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IsIntAndGet(v.instruction->InputAt(1), &value) && v.a_constant == value) {
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return InductionVarRange::Value(v.instruction->InputAt(0), 1, v.b_constant);
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}
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return v;
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}
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/**
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* Corrects a value for type to account for arithmetic wrap-around in lower precision.
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*/
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static InductionVarRange::Value CorrectForType(InductionVarRange::Value v, Primitive::Type type) {
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switch (type) {
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case Primitive::kPrimShort:
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case Primitive::kPrimChar:
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case Primitive::kPrimByte: {
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// Constants within range only.
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// TODO: maybe some room for improvement, like allowing widening conversions
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const int32_t min = Primitive::MinValueOfIntegralType(type);
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const int32_t max = Primitive::MaxValueOfIntegralType(type);
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return (v.is_known && v.a_constant == 0 && min <= v.b_constant && v.b_constant <= max)
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? v
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: InductionVarRange::Value();
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}
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default:
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// At int or higher.
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return v;
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}
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}
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/** Helper method to test for a constant value. */
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static bool IsConstantValue(InductionVarRange::Value v) {
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return v.is_known && v.a_constant == 0;
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}
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/** Helper method to test for same constant value. */
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static bool IsSameConstantValue(InductionVarRange::Value v1, InductionVarRange::Value v2) {
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return IsConstantValue(v1) && IsConstantValue(v2) && v1.b_constant == v2.b_constant;
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}
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/** Helper method to insert an instruction. */
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static HInstruction* Insert(HBasicBlock* block, HInstruction* instruction) {
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DCHECK(block != nullptr);
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DCHECK(block->GetLastInstruction() != nullptr) << block->GetBlockId();
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DCHECK(instruction != nullptr);
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block->InsertInstructionBefore(instruction, block->GetLastInstruction());
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return instruction;
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}
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//
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// Public class methods.
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//
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InductionVarRange::InductionVarRange(HInductionVarAnalysis* induction_analysis)
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: induction_analysis_(induction_analysis) {
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DCHECK(induction_analysis != nullptr);
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}
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bool InductionVarRange::GetInductionRange(HInstruction* context,
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HInstruction* instruction,
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/*out*/Value* min_val,
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/*out*/Value* max_val,
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/*out*/bool* needs_finite_test) {
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HLoopInformation* loop = context->GetBlock()->GetLoopInformation(); // closest enveloping loop
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if (loop == nullptr) {
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return false; // no loop
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}
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HInductionVarAnalysis::InductionInfo* info = induction_analysis_->LookupInfo(loop, instruction);
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if (info == nullptr) {
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return false; // no induction information
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}
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// Type int or lower (this is not too restrictive since intended clients, like
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// bounds check elimination, will have truncated higher precision induction
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// at their use point already).
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switch (info->type) {
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case Primitive::kPrimInt:
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case Primitive::kPrimShort:
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case Primitive::kPrimChar:
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case Primitive::kPrimByte:
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break;
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default:
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return false;
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}
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// Set up loop information.
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HBasicBlock* header = loop->GetHeader();
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bool in_body = context->GetBlock() != header;
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HInductionVarAnalysis::InductionInfo* trip =
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induction_analysis_->LookupInfo(loop, header->GetLastInstruction());
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// Find range.
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*min_val = GetVal(info, trip, in_body, /* is_min */ true);
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*max_val = SimplifyMax(GetVal(info, trip, in_body, /* is_min */ false));
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*needs_finite_test = NeedsTripCount(info) && IsUnsafeTripCount(trip);
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return true;
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}
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bool InductionVarRange::RefineOuter(/*in-out*/ Value* min_val,
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/*in-out*/ Value* max_val) const {
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if (min_val->instruction != nullptr || max_val->instruction != nullptr) {
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Value v1_min = RefineOuter(*min_val, /* is_min */ true);
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Value v2_max = RefineOuter(*max_val, /* is_min */ false);
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// The refined range is safe if both sides refine the same instruction. Otherwise, since two
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// different ranges are combined, the new refined range is safe to pass back to the client if
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// the extremes of the computed ranges ensure no arithmetic wrap-around anomalies occur.
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if (min_val->instruction != max_val->instruction) {
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Value v1_max = RefineOuter(*min_val, /* is_min */ false);
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Value v2_min = RefineOuter(*max_val, /* is_min */ true);
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if (!IsConstantValue(v1_max) ||
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!IsConstantValue(v2_min) ||
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v1_max.b_constant > v2_min.b_constant) {
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return false;
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}
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}
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// Did something change?
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if (v1_min.instruction != min_val->instruction || v2_max.instruction != max_val->instruction) {
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*min_val = v1_min;
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*max_val = v2_max;
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return true;
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}
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}
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return false;
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}
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bool InductionVarRange::CanGenerateCode(HInstruction* context,
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HInstruction* instruction,
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/*out*/bool* needs_finite_test,
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/*out*/bool* needs_taken_test) {
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return GenerateCode(context,
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instruction,
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nullptr, nullptr, nullptr, nullptr, nullptr, // nothing generated yet
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needs_finite_test,
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needs_taken_test);
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}
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void InductionVarRange::GenerateRangeCode(HInstruction* context,
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HInstruction* instruction,
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HGraph* graph,
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HBasicBlock* block,
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/*out*/HInstruction** lower,
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/*out*/HInstruction** upper) {
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bool b1, b2; // unused
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if (!GenerateCode(context, instruction, graph, block, lower, upper, nullptr, &b1, &b2)) {
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LOG(FATAL) << "Failed precondition: GenerateCode()";
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}
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}
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void InductionVarRange::GenerateTakenTest(HInstruction* context,
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HGraph* graph,
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HBasicBlock* block,
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/*out*/HInstruction** taken_test) {
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bool b1, b2; // unused
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if (!GenerateCode(context, context, graph, block, nullptr, nullptr, taken_test, &b1, &b2)) {
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LOG(FATAL) << "Failed precondition: GenerateCode()";
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}
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}
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//
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// Private class methods.
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//
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bool InductionVarRange::IsConstant(HInductionVarAnalysis::InductionInfo* info,
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ConstantRequest request,
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/*out*/ int64_t *value) const {
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if (info != nullptr) {
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// A direct 32-bit or 64-bit constant fetch. This immediately satisfies
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// any of the three requests (kExact, kAtMost, and KAtLeast).
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if (info->induction_class == HInductionVarAnalysis::kInvariant &&
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info->operation == HInductionVarAnalysis::kFetch) {
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if (IsIntAndGet(info->fetch, value)) {
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return true;
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}
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}
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// Try range analysis while traversing outward on loops.
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bool in_body = true; // no known trip count
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Value v_min = GetVal(info, nullptr, in_body, /* is_min */ true);
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Value v_max = GetVal(info, nullptr, in_body, /* is_min */ false);
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do {
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// Make sure *both* extremes are known to avoid arithmetic wrap-around anomalies.
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if (IsConstantValue(v_min) && IsConstantValue(v_max) && v_min.b_constant <= v_max.b_constant) {
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if ((request == kExact && v_min.b_constant == v_max.b_constant) || request == kAtMost) {
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*value = v_max.b_constant;
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return true;
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} else if (request == kAtLeast) {
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*value = v_min.b_constant;
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return true;
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}
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}
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} while (RefineOuter(&v_min, &v_max));
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// Exploit array length + c >= c, with c <= 0 to avoid arithmetic wrap-around anomalies
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// (e.g. array length == maxint and c == 1 would yield minint).
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if (request == kAtLeast) {
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if (v_min.a_constant == 1 && v_min.b_constant <= 0 && v_min.instruction->IsArrayLength()) {
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*value = v_min.b_constant;
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return true;
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}
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}
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}
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return false;
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}
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bool InductionVarRange::NeedsTripCount(HInductionVarAnalysis::InductionInfo* info) const {
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if (info != nullptr) {
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if (info->induction_class == HInductionVarAnalysis::kLinear) {
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return true;
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} else if (info->induction_class == HInductionVarAnalysis::kWrapAround) {
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return NeedsTripCount(info->op_b);
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}
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}
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return false;
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}
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bool InductionVarRange::IsBodyTripCount(HInductionVarAnalysis::InductionInfo* trip) const {
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if (trip != nullptr) {
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if (trip->induction_class == HInductionVarAnalysis::kInvariant) {
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return trip->operation == HInductionVarAnalysis::kTripCountInBody ||
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trip->operation == HInductionVarAnalysis::kTripCountInBodyUnsafe;
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}
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}
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return false;
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}
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bool InductionVarRange::IsUnsafeTripCount(HInductionVarAnalysis::InductionInfo* trip) const {
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if (trip != nullptr) {
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if (trip->induction_class == HInductionVarAnalysis::kInvariant) {
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return trip->operation == HInductionVarAnalysis::kTripCountInBodyUnsafe ||
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trip->operation == HInductionVarAnalysis::kTripCountInLoopUnsafe;
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}
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}
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return false;
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}
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InductionVarRange::Value InductionVarRange::GetLinear(HInductionVarAnalysis::InductionInfo* info,
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HInductionVarAnalysis::InductionInfo* trip,
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bool in_body,
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bool is_min) const {
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// Detect common situation where an offset inside the trip count cancels out during range
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// analysis (finding max a * (TC - 1) + OFFSET for a == 1 and TC = UPPER - OFFSET or finding
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// min a * (TC - 1) + OFFSET for a == -1 and TC = OFFSET - UPPER) to avoid losing information
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// with intermediate results that only incorporate single instructions.
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if (trip != nullptr) {
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HInductionVarAnalysis::InductionInfo* trip_expr = trip->op_a;
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if (trip_expr->operation == HInductionVarAnalysis::kSub) {
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int64_t stride_value = 0;
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if (IsConstant(info->op_a, kExact, &stride_value)) {
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if (!is_min && stride_value == 1) {
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// Test original trip's negative operand (trip_expr->op_b) against offset of induction.
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if (HInductionVarAnalysis::InductionEqual(trip_expr->op_b, info->op_b)) {
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// Analyze cancelled trip with just the positive operand (trip_expr->op_a).
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HInductionVarAnalysis::InductionInfo cancelled_trip(
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trip->induction_class,
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trip->operation,
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trip_expr->op_a,
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trip->op_b,
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nullptr,
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trip->type);
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return GetVal(&cancelled_trip, trip, in_body, is_min);
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}
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} else if (is_min && stride_value == -1) {
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// Test original trip's positive operand (trip_expr->op_a) against offset of induction.
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if (HInductionVarAnalysis::InductionEqual(trip_expr->op_a, info->op_b)) {
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// Analyze cancelled trip with just the negative operand (trip_expr->op_b).
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HInductionVarAnalysis::InductionInfo neg(
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HInductionVarAnalysis::kInvariant,
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HInductionVarAnalysis::kNeg,
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nullptr,
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trip_expr->op_b,
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nullptr,
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trip->type);
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HInductionVarAnalysis::InductionInfo cancelled_trip(
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trip->induction_class, trip->operation, &neg, trip->op_b, nullptr, trip->type);
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return SubValue(Value(0), GetVal(&cancelled_trip, trip, in_body, !is_min));
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}
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}
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}
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}
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}
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// General rule of linear induction a * i + b, for normalized 0 <= i < TC.
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return AddValue(GetMul(info->op_a, trip, trip, in_body, is_min),
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GetVal(info->op_b, trip, in_body, is_min));
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}
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InductionVarRange::Value InductionVarRange::GetFetch(HInstruction* instruction,
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HInductionVarAnalysis::InductionInfo* trip,
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bool in_body,
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bool is_min) const {
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// Detect constants and chase the fetch a bit deeper into the HIR tree, so that it becomes
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// more likely range analysis will compare the same instructions as terminal nodes.
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int64_t value;
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if (IsIntAndGet(instruction, &value) && CanLongValueFitIntoInt(value)) {
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return Value(static_cast<int32_t>(value));
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} else if (instruction->IsAdd()) {
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if (IsIntAndGet(instruction->InputAt(0), &value) && CanLongValueFitIntoInt(value)) {
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return AddValue(Value(static_cast<int32_t>(value)),
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GetFetch(instruction->InputAt(1), trip, in_body, is_min));
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} else if (IsIntAndGet(instruction->InputAt(1), &value) && CanLongValueFitIntoInt(value)) {
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return AddValue(GetFetch(instruction->InputAt(0), trip, in_body, is_min),
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Value(static_cast<int32_t>(value)));
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}
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} else if (instruction->IsArrayLength() && instruction->InputAt(0)->IsNewArray()) {
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return GetFetch(instruction->InputAt(0)->InputAt(0), trip, in_body, is_min);
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} else if (instruction->IsTypeConversion()) {
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// Since analysis is 32-bit (or narrower) we allow a widening along the path.
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if (instruction->AsTypeConversion()->GetInputType() == Primitive::kPrimInt &&
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instruction->AsTypeConversion()->GetResultType() == Primitive::kPrimLong) {
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return GetFetch(instruction->InputAt(0), trip, in_body, is_min);
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}
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} else if (is_min) {
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// Special case for finding minimum: minimum of trip-count in loop-body is 1.
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if (trip != nullptr && in_body && instruction == trip->op_a->fetch) {
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return Value(1);
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}
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}
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return Value(instruction, 1, 0);
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}
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InductionVarRange::Value InductionVarRange::GetVal(HInductionVarAnalysis::InductionInfo* info,
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HInductionVarAnalysis::InductionInfo* trip,
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bool in_body,
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bool is_min) const {
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if (info != nullptr) {
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switch (info->induction_class) {
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case HInductionVarAnalysis::kInvariant:
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// Invariants.
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switch (info->operation) {
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case HInductionVarAnalysis::kAdd:
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return AddValue(GetVal(info->op_a, trip, in_body, is_min),
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GetVal(info->op_b, trip, in_body, is_min));
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case HInductionVarAnalysis::kSub: // second reversed!
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return SubValue(GetVal(info->op_a, trip, in_body, is_min),
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GetVal(info->op_b, trip, in_body, !is_min));
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case HInductionVarAnalysis::kNeg: // second reversed!
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return SubValue(Value(0),
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GetVal(info->op_b, trip, in_body, !is_min));
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case HInductionVarAnalysis::kMul:
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return GetMul(info->op_a, info->op_b, trip, in_body, is_min);
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case HInductionVarAnalysis::kDiv:
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return GetDiv(info->op_a, info->op_b, trip, in_body, is_min);
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case HInductionVarAnalysis::kFetch:
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return GetFetch(info->fetch, trip, in_body, is_min);
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case HInductionVarAnalysis::kTripCountInLoop:
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case HInductionVarAnalysis::kTripCountInLoopUnsafe:
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if (!in_body && !is_min) { // one extra!
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return GetVal(info->op_a, trip, in_body, is_min);
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}
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FALLTHROUGH_INTENDED;
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case HInductionVarAnalysis::kTripCountInBody:
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case HInductionVarAnalysis::kTripCountInBodyUnsafe:
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if (is_min) {
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return Value(0);
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} else if (in_body) {
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return SubValue(GetVal(info->op_a, trip, in_body, is_min), Value(1));
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}
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break;
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default:
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break;
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}
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break;
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case HInductionVarAnalysis::kLinear: {
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return CorrectForType(GetLinear(info, trip, in_body, is_min), info->type);
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}
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case HInductionVarAnalysis::kWrapAround:
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case HInductionVarAnalysis::kPeriodic:
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return MergeVal(GetVal(info->op_a, trip, in_body, is_min),
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GetVal(info->op_b, trip, in_body, is_min), is_min);
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}
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}
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return Value();
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}
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InductionVarRange::Value InductionVarRange::GetMul(HInductionVarAnalysis::InductionInfo* info1,
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HInductionVarAnalysis::InductionInfo* info2,
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HInductionVarAnalysis::InductionInfo* trip,
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bool in_body,
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bool is_min) const {
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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
|