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sdk/runtime/vm/compiler/backend/range_analysis.cc
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Liam Appelbe e4196ce8c6 [vm] Namespace constants like offsets and sizeofs to use runtime_api.h 
Second sub-CL of https://dart-review.googlesource.com/c/sdk/+/100644
The first was here https://dart-review.googlesource.com/c/sdk/+/103487

Now that offsets_extractor is checked in, and we have a big header full
of hard coded constants, the next step is to make sure everything is
using those constants. This is essentially everything in the original
CL, except the new simarm_x64 architecture.

Bug: https://github.com/dart-lang/sdk/issues/36839
Change-Id: I236e4f30aa1df6d92209891c983b792d1835b608
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104286
Commit-Queue: Liam Appelbe <liama@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
2019-06-10 02:55:25 +00:00

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// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#if !defined(DART_PRECOMPILED_RUNTIME)
#include "vm/compiler/backend/range_analysis.h"
#include "vm/bit_vector.h"
#include "vm/compiler/backend/il_printer.h"
#include "vm/compiler/backend/loops.h"
namespace dart {
DEFINE_FLAG(bool,
array_bounds_check_elimination,
true,
"Eliminate redundant bounds checks.");
DEFINE_FLAG(bool, trace_range_analysis, false, "Trace range analysis progress");
DEFINE_FLAG(bool,
trace_integer_ir_selection,
false,
"Print integer IR selection optimization pass.");
DECLARE_FLAG(bool, trace_constant_propagation);
// Quick access to the locally defined isolate() and zone() methods.
#define I (isolate())
#define Z (zone())
void RangeAnalysis::Analyze() {
CollectValues();
InsertConstraints();
flow_graph_->GetLoopHierarchy().ComputeInduction();
InferRanges();
EliminateRedundantBoundsChecks();
MarkUnreachableBlocks();
NarrowMintToInt32();
IntegerInstructionSelector iis(flow_graph_);
iis.Select();
RemoveConstraints();
}
// Helper method to chase to a constrained definition.
static Definition* UnwrapConstraint(Definition* defn) {
while (defn->IsConstraint()) {
defn = defn->AsConstraint()->value()->definition();
}
return defn;
}
void RangeAnalysis::CollectValues() {
auto graph_entry = flow_graph_->graph_entry();
auto& initial = *graph_entry->initial_definitions();
for (intptr_t i = 0; i < initial.length(); ++i) {
Definition* current = initial[i];
if (IsIntegerDefinition(current)) {
values_.Add(current);
}
}
for (intptr_t i = 0; i < graph_entry->SuccessorCount(); ++i) {
auto successor = graph_entry->SuccessorAt(i);
if (auto entry = successor->AsBlockEntryWithInitialDefs()) {
const auto& initial = *entry->initial_definitions();
for (intptr_t j = 0; j < initial.length(); ++j) {
Definition* current = initial[j];
if (IsIntegerDefinition(current)) {
values_.Add(current);
}
}
}
}
for (BlockIterator block_it = flow_graph_->reverse_postorder_iterator();
!block_it.Done(); block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
JoinEntryInstr* join = block->AsJoinEntry();
if (join != NULL) {
for (PhiIterator phi_it(join); !phi_it.Done(); phi_it.Advance()) {
PhiInstr* current = phi_it.Current();
if (current->Type()->IsInt()) {
values_.Add(current);
}
}
}
for (ForwardInstructionIterator instr_it(block); !instr_it.Done();
instr_it.Advance()) {
Instruction* current = instr_it.Current();
Definition* defn = current->AsDefinition();
if (defn != NULL) {
if (defn->HasSSATemp() && IsIntegerDefinition(defn)) {
values_.Add(defn);
if (defn->IsBinaryInt64Op()) {
binary_int64_ops_.Add(defn->AsBinaryInt64Op());
} else if (defn->IsShiftInt64Op() ||
defn->IsSpeculativeShiftInt64Op()) {
shift_int64_ops_.Add(defn->AsShiftIntegerOp());
}
}
}
if (current->IsCheckArrayBound() || current->IsGenericCheckBound()) {
bounds_checks_.Add(current);
}
}
}
}
// Given a boundary (right operand) and a comparison operation return
// a symbolic range constraint for the left operand of the comparison assuming
// that it evaluated to true.
// For example for the comparison a < b symbol a is constrained with range
// [Smi::kMinValue, b - 1].
Range* RangeAnalysis::ConstraintSmiRange(Token::Kind op, Definition* boundary) {
switch (op) {
case Token::kEQ:
return new (Z) Range(RangeBoundary::FromDefinition(boundary),
RangeBoundary::FromDefinition(boundary));
case Token::kNE:
return new (Z) Range(Range::Full(RangeBoundary::kRangeBoundarySmi));
case Token::kLT:
return new (Z) Range(RangeBoundary::MinSmi(),
RangeBoundary::FromDefinition(boundary, -1));
case Token::kGT:
return new (Z) Range(RangeBoundary::FromDefinition(boundary, 1),
RangeBoundary::MaxSmi());
case Token::kLTE:
return new (Z) Range(RangeBoundary::MinSmi(),
RangeBoundary::FromDefinition(boundary));
case Token::kGTE:
return new (Z) Range(RangeBoundary::FromDefinition(boundary),
RangeBoundary::MaxSmi());
default:
UNREACHABLE();
return NULL;
}
}
ConstraintInstr* RangeAnalysis::InsertConstraintFor(Value* use,
Definition* defn,
Range* constraint_range,
Instruction* after) {
// No need to constrain constants.
if (defn->IsConstant()) return NULL;
// Check if the value is already constrained to avoid inserting duplicated
// constraints.
ConstraintInstr* constraint = after->next()->AsConstraint();
while (constraint != NULL) {
if ((constraint->value()->definition() == defn) &&
constraint->constraint()->Equals(constraint_range)) {
return NULL;
}
constraint = constraint->next()->AsConstraint();
}
constraint = new (Z) ConstraintInstr(use->CopyWithType(), constraint_range);
flow_graph_->InsertAfter(after, constraint, NULL, FlowGraph::kValue);
FlowGraph::RenameDominatedUses(defn, constraint, constraint);
constraints_.Add(constraint);
return constraint;
}
bool RangeAnalysis::ConstrainValueAfterBranch(Value* use, Definition* defn) {
BranchInstr* branch = use->instruction()->AsBranch();
RelationalOpInstr* rel_op = branch->comparison()->AsRelationalOp();
if ((rel_op != NULL) && (rel_op->operation_cid() == kSmiCid)) {
// Found comparison of two smis. Constrain defn at true and false
// successors using the other operand as a boundary.
Definition* boundary;
Token::Kind op_kind;
if (use->use_index() == 0) { // Left operand.
boundary = rel_op->InputAt(1)->definition();
op_kind = rel_op->kind();
} else {
ASSERT(use->use_index() == 1); // Right operand.
boundary = rel_op->InputAt(0)->definition();
// InsertConstraintFor assumes that defn is left operand of a
// comparison if it is right operand flip the comparison.
op_kind = Token::FlipComparison(rel_op->kind());
}
// Constrain definition at the true successor.
ConstraintInstr* true_constraint =
InsertConstraintFor(use, defn, ConstraintSmiRange(op_kind, boundary),
branch->true_successor());
if (true_constraint != NULL) {
true_constraint->set_target(branch->true_successor());
}
// Constrain definition with a negated condition at the false successor.
ConstraintInstr* false_constraint = InsertConstraintFor(
use, defn,
ConstraintSmiRange(Token::NegateComparison(op_kind), boundary),
branch->false_successor());
if (false_constraint != NULL) {
false_constraint->set_target(branch->false_successor());
}
return true;
}
return false;
}
void RangeAnalysis::InsertConstraintsFor(Definition* defn) {
for (Value* use = defn->input_use_list(); use != NULL;
use = use->next_use()) {
if (auto branch = use->instruction()->AsBranch()) {
if (ConstrainValueAfterBranch(use, defn)) {
Value* other_value = branch->InputAt(1 - use->use_index());
if (!IsIntegerDefinition(other_value->definition())) {
ConstrainValueAfterBranch(other_value, other_value->definition());
}
}
} else if (auto check = use->instruction()->AsCheckBoundBase()) {
ConstrainValueAfterCheckBound(use, check, defn);
}
}
}
void RangeAnalysis::ConstrainValueAfterCheckBound(Value* use,
CheckBoundBase* check,
Definition* defn) {
const intptr_t use_index = use->use_index();
Range* constraint_range = NULL;
if (use_index == CheckBoundBase::kIndexPos) {
Definition* length = check->length()->definition();
constraint_range = new (Z) Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromDefinition(length, -1));
} else {
ASSERT(use_index == CheckBoundBase::kLengthPos);
Definition* index = check->index()->definition();
constraint_range = new (Z)
Range(RangeBoundary::FromDefinition(index, 1), RangeBoundary::MaxSmi());
}
InsertConstraintFor(use, defn, constraint_range, check);
}
void RangeAnalysis::InsertConstraints() {
for (intptr_t i = 0; i < values_.length(); i++) {
InsertConstraintsFor(values_[i]);
}
for (intptr_t i = 0; i < constraints_.length(); i++) {
InsertConstraintsFor(constraints_[i]);
}
}
const Range* RangeAnalysis::GetSmiRange(Value* value) const {
Definition* defn = value->definition();
const Range* range = defn->range();
if ((range == NULL) && (defn->Type()->ToCid() != kSmiCid)) {
// Type propagator determined that reaching type for this use is Smi.
// However the definition itself is not a smi-definition and
// thus it will never have range assigned to it. Just return the widest
// range possible for this value.
// We don't need to handle kMintCid here because all external mints
// (e.g. results of loads or function call) can be used only after they
// pass through UnboxInt64Instr which is considered as mint-definition
// and will have a range assigned to it.
// Note: that we can't return NULL here because it is used as lattice's
// bottom element to indicate that the range was not computed *yet*.
return &smi_range_;
}
return range;
}
const Range* RangeAnalysis::GetIntRange(Value* value) const {
Definition* defn = value->definition();
const Range* range = defn->range();
if ((range == NULL) && !defn->Type()->IsInt()) {
// Type propagator determined that reaching type for this use is int.
// However the definition itself is not a int-definition and
// thus it will never have range assigned to it. Just return the widest
// range possible for this value.
// Note: that we can't return NULL here because it is used as lattice's
// bottom element to indicate that the range was not computed *yet*.
return &int64_range_;
}
return range;
}
static bool AreEqualDefinitions(Definition* a, Definition* b) {
a = UnwrapConstraint(a);
b = UnwrapConstraint(b);
return (a == b) || (a->AllowsCSE() && b->AllowsCSE() && a->Equals(b));
}
static bool DependOnSameSymbol(const RangeBoundary& a, const RangeBoundary& b) {
return a.IsSymbol() && b.IsSymbol() &&
AreEqualDefinitions(a.symbol(), b.symbol());
}
// Given the current range of a phi and a newly computed range check
// if it is growing towards negative infinity, if it does widen it to
// MinSmi.
static RangeBoundary WidenMin(const Range* range,
const Range* new_range,
RangeBoundary::RangeSize size) {
RangeBoundary min = range->min();
RangeBoundary new_min = new_range->min();
if (min.IsSymbol()) {
if (min.LowerBound().Overflowed(size)) {
return RangeBoundary::MinConstant(size);
} else if (DependOnSameSymbol(min, new_min)) {
return min.offset() <= new_min.offset()
? min
: RangeBoundary::MinConstant(size);
} else if (min.UpperBound(size) <= new_min.LowerBound(size)) {
return min;
}
}
min = Range::ConstantMin(range, size);
new_min = Range::ConstantMin(new_range, size);
return (min.ConstantValue() <= new_min.ConstantValue())
? min
: RangeBoundary::MinConstant(size);
}
// Given the current range of a phi and a newly computed range check
// if it is growing towards positive infinity, if it does widen it to
// MaxSmi.
static RangeBoundary WidenMax(const Range* range,
const Range* new_range,
RangeBoundary::RangeSize size) {
RangeBoundary max = range->max();
RangeBoundary new_max = new_range->max();
if (max.IsSymbol()) {
if (max.UpperBound().Overflowed(size)) {
return RangeBoundary::MaxConstant(size);
} else if (DependOnSameSymbol(max, new_max)) {
return max.offset() >= new_max.offset()
? max
: RangeBoundary::MaxConstant(size);
} else if (max.LowerBound(size) >= new_max.UpperBound(size)) {
return max;
}
}
max = Range::ConstantMax(range, size);
new_max = Range::ConstantMax(new_range, size);
return (max.ConstantValue() >= new_max.ConstantValue())
? max
: RangeBoundary::MaxConstant(size);
}
// Given the current range of a phi and a newly computed range check
// if we can perform narrowing: use newly computed minimum to improve precision
// of the computed range. We do it only if current minimum was widened and is
// equal to MinSmi.
// Newly computed minimum is expected to be greater or equal than old one as
// we are running after widening phase.
static RangeBoundary NarrowMin(const Range* range,
const Range* new_range,
RangeBoundary::RangeSize size) {
const RangeBoundary min = Range::ConstantMin(range, size);
const RangeBoundary new_min = Range::ConstantMin(new_range, size);
if (min.ConstantValue() > new_min.ConstantValue()) return range->min();
// TODO(vegorov): consider using negative infinity to indicate widened bound.
return range->min().IsMinimumOrBelow(size) ? new_range->min() : range->min();
}
// Given the current range of a phi and a newly computed range check
// if we can perform narrowing: use newly computed maximum to improve precision
// of the computed range. We do it only if current maximum was widened and is
// equal to MaxSmi.
// Newly computed maximum is expected to be less or equal than old one as
// we are running after widening phase.
static RangeBoundary NarrowMax(const Range* range,
const Range* new_range,
RangeBoundary::RangeSize size) {
const RangeBoundary max = Range::ConstantMax(range, size);
const RangeBoundary new_max = Range::ConstantMax(new_range, size);
if (max.ConstantValue() < new_max.ConstantValue()) return range->max();
// TODO(vegorov): consider using positive infinity to indicate widened bound.
return range->max().IsMaximumOrAbove(size) ? new_range->max() : range->max();
}
char RangeAnalysis::OpPrefix(JoinOperator op) {
switch (op) {
case WIDEN:
return 'W';
case NARROW:
return 'N';
case NONE:
return 'I';
}
UNREACHABLE();
return ' ';
}
static RangeBoundary::RangeSize RangeSizeForPhi(Definition* phi) {
ASSERT(phi->IsPhi());
if (phi->Type()->ToCid() == kSmiCid) {
return RangeBoundary::kRangeBoundarySmi;
} else if (phi->representation() == kUnboxedInt32) {
return RangeBoundary::kRangeBoundaryInt32;
} else if (phi->Type()->IsInt()) {
return RangeBoundary::kRangeBoundaryInt64;
} else {
UNREACHABLE();
return RangeBoundary::kRangeBoundaryInt64;
}
}
bool RangeAnalysis::InferRange(JoinOperator op,
Definition* defn,
intptr_t iteration) {
Range range;
defn->InferRange(this, &range);
if (!Range::IsUnknown(&range)) {
if (!Range::IsUnknown(defn->range()) && defn->IsPhi()) {
const RangeBoundary::RangeSize size = RangeSizeForPhi(defn);
if (op == WIDEN) {
range = Range(WidenMin(defn->range(), &range, size),
WidenMax(defn->range(), &range, size));
} else if (op == NARROW) {
range = Range(NarrowMin(defn->range(), &range, size),
NarrowMax(defn->range(), &range, size));
}
}
if (!range.Equals(defn->range())) {
#ifndef PRODUCT
if (FLAG_support_il_printer && FLAG_trace_range_analysis) {
THR_Print("%c [%" Pd "] %s: %s => %s\n", OpPrefix(op), iteration,
defn->ToCString(), Range::ToCString(defn->range()),
Range::ToCString(&range));
}
#endif // !PRODUCT
defn->set_range(range);
return true;
}
}
return false;
}
void RangeAnalysis::CollectDefinitions(BitVector* set) {
for (BlockIterator block_it = flow_graph_->reverse_postorder_iterator();
!block_it.Done(); block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
JoinEntryInstr* join = block->AsJoinEntry();
if (join != NULL) {
for (PhiIterator it(join); !it.Done(); it.Advance()) {
PhiInstr* phi = it.Current();
if (set->Contains(phi->ssa_temp_index())) {
definitions_.Add(phi);
}
}
}
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
Definition* defn = it.Current()->AsDefinition();
if ((defn != NULL) && defn->HasSSATemp() &&
set->Contains(defn->ssa_temp_index())) {
definitions_.Add(defn);
}
}
}
}
void RangeAnalysis::Iterate(JoinOperator op, intptr_t max_iterations) {
// TODO(vegorov): switch to worklist if this becomes performance bottleneck.
intptr_t iteration = 0;
bool changed;
do {
changed = false;
for (intptr_t i = 0; i < definitions_.length(); i++) {
Definition* defn = definitions_[i];
if (InferRange(op, defn, iteration)) {
changed = true;
}
}
iteration++;
} while (changed && (iteration < max_iterations));
}
void RangeAnalysis::InferRanges() {
Zone* zone = flow_graph_->zone();
// Initialize bitvector for quick filtering of int values.
BitVector* set =
new (zone) BitVector(zone, flow_graph_->current_ssa_temp_index());
for (intptr_t i = 0; i < values_.length(); i++) {
set->Add(values_[i]->ssa_temp_index());
}
for (intptr_t i = 0; i < constraints_.length(); i++) {
set->Add(constraints_[i]->ssa_temp_index());
}
// Collect integer definitions (including constraints) in the reverse
// postorder. This improves convergence speed compared to iterating
// values_ and constraints_ array separately.
auto graph_entry = flow_graph_->graph_entry();
const auto& initial = *graph_entry->initial_definitions();
for (intptr_t i = 0; i < initial.length(); ++i) {
Definition* definition = initial[i];
if (set->Contains(definition->ssa_temp_index())) {
definitions_.Add(definition);
}
}
for (intptr_t i = 0; i < graph_entry->SuccessorCount(); ++i) {
auto successor = graph_entry->SuccessorAt(i);
if (auto function_entry = successor->AsFunctionEntry()) {
const auto& initial = *function_entry->initial_definitions();
for (intptr_t j = 0; j < initial.length(); ++j) {
Definition* definition = initial[j];
if (set->Contains(definition->ssa_temp_index())) {
definitions_.Add(definition);
}
}
}
}
CollectDefinitions(set);
// Perform an iteration of range inference just propagating ranges
// through the graph as-is without applying widening or narrowing.
// This helps to improve precision of initial bounds.
// We are doing 2 iterations to hit common cases where phi range
// stabilizes quickly and yields a better precision than after
// widening and narrowing.
Iterate(NONE, 2);
// Perform fix-point iteration of range inference applying widening
// operator to phis to ensure fast convergence.
// Widening simply maps growing bounds to the respective range bound.
Iterate(WIDEN, kMaxInt32);
// Perform fix-point iteration of range inference applying narrowing
// to phis to compute more accurate range.
// Narrowing only improves those boundaries that were widened up to
// range boundary and leaves other boundaries intact.
Iterate(NARROW, kMaxInt32);
}
void RangeAnalysis::AssignRangesRecursively(Definition* defn) {
if (!Range::IsUnknown(defn->range())) {
return;
}
if (!IsIntegerDefinition(defn)) {
return;
}
for (intptr_t i = 0; i < defn->InputCount(); i++) {
Definition* input_defn = defn->InputAt(i)->definition();
if (!input_defn->HasSSATemp() || input_defn->IsConstant()) {
AssignRangesRecursively(input_defn);
}
}
Range new_range;
defn->InferRange(this, &new_range);
if (!Range::IsUnknown(&new_range)) {
defn->set_range(new_range);
}
}
// Scheduler is a helper class that inserts floating control-flow less
// subgraphs into the flow graph.
// It always attempts to schedule instructions into the loop preheader in the
// way similar to LICM optimization pass.
// Scheduler supports rollback - that is it keeps track of instructions it
// schedules and can remove all instructions it inserted from the graph.
class Scheduler {
public:
explicit Scheduler(FlowGraph* flow_graph)
: flow_graph_(flow_graph),
loop_headers_(flow_graph->GetLoopHierarchy().headers()),
pre_headers_(loop_headers_.length()) {
for (intptr_t i = 0; i < loop_headers_.length(); i++) {
pre_headers_.Add(loop_headers_[i]->ImmediateDominator());
}
}
// Clear the list of emitted instructions.
void Start() { emitted_.Clear(); }
// Given the floating instruction attempt to schedule it into one of the
// loop preheaders that dominates given post_dominator instruction.
// Some of the instruction inputs can potentially be unscheduled as well.
// Returns NULL is the scheduling fails (e.g. inputs are not invariant for
// any loop containing post_dominator).
// Resulting schedule should be equivalent to one obtained by inserting
// instructions right before post_dominator and running CSE and LICM passes.
template <typename T>
T* Emit(T* instruction, Instruction* post_dominator) {
return static_cast<T*>(EmitRecursively(instruction, post_dominator));
}
// Undo all insertions recorded in the list of emitted instructions.
void Rollback() {
for (intptr_t i = emitted_.length() - 1; i >= 0; i--) {
emitted_[i]->RemoveFromGraph();
}
emitted_.Clear();
}
private:
typedef DirectChainedHashMap<PointerKeyValueTrait<Instruction> > Map;
Instruction* EmitRecursively(Instruction* instruction, Instruction* sink) {
// Schedule all unscheduled inputs and unwrap all constrained inputs.
for (intptr_t i = 0; i < instruction->InputCount(); i++) {
Definition* defn = instruction->InputAt(i)->definition();
// Instruction is not in the graph yet which means that none of
// its input uses should be recorded at defn's use chains.
// Verify this assumption to ensure that we are not going to
// leave use-lists in an inconsistent state when we start
// rewriting inputs via set_definition.
ASSERT(instruction->InputAt(i)->IsSingleUse() &&
!defn->HasOnlyInputUse(instruction->InputAt(i)));
if (!defn->HasSSATemp()) {
Definition* scheduled = Emit(defn, sink);
if (scheduled == NULL) {
return NULL;
}
instruction->InputAt(i)->set_definition(scheduled);
} else if (defn->IsConstraint()) {
instruction->InputAt(i)->set_definition(UnwrapConstraint(defn));
}
}
// Attempt to find equivalent instruction that was already scheduled.
// If the instruction is still in the graph (it could have been
// un-scheduled by a rollback action) and it dominates the sink - use it.
Instruction* emitted = map_.LookupValue(instruction);
if (emitted != NULL && !emitted->WasEliminated() &&
sink->IsDominatedBy(emitted)) {
return emitted;
}
// Attempt to find suitable pre-header. Iterate loop headers backwards to
// attempt scheduling into the outermost loop first.
for (intptr_t i = loop_headers_.length() - 1; i >= 0; i--) {
BlockEntryInstr* header = loop_headers_[i];
BlockEntryInstr* pre_header = pre_headers_[i];
if (pre_header == NULL) {
continue;
}
if (!sink->IsDominatedBy(header)) {
continue;
}
Instruction* last = pre_header->last_instruction();
bool inputs_are_invariant = true;
for (intptr_t j = 0; j < instruction->InputCount(); j++) {
Definition* defn = instruction->InputAt(j)->definition();
if (!last->IsDominatedBy(defn)) {
inputs_are_invariant = false;
break;
}
}
if (inputs_are_invariant) {
EmitTo(pre_header, instruction);
return instruction;
}
}
return NULL;
}
void EmitTo(BlockEntryInstr* block, Instruction* instr) {
GotoInstr* last = block->last_instruction()->AsGoto();
flow_graph_->InsertBefore(
last, instr, last->env(),
instr->IsDefinition() ? FlowGraph::kValue : FlowGraph::kEffect);
instr->CopyDeoptIdFrom(*last);
map_.Insert(instr);
emitted_.Add(instr);
}
FlowGraph* flow_graph_;
Map map_;
const ZoneGrowableArray<BlockEntryInstr*>& loop_headers_;
GrowableArray<BlockEntryInstr*> pre_headers_;
GrowableArray<Instruction*> emitted_;
};
// If bounds check 0 <= index < length is not redundant we attempt to
// replace it with a sequence of checks that guarantee
//
// 0 <= LowerBound(index) < UpperBound(index) < length
//
// and hoist all of those checks out of the enclosing loop.
//
// Upper/Lower bounds are symbolic arithmetic expressions with +, -, *
// operations.
class BoundsCheckGeneralizer {
public:
BoundsCheckGeneralizer(RangeAnalysis* range_analysis, FlowGraph* flow_graph)
: range_analysis_(range_analysis),
flow_graph_(flow_graph),
scheduler_(flow_graph) {}
void TryGeneralize(CheckArrayBoundInstr* check,
const RangeBoundary& array_length) {
Definition* upper_bound =
ConstructUpperBound(check->index()->definition(), check);
if (upper_bound == UnwrapConstraint(check->index()->definition())) {
// Unable to construct upper bound for the index.
if (FLAG_support_il_printer && FLAG_trace_range_analysis) {
THR_Print("Failed to construct upper bound for %s index\n",
check->ToCString());
}
return;
}
// Re-associate subexpressions inside upper_bound to collect all constants
// together. This will expose more redundancies when we are going to emit
// upper bound through scheduler.
if (!Simplify(&upper_bound, NULL)) {
if (FLAG_support_il_printer && FLAG_trace_range_analysis) {
THR_Print("Failed to simplify upper bound for %s index\n",
check->ToCString());
}
return;
}
upper_bound = ApplyConstraints(upper_bound, check);
range_analysis_->AssignRangesRecursively(upper_bound);
// We are going to constrain any symbols participating in + and * operations
// to guarantee that they are positive. Find all symbols that need
// constraining. If there is a subtraction subexpression with non-positive
// range give up on generalization for simplicity.
GrowableArray<Definition*> non_positive_symbols;
if (!FindNonPositiveSymbols(&non_positive_symbols, upper_bound)) {
#ifndef PRODUCT
if (FLAG_support_il_printer && FLAG_trace_range_analysis) {
THR_Print(
"Failed to generalize %s index to %s"
" (can't ensure positivity)\n",
check->ToCString(), IndexBoundToCString(upper_bound));
}
#endif // !PRODUCT
return;
}
// Check that we can statically prove that lower bound of the index is
// non-negative under the assumption that all potentially non-positive
// symbols are positive.
GrowableArray<ConstraintInstr*> positive_constraints(
non_positive_symbols.length());
Range* positive_range =
new Range(RangeBoundary::FromConstant(0),
RangeBoundary::MaxConstant(RangeBoundary::kRangeBoundarySmi));
for (intptr_t i = 0; i < non_positive_symbols.length(); i++) {
Definition* symbol = non_positive_symbols[i];
positive_constraints.Add(
new ConstraintInstr(new Value(symbol), positive_range));
}
Definition* lower_bound =
ConstructLowerBound(check->index()->definition(), check);
// No need to simplify lower bound before applying constraints as
// we are not going to emit it.
lower_bound = ApplyConstraints(lower_bound, check, &positive_constraints);
range_analysis_->AssignRangesRecursively(lower_bound);
if (!RangeUtils::IsPositive(lower_bound->range())) {
// Can't prove that lower bound is positive even with additional checks
// against potentially non-positive symbols. Give up.
#ifndef PRODUCT
if (FLAG_support_il_printer && FLAG_trace_range_analysis) {
THR_Print(
"Failed to generalize %s index to %s"
" (lower bound is not positive)\n",
check->ToCString(), IndexBoundToCString(upper_bound));
}
#endif // !PRODUCT
return;
}
#ifndef PRODUCT
if (FLAG_support_il_printer && FLAG_trace_range_analysis) {
THR_Print("For %s computed index bounds [%s, %s]\n", check->ToCString(),
IndexBoundToCString(lower_bound),
IndexBoundToCString(upper_bound));
}
#endif // !PRODUCT
// At this point we know that 0 <= index < UpperBound(index) under
// certain preconditions. Start by emitting this preconditions.
scheduler_.Start();
// AOT should only see non-deopting GenericCheckBound.
ASSERT(!FLAG_precompiled_mode);
ConstantInstr* max_smi = flow_graph_->GetConstant(
Smi::Handle(Smi::New(compiler::target::kSmiMax)));
for (intptr_t i = 0; i < non_positive_symbols.length(); i++) {
CheckArrayBoundInstr* precondition = new CheckArrayBoundInstr(
new Value(max_smi), new Value(non_positive_symbols[i]),
DeoptId::kNone);
precondition->mark_generalized();
precondition = scheduler_.Emit(precondition, check);
if (precondition == NULL) {
if (FLAG_trace_range_analysis) {
THR_Print(" => failed to insert positivity constraint\n");
}
scheduler_.Rollback();
return;
}
}
CheckArrayBoundInstr* new_check = new CheckArrayBoundInstr(
new Value(UnwrapConstraint(check->length()->definition())),
new Value(upper_bound), DeoptId::kNone);
new_check->mark_generalized();
if (new_check->IsRedundant(array_length)) {
if (FLAG_trace_range_analysis) {
THR_Print(" => generalized check is redundant\n");
}
RemoveGeneralizedCheck(check);
return;
}
new_check = scheduler_.Emit(new_check, check);
if (new_check != NULL) {
if (FLAG_trace_range_analysis) {
THR_Print(" => generalized check was hoisted into B%" Pd "\n",
new_check->GetBlock()->block_id());
}
RemoveGeneralizedCheck(check);
} else {
if (FLAG_trace_range_analysis) {
THR_Print(" => generalized check can't be hoisted\n");
}
scheduler_.Rollback();
}
}
static void RemoveGeneralizedCheck(CheckArrayBoundInstr* check) {
BinarySmiOpInstr* binary_op = check->index()->definition()->AsBinarySmiOp();
if (binary_op != NULL) {
binary_op->set_can_overflow(false);
}
check->ReplaceUsesWith(check->index()->definition());
check->RemoveFromGraph();
}
private:
BinarySmiOpInstr* MakeBinaryOp(Token::Kind op_kind,
Definition* left,
Definition* right) {
return new BinarySmiOpInstr(op_kind, new Value(left), new Value(right),
DeoptId::kNone);
}
BinarySmiOpInstr* MakeBinaryOp(Token::Kind op_kind,
Definition* left,
intptr_t right) {
ConstantInstr* constant_right =
flow_graph_->GetConstant(Smi::Handle(Smi::New(right)));
return MakeBinaryOp(op_kind, left, constant_right);
}
Definition* RangeBoundaryToDefinition(const RangeBoundary& bound) {
Definition* symbol = UnwrapConstraint(bound.symbol());
if (bound.offset() == 0) {
return symbol;
} else {
return MakeBinaryOp(Token::kADD, symbol, bound.offset());
}
}
typedef Definition* (BoundsCheckGeneralizer::*PhiBoundFunc)(PhiInstr*,
LoopInfo*,
InductionVar*,
Instruction*);
// Construct symbolic lower bound for a value at the given point.
Definition* ConstructLowerBound(Definition* value, Instruction* point) {
return ConstructBound(&BoundsCheckGeneralizer::InductionVariableLowerBound,
value, point);
}
// Construct symbolic upper bound for a value at the given point.
Definition* ConstructUpperBound(Definition* value, Instruction* point) {
return ConstructBound(&BoundsCheckGeneralizer::InductionVariableUpperBound,
value, point);
}
// Helper methods to implement "older" business logic.
// TODO(ajcbik): generalize with new induction variable information
// Only accept loops with a smi constraint on smi induction.
LoopInfo* GetSmiBoundedLoop(PhiInstr* phi) {
LoopInfo* loop = phi->GetBlock()->loop_info();
if (loop == nullptr) {
return nullptr;
}
ConstraintInstr* limit = loop->limit();
if (limit == nullptr) {
return nullptr;
}
Definition* def = UnwrapConstraint(limit->value()->definition());
Range* constraining_range = limit->constraint();
if (GetSmiInduction(loop, def) != nullptr &&
constraining_range->min().Equals(RangeBoundary::MinSmi()) &&
constraining_range->max().IsSymbol() &&
def->IsDominatedBy(constraining_range->max().symbol())) {
return loop;
}
return nullptr;
}
// Only accept smi linear induction with unit stride.
InductionVar* GetSmiInduction(LoopInfo* loop, Definition* def) {
if (loop != nullptr && def->Type()->ToCid() == kSmiCid) {
InductionVar* induc = loop->LookupInduction(def);
if (induc != nullptr && induc->kind() == InductionVar::kLinear &&
induc->next()->offset() == 1 && induc->next()->mult() == 0) {
return induc;
}
}
return nullptr;
}
// Reconstruct invariant (phi-init is always already in the graph).
Definition* GenerateInvariant(InductionVar* induc) {
if (induc->mult() == 0) {
return flow_graph_->GetConstant(
Smi::ZoneHandle(Smi::New(induc->offset())));
}
ASSERT(induc->offset() == 0 && induc->mult() == 1);
return induc->def();
}
// Construct symbolic bound for a value at the given point:
//
// 1. if value is an induction variable use its bounds;
// 2. if value is addition or multiplication construct bounds for left
// and right hand sides separately and use addition/multiplication
// of bounds as a bound (addition and multiplication are monotone
// operations for both operands);
// 3. if value is a substraction then construct bound for the left hand
// side and use substraction of the right hand side from the left hand
// side bound as a bound for an expression (substraction is monotone for
// the left hand side operand).
//
Definition* ConstructBound(PhiBoundFunc phi_bound_func,
Definition* value,
Instruction* point) {
value = UnwrapConstraint(value);
if (value->IsPhi()) {
PhiInstr* phi = value->AsPhi();
LoopInfo* loop = GetSmiBoundedLoop(phi);
InductionVar* induc = GetSmiInduction(loop, phi);
if (induc != nullptr) {
return (this->*phi_bound_func)(phi, loop, induc, point);
}
} else if (value->IsBinarySmiOp()) {
BinarySmiOpInstr* bin_op = value->AsBinarySmiOp();
if ((bin_op->op_kind() == Token::kADD) ||
(bin_op->op_kind() == Token::kMUL) ||
(bin_op->op_kind() == Token::kSUB)) {
Definition* new_left =
ConstructBound(phi_bound_func, bin_op->left()->definition(), point);
Definition* new_right =
(bin_op->op_kind() != Token::kSUB)
? ConstructBound(phi_bound_func, bin_op->right()->definition(),
point)
: UnwrapConstraint(bin_op->right()->definition());
if ((new_left != UnwrapConstraint(bin_op->left()->definition())) ||
(new_right != UnwrapConstraint(bin_op->right()->definition()))) {
return MakeBinaryOp(bin_op->op_kind(), new_left, new_right);
}
}
}
return value;
}
Definition* InductionVariableUpperBound(PhiInstr* phi,
LoopInfo* loop,
InductionVar* induc,
Instruction* point) {
// Test if limit dominates given point.
ConstraintInstr* limit = loop->limit();
if (!point->IsDominatedBy(limit)) {
return phi;
}
// Decide between direct or indirect bound.
Definition* bounded_def = UnwrapConstraint(limit->value()->definition());
if (bounded_def == phi) {
// Given a smi bounded loop with smi induction variable
//
// x <- phi(x0, x + 1)
//
// and a constraint x <= M that dominates the given
// point we conclude that M is an upper bound for x.
return RangeBoundaryToDefinition(limit->constraint()->max());
} else {
// Given a smi bounded loop with two smi induction variables
//
// x <- phi(x0, x + 1)
// y <- phi(y0, y + 1)
//
// and a constraint x <= M that dominates the given
// point we can conclude that
//
// y <= y0 + (M - x0)
//
InductionVar* bounded_induc = GetSmiInduction(loop, bounded_def);
Definition* x0 = GenerateInvariant(bounded_induc->initial());
Definition* y0 = GenerateInvariant(induc->initial());
Definition* m = RangeBoundaryToDefinition(limit->constraint()->max());
BinarySmiOpInstr* loop_length =
MakeBinaryOp(Token::kSUB, ConstructUpperBound(m, point),
ConstructLowerBound(x0, point));
return MakeBinaryOp(Token::kADD, ConstructUpperBound(y0, point),
loop_length);
}
}
Definition* InductionVariableLowerBound(PhiInstr* phi,
LoopInfo* loop,
InductionVar* induc,
Instruction* point) {
// Given a smi bounded loop with smi induction variable
//
// x <- phi(x0, x + 1)
//
// we can conclude that LowerBound(x) == x0.
return ConstructLowerBound(GenerateInvariant(induc->initial()), point);
}
// Try to re-associate binary operations in the floating DAG of operations
// to collect all constants together, e.g. x + C0 + y + C1 is simplified into
// x + y + (C0 + C1).
bool Simplify(Definition** defn, intptr_t* constant) {
if ((*defn)->IsBinarySmiOp()) {
BinarySmiOpInstr* binary_op = (*defn)->AsBinarySmiOp();
Definition* left = binary_op->left()->definition();
Definition* right = binary_op->right()->definition();
intptr_t c = 0;
if (binary_op->op_kind() == Token::kADD) {
intptr_t left_const = 0;
intptr_t right_const = 0;
if (!Simplify(&left, &left_const) || !Simplify(&right, &right_const)) {
return false;
}
c = left_const + right_const;
if (Utils::WillAddOverflow(left_const, right_const) ||
!compiler::target::IsSmi(c)) {
return false; // Abort.
}
if (constant != NULL) {
*constant = c;
}
if ((left == NULL) && (right == NULL)) {
if (constant != NULL) {
*defn = NULL;
} else {
*defn = flow_graph_->GetConstant(Smi::Handle(Smi::New(c)));
}
return true;
}
if (left == NULL) {
if ((constant != NULL) || (c == 0)) {
*defn = right;
return true;
} else {
left = right;
right = NULL;
}
}
if (right == NULL) {
if ((constant != NULL) || (c == 0)) {
*defn = left;
return true;
} else {
right = flow_graph_->GetConstant(Smi::Handle(Smi::New(c)));
c = 0;
}
}
} else if (binary_op->op_kind() == Token::kSUB) {
intptr_t left_const = 0;
intptr_t right_const = 0;
if (!Simplify(&left, &left_const) || !Simplify(&right, &right_const)) {
return false;
}
c = (left_const - right_const);
if (Utils::WillSubOverflow(left_const, right_const) ||
!compiler::target::IsSmi(c)) {
return false; // Abort.
}
if (constant != NULL) {
*constant = c;
}
if ((left == NULL) && (right == NULL)) {
if (constant != NULL) {
*defn = NULL;
} else {
*defn = flow_graph_->GetConstant(Smi::Handle(Smi::New(c)));
}
return true;
}
if (left == NULL) {
left = flow_graph_->GetConstant(Smi::Handle(Smi::New(0)));
}
if (right == NULL) {
if ((constant != NULL) || (c == 0)) {
*defn = left;
return true;
} else {
right = flow_graph_->GetConstant(Smi::Handle(Smi::New(-c)));
c = 0;
}
}
} else if (binary_op->op_kind() == Token::kMUL) {
if (!Simplify(&left, NULL) || !Simplify(&right, NULL)) {
return false;
}
} else {
// Don't attempt to simplify any other binary operation.
return true;
}
ASSERT(left != NULL);
ASSERT(right != NULL);
const bool left_changed = (left != binary_op->left()->definition());
const bool right_changed = (right != binary_op->right()->definition());
if (left_changed || right_changed) {
if (!(*defn)->HasSSATemp()) {
if (left_changed) binary_op->left()->set_definition(left);
if (right_changed) binary_op->right()->set_definition(right);
*defn = binary_op;
} else {
*defn = MakeBinaryOp(binary_op->op_kind(), UnwrapConstraint(left),
UnwrapConstraint(right));
}
}
if ((c != 0) && (constant == NULL)) {
*defn = MakeBinaryOp(Token::kADD, *defn, c);
}
} else if ((*defn)->IsConstant()) {
ConstantInstr* constant_defn = (*defn)->AsConstant();
if ((constant != NULL) && constant_defn->IsSmi()) {
*defn = NULL;
*constant = Smi::Cast(constant_defn->value()).Value();
}
}
return true;
}
// If possible find a set of symbols that need to be non-negative to
// guarantee that expression as whole is non-negative.
bool FindNonPositiveSymbols(GrowableArray<Definition*>* symbols,
Definition* defn) {
if (defn->IsConstant()) {
const Object& value = defn->AsConstant()->value();
return compiler::target::IsSmi(value) && (Smi::Cast(value).Value() >= 0);
} else if (defn->HasSSATemp()) {
if (!RangeUtils::IsPositive(defn->range())) {
symbols->Add(defn);
}
return true;
} else if (defn->IsBinarySmiOp()) {
BinarySmiOpInstr* binary_op = defn->AsBinarySmiOp();
ASSERT((binary_op->op_kind() == Token::kADD) ||
(binary_op->op_kind() == Token::kSUB) ||
(binary_op->op_kind() == Token::kMUL));
if (RangeUtils::IsPositive(defn->range())) {
// We can statically prove that this subexpression is always positive.
// No need to inspect its subexpressions.
return true;
}
if (binary_op->op_kind() == Token::kSUB) {
// For addition and multiplication it's enough to ensure that
// lhs and rhs are positive to guarantee that defn as whole is
// positive. This does not work for substraction so just give up.
return false;
}
return FindNonPositiveSymbols(symbols, binary_op->left()->definition()) &&
FindNonPositiveSymbols(symbols, binary_op->right()->definition());
}
UNREACHABLE();
return false;
}
// Find innermost constraint for the given definition dominating given
// instruction.
static Definition* FindInnermostConstraint(Definition* defn,
Instruction* post_dominator) {
for (Value* use = defn->input_use_list(); use != NULL;
use = use->next_use()) {
ConstraintInstr* constraint = use->instruction()->AsConstraint();
if ((constraint != NULL) && post_dominator->IsDominatedBy(constraint)) {
return FindInnermostConstraint(constraint, post_dominator);
}
}
return defn;
}
// Replace symbolic parts of the boundary with respective constraints
// that hold at the given point in the flow graph signified by
// post_dominator.
// Constraints array allows to provide a set of additional floating
// constraints that were not inserted into the graph.
static Definition* ApplyConstraints(
Definition* defn,
Instruction* post_dominator,
GrowableArray<ConstraintInstr*>* constraints = NULL) {
if (defn->HasSSATemp()) {
defn = FindInnermostConstraint(defn, post_dominator);
if (constraints != NULL) {
for (intptr_t i = 0; i < constraints->length(); i++) {
ConstraintInstr* constraint = (*constraints)[i];
if (constraint->value()->definition() == defn) {
return constraint;
}
}
}
return defn;
}
for (intptr_t i = 0; i < defn->InputCount(); i++) {
defn->InputAt(i)->set_definition(ApplyConstraints(
defn->InputAt(i)->definition(), post_dominator, constraints));
}
return defn;
}
#ifndef PRODUCT
static void PrettyPrintIndexBoundRecursively(BufferFormatter* f,
Definition* index_bound) {
BinarySmiOpInstr* binary_op = index_bound->AsBinarySmiOp();
if (binary_op != NULL) {
f->Print("(");
PrettyPrintIndexBoundRecursively(f, binary_op->left()->definition());
f->Print(" %s ", Token::Str(binary_op->op_kind()));
PrettyPrintIndexBoundRecursively(f, binary_op->right()->definition());
f->Print(")");
} else if (index_bound->IsConstant()) {
f->Print("%" Pd "",
Smi::Cast(index_bound->AsConstant()->value()).Value());
} else {
f->Print("v%" Pd "", index_bound->ssa_temp_index());
}
f->Print(" {%s}", Range::ToCString(index_bound->range()));
}
static const char* IndexBoundToCString(Definition* index_bound) {
char buffer[1024];
BufferFormatter f(buffer, sizeof(buffer));
PrettyPrintIndexBoundRecursively(&f, index_bound);
return Thread::Current()->zone()->MakeCopyOfString(buffer);
}
#endif // !PRODUCT
RangeAnalysis* range_analysis_;
FlowGraph* flow_graph_;
Scheduler scheduler_;
};
void RangeAnalysis::EliminateRedundantBoundsChecks() {
if (FLAG_array_bounds_check_elimination) {
const Function& function = flow_graph_->function();
// Generalization only if we have not deoptimized on a generalized
// check earlier, or we're compiling precompiled code (no
// optimistic hoisting of checks possible)
const bool try_generalization =
!function.ProhibitsBoundsCheckGeneralization() &&
!FLAG_precompiled_mode;
BoundsCheckGeneralizer generalizer(this, flow_graph_);
for (intptr_t i = 0; i < bounds_checks_.length(); i++) {
// Is this a non-speculative check bound?
auto aot_check = bounds_checks_[i]->AsGenericCheckBound();
if (aot_check != nullptr) {
auto length = aot_check->length()
->definition()
->OriginalDefinitionIgnoreBoxingAndConstraints();
auto array_length = RangeBoundary::FromDefinition(length);
if (aot_check->IsRedundant(array_length)) {
aot_check->ReplaceUsesWith(aot_check->index()->definition());
aot_check->RemoveFromGraph();
}
continue;
}
// Must be a speculative check bound.
CheckArrayBoundInstr* check = bounds_checks_[i]->AsCheckArrayBound();
ASSERT(check != nullptr);
RangeBoundary array_length =
RangeBoundary::FromDefinition(check->length()->definition());
if (check->IsRedundant(array_length)) {
check->ReplaceUsesWith(check->index()->definition());
check->RemoveFromGraph();
} else if (try_generalization) {
generalizer.TryGeneralize(check, array_length);
}
}
}
}
void RangeAnalysis::MarkUnreachableBlocks() {
for (intptr_t i = 0; i < constraints_.length(); i++) {
if (Range::IsUnknown(constraints_[i]->range())) {
TargetEntryInstr* target = constraints_[i]->target();
if (target == NULL) {
// TODO(vegorov): replace Constraint with an uncoditional
// deoptimization and kill all dominated dead code.
continue;
}
BranchInstr* branch =
target->PredecessorAt(0)->last_instruction()->AsBranch();
if (target == branch->true_successor()) {
// True unreachable.
if (FLAG_trace_constant_propagation && flow_graph_->should_print()) {
THR_Print("Range analysis: True unreachable (B%" Pd ")\n",
branch->true_successor()->block_id());
}
branch->set_constant_target(branch->false_successor());
} else {
ASSERT(target == branch->false_successor());
// False unreachable.
if (FLAG_trace_constant_propagation && flow_graph_->should_print()) {
THR_Print("Range analysis: False unreachable (B%" Pd ")\n",
branch->false_successor()->block_id());
}
branch->set_constant_target(branch->true_successor());
}
}
}
}
void RangeAnalysis::RemoveConstraints() {
for (intptr_t i = 0; i < constraints_.length(); i++) {
Definition* def = constraints_[i]->value()->definition();
// Some constraints might be constraining constraints. Unwind the chain of
// constraints until we reach the actual definition.
while (def->IsConstraint()) {
def = def->AsConstraint()->value()->definition();
}
constraints_[i]->ReplaceUsesWith(def);
constraints_[i]->RemoveFromGraph();
}
}
static void NarrowBinaryInt64Op(BinaryInt64OpInstr* int64_op) {
if (RangeUtils::Fits(int64_op->range(), RangeBoundary::kRangeBoundaryInt32) &&
RangeUtils::Fits(int64_op->left()->definition()->range(),
RangeBoundary::kRangeBoundaryInt32) &&
RangeUtils::Fits(int64_op->right()->definition()->range(),
RangeBoundary::kRangeBoundaryInt32) &&
BinaryInt32OpInstr::IsSupported(int64_op->op_kind(), int64_op->left(),
int64_op->right())) {
BinaryInt32OpInstr* int32_op = new BinaryInt32OpInstr(
int64_op->op_kind(), int64_op->left()->CopyWithType(),
int64_op->right()->CopyWithType(), int64_op->DeoptimizationTarget());
int32_op->set_range(*int64_op->range());
int32_op->set_can_overflow(false);
int64_op->ReplaceWith(int32_op, NULL);
}
}
static void NarrowShiftInt64Op(ShiftIntegerOpInstr* int64_op) {
if (RangeUtils::Fits(int64_op->range(), RangeBoundary::kRangeBoundaryInt32) &&
RangeUtils::Fits(int64_op->left()->definition()->range(),
RangeBoundary::kRangeBoundaryInt32) &&
RangeUtils::Fits(int64_op->right()->definition()->range(),
RangeBoundary::kRangeBoundaryInt32) &&
BinaryInt32OpInstr::IsSupported(int64_op->op_kind(), int64_op->left(),
int64_op->right())) {
BinaryInt32OpInstr* int32_op = new BinaryInt32OpInstr(
int64_op->op_kind(), int64_op->left()->CopyWithType(),
int64_op->right()->CopyWithType(), int64_op->DeoptimizationTarget());
int32_op->set_range(*int64_op->range());
int32_op->set_can_overflow(false);
int64_op->ReplaceWith(int32_op, NULL);
}
}
void RangeAnalysis::NarrowMintToInt32() {
for (intptr_t i = 0; i < binary_int64_ops_.length(); i++) {
NarrowBinaryInt64Op(binary_int64_ops_[i]);
}
for (intptr_t i = 0; i < shift_int64_ops_.length(); i++) {
NarrowShiftInt64Op(shift_int64_ops_[i]);
}
}
IntegerInstructionSelector::IntegerInstructionSelector(FlowGraph* flow_graph)
: flow_graph_(flow_graph) {
ASSERT(flow_graph_ != NULL);
zone_ = flow_graph_->zone();
selected_uint32_defs_ =
new (zone_) BitVector(zone_, flow_graph_->current_ssa_temp_index());
}
void IntegerInstructionSelector::Select() {
if (FLAG_trace_integer_ir_selection) {
THR_Print("---- starting integer ir selection -------\n");
}
FindPotentialUint32Definitions();
FindUint32NarrowingDefinitions();
Propagate();
ReplaceInstructions();
if (FLAG_support_il_printer && FLAG_trace_integer_ir_selection) {
THR_Print("---- after integer ir selection -------\n");
FlowGraphPrinter printer(*flow_graph_);
printer.PrintBlocks();
}
}
bool IntegerInstructionSelector::IsPotentialUint32Definition(Definition* def) {
// TODO(johnmccutchan): Consider Smi operations, to avoid unnecessary tagging
// & untagged of intermediate results.
// TODO(johnmccutchan): Consider phis.
return def->IsBoxInt64() || def->IsUnboxInt64() || def->IsShiftInt64Op() ||
def->IsSpeculativeShiftInt64Op() ||
(def->IsBinaryInt64Op() && BinaryUint32OpInstr::IsSupported(
def->AsBinaryInt64Op()->op_kind())) ||
(def->IsUnaryInt64Op() &&
UnaryUint32OpInstr::IsSupported(def->AsUnaryInt64Op()->op_kind()));
}
void IntegerInstructionSelector::FindPotentialUint32Definitions() {
if (FLAG_trace_integer_ir_selection) {
THR_Print("++++ Finding potential Uint32 definitions:\n");
}
for (BlockIterator block_it = flow_graph_->reverse_postorder_iterator();
!block_it.Done(); block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
for (ForwardInstructionIterator instr_it(block); !instr_it.Done();
instr_it.Advance()) {
Instruction* current = instr_it.Current();
Definition* defn = current->AsDefinition();
if ((defn != NULL) && defn->HasSSATemp()) {
if (IsPotentialUint32Definition(defn)) {
if (FLAG_support_il_printer && FLAG_trace_integer_ir_selection) {
THR_Print("Adding %s\n", current->ToCString());
}
potential_uint32_defs_.Add(defn);
}
}
}
}
}
// BinaryInt64Op masks and stores into unsigned typed arrays that truncate the
// value into a Uint32 range.
bool IntegerInstructionSelector::IsUint32NarrowingDefinition(Definition* def) {
if (def->IsBinaryInt64Op()) {
BinaryInt64OpInstr* op = def->AsBinaryInt64Op();
// Must be a mask operation.
if (op->op_kind() != Token::kBIT_AND) {
return false;
}
Range* range = op->range();
if ((range == NULL) ||
!range->IsWithin(0, static_cast<int64_t>(kMaxUint32))) {
return false;
}
return true;
}
// TODO(johnmccutchan): Add typed array stores.
return false;
}
void IntegerInstructionSelector::FindUint32NarrowingDefinitions() {
ASSERT(selected_uint32_defs_ != NULL);
if (FLAG_trace_integer_ir_selection) {
THR_Print("++++ Selecting Uint32 definitions:\n");
THR_Print("++++ Initial set:\n");
}
for (intptr_t i = 0; i < potential_uint32_defs_.length(); i++) {
Definition* defn = potential_uint32_defs_[i];
if (IsUint32NarrowingDefinition(defn)) {
if (FLAG_support_il_printer && FLAG_trace_integer_ir_selection) {
THR_Print("Adding %s\n", defn->ToCString());
}
selected_uint32_defs_->Add(defn->ssa_temp_index());
}
}
}
bool IntegerInstructionSelector::AllUsesAreUint32Narrowing(Value* list_head) {
for (Value::Iterator it(list_head); !it.Done(); it.Advance()) {
Value* use = it.Current();
Definition* defn = use->instruction()->AsDefinition();
if ((defn == NULL) || !defn->HasSSATemp() ||
!selected_uint32_defs_->Contains(defn->ssa_temp_index())) {
return false;
}
// Right-hand side operand of ShiftInt64Op is not narrowing (all its bits
// should be taken into account).
if (ShiftIntegerOpInstr* shift = defn->AsShiftIntegerOp()) {
if (use == shift->right()) {
return false;
}
}
}
return true;
}
bool IntegerInstructionSelector::CanBecomeUint32(Definition* def) {
ASSERT(IsPotentialUint32Definition(def));
if (def->IsBoxInt64()) {
// If a BoxInt64's input is a candidate, the box is a candidate.
Definition* box_input = def->AsBoxInt64()->value()->definition();
return selected_uint32_defs_->Contains(box_input->ssa_temp_index());
}
// A right shift with an input outside of Uint32 range cannot be converted
// because we need the high bits.
if (def->IsShiftInt64Op() || def->IsSpeculativeShiftInt64Op()) {
ShiftIntegerOpInstr* op = def->AsShiftIntegerOp();
if (op->op_kind() == Token::kSHR) {
Definition* shift_input = op->left()->definition();
ASSERT(shift_input != NULL);
Range* range = shift_input->range();
if ((range == NULL) ||
!range->IsWithin(0, static_cast<int64_t>(kMaxUint32))) {
return false;
}
}
}
if (!def->HasUses()) {
// No uses, skip.
return false;
}
return AllUsesAreUint32Narrowing(def->input_use_list()) &&
AllUsesAreUint32Narrowing(def->env_use_list());
}
void IntegerInstructionSelector::Propagate() {
ASSERT(selected_uint32_defs_ != NULL);
bool changed = true;
intptr_t iteration = 0;
while (changed) {
if (FLAG_trace_integer_ir_selection) {
THR_Print("+++ Iteration: %" Pd "\n", iteration++);
}
changed = false;
for (intptr_t i = 0; i < potential_uint32_defs_.length(); i++) {
Definition* defn = potential_uint32_defs_[i];
if (selected_uint32_defs_->Contains(defn->ssa_temp_index())) {
// Already marked as a candidate, skip.
continue;
}
if (defn->IsConstant()) {
// Skip constants.
continue;
}
if (CanBecomeUint32(defn)) {
if (FLAG_support_il_printer && FLAG_trace_integer_ir_selection) {
THR_Print("Adding %s\n", defn->ToCString());
}
// Found a new candidate.
selected_uint32_defs_->Add(defn->ssa_temp_index());
// Haven't reached fixed point yet.
changed = true;
}
}
}
if (FLAG_trace_integer_ir_selection) {
THR_Print("Reached fixed point\n");
}
}
Definition* IntegerInstructionSelector::ConstructReplacementFor(
Definition* def) {
// Should only see mint definitions.
ASSERT(IsPotentialUint32Definition(def));
// Should not see constant instructions.
ASSERT(!def->IsConstant());
if (def->IsBinaryIntegerOp()) {
BinaryIntegerOpInstr* op = def->AsBinaryIntegerOp();
Token::Kind op_kind = op->op_kind();
Value* left = op->left()->CopyWithType();
Value* right = op->right()->CopyWithType();
intptr_t deopt_id = op->DeoptimizationTarget();
if (def->IsBinaryInt64Op()) {
return new (Z) BinaryUint32OpInstr(op_kind, left, right, deopt_id);
} else if (def->IsShiftInt64Op()) {
return new (Z) ShiftUint32OpInstr(op_kind, left, right, deopt_id);
} else if (def->IsSpeculativeShiftInt64Op()) {
return new (Z)
SpeculativeShiftUint32OpInstr(op_kind, left, right, deopt_id);
} else {
UNREACHABLE();
}
} else if (def->IsBoxInt64()) {
Value* value = def->AsBoxInt64()->value()->CopyWithType();
return new (Z) BoxUint32Instr(value);
} else if (def->IsUnboxInt64()) {
UnboxInstr* unbox = def->AsUnboxInt64();
Value* value = unbox->value()->CopyWithType();
intptr_t deopt_id = unbox->DeoptimizationTarget();
return new (Z) UnboxUint32Instr(value, deopt_id, def->speculative_mode());
} else if (def->IsUnaryInt64Op()) {
UnaryInt64OpInstr* op = def->AsUnaryInt64Op();
Token::Kind op_kind = op->op_kind();
Value* value = op->value()->CopyWithType();
intptr_t deopt_id = op->DeoptimizationTarget();
return new (Z) UnaryUint32OpInstr(op_kind, value, deopt_id);
}
UNREACHABLE();
return NULL;
}
void IntegerInstructionSelector::ReplaceInstructions() {
if (FLAG_trace_integer_ir_selection) {
THR_Print("++++ Replacing instructions:\n");
}
for (intptr_t i = 0; i < potential_uint32_defs_.length(); i++) {
Definition* defn = potential_uint32_defs_[i];
if (!selected_uint32_defs_->Contains(defn->ssa_temp_index())) {
// Not a candidate.
continue;
}
Definition* replacement = ConstructReplacementFor(defn);
ASSERT(replacement != NULL);
if (!Range::IsUnknown(defn->range())) {
if (defn->range()->IsPositive()) {
replacement->set_range(*defn->range());
} else {
replacement->set_range(Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(kMaxUint32)));
}
}
if (FLAG_support_il_printer && FLAG_trace_integer_ir_selection) {
THR_Print("Replacing %s with %s\n", defn->ToCString(),
replacement->ToCString());
}
defn->ReplaceWith(replacement, NULL);
}
}
RangeBoundary RangeBoundary::FromDefinition(Definition* defn, int64_t offs) {
if (defn->IsConstant() && defn->AsConstant()->IsSmi()) {
return FromConstant(Smi::Cast(defn->AsConstant()->value()).Value() + offs);
}
ASSERT(IsValidOffsetForSymbolicRangeBoundary(offs));
return RangeBoundary(kSymbol, reinterpret_cast<intptr_t>(defn), offs);
}
RangeBoundary RangeBoundary::LowerBound() const {
if (IsInfinity()) {
return NegativeInfinity();
}
if (IsConstant()) return *this;
return Add(Range::ConstantMinSmi(symbol()->range()),
RangeBoundary::FromConstant(offset_), NegativeInfinity());
}
RangeBoundary RangeBoundary::UpperBound() const {
if (IsInfinity()) {
return PositiveInfinity();
}
if (IsConstant()) return *this;
return Add(Range::ConstantMaxSmi(symbol()->range()),
RangeBoundary::FromConstant(offset_), PositiveInfinity());
}
RangeBoundary RangeBoundary::Add(const RangeBoundary& a,
const RangeBoundary& b,
const RangeBoundary& overflow) {
if (a.IsInfinity() || b.IsInfinity()) return overflow;
ASSERT(a.IsConstant() && b.IsConstant());
if (Utils::WillAddOverflow(a.ConstantValue(), b.ConstantValue())) {
return overflow;
}
int64_t result = a.ConstantValue() + b.ConstantValue();
return RangeBoundary::FromConstant(result);
}
RangeBoundary RangeBoundary::Sub(const RangeBoundary& a,
const RangeBoundary& b,
const RangeBoundary& overflow) {
if (a.IsInfinity() || b.IsInfinity()) return overflow;
ASSERT(a.IsConstant() && b.IsConstant());
if (Utils::WillSubOverflow(a.ConstantValue(), b.ConstantValue())) {
return overflow;
}
int64_t result = a.ConstantValue() - b.ConstantValue();
return RangeBoundary::FromConstant(result);
}
bool RangeBoundary::SymbolicAdd(const RangeBoundary& a,
const RangeBoundary& b,
RangeBoundary* result) {
if (a.IsSymbol() && b.IsConstant()) {
if (Utils::WillAddOverflow(a.offset(), b.ConstantValue())) {
return false;
}
const int64_t offset = a.offset() + b.ConstantValue();
if (!IsValidOffsetForSymbolicRangeBoundary(offset)) {
return false;
}
*result = RangeBoundary::FromDefinition(a.symbol(), offset);
return true;
} else if (b.IsSymbol() && a.IsConstant()) {
return SymbolicAdd(b, a, result);
}
return false;
}
bool RangeBoundary::SymbolicSub(const RangeBoundary& a,
const RangeBoundary& b,
RangeBoundary* result) {
if (a.IsSymbol() && b.IsConstant()) {
if (Utils::WillSubOverflow(a.offset(), b.ConstantValue())) {
return false;
}
const int64_t offset = a.offset() - b.ConstantValue();
if (!IsValidOffsetForSymbolicRangeBoundary(offset)) {
return false;
}
*result = RangeBoundary::FromDefinition(a.symbol(), offset);
return true;
}
return false;
}
bool RangeBoundary::Equals(const RangeBoundary& other) const {
if (IsConstant() && other.IsConstant()) {
return ConstantValue() == other.ConstantValue();
} else if (IsInfinity() && other.IsInfinity()) {
return kind() == other.kind();
} else if (IsSymbol() && other.IsSymbol()) {
return (offset() == other.offset()) && DependOnSameSymbol(*this, other);
} else if (IsUnknown() && other.IsUnknown()) {
return true;
}
return false;
}
RangeBoundary RangeBoundary::Shl(const RangeBoundary& value_boundary,
int64_t shift_count,
const RangeBoundary& overflow) {
ASSERT(value_boundary.IsConstant());
ASSERT(shift_count >= 0);
int64_t limit = 64 - shift_count;
int64_t value = value_boundary.ConstantValue();
if ((value == 0) || (shift_count == 0) ||
((limit > 0) && Utils::IsInt(static_cast<int>(limit), value))) {
// Result stays in 64 bit range.
int64_t result = value << shift_count;
return RangeBoundary(result);
}
return overflow;
}
static RangeBoundary CanonicalizeBoundary(const RangeBoundary& a,
const RangeBoundary& overflow) {
if (a.IsConstant() || a.IsInfinity()) {
return a;
}
int64_t offset = a.offset();
Definition* symbol = a.symbol();
bool changed;
do {
changed = false;
if (symbol->IsConstraint()) {
symbol = symbol->AsConstraint()->value()->definition();
changed = true;
} else if (symbol->IsBinarySmiOp()) {
BinarySmiOpInstr* op = symbol->AsBinarySmiOp();
Definition* left = op->left()->definition();
Definition* right = op->right()->definition();
switch (op->op_kind()) {
case Token::kADD:
if (right->IsConstant()) {
int64_t rhs = Smi::Cast(right->AsConstant()->value()).Value();
if (Utils::WillAddOverflow(offset, rhs)) {
return overflow;
}
offset += rhs;
symbol = left;
changed = true;
} else if (left->IsConstant()) {
int64_t rhs = Smi::Cast(left->AsConstant()->value()).Value();
if (Utils::WillAddOverflow(offset, rhs)) {
return overflow;
}
offset += rhs;
symbol = right;
changed = true;
}
break;
case Token::kSUB:
if (right->IsConstant()) {
int64_t rhs = Smi::Cast(right->AsConstant()->value()).Value();
if (Utils::WillSubOverflow(offset, rhs)) {
return overflow;
}
offset -= rhs;
symbol = left;
changed = true;
}
break;
default:
break;
}
}
} while (changed);
if (!RangeBoundary::IsValidOffsetForSymbolicRangeBoundary(offset)) {
return overflow;
}
return RangeBoundary::FromDefinition(symbol, offset);
}
static bool CanonicalizeMaxBoundary(RangeBoundary* a) {
if (!a->IsSymbol()) return false;
Range* range = a->symbol()->range();
if ((range == NULL) || !range->max().IsSymbol()) return false;
if (Utils::WillAddOverflow(range->max().offset(), a->offset())) {
*a = RangeBoundary::PositiveInfinity();
return true;
}
const int64_t offset = range->max().offset() + a->offset();
if (!RangeBoundary::IsValidOffsetForSymbolicRangeBoundary(offset)) {
*a = RangeBoundary::PositiveInfinity();
return true;
}
*a = CanonicalizeBoundary(
RangeBoundary::FromDefinition(range->max().symbol(), offset),
RangeBoundary::PositiveInfinity());
return true;
}
static bool CanonicalizeMinBoundary(RangeBoundary* a) {
if (!a->IsSymbol()) return false;
Range* range = a->symbol()->range();
if ((range == NULL) || !range->min().IsSymbol()) return false;
if (Utils::WillAddOverflow(range->min().offset(), a->offset())) {
*a = RangeBoundary::NegativeInfinity();
return true;
}
const int64_t offset = range->min().offset() + a->offset();
if (!RangeBoundary::IsValidOffsetForSymbolicRangeBoundary(offset)) {
*a = RangeBoundary::NegativeInfinity();
return true;
}
*a = CanonicalizeBoundary(
RangeBoundary::FromDefinition(range->min().symbol(), offset),
RangeBoundary::NegativeInfinity());
return true;
}
typedef bool (*BoundaryOp)(RangeBoundary*);
static bool CanonicalizeForComparison(RangeBoundary* a,
RangeBoundary* b,
BoundaryOp op,
const RangeBoundary& overflow) {
if (!a->IsSymbol() || !b->IsSymbol()) {
return false;
}
RangeBoundary canonical_a = *a;
RangeBoundary canonical_b = *b;
do {
if (DependOnSameSymbol(canonical_a, canonical_b)) {
*a = canonical_a;
*b = canonical_b;
return true;
}
} while (op(&canonical_a) || op(&canonical_b));
return false;
}
RangeBoundary RangeBoundary::JoinMin(RangeBoundary a,
RangeBoundary b,
RangeBoundary::RangeSize size) {
if (a.Equals(b)) {
return b;
}
if (CanonicalizeForComparison(&a, &b, &CanonicalizeMinBoundary,
RangeBoundary::NegativeInfinity())) {
return (a.offset() <= b.offset()) ? a : b;
}
const int64_t inf_a = a.LowerBound(size);
const int64_t inf_b = b.LowerBound(size);
const int64_t sup_a = a.UpperBound(size);
const int64_t sup_b = b.UpperBound(size);
if ((sup_a <= inf_b) && !a.LowerBound().Overflowed(size)) {
return a;
} else if ((sup_b <= inf_a) && !b.LowerBound().Overflowed(size)) {
return b;
} else {
return RangeBoundary::FromConstant(Utils::Minimum(inf_a, inf_b));
}
}
RangeBoundary RangeBoundary::JoinMax(RangeBoundary a,
RangeBoundary b,
RangeBoundary::RangeSize size) {
if (a.Equals(b)) {
return b;
}
if (CanonicalizeForComparison(&a, &b, &CanonicalizeMaxBoundary,
RangeBoundary::PositiveInfinity())) {
return (a.offset() >= b.offset()) ? a : b;
}
const int64_t inf_a = a.LowerBound(size);
const int64_t inf_b = b.LowerBound(size);
const int64_t sup_a = a.UpperBound(size);
const int64_t sup_b = b.UpperBound(size);
if ((sup_a <= inf_b) && !b.UpperBound().Overflowed(size)) {
return b;
} else if ((sup_b <= inf_a) && !a.UpperBound().Overflowed(size)) {
return a;
} else {
return RangeBoundary::FromConstant(Utils::Maximum(sup_a, sup_b));
}
}
RangeBoundary RangeBoundary::IntersectionMin(RangeBoundary a, RangeBoundary b) {
ASSERT(!a.IsPositiveInfinity() && !b.IsPositiveInfinity());
ASSERT(!a.IsUnknown() && !b.IsUnknown());
if (a.Equals(b)) {
return a;
}
if (a.IsMinimumOrBelow(RangeBoundary::kRangeBoundarySmi)) {
return b;
} else if (b.IsMinimumOrBelow(RangeBoundary::kRangeBoundarySmi)) {
return a;
}
if (CanonicalizeForComparison(&a, &b, &CanonicalizeMinBoundary,
RangeBoundary::NegativeInfinity())) {
return (a.offset() >= b.offset()) ? a : b;
}
const int64_t inf_a = a.SmiLowerBound();
const int64_t inf_b = b.SmiLowerBound();
return (inf_a >= inf_b) ? a : b;
}
RangeBoundary RangeBoundary::IntersectionMax(RangeBoundary a, RangeBoundary b) {
ASSERT(!a.IsNegativeInfinity() && !b.IsNegativeInfinity());
ASSERT(!a.IsUnknown() && !b.IsUnknown());
if (a.Equals(b)) {
return a;
}
if (a.IsMaximumOrAbove(RangeBoundary::kRangeBoundarySmi)) {
return b;
} else if (b.IsMaximumOrAbove(RangeBoundary::kRangeBoundarySmi)) {
return a;
}
if (CanonicalizeForComparison(&a, &b, &CanonicalizeMaxBoundary,
RangeBoundary::PositiveInfinity())) {
return (a.offset() <= b.offset()) ? a : b;
}
const int64_t sup_a = a.SmiUpperBound();
const int64_t sup_b = b.SmiUpperBound();
return (sup_a <= sup_b) ? a : b;
}
int64_t RangeBoundary::ConstantValue() const {
ASSERT(IsConstant());
return value_;
}
bool Range::IsPositive() const {
return OnlyGreaterThanOrEqualTo(0);
}
bool Range::OnlyLessThanOrEqualTo(int64_t val) const {
const RangeBoundary upper_bound = max().UpperBound();
return !upper_bound.IsPositiveInfinity() &&
(upper_bound.ConstantValue() <= val);
}
bool Range::OnlyGreaterThanOrEqualTo(int64_t val) const {
const RangeBoundary lower_bound = min().LowerBound();
return !lower_bound.IsNegativeInfinity() &&
(lower_bound.ConstantValue() >= val);
}
// Inclusive.
bool Range::IsWithin(int64_t min_int, int64_t max_int) const {
return OnlyGreaterThanOrEqualTo(min_int) && OnlyLessThanOrEqualTo(max_int);
}
bool Range::Overlaps(int64_t min_int, int64_t max_int) const {
RangeBoundary lower = min().LowerBound();
RangeBoundary upper = max().UpperBound();
const int64_t this_min =
lower.IsNegativeInfinity() ? RangeBoundary::kMin : lower.ConstantValue();
const int64_t this_max =
upper.IsPositiveInfinity() ? RangeBoundary::kMax : upper.ConstantValue();
if ((this_min <= min_int) && (min_int <= this_max)) return true;
if ((this_min <= max_int) && (max_int <= this_max)) return true;
if ((min_int < this_min) && (max_int > this_max)) return true;
return false;
}
bool Range::IsUnsatisfiable() const {
// Infinity case: [+inf, ...] || [..., -inf]
if (min().IsPositiveInfinity() || max().IsNegativeInfinity()) {
return true;
}
// Constant case: For example [0, -1].
if (Range::ConstantMin(this).ConstantValue() >
Range::ConstantMax(this).ConstantValue()) {
return true;
}
// Symbol case: For example [v+1, v].
return DependOnSameSymbol(min(), max()) && min().offset() > max().offset();
}
void Range::Clamp(RangeBoundary::RangeSize size) {
min_ = min_.Clamp(size);
max_ = max_.Clamp(size);
}
void Range::ClampToConstant(RangeBoundary::RangeSize size) {
min_ = min_.LowerBound().Clamp(size);
max_ = max_.UpperBound().Clamp(size);
}
void Range::Shl(const Range* left,
const Range* right,
RangeBoundary* result_min,
RangeBoundary* result_max) {
ASSERT(left != NULL);
ASSERT(right != NULL);
ASSERT(result_min != NULL);
ASSERT(result_max != NULL);
RangeBoundary left_max = Range::ConstantMax(left);
RangeBoundary left_min = Range::ConstantMin(left);
// A negative shift count always deoptimizes (and throws), so the minimum
// shift count is zero.
int64_t right_max = Utils::Maximum(Range::ConstantMax(right).ConstantValue(),
static_cast<int64_t>(0));
int64_t right_min = Utils::Maximum(Range::ConstantMin(right).ConstantValue(),
static_cast<int64_t>(0));
*result_min = RangeBoundary::Shl(
left_min, left_min.ConstantValue() > 0 ? right_min : right_max,
left_min.ConstantValue() > 0 ? RangeBoundary::PositiveInfinity()
: RangeBoundary::NegativeInfinity());
*result_max = RangeBoundary::Shl(
left_max, left_max.ConstantValue() > 0 ? right_max : right_min,
left_max.ConstantValue() > 0 ? RangeBoundary::PositiveInfinity()
: RangeBoundary::NegativeInfinity());
}
void Range::Shr(const Range* left,
const Range* right,
RangeBoundary* result_min,
RangeBoundary* result_max) {
RangeBoundary left_max = Range::ConstantMax(left);
RangeBoundary left_min = Range::ConstantMin(left);
// A negative shift count always deoptimizes (and throws), so the minimum
// shift count is zero.
int64_t right_max = Utils::Maximum(Range::ConstantMax(right).ConstantValue(),
static_cast<int64_t>(0));
int64_t right_min = Utils::Maximum(Range::ConstantMin(right).ConstantValue(),
static_cast<int64_t>(0));
*result_min = RangeBoundary::Shr(
left_min, left_min.ConstantValue() > 0 ? right_max : right_min);
*result_max = RangeBoundary::Shr(
left_max, left_max.ConstantValue() > 0 ? right_min : right_max);
}
void Range::And(const Range* left_range,
const Range* right_range,
RangeBoundary* result_min,
RangeBoundary* result_max) {
ASSERT(left_range != NULL);
ASSERT(right_range != NULL);
ASSERT(result_min != NULL);
ASSERT(result_max != NULL);
if (Range::ConstantMin(right_range).ConstantValue() >= 0) {
*result_min = RangeBoundary::FromConstant(0);
*result_max = Range::ConstantMax(right_range);
return;
}
if (Range::ConstantMin(left_range).ConstantValue() >= 0) {
*result_min = RangeBoundary::FromConstant(0);
*result_max = Range::ConstantMax(left_range);
return;
}
BitwiseOp(left_range, right_range, result_min, result_max);
}
static int BitSize(const Range* range) {
const int64_t min = Range::ConstantMin(range).ConstantValue();
const int64_t max = Range::ConstantMax(range).ConstantValue();
return Utils::Maximum(Utils::BitLength(min), Utils::BitLength(max));
}
void Range::BitwiseOp(const Range* left_range,
const Range* right_range,
RangeBoundary* result_min,
RangeBoundary* result_max) {
const int bitsize = Utils::Maximum(BitSize(left_range), BitSize(right_range));
if (left_range->IsPositive() && right_range->IsPositive()) {
*result_min = RangeBoundary::FromConstant(0);
} else {
*result_min =
RangeBoundary::FromConstant(-(static_cast<uint64_t>(1) << bitsize));
}
*result_max =
RangeBoundary::FromConstant((static_cast<uint64_t>(1) << bitsize) - 1);
}
static bool IsArrayLength(Definition* defn) {
if (defn == NULL) {
return false;
}
LoadFieldInstr* load = UnwrapConstraint(defn)->AsLoadField();
return (load != NULL) && load->IsImmutableLengthLoad();
}
void Range::Add(const Range* left_range,
const Range* right_range,
RangeBoundary* result_min,
RangeBoundary* result_max,
Definition* left_defn) {
ASSERT(left_range != NULL);
ASSERT(right_range != NULL);
ASSERT(result_min != NULL);
ASSERT(result_max != NULL);
RangeBoundary left_min = IsArrayLength(left_defn)
? RangeBoundary::FromDefinition(left_defn)
: left_range->min();
RangeBoundary left_max = IsArrayLength(left_defn)
? RangeBoundary::FromDefinition(left_defn)
: left_range->max();
if (!RangeBoundary::SymbolicAdd(left_min, right_range->min(), result_min)) {
*result_min = RangeBoundary::Add(left_range->min().LowerBound(),
right_range->min().LowerBound(),
RangeBoundary::NegativeInfinity());
}
if (!RangeBoundary::SymbolicAdd(left_max, right_range->max(), result_max)) {
*result_max = RangeBoundary::Add(right_range->max().UpperBound(),
left_range->max().UpperBound(),
RangeBoundary::PositiveInfinity());
}
}
void Range::Sub(const Range* left_range,
const Range* right_range,
RangeBoundary* result_min,
RangeBoundary* result_max,
Definition* left_defn) {
ASSERT(left_range != NULL);
ASSERT(right_range != NULL);
ASSERT(result_min != NULL);
ASSERT(result_max != NULL);
RangeBoundary left_min = IsArrayLength(left_defn)
? RangeBoundary::FromDefinition(left_defn)
: left_range->min();
RangeBoundary left_max = IsArrayLength(left_defn)
? RangeBoundary::FromDefinition(left_defn)
: left_range->max();
if (!RangeBoundary::SymbolicSub(left_min, right_range->max(), result_min)) {
*result_min = RangeBoundary::Sub(left_range->min().LowerBound(),
right_range->max().UpperBound(),
RangeBoundary::NegativeInfinity());
}
if (!RangeBoundary::SymbolicSub(left_max, right_range->min(), result_max)) {
*result_max = RangeBoundary::Sub(left_range->max().UpperBound(),
right_range->min().LowerBound(),
RangeBoundary::PositiveInfinity());
}
}
void Range::Mul(const Range* left_range,
const Range* right_range,
RangeBoundary* result_min,
RangeBoundary* result_max) {
ASSERT(left_range != NULL);
ASSERT(right_range != NULL);
ASSERT(result_min != NULL);
ASSERT(result_max != NULL);
const int64_t left_max = ConstantAbsMax(left_range);
const int64_t right_max = ConstantAbsMax(right_range);
if ((left_max <= -compiler::target::kSmiMin) &&
(right_max <= -compiler::target::kSmiMin) &&
((left_max == 0) || (right_max <= kMaxInt64 / left_max))) {
// Product of left and right max values stays in 64 bit range.
const int64_t mul_max = left_max * right_max;
if (OnlyPositiveOrZero(*left_range, *right_range) ||
OnlyNegativeOrZero(*left_range, *right_range)) {
// If both ranges are of the same sign then the range of the result
// is positive and is between multiplications of absolute minimums
// and absolute maximums.
const int64_t mul_min =
ConstantAbsMin(left_range) * ConstantAbsMin(right_range);
*result_min = RangeBoundary::FromConstant(mul_min);
*result_max = RangeBoundary::FromConstant(mul_max);
} else {
// If ranges have mixed signs then use conservative approximation:
// absolute value of the result is less or equal to multiplication
// of absolute maximums.
*result_min = RangeBoundary::FromConstant(-mul_max);
*result_max = RangeBoundary::FromConstant(mul_max);
}
return;
}
// TODO(vegorov): handle mixed sign case that leads to (-Infinity, 0] range.
if (OnlyPositiveOrZero(*left_range, *right_range) ||
OnlyNegativeOrZero(*left_range, *right_range)) {
*result_min = RangeBoundary::FromConstant(0);
*result_max = RangeBoundary::PositiveInfinity();
return;
}
*result_min = RangeBoundary::NegativeInfinity();
*result_max = RangeBoundary::PositiveInfinity();
}
void Range::TruncDiv(const Range* left_range,
const Range* right_range,
RangeBoundary* result_min,
RangeBoundary* result_max) {
ASSERT(left_range != nullptr);
ASSERT(right_range != nullptr);
ASSERT(result_min != nullptr);
ASSERT(result_max != nullptr);
if (left_range->OnlyGreaterThanOrEqualTo(0) &&
right_range->OnlyGreaterThanOrEqualTo(1)) {
const int64_t left_max = ConstantAbsMax(left_range);
const int64_t left_min = ConstantAbsMin(left_range);
const int64_t right_max = ConstantAbsMax(right_range);
const int64_t right_min = ConstantAbsMin(right_range);
*result_max = RangeBoundary::FromConstant(left_max / right_min);
*result_min = RangeBoundary::FromConstant(left_min / right_max);
return;
}
*result_min = RangeBoundary::NegativeInfinity();
*result_max = RangeBoundary::PositiveInfinity();
}
// Both the a and b ranges are >= 0.
bool Range::OnlyPositiveOrZero(const Range& a, const Range& b) {
return a.OnlyGreaterThanOrEqualTo(0) && b.OnlyGreaterThanOrEqualTo(0);
}
// Both the a and b ranges are <= 0.
bool Range::OnlyNegativeOrZero(const Range& a, const Range& b) {
return a.OnlyLessThanOrEqualTo(0) && b.OnlyLessThanOrEqualTo(0);
}
// Return the maximum absolute value included in range.
int64_t Range::ConstantAbsMax(const Range* range) {
if (range == NULL) {
return RangeBoundary::kMax;
}
const int64_t abs_min =
Utils::AbsWithSaturation(Range::ConstantMin(range).ConstantValue());
const int64_t abs_max =
Utils::AbsWithSaturation(Range::ConstantMax(range).ConstantValue());
return Utils::Maximum(abs_min, abs_max);
}
// Return the minimum absolute value included in range.
int64_t Range::ConstantAbsMin(const Range* range) {
if (range == NULL) {
return 0;
}
const int64_t abs_min =
Utils::AbsWithSaturation(Range::ConstantMin(range).ConstantValue());
const int64_t abs_max =
Utils::AbsWithSaturation(Range::ConstantMax(range).ConstantValue());
return Utils::Minimum(abs_min, abs_max);
}
void Range::BinaryOp(const Token::Kind op,
const Range* left_range,
const Range* right_range,
Definition* left_defn,
Range* result) {
ASSERT(left_range != NULL);
ASSERT(right_range != NULL);
// Both left and right ranges are finite.
ASSERT(left_range->IsFinite());
ASSERT(right_range->IsFinite());
RangeBoundary min;
RangeBoundary max;
ASSERT(min.IsUnknown() && max.IsUnknown());
switch (op) {
case Token::kADD:
Range::Add(left_range, right_range, &min, &max, left_defn);
break;
case Token::kSUB:
Range::Sub(left_range, right_range, &min, &max, left_defn);
break;
case Token::kMUL:
Range::Mul(left_range, right_range, &min, &max);
break;
case Token::kTRUNCDIV:
Range::TruncDiv(left_range, right_range, &min, &max);
break;
case Token::kSHL:
Range::Shl(left_range, right_range, &min, &max);
break;
case Token::kSHR:
Range::Shr(left_range, right_range, &min, &max);
break;
case Token::kBIT_AND:
Range::And(left_range, right_range, &min, &max);
break;
case Token::kBIT_XOR:
case Token::kBIT_OR:
Range::BitwiseOp(left_range, right_range, &min, &max);
break;
default:
*result = Range(RangeBoundary::NegativeInfinity(),
RangeBoundary::PositiveInfinity());
return;
}
ASSERT(!min.IsUnknown() && !max.IsUnknown());
*result = Range(min, max);
}
void Definition::set_range(const Range& range) {
if (range_ == NULL) {
range_ = new Range();
}
*range_ = range;
}
void Definition::InferRange(RangeAnalysis* analysis, Range* range) {
if (Type()->ToCid() == kSmiCid) {
*range = Range::Full(RangeBoundary::kRangeBoundarySmi);
} else if (IsInt64Definition()) {
*range = Range::Full(RangeBoundary::kRangeBoundaryInt64);
} else if (IsInt32Definition()) {
*range = Range::Full(RangeBoundary::kRangeBoundaryInt32);
} else if (Type()->IsInt()) {
*range = Range::Full(RangeBoundary::kRangeBoundaryInt64);
} else {
// Only Smi and Mint supported.
UNREACHABLE();
}
}
static bool DependsOnSymbol(const RangeBoundary& a, Definition* symbol) {
return a.IsSymbol() && (UnwrapConstraint(a.symbol()) == symbol);
}
// Given the range and definition update the range so that
// it covers both original range and definitions range.
//
// The following should also hold:
//
// [_|_, _|_] U a = a U [_|_, _|_] = a
//
static void Join(Range* range,
Definition* defn,
const Range* defn_range,
RangeBoundary::RangeSize size) {
if (Range::IsUnknown(defn_range)) {
return;
}
if (Range::IsUnknown(range)) {
*range = *defn_range;
return;
}
Range other = *defn_range;
// Handle patterns where range already depends on defn as a symbol:
//
// (..., S+o] U range(S) and [S+o, ...) U range(S)
//
// To improve precision of the computed join use [S, S] instead of
// using range(S). It will be canonicalized away by JoinMin/JoinMax
// functions.
Definition* unwrapped = UnwrapConstraint(defn);
if (DependsOnSymbol(range->min(), unwrapped) ||
DependsOnSymbol(range->max(), unwrapped)) {
other = Range(RangeBoundary::FromDefinition(defn, 0),
RangeBoundary::FromDefinition(defn, 0));
}
// First try to compare ranges based on their upper and lower bounds.
const int64_t inf_range = range->min().LowerBound(size);
const int64_t inf_other = other.min().LowerBound(size);
const int64_t sup_range = range->max().UpperBound(size);
const int64_t sup_other = other.max().UpperBound(size);
if (sup_range <= inf_other) {
// The range is fully below defn's range. Keep the minimum and
// expand the maximum.
range->set_max(other.max());
} else if (sup_other <= inf_range) {
// The range is fully above defn's range. Keep the maximum and
// expand the minimum.
range->set_min(other.min());
} else {
// Can't compare ranges as whole. Join minimum and maximum separately.
*range = Range(RangeBoundary::JoinMin(range->min(), other.min(), size),
RangeBoundary::JoinMax(range->max(), other.max(), size));
}
}
// A definition dominates a phi if its block dominates the phi's block
// and the two blocks are different.
static bool DominatesPhi(BlockEntryInstr* a, BlockEntryInstr* phi_block) {
return a->Dominates(phi_block) && (a != phi_block);
}
// When assigning range to a phi we must take care to avoid self-reference
// cycles when phi's range depends on the phi itself.
// To prevent such cases we impose additional restriction on symbols that
// can be used as boundaries for phi's range: they must dominate
// phi's definition.
static RangeBoundary EnsureAcyclicSymbol(BlockEntryInstr* phi_block,
const RangeBoundary& a,
const RangeBoundary& limit) {
if (!a.IsSymbol() || DominatesPhi(a.symbol()->GetBlock(), phi_block)) {
return a;
}
// Symbol does not dominate phi. Try unwrapping constraint and check again.
Definition* unwrapped = UnwrapConstraint(a.symbol());
if ((unwrapped != a.symbol()) &&
DominatesPhi(unwrapped->GetBlock(), phi_block)) {
return RangeBoundary::FromDefinition(unwrapped, a.offset());
}
return limit;
}
static const Range* GetInputRange(RangeAnalysis* analysis,
RangeBoundary::RangeSize size,
Value* input) {
switch (size) {
case RangeBoundary::kRangeBoundarySmi:
return analysis->GetSmiRange(input);
case RangeBoundary::kRangeBoundaryInt32:
return input->definition()->range();
case RangeBoundary::kRangeBoundaryInt64:
return analysis->GetIntRange(input);
default:
UNREACHABLE();
return NULL;
}
}
void PhiInstr::InferRange(RangeAnalysis* analysis, Range* range) {
const RangeBoundary::RangeSize size = RangeSizeForPhi(this);
for (intptr_t i = 0; i < InputCount(); i++) {
Value* input = InputAt(i);
Join(range, input->definition(), GetInputRange(analysis, size, input),
size);
}
BlockEntryInstr* phi_block = GetBlock();
range->set_min(
EnsureAcyclicSymbol(phi_block, range->min(), RangeBoundary::MinSmi()));
range->set_max(
EnsureAcyclicSymbol(phi_block, range->max(), RangeBoundary::MaxSmi()));
}
void ConstantInstr::InferRange(RangeAnalysis* analysis, Range* range) {
if (value_.IsSmi()) {
int64_t value = Smi::Cast(value_).Value();
*range = Range(RangeBoundary::FromConstant(value),
RangeBoundary::FromConstant(value));
} else if (value_.IsMint()) {
int64_t value = Mint::Cast(value_).value();
*range = Range(RangeBoundary::FromConstant(value),
RangeBoundary::FromConstant(value));
} else {
// Only Smi and Mint supported.
UNREACHABLE();
}
}
void ConstraintInstr::InferRange(RangeAnalysis* analysis, Range* range) {
const Range* value_range = analysis->GetSmiRange(value());
if (Range::IsUnknown(value_range)) {
return;
}
// TODO(vegorov) check if precision of the analysis can be improved by
// recognizing intersections of the form:
//
// (..., S+x] ^ [S+x, ...) = [S+x, S+x]
//
Range result = value_range->Intersect(constraint());
if (result.IsUnsatisfiable()) {
return;
}
*range = result;
}
void LoadFieldInstr::InferRange(RangeAnalysis* analysis, Range* range) {
switch (slot().kind()) {
case Slot::Kind::kArray_length:
case Slot::Kind::kGrowableObjectArray_length:
*range = Range(
RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(compiler::target::Array::kMaxElements));
break;
case Slot::Kind::kTypedDataBase_length:
case Slot::Kind::kTypedDataView_offset_in_bytes:
*range = Range(RangeBoundary::FromConstant(0), RangeBoundary::MaxSmi());
break;
case Slot::Kind::kString_length:
*range = Range(
RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(compiler::target::String::kMaxElements));
break;
case Slot::Kind::kDartField:
case Slot::Kind::kCapturedVariable:
// Use default value.
Definition::InferRange(analysis, range);
break;
case Slot::Kind::kLinkedHashMap_index:
case Slot::Kind::kLinkedHashMap_data:
case Slot::Kind::kGrowableObjectArray_data:
case Slot::Kind::kContext_parent:
case Slot::Kind::kTypeArguments:
case Slot::Kind::kClosure_context:
case Slot::Kind::kClosure_delayed_type_arguments:
case Slot::Kind::kClosure_function:
case Slot::Kind::kClosure_function_type_arguments:
case Slot::Kind::kClosure_instantiator_type_arguments:
case Slot::Kind::kPointer_c_memory_address:
case Slot::Kind::kTypedDataBase_data_field:
case Slot::Kind::kTypedDataView_data:
// Not an integer valued field.
UNREACHABLE();
break;
case Slot::Kind::kClosure_hash:
case Slot::Kind::kLinkedHashMap_hash_mask:
case Slot::Kind::kLinkedHashMap_used_data:
case Slot::Kind::kLinkedHashMap_deleted_keys:
*range = Range(RangeBoundary::FromConstant(0), RangeBoundary::MaxSmi());
break;
case Slot::Kind::kArgumentsDescriptor_type_args_len:
case Slot::Kind::kArgumentsDescriptor_positional_count:
case Slot::Kind::kArgumentsDescriptor_count:
*range = Range(RangeBoundary::FromConstant(0), RangeBoundary::MaxSmi());
break;
}
}
void LoadIndexedInstr::InferRange(RangeAnalysis* analysis, Range* range) {
switch (class_id()) {
case kTypedDataInt8ArrayCid:
*range = Range(RangeBoundary::FromConstant(-128),
RangeBoundary::FromConstant(127));
break;
case kTypedDataUint8ArrayCid:
case kTypedDataUint8ClampedArrayCid:
case kExternalTypedDataUint8ArrayCid:
case kExternalTypedDataUint8ClampedArrayCid:
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(255));
break;
case kTypedDataInt16ArrayCid:
*range = Range(RangeBoundary::FromConstant(-32768),
RangeBoundary::FromConstant(32767));
break;
case kTypedDataUint16ArrayCid:
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(65535));
break;
case kTypedDataInt32ArrayCid:
*range = Range(RangeBoundary::FromConstant(kMinInt32),
RangeBoundary::FromConstant(kMaxInt32));
break;
case kTypedDataUint32ArrayCid:
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(kMaxUint32));
break;
case kOneByteStringCid:
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(0xFF));
break;
case kTwoByteStringCid:
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(0xFFFF));
break;
default:
Definition::InferRange(analysis, range);
break;
}
}
void LoadCodeUnitsInstr::InferRange(RangeAnalysis* analysis, Range* range) {
ASSERT(RawObject::IsStringClassId(class_id()));
RangeBoundary zero = RangeBoundary::FromConstant(0);
// Take the number of loaded characters into account when determining the
// range of the result.
ASSERT(element_count_ > 0);
switch (class_id()) {
case kOneByteStringCid:
case kExternalOneByteStringCid:
ASSERT(element_count_ <= 4);
*range = Range(zero, RangeBoundary::FromConstant(
Utils::NBitMask(kBitsPerByte * element_count_)));
break;
case kTwoByteStringCid:
case kExternalTwoByteStringCid:
ASSERT(element_count_ <= 2);
*range = Range(zero, RangeBoundary::FromConstant(Utils::NBitMask(
2 * kBitsPerByte * element_count_)));
break;
default:
UNREACHABLE();
break;
}
}
void IfThenElseInstr::InferRange(RangeAnalysis* analysis, Range* range) {
const intptr_t min = Utils::Minimum(if_true_, if_false_);
const intptr_t max = Utils::Maximum(if_true_, if_false_);
*range =
Range(RangeBoundary::FromConstant(min), RangeBoundary::FromConstant(max));
}
static RangeBoundary::RangeSize RepresentationToRangeSize(Representation r) {
switch (r) {
case kTagged:
return RangeBoundary::kRangeBoundarySmi;
case kUnboxedInt32:
return RangeBoundary::kRangeBoundaryInt32;
case kUnboxedInt64:
return RangeBoundary::kRangeBoundaryInt64;
default:
UNREACHABLE();
return RangeBoundary::kRangeBoundarySmi;
}
}
void BinaryIntegerOpInstr::InferRangeHelper(const Range* left_range,
const Range* right_range,
Range* range) {
// TODO(vegorov): canonicalize BinaryIntegerOp to always have constant on the
// right and a non-constant on the left.
if (Range::IsUnknown(left_range) || Range::IsUnknown(right_range)) {
return;
}
Range::BinaryOp(op_kind(), left_range, right_range, left()->definition(),
range);
ASSERT(!Range::IsUnknown(range));
const RangeBoundary::RangeSize range_size =
RepresentationToRangeSize(representation());
// Calculate overflowed status before clamping if operation is
// not truncating.
if (!is_truncating()) {
set_can_overflow(!range->Fits(range_size));
}
range->Clamp(range_size);
}
static void CacheRange(Range** slot,
const Range* range,
RangeBoundary::RangeSize size) {
if (range != NULL) {
if (*slot == NULL) {
*slot = new Range();
}
**slot = *range;
// Eliminate any symbolic dependencies from the range information.
(*slot)->ClampToConstant(size);
} else if (*slot != NULL) {
**slot = Range(); // Clear cached range information.
}
}
void BinarySmiOpInstr::InferRange(RangeAnalysis* analysis, Range* range) {
const Range* right_smi_range = analysis->GetSmiRange(right());
// TODO(vegorov) completely remove this once GetSmiRange is eliminated.
if (op_kind() == Token::kSHR || op_kind() == Token::kSHL ||
op_kind() == Token::kMOD || op_kind() == Token::kTRUNCDIV) {
CacheRange(&right_range_, right_smi_range,
RangeBoundary::kRangeBoundarySmi);
}
InferRangeHelper(analysis->GetSmiRange(left()), right_smi_range, range);
}
void BinaryInt32OpInstr::InferRange(RangeAnalysis* analysis, Range* range) {
InferRangeHelper(analysis->GetSmiRange(left()),
analysis->GetSmiRange(right()), range);
}
void BinaryInt64OpInstr::InferRange(RangeAnalysis* analysis, Range* range) {
InferRangeHelper(left()->definition()->range(),
right()->definition()->range(), range);
}
void ShiftIntegerOpInstr::InferRange(RangeAnalysis* analysis, Range* range) {
const Range* right_range = RequiredInputRepresentation(1) == kTagged
? analysis->GetSmiRange(right())
: right()->definition()->range();
CacheRange(&shift_range_, right()->definition()->range(),
RangeBoundary::kRangeBoundaryInt64);
InferRangeHelper(left()->definition()->range(), right_range, range);
}
void BoxIntegerInstr::InferRange(RangeAnalysis* analysis, Range* range) {
const Range* value_range = value()->definition()->range();
if (!Range::IsUnknown(value_range)) {
*range = *value_range;
}
}
void UnboxInt32Instr::InferRange(RangeAnalysis* analysis, Range* range) {
if (value()->Type()->ToCid() == kSmiCid) {
const Range* value_range = analysis->GetSmiRange(value());
if (!Range::IsUnknown(value_range)) {
*range = *value_range;
}
} else if (RangeAnalysis::IsIntegerDefinition(value()->definition())) {
const Range* value_range = analysis->GetIntRange(value());
if (!Range::IsUnknown(value_range)) {
*range = *value_range;
}
} else if (value()->Type()->ToCid() == kSmiCid) {
*range = Range::Full(RangeBoundary::kRangeBoundarySmi);
} else {
*range = Range::Full(RangeBoundary::kRangeBoundaryInt32);
}
}
void UnboxUint32Instr::InferRange(RangeAnalysis* analysis, Range* range) {
const Range* value_range = NULL;
if (value()->Type()->ToCid() == kSmiCid) {
value_range = analysis->GetSmiRange(value());
} else if (RangeAnalysis::IsIntegerDefinition(value()->definition())) {
value_range = analysis->GetIntRange(value());
} else {
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(kMaxUint32));
return;
}
if (!Range::IsUnknown(value_range)) {
if (value_range->IsPositive()) {
*range = *value_range;
} else {
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(kMaxUint32));
}
}
}
void UnboxInt64Instr::InferRange(RangeAnalysis* analysis, Range* range) {
const Range* value_range = value()->definition()->range();
if (value_range != NULL) {
*range = *value_range;
} else if (!value()->definition()->IsInt64Definition() &&
(value()->definition()->Type()->ToCid() != kSmiCid)) {
*range = Range::Full(RangeBoundary::kRangeBoundaryInt64);
}
}
void IntConverterInstr::InferRange(RangeAnalysis* analysis, Range* range) {
if (from() == kUntagged || to() == kUntagged) {
ASSERT((from() == kUntagged && to() == kUnboxedIntPtr) ||
(from() == kUnboxedIntPtr && to() == kUntagged));
} else {
ASSERT(from() == kUnboxedInt32 || from() == kUnboxedInt64 ||
from() == kUnboxedUint32);
ASSERT(to() == kUnboxedInt32 || to() == kUnboxedInt64 ||
to() == kUnboxedUint32);
}
const Range* value_range = value()->definition()->range();
if (Range::IsUnknown(value_range)) {
return;
}
if (to() == kUnboxedUint32) {
// TODO(vegorov): improve range information for unboxing to Uint32.
*range =
Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(static_cast<int64_t>(kMaxUint32)));
} else {
*range = *value_range;
if (to() == kUnboxedInt32) {
range->Clamp(RangeBoundary::kRangeBoundaryInt32);
}
}
}
bool CheckArrayBoundInstr::IsRedundant(const RangeBoundary& length) {
Range* index_range = index()->definition()->range();
// Range of the index is unknown can't decide if the check is redundant.
if (index_range == NULL) {
if (!(index()->BindsToConstant() &&
compiler::target::IsSmi(index()->BoundConstant()))) {
return false;
}
Range range;
index()->definition()->InferRange(NULL, &range);
ASSERT(!Range::IsUnknown(&range));
index()->definition()->set_range(range);
index_range = index()->definition()->range();
}
// Range of the index is not positive. Check can't be redundant.
if (Range::ConstantMinSmi(index_range).ConstantValue() < 0) {
return false;
}
RangeBoundary max = RangeBoundary::FromDefinition(index()->definition());
RangeBoundary max_upper = max.UpperBound();
RangeBoundary length_lower = length.LowerBound();
if (max_upper.OverflowedSmi() || length_lower.OverflowedSmi()) {
return false;
}
// Try to compare constant boundaries.
if (max_upper.ConstantValue() < length_lower.ConstantValue()) {
return true;
}
RangeBoundary canonical_length =
CanonicalizeBoundary(length, RangeBoundary::PositiveInfinity());
if (canonical_length.OverflowedSmi()) {
return false;
}
// Try symbolic comparison.
do {
if (DependOnSameSymbol(max, canonical_length)) {
return max.offset() < canonical_length.offset();
}
} while (CanonicalizeMaxBoundary(&max) ||
CanonicalizeMinBoundary(&canonical_length));
// Failed to prove that maximum is bounded with array length.
return false;
}
// Check if range boundary and invariant limit are the same boundary.
static bool IsSameBound(const RangeBoundary& a, InductionVar* b) {
ASSERT(InductionVar::IsInvariant(b));
if (a.IsSymbol()) {
// Check for exactly the same symbol as length.
return a.symbol() == b->def() && b->mult() == 1 &&
a.offset() == b->offset();
} else if (a.IsConstant()) {
// Check for constant in right range 0 < c <= length.
int64_t c = 0;
return InductionVar::IsConstant(b, &c) && 0 < c && c <= a.ConstantValue();
}
return false;
}
bool GenericCheckBoundInstr::IsRedundant(const RangeBoundary& length) {
// In loop, with index as induction?
LoopInfo* loop = GetBlock()->loop_info();
if (loop == nullptr) {
return false;
}
InductionVar* induc = loop->LookupInduction(index()->definition());
if (induc == nullptr) {
return false;
}
// Under 64-bit wrap-around arithmetic, it is always safe to remove the
// bounds check from the following, if initial >= 0 and the corresponding
// exit branch dominates the bounds check:
// for (int i = initial; i < length; i++)
// .... a[i] ....
int64_t stride = 0;
int64_t initial = 0;
if (InductionVar::IsLinear(induc, &stride) &&
InductionVar::IsConstant(induc->initial(), &initial)) {
if (stride == 1 && initial >= 0) {
for (auto bound : induc->bounds()) {
if (IsSameBound(length, bound.limit_) &&
this->IsDominatedBy(bound.branch_)) {
return true;
}
}
}
}
return false;
}
} // namespace dart
#endif // !defined(DART_PRECOMPILED_RUNTIME)
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