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dart / sdk.git / 97004589756b0022bfdbb127c4ae0bc275f07b4b / . / runtime / vm / compiler / backend / range_analysis.cc
blob: 902573877b19b672181e4a758f93b68f8a651d1e [file] [log] [blame]
// 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.
#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 (auto check = current->AsCheckBoundBase()) {
bounds_checks_.Add(check);
}
}
}
}
// 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;
}
const char* RangeBoundary::KindToCString(Kind kind) {
switch (kind) {
#define KIND_CASE(name) \
case Kind::k##name: \
return #name;
FOR_EACH_RANGE_BOUNDARY_KIND(KIND_CASE)
#undef KIND_CASE
default:
UNREACHABLE();
return nullptr;
}
}
bool RangeBoundary::ParseKind(const char* str, Kind* out) {
#define KIND_CASE(name) \
if (strcmp(str, #name) == 0) { \
*out = Kind::k##name; \
return true; \
}
FOR_EACH_RANGE_BOUNDARY_KIND(KIND_CASE)
#undef KIND_CASE
return false;
}
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:
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_;
PointerSet<Instruction> 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) {
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(!CompilerState::Current().is_aot());
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()) {
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;
}
// Returns true if x is invariant and is either based on a Smi definition
// or is a Smi constant.
static bool IsSmiInvariant(const InductionVar* x) {
return InductionVar::IsInvariant(x) && Smi::IsValid(x->offset()) &&
Smi::IsValid(x->mult()) &&
(x->mult() == 0 || x->def()->Type()->ToCid() == kSmiCid);
}
// 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);
int64_t stride;
if (induc != nullptr && InductionVar::IsLinear(induc, &stride) &&
stride == 1 && IsSmiInvariant(induc->initial())) {
return induc;
}
}
return nullptr;
}
// Reconstruct invariant.
Definition* GenerateInvariant(InductionVar* induc) {
Definition* res = nullptr;
if (induc->mult() == 0) {
res =
flow_graph_->GetConstant(Smi::ZoneHandle(Smi::New(induc->offset())));
} else {
res = induc->def();
if (induc->mult() != 1) {
res = MakeBinaryOp(Token::kMUL, res, induc->mult());
}
if (induc->offset() != 0) {
res = MakeBinaryOp(Token::kADD, res, induc->offset());
}
}
return res;
}
// 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(Object::smi_zero());
}
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(BaseTextBuffer* f,
Definition* index_bound) {
BinarySmiOpInstr* binary_op = index_bound->AsBinarySmiOp();
if (binary_op != NULL) {
f->AddString("(");
PrettyPrintIndexBoundRecursively(f, binary_op->left()->definition());
f->Printf(" %s ", Token::Str(binary_op->op_kind()));
PrettyPrintIndexBoundRecursively(f, binary_op->right()->definition());
f->AddString(")");
} else if (index_bound->IsConstant()) {
f->Printf("%" Pd "",
Smi::Cast(index_bound->AsConstant()->value()).Value());
} else {
f->Printf("v%" Pd "", index_bound->ssa_temp_index());
}
f->Printf(" {%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 and we are not compiling precompiled code
// (no optimistic hoisting of checks possible)
const bool try_generalization =
!CompilerState::Current().is_aot() &&
!function.ProhibitsBoundsCheckGeneralization();
BoundsCheckGeneralizer generalizer(this, flow_graph_);
for (CheckBoundBase* check : bounds_checks_) {
if (check->IsRedundant(/*use_loops=*/true)) {
check->ReplaceUsesWith(check->index()->definition());
check->RemoveFromGraph();
} else if (try_generalization) {
if (auto jit_check = check->AsCheckArrayBound()) {
generalizer.TryGeneralize(jit_check);
}
}
}
}
}
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) || (op->op_kind() == Token::kUSHR)) {
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();
return BinaryIntegerOpInstr::Make(
kUnboxedUint32, op_kind, left, right, deopt_id,
def->IsSpeculativeShiftInt64Op() ? Instruction::kGuardInputs
: Instruction::kNotSpeculative);
} 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->SpeculativeModeOfInputs());
} 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) {
return RangeBoundary::FromConstant(0);
} else if (shift_count == 0 ||
(limit > 0 && Utils::IsInt(static_cast<int>(limit), value))) {
// Result stays in 64 bit range.
const int64_t result = static_cast<uint64_t>(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::IsNegative() const {
return OnlyLessThanOrEqualTo(-1);
}
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);
}
static void ConvertRangeToUnsigned(int64_t a,
int64_t b,
uint64_t* ua,
uint64_t* ub) {
ASSERT(a <= b);
if ((a < 0) && (b >= 0)) {
// Range contains -1 and 0 and wraps-around as unsigned.
*ua = 0;
*ub = kMaxUint64;
} else {
// Range is fully in the negative or non-negative part
// and doesn't wrap-around if interpreted as unsigned.
*ua = static_cast<uint64_t>(a);
*ub = static_cast<uint64_t>(b);
}
}
static void ConvertRangeToSigned(uint64_t a,
uint64_t b,
int64_t* sa,
int64_t* sb) {
ASSERT(a <= b);
if ((a <= static_cast<uint64_t>(kMaxInt64)) &&
(b >= static_cast<uint64_t>(kMinInt64))) {
// Range contains kMinInt64 and kMaxInt64 and wraps-around as signed.
*sa = kMinInt64;
*sb = kMaxInt64;
} else {
// Range is fully in the negative or non-negative part
// and doesn't wrap-around if interpreted as signed.
*sa = static_cast<int64_t>(a);
*sb = static_cast<int64_t>(b);
}
}
void Range::Ushr(const Range* left,
const Range* right,
RangeBoundary* result_min,
RangeBoundary* result_max) {
const int64_t left_max = Range::ConstantMax(left).ConstantValue();
const int64_t left_min = Range::ConstantMin(left).ConstantValue();
// A negative shift count always deoptimizes (and throws), so the minimum
// shift count is zero.
const int64_t right_max = Utils::Maximum(
Range::ConstantMax(right).ConstantValue(), static_cast<int64_t>(0));
const int64_t right_min = Utils::Maximum(
Range::ConstantMin(right).ConstantValue(), static_cast<int64_t>(0));
uint64_t unsigned_left_min, unsigned_left_max;
ConvertRangeToUnsigned(left_min, left_max, &unsigned_left_min,
&unsigned_left_max);
const uint64_t unsigned_result_min =
(right_max >= kBitsPerInt64)
? 0
: unsigned_left_min >> static_cast<uint64_t>(right_max);
const uint64_t unsigned_result_max =
(right_min >= kBitsPerInt64)
? 0
: unsigned_left_max >> static_cast<uint64_t>(right_min);
int64_t signed_result_min, signed_result_max;
ConvertRangeToSigned(unsigned_result_min, unsigned_result_max,
&signed_result_min, &signed_result_max);
*result_min = RangeBoundary(signed_result_min);
*result_max = RangeBoundary(signed_result_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);
}
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 = Definition::IsArrayLength(left_defn)
? RangeBoundary::FromDefinition(left_defn)
: left_range->min();
RangeBoundary left_max = Definition::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 = Definition::IsArrayLength(left_defn)
? RangeBoundary::FromDefinition(left_defn)
: left_range->min();
RangeBoundary left_max = Definition::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();
}
void Range::Mod(const Range* right_range,
RangeBoundary* result_min,
RangeBoundary* result_max) {
ASSERT(right_range != nullptr);
ASSERT(result_min != nullptr);
ASSERT(result_max != nullptr);
// Each modulo result is positive and bounded by one less than
// the maximum of the right-hand-side (it is unlikely that the
// left-hand-side further refines this in typical programs).
// Note that x % MinInt can be MaxInt and x % 0 always throws.
const int64_t kModMin = 0;
int64_t mod_max = kMaxInt64;
if (Range::ConstantMin(right_range).ConstantValue() != kMinInt64) {
const int64_t right_max = ConstantAbsMax(right_range);
mod_max = Utils::Maximum(right_max - 1, kModMin);
}
*result_min = RangeBoundary::FromConstant(kModMin);
*result_max = RangeBoundary::FromConstant(mod_max);
}
// 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::kMOD:
Range::Mod(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::kUSHR:
Range::Ushr(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());
// Sanity: avoid [l, u] with constants l > u.
ASSERT(!min.IsConstant() || !max.IsConstant() ||
min.ConstantValue() <= max.ConstantValue());
*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.
FATAL1("Unexpected constant: %s\n", value_.ToCString());
}
}
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;
}
static RangeBoundary::RangeSize RepresentationToRangeSize(Representation r) {
switch (r) {
case kTagged:
return RangeBoundary::kRangeBoundarySmi;
case kUnboxedUint8: // Overapproximate Uint8 as Int16.
return RangeBoundary::kRangeBoundaryInt16;
case kUnboxedInt32:
case kUnboxedUint16: // Overapproximate Uint16 as Int32.
return RangeBoundary::kRangeBoundaryInt32;
case kUnboxedInt64:
case kUnboxedUint32: // Overapproximate Uint32 as Int64.
return RangeBoundary::kRangeBoundaryInt64;
default:
UNREACHABLE();
return RangeBoundary::kRangeBoundarySmi;
}
}
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::kTypeArguments_length:
*range = Range(RangeBoundary::FromConstant(0),
RangeBoundary::FromConstant(
compiler::target::TypeArguments::kMaxElements));
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::kLinkedHashBase_index:
case Slot::Kind::kImmutableLinkedHashBase_index:
case Slot::Kind::kLinkedHashBase_data:
case Slot::Kind::kImmutableLinkedHashBase_data:
case Slot::Kind::kGrowableObjectArray_data:
case Slot::Kind::kContext_parent:
case Slot::Kind::kTypeArguments:
case Slot::Kind::kArray_type_arguments:
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::kFinalizer_callback:
case Slot::Kind::kFinalizer_type_arguments:
case Slot::Kind::kFinalizerBase_all_entries:
case Slot::Kind::kFinalizerBase_detachments:
case Slot::Kind::kFinalizerBase_entries_collected:
case Slot::Kind::kFinalizerEntry_detach:
case Slot::Kind::kFinalizerEntry_finalizer:
case Slot::Kind::kFinalizerEntry_next:
case Slot::Kind::kFinalizerEntry_token:
case Slot::Kind::kFinalizerEntry_value:
case Slot::Kind::kNativeFinalizer_callback:
case Slot::Kind::kFunction_data:
case Slot::Kind::kFunction_signature:
case Slot::Kind::kFunctionType_named_parameter_names:
case Slot::Kind::kFunctionType_parameter_types:
case Slot::Kind::kFunctionType_type_parameters:
case Slot::Kind::kInstance_native_fields_array:
case Slot::Kind::kSuspendState_function_data:
case Slot::Kind::kSuspendState_then_callback:
case Slot::Kind::kSuspendState_error_callback:
case Slot::Kind::kTypedDataView_typed_data:
case Slot::Kind::kType_arguments:
case Slot::Kind::kTypeArgumentsIndex:
case Slot::Kind::kTypeParameters_names:
case Slot::Kind::kTypeParameters_flags:
case Slot::Kind::kTypeParameters_bounds:
case Slot::Kind::kTypeParameters_defaults:
case Slot::Kind::kTypeParameter_bound:
case Slot::Kind::kUnhandledException_exception:
case Slot::Kind::kUnhandledException_stacktrace:
case Slot::Kind::kWeakProperty_key:
case Slot::Kind::kWeakProperty_value:
case Slot::Kind::kWeakReference_target:
case Slot::Kind::kWeakReference_type_arguments:
// Not an integer valued field.
UNREACHABLE();
break;
case Slot::Kind::kArrayElement:
// Should not be used in LoadField instructions.
UNREACHABLE();
break;
#define UNBOXED_NATIVE_SLOT_CASE(Class, Untagged, Field, Rep, IsFinal) \
case Slot::Kind::k##Class##_##Field:
UNBOXED_NATIVE_SLOTS_LIST(UNBOXED_NATIVE_SLOT_CASE)
#undef UNBOXED_NATIVE_SLOT_CASE
*range = Range::Full(RepresentationToRangeSize(slot().representation()));
break;
case Slot::Kind::kClosure_hash:
case Slot::Kind::kLinkedHashBase_hash_mask:
case Slot::Kind::kLinkedHashBase_used_data:
case Slot::Kind::kLinkedHashBase_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:
case Slot::Kind::kArgumentsDescriptor_size:
*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(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 Utf8ScanInstr::InferRange(RangeAnalysis* analysis, Range* range) {
// The input bytes given to the Utf8Scan instruction are in non-negative Smi
// range and so is the resulting computed length.
*range = Range(RangeBoundary::FromConstant(0), RangeBoundary::MaxSmi());
}
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));
}
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 BinaryIntegerOpInstr::InferRange(RangeAnalysis* analysis, Range* range) {
auto const left_size =
RepresentationToRangeSize(RequiredInputRepresentation(0));
auto const right_size =
RepresentationToRangeSize(RequiredInputRepresentation(1));
InferRangeHelper(GetInputRange(analysis, left_size, left()),
GetInputRange(analysis, right_size, right()), range);
}
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::kSHL || op_kind() == Token::kSHR ||
op_kind() == Token::kUSHR || 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 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 || to() == kUnboxedFfiIntPtr)) ||
((from() == kUnboxedIntPtr || from() == kUnboxedFfiIntPtr) &&
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);
}
}
}
void AssertAssignableInstr::InferRange(RangeAnalysis* analysis, Range* range) {
const Range* value_range = value()->definition()->range();
if (!Range::IsUnknown(value_range)) {
*range = *value_range;
} else {
*range = Range::Full(RangeBoundary::kRangeBoundaryInt64);
}
}
static bool IsRedundantBasedOnRangeInformation(Value* index, Value* length) {
if (index->BindsToSmiConstant() && length->BindsToSmiConstant()) {
const auto index_val = index->BoundSmiConstant();
const auto length_val = length->BoundSmiConstant();
return (0 <= index_val && index_val < length_val);
}
// Range of the index is unknown can't decide if the check is redundant.
Range* index_range = index->definition()->range();
if (index_range == nullptr) {
if (!(index->BindsToConstant() &&
compiler::target::IsSmi(index->BoundConstant()))) {
return false;
}
Range range;
index->definition()->InferRange(nullptr, &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 array_length =
RangeBoundary::FromDefinition(length->definition());
RangeBoundary length_lower = array_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(array_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;
}
bool CheckBoundBase::IsRedundant(bool use_loops) {
// First, try to prove redundancy with the results of range analysis.
if (IsRedundantBasedOnRangeInformation(index(), length())) {
return true;
} else if (!use_loops) {
return false;
}
// Next, try to prove redundancy with the results of induction analysis.
LoopInfo* loop = GetBlock()->loop_info();
if (loop != nullptr) {
return loop->IsInRange(this, index(), length());
}
return false;
}
} // namespace dart