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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/torque/cfg.h"
#include "src/torque/type-oracle.h"
namespace v8 {
namespace internal {
namespace torque {
void Block::SetInputTypes(const Stack<const Type*>& input_types) {
if (!input_types_) {
input_types_ = input_types;
return;
} else if (*input_types_ == input_types) {
return;
}
DCHECK_EQ(input_types.Size(), input_types_->Size());
Stack<const Type*> merged_types;
bool widened = false;
auto c2_iterator = input_types.begin();
for (const Type* c1 : *input_types_) {
const Type* merged_type = TypeOracle::GetUnionType(c1, *c2_iterator++);
if (!merged_type->IsSubtypeOf(c1)) {
widened = true;
}
merged_types.Push(merged_type);
}
if (merged_types.Size() == input_types_->Size()) {
if (widened) {
input_types_ = merged_types;
Retype();
}
return;
}
std::stringstream error;
error << "incompatible types at branch:\n";
for (intptr_t i = std::max(input_types_->Size(), input_types.Size()) - 1;
i >= 0; --i) {
base::Optional<const Type*> left;
base::Optional<const Type*> right;
if (static_cast<size_t>(i) < input_types.Size()) {
left = input_types.Peek(BottomOffset{static_cast<size_t>(i)});
}
if (static_cast<size_t>(i) < input_types_->Size()) {
right = input_types_->Peek(BottomOffset{static_cast<size_t>(i)});
}
if (left && right && *left == *right) {
error << **left << "\n";
} else {
if (left) {
error << **left;
} else {
error << "/*missing*/";
}
error << " => ";
if (right) {
error << **right;
} else {
error << "/*missing*/";
}
error << "\n";
}
}
ReportError(error.str());
}
void CfgAssembler::Bind(Block* block) {
DCHECK(current_block_->IsComplete());
DCHECK(block->instructions().empty());
DCHECK(block->HasInputTypes());
current_block_ = block;
current_stack_ = block->InputTypes();
cfg_.PlaceBlock(block);
}
void CfgAssembler::Goto(Block* block) {
if (block->HasInputTypes()) {
DropTo(block->InputTypes().AboveTop());
}
Emit(GotoInstruction{block});
}
StackRange CfgAssembler::Goto(Block* block, size_t preserved_slots) {
DCHECK(block->HasInputTypes());
DCHECK_GE(CurrentStack().Size(), block->InputTypes().Size());
Emit(DeleteRangeInstruction{
StackRange{block->InputTypes().AboveTop() - preserved_slots,
CurrentStack().AboveTop() - preserved_slots}});
StackRange preserved_slot_range = TopRange(preserved_slots);
Emit(GotoInstruction{block});
return preserved_slot_range;
}
void CfgAssembler::Branch(Block* if_true, Block* if_false) {
Emit(BranchInstruction{if_true, if_false});
}
// Delete the specified range of slots, moving upper slots to fill the gap.
void CfgAssembler::DeleteRange(StackRange range) {
DCHECK_LE(range.end(), current_stack_.AboveTop());
if (range.Size() == 0) return;
Emit(DeleteRangeInstruction{range});
}
void CfgAssembler::DropTo(BottomOffset new_level) {
DeleteRange(StackRange{new_level, CurrentStack().AboveTop()});
}
StackRange CfgAssembler::Peek(StackRange range,
base::Optional<const Type*> type) {
std::vector<const Type*> lowered_types;
if (type) {
lowered_types = LowerType(*type);
DCHECK_EQ(lowered_types.size(), range.Size());
}
for (size_t i = 0; i < range.Size(); ++i) {
Emit(PeekInstruction{
range.begin() + i,
type ? lowered_types[i] : base::Optional<const Type*>{}});
}
return TopRange(range.Size());
}
void CfgAssembler::Poke(StackRange destination, StackRange origin,
base::Optional<const Type*> type) {
DCHECK_EQ(destination.Size(), origin.Size());
DCHECK_LE(destination.end(), origin.begin());
DCHECK_EQ(origin.end(), CurrentStack().AboveTop());
std::vector<const Type*> lowered_types;
if (type) {
lowered_types = LowerType(*type);
DCHECK_EQ(lowered_types.size(), origin.Size());
}
for (intptr_t i = origin.Size() - 1; i >= 0; --i) {
Emit(PokeInstruction{
destination.begin() + i,
type ? lowered_types[i] : base::Optional<const Type*>{}});
}
}
void CfgAssembler::Print(std::string s) {
Emit(PrintErrorInstruction{std::move(s)});
}
void CfgAssembler::AssertionFailure(std::string message) {
Emit(AbortInstruction{AbortInstruction::Kind::kAssertionFailure,
std::move(message)});
}
void CfgAssembler::Unreachable() {
Emit(AbortInstruction{AbortInstruction::Kind::kUnreachable});
}
void CfgAssembler::DebugBreak() {
Emit(AbortInstruction{AbortInstruction::Kind::kDebugBreak});
}
std::vector<std::size_t> CountBlockPredecessors(const ControlFlowGraph& cfg) {
std::vector<std::size_t> count(cfg.NumberOfBlockIds(), 0);
count[cfg.start()->id()] = 1;
for (const Block* block : cfg.blocks()) {
std::vector<Block*> successors;
for (const auto& instruction : block->instructions()) {
instruction->AppendSuccessorBlocks(&successors);
}
for (Block* successor : successors) {
DCHECK_LT(successor->id(), count.size());
++count[successor->id()];
}
}
return count;
}
void CfgAssembler::OptimizeCfg() {
auto predecessor_count = CountBlockPredecessors(cfg_);
for (Block* block : cfg_.blocks()) {
if (cfg_.end() && *cfg_.end() == block) continue;
if (predecessor_count[block->id()] == 0) continue;
while (!block->instructions().empty()) {
const auto& instruction = block->instructions().back();
if (!instruction.Is<GotoInstruction>()) break;
Block* destination = instruction.Cast<GotoInstruction>().destination;
if (destination == block) break;
if (cfg_.end() && *cfg_.end() == destination) break;
DCHECK_GT(predecessor_count[destination->id()], 0);
if (predecessor_count[destination->id()] != 1) break;
DCHECK_GT(destination->instructions().size(), 0);
block->instructions().pop_back();
block->instructions().insert(block->instructions().end(),
destination->instructions().begin(),
destination->instructions().end());
--predecessor_count[destination->id()];
DCHECK_EQ(predecessor_count[destination->id()], 0);
}
}
cfg_.UnplaceBlockIf(
[&](Block* b) { return predecessor_count[b->id()] == 0; });
}
void CfgAssembler::ComputeInputDefinitions() {
Worklist<Block*> worklist;
// Setup start block.
Stack<DefinitionLocation> parameter_defs;
for (std::size_t i = 0; i < cfg_.ParameterCount(); ++i) {
parameter_defs.Push(DefinitionLocation::Parameter(i));
}
cfg_.start()->MergeInputDefinitions(parameter_defs, &worklist);
// Run fixpoint algorithm.
while (!worklist.IsEmpty()) {
Block* block = worklist.Dequeue();
Stack<DefinitionLocation> definitions = block->InputDefinitions();
// Propagate through block's instructions.
for (const auto& instruction : block->instructions()) {
instruction.RecomputeDefinitionLocations(&definitions, &worklist);
}
}
for (Block* block : cfg_.blocks()) {
DCHECK_IMPLIES(!block->IsDead(), block->InputDefinitions().Size() ==
block->InputTypes().Size());
USE(block);
}
}
} // namespace torque
} // namespace internal
} // namespace v8
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