Remove unused AssignedVariableAnalyzer.
Not used in Crankshaft anymore. Review URL: http://codereview.chromium.org/6849023 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7619 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
fschneider@chromium.org
parent
86577062a9
commit
f20ff991f7
473
src/data-flow.cc
473
src/data-flow.cc
@ -63,477 +63,4 @@ void BitVector::Iterator::Advance() {
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current_value_ = val >> 1;
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}
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bool AssignedVariablesAnalyzer::Analyze(CompilationInfo* info) {
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Scope* scope = info->scope();
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int size = scope->num_parameters() + scope->num_stack_slots();
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if (size == 0) return true;
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AssignedVariablesAnalyzer analyzer(info, size);
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return analyzer.Analyze();
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}
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AssignedVariablesAnalyzer::AssignedVariablesAnalyzer(CompilationInfo* info,
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int size)
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: info_(info), av_(size) {
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}
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bool AssignedVariablesAnalyzer::Analyze() {
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ASSERT(av_.length() > 0);
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VisitStatements(info_->function()->body());
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return !HasStackOverflow();
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}
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Variable* AssignedVariablesAnalyzer::FindSmiLoopVariable(ForStatement* stmt) {
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// The loop must have all necessary parts.
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if (stmt->init() == NULL || stmt->cond() == NULL || stmt->next() == NULL) {
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return NULL;
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}
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// The initialization statement has to be a simple assignment.
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Assignment* init = stmt->init()->StatementAsSimpleAssignment();
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if (init == NULL) return NULL;
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// We only deal with local variables.
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Variable* loop_var = init->target()->AsVariableProxy()->AsVariable();
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if (loop_var == NULL || !loop_var->IsStackAllocated()) return NULL;
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// Don't try to get clever with const or dynamic variables.
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if (loop_var->mode() != Variable::VAR) return NULL;
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// The initial value has to be a smi.
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Literal* init_lit = init->value()->AsLiteral();
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if (init_lit == NULL || !init_lit->handle()->IsSmi()) return NULL;
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int init_value = Smi::cast(*init_lit->handle())->value();
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// The condition must be a compare of variable with <, <=, >, or >=.
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CompareOperation* cond = stmt->cond()->AsCompareOperation();
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if (cond == NULL) return NULL;
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if (cond->op() != Token::LT
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&& cond->op() != Token::LTE
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&& cond->op() != Token::GT
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&& cond->op() != Token::GTE) return NULL;
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// The lhs must be the same variable as in the init expression.
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if (cond->left()->AsVariableProxy()->AsVariable() != loop_var) return NULL;
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// The rhs must be a smi.
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Literal* term_lit = cond->right()->AsLiteral();
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if (term_lit == NULL || !term_lit->handle()->IsSmi()) return NULL;
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int term_value = Smi::cast(*term_lit->handle())->value();
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// The count operation updates the same variable as in the init expression.
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CountOperation* update = stmt->next()->StatementAsCountOperation();
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if (update == NULL) return NULL;
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if (update->expression()->AsVariableProxy()->AsVariable() != loop_var) {
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return NULL;
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}
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// The direction of the count operation must agree with the start and the end
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// value. We currently do not allow the initial value to be the same as the
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// terminal value. This _would_ be ok as long as the loop body never executes
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// or executes exactly one time.
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if (init_value == term_value) return NULL;
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if (init_value < term_value && update->op() != Token::INC) return NULL;
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if (init_value > term_value && update->op() != Token::DEC) return NULL;
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// Check that the update operation cannot overflow the smi range. This can
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// occur in the two cases where the loop bound is equal to the largest or
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// smallest smi.
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if (update->op() == Token::INC && term_value == Smi::kMaxValue) return NULL;
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if (update->op() == Token::DEC && term_value == Smi::kMinValue) return NULL;
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// Found a smi loop variable.
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return loop_var;
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}
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int AssignedVariablesAnalyzer::BitIndex(Variable* var) {
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ASSERT(var != NULL);
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ASSERT(var->IsStackAllocated());
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Slot* slot = var->AsSlot();
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if (slot->type() == Slot::PARAMETER) {
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return slot->index();
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} else {
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return info_->scope()->num_parameters() + slot->index();
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}
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}
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void AssignedVariablesAnalyzer::RecordAssignedVar(Variable* var) {
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ASSERT(var != NULL);
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if (var->IsStackAllocated()) {
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av_.Add(BitIndex(var));
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}
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}
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void AssignedVariablesAnalyzer::MarkIfTrivial(Expression* expr) {
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Variable* var = expr->AsVariableProxy()->AsVariable();
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if (var != NULL &&
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var->IsStackAllocated() &&
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!var->is_arguments() &&
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var->mode() != Variable::CONST &&
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(var->is_this() || !av_.Contains(BitIndex(var)))) {
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expr->AsVariableProxy()->MarkAsTrivial();
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}
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}
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void AssignedVariablesAnalyzer::ProcessExpression(Expression* expr) {
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BitVector saved_av(av_);
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av_.Clear();
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Visit(expr);
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av_.Union(saved_av);
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}
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void AssignedVariablesAnalyzer::VisitBlock(Block* stmt) {
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VisitStatements(stmt->statements());
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}
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void AssignedVariablesAnalyzer::VisitExpressionStatement(
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ExpressionStatement* stmt) {
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ProcessExpression(stmt->expression());
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}
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void AssignedVariablesAnalyzer::VisitEmptyStatement(EmptyStatement* stmt) {
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// Do nothing.
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}
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void AssignedVariablesAnalyzer::VisitIfStatement(IfStatement* stmt) {
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ProcessExpression(stmt->condition());
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Visit(stmt->then_statement());
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Visit(stmt->else_statement());
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}
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void AssignedVariablesAnalyzer::VisitContinueStatement(
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ContinueStatement* stmt) {
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// Nothing to do.
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}
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void AssignedVariablesAnalyzer::VisitBreakStatement(BreakStatement* stmt) {
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// Nothing to do.
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}
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void AssignedVariablesAnalyzer::VisitReturnStatement(ReturnStatement* stmt) {
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ProcessExpression(stmt->expression());
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}
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void AssignedVariablesAnalyzer::VisitWithEnterStatement(
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WithEnterStatement* stmt) {
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ProcessExpression(stmt->expression());
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}
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void AssignedVariablesAnalyzer::VisitWithExitStatement(
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WithExitStatement* stmt) {
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// Nothing to do.
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}
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void AssignedVariablesAnalyzer::VisitSwitchStatement(SwitchStatement* stmt) {
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BitVector result(av_);
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av_.Clear();
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Visit(stmt->tag());
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result.Union(av_);
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for (int i = 0; i < stmt->cases()->length(); i++) {
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CaseClause* clause = stmt->cases()->at(i);
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if (!clause->is_default()) {
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av_.Clear();
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Visit(clause->label());
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result.Union(av_);
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}
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VisitStatements(clause->statements());
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}
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av_.Union(result);
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}
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void AssignedVariablesAnalyzer::VisitDoWhileStatement(DoWhileStatement* stmt) {
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ProcessExpression(stmt->cond());
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Visit(stmt->body());
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}
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void AssignedVariablesAnalyzer::VisitWhileStatement(WhileStatement* stmt) {
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ProcessExpression(stmt->cond());
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Visit(stmt->body());
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}
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void AssignedVariablesAnalyzer::VisitForStatement(ForStatement* stmt) {
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if (stmt->init() != NULL) Visit(stmt->init());
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if (stmt->cond() != NULL) ProcessExpression(stmt->cond());
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if (stmt->next() != NULL) Visit(stmt->next());
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// Process loop body. After visiting the loop body av_ contains
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// the assigned variables of the loop body.
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BitVector saved_av(av_);
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av_.Clear();
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Visit(stmt->body());
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Variable* var = FindSmiLoopVariable(stmt);
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if (var != NULL && !av_.Contains(BitIndex(var))) {
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stmt->set_loop_variable(var);
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}
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av_.Union(saved_av);
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}
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void AssignedVariablesAnalyzer::VisitForInStatement(ForInStatement* stmt) {
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ProcessExpression(stmt->each());
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ProcessExpression(stmt->enumerable());
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Visit(stmt->body());
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}
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void AssignedVariablesAnalyzer::VisitTryCatchStatement(
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TryCatchStatement* stmt) {
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Visit(stmt->try_block());
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Visit(stmt->catch_block());
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}
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void AssignedVariablesAnalyzer::VisitTryFinallyStatement(
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TryFinallyStatement* stmt) {
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Visit(stmt->try_block());
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Visit(stmt->finally_block());
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}
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void AssignedVariablesAnalyzer::VisitDebuggerStatement(
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DebuggerStatement* stmt) {
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// Nothing to do.
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}
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void AssignedVariablesAnalyzer::VisitFunctionLiteral(FunctionLiteral* expr) {
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// Nothing to do.
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ASSERT(av_.IsEmpty());
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}
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void AssignedVariablesAnalyzer::VisitSharedFunctionInfoLiteral(
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SharedFunctionInfoLiteral* expr) {
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// Nothing to do.
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ASSERT(av_.IsEmpty());
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}
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void AssignedVariablesAnalyzer::VisitConditional(Conditional* expr) {
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ASSERT(av_.IsEmpty());
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Visit(expr->condition());
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BitVector result(av_);
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av_.Clear();
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Visit(expr->then_expression());
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result.Union(av_);
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av_.Clear();
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Visit(expr->else_expression());
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av_.Union(result);
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}
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void AssignedVariablesAnalyzer::VisitVariableProxy(VariableProxy* expr) {
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// Nothing to do.
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ASSERT(av_.IsEmpty());
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}
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void AssignedVariablesAnalyzer::VisitLiteral(Literal* expr) {
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// Nothing to do.
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ASSERT(av_.IsEmpty());
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}
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void AssignedVariablesAnalyzer::VisitRegExpLiteral(RegExpLiteral* expr) {
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// Nothing to do.
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ASSERT(av_.IsEmpty());
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}
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void AssignedVariablesAnalyzer::VisitObjectLiteral(ObjectLiteral* expr) {
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ASSERT(av_.IsEmpty());
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BitVector result(av_.length());
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for (int i = 0; i < expr->properties()->length(); i++) {
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Visit(expr->properties()->at(i)->value());
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result.Union(av_);
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av_.Clear();
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}
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av_ = result;
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}
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void AssignedVariablesAnalyzer::VisitArrayLiteral(ArrayLiteral* expr) {
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ASSERT(av_.IsEmpty());
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BitVector result(av_.length());
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for (int i = 0; i < expr->values()->length(); i++) {
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Visit(expr->values()->at(i));
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result.Union(av_);
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av_.Clear();
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}
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av_ = result;
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}
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void AssignedVariablesAnalyzer::VisitCatchExtensionObject(
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CatchExtensionObject* expr) {
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ASSERT(av_.IsEmpty());
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Visit(expr->key());
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ProcessExpression(expr->value());
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}
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void AssignedVariablesAnalyzer::VisitAssignment(Assignment* expr) {
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ASSERT(av_.IsEmpty());
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// There are three kinds of assignments: variable assignments, property
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// assignments, and reference errors (invalid left-hand sides).
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Variable* var = expr->target()->AsVariableProxy()->AsVariable();
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Property* prop = expr->target()->AsProperty();
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ASSERT(var == NULL || prop == NULL);
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if (var != NULL) {
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MarkIfTrivial(expr->value());
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Visit(expr->value());
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if (expr->is_compound()) {
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// Left-hand side occurs also as an rvalue.
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MarkIfTrivial(expr->target());
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ProcessExpression(expr->target());
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}
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RecordAssignedVar(var);
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} else if (prop != NULL) {
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MarkIfTrivial(expr->value());
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Visit(expr->value());
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if (!prop->key()->IsPropertyName()) {
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MarkIfTrivial(prop->key());
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ProcessExpression(prop->key());
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}
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MarkIfTrivial(prop->obj());
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ProcessExpression(prop->obj());
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} else {
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Visit(expr->target());
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}
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}
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void AssignedVariablesAnalyzer::VisitThrow(Throw* expr) {
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ASSERT(av_.IsEmpty());
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Visit(expr->exception());
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}
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void AssignedVariablesAnalyzer::VisitProperty(Property* expr) {
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ASSERT(av_.IsEmpty());
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if (!expr->key()->IsPropertyName()) {
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MarkIfTrivial(expr->key());
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Visit(expr->key());
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}
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MarkIfTrivial(expr->obj());
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ProcessExpression(expr->obj());
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}
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void AssignedVariablesAnalyzer::VisitCall(Call* expr) {
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ASSERT(av_.IsEmpty());
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Visit(expr->expression());
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BitVector result(av_);
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for (int i = 0; i < expr->arguments()->length(); i++) {
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av_.Clear();
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Visit(expr->arguments()->at(i));
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result.Union(av_);
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}
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av_ = result;
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}
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void AssignedVariablesAnalyzer::VisitCallNew(CallNew* expr) {
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ASSERT(av_.IsEmpty());
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Visit(expr->expression());
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BitVector result(av_);
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for (int i = 0; i < expr->arguments()->length(); i++) {
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av_.Clear();
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Visit(expr->arguments()->at(i));
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result.Union(av_);
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}
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av_ = result;
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}
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void AssignedVariablesAnalyzer::VisitCallRuntime(CallRuntime* expr) {
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ASSERT(av_.IsEmpty());
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BitVector result(av_);
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for (int i = 0; i < expr->arguments()->length(); i++) {
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av_.Clear();
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Visit(expr->arguments()->at(i));
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result.Union(av_);
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}
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av_ = result;
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}
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void AssignedVariablesAnalyzer::VisitUnaryOperation(UnaryOperation* expr) {
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ASSERT(av_.IsEmpty());
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MarkIfTrivial(expr->expression());
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Visit(expr->expression());
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}
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void AssignedVariablesAnalyzer::VisitCountOperation(CountOperation* expr) {
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ASSERT(av_.IsEmpty());
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if (expr->is_prefix()) MarkIfTrivial(expr->expression());
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Visit(expr->expression());
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Variable* var = expr->expression()->AsVariableProxy()->AsVariable();
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if (var != NULL) RecordAssignedVar(var);
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}
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void AssignedVariablesAnalyzer::VisitBinaryOperation(BinaryOperation* expr) {
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ASSERT(av_.IsEmpty());
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MarkIfTrivial(expr->right());
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Visit(expr->right());
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MarkIfTrivial(expr->left());
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ProcessExpression(expr->left());
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}
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void AssignedVariablesAnalyzer::VisitCompareOperation(CompareOperation* expr) {
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ASSERT(av_.IsEmpty());
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MarkIfTrivial(expr->right());
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Visit(expr->right());
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MarkIfTrivial(expr->left());
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ProcessExpression(expr->left());
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}
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void AssignedVariablesAnalyzer::VisitCompareToNull(CompareToNull* expr) {
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ASSERT(av_.IsEmpty());
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MarkIfTrivial(expr->expression());
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Visit(expr->expression());
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}
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void AssignedVariablesAnalyzer::VisitThisFunction(ThisFunction* expr) {
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// Nothing to do.
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ASSERT(av_.IsEmpty());
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}
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void AssignedVariablesAnalyzer::VisitDeclaration(Declaration* decl) {
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UNREACHABLE();
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}
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} } // namespace v8::internal
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@ -335,44 +335,6 @@ class WorkList BASE_EMBEDDED {
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List<T*> queue_;
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};
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// Computes the set of assigned variables and annotates variables proxies
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// that are trivial sub-expressions and for-loops where the loop variable
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// is guaranteed to be a smi.
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class AssignedVariablesAnalyzer : public AstVisitor {
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public:
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static bool Analyze(CompilationInfo* info);
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private:
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AssignedVariablesAnalyzer(CompilationInfo* info, int bits);
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bool Analyze();
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Variable* FindSmiLoopVariable(ForStatement* stmt);
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int BitIndex(Variable* var);
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void RecordAssignedVar(Variable* var);
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void MarkIfTrivial(Expression* expr);
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// Visits an expression saving the accumulator before, clearing
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// it before visting and restoring it after visiting.
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void ProcessExpression(Expression* expr);
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// AST node visit functions.
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#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
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AST_NODE_LIST(DECLARE_VISIT)
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#undef DECLARE_VISIT
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CompilationInfo* info_;
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// Accumulator for assigned variables set.
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BitVector av_;
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DISALLOW_COPY_AND_ASSIGN(AssignedVariablesAnalyzer);
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};
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} } // namespace v8::internal
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