diff options
| -rw-r--r-- | elaborate.cxx | 106 |
1 files changed, 49 insertions, 57 deletions
diff --git a/elaborate.cxx b/elaborate.cxx index c15fb1c2..dd2b4acf 100644 --- a/elaborate.cxx +++ b/elaborate.cxx @@ -2251,13 +2251,15 @@ struct void_statement_reducer: public traversing_visitor systemtap_session& session; bool& relaxed_p; statement** current_stmt; // pointer to current stmt* being iterated + expr_statement* current_expr; // pointer to current expr being iterated set<vardecl*> focal_vars; // vars considered subject to side-effects void_statement_reducer(systemtap_session& s, bool& r): - session(s), relaxed_p(r), current_stmt(0) {} + session(s), relaxed_p(r), current_stmt(0), current_expr(0) {} // these just maintain current_stmt while recursing, but don't visit // expressions in the conditional / loop controls. + void visit_expr_statement (expr_statement* s); void visit_block (block *s); void visit_if_statement (if_statement* s); void visit_for_loop (for_loop* s); @@ -2293,6 +2295,15 @@ struct void_statement_reducer: public traversing_visitor void +void_statement_reducer::visit_expr_statement (expr_statement* s) +{ + assert(!current_expr); // it shouldn't be possible to have nested expr's + current_expr = s; + s->value->visit (this); + current_expr = NULL; +} + +void void_statement_reducer::visit_block (block *s) { statement** last_stmt = current_stmt; @@ -2343,8 +2354,7 @@ void_statement_reducer::visit_logical_or_expr (logical_or_expr* e) // In void context, the evaluation of "a || b" is exactly like // "if (!a) b", so let's do that instead. - expr_statement *es = dynamic_cast<expr_statement *>(*current_stmt); - assert(es && es->value == e); + assert(current_expr && current_expr->value == e); if (session.verbose>2) clog << "Creating if statement from unused logical-or " @@ -2354,6 +2364,7 @@ void_statement_reducer::visit_logical_or_expr (logical_or_expr* e) is->tok = e->tok; is->elseblock = 0; *current_stmt = is; + current_expr = NULL; unary_expression *ue = new unary_expression; ue->operand = e->left; @@ -2361,7 +2372,7 @@ void_statement_reducer::visit_logical_or_expr (logical_or_expr* e) ue->op = "!"; is->condition = ue; - // NB: reusing the expr_statement for the thenblock + expr_statement *es = new expr_statement; es->value = e->right; es->tok = es->value->tok; is->thenblock = es; @@ -2376,8 +2387,7 @@ void_statement_reducer::visit_logical_and_expr (logical_and_expr* e) // In void context, the evaluation of "a && b" is exactly like // "if (a) b", so let's do that instead. - expr_statement *es = dynamic_cast<expr_statement *>(*current_stmt); - assert(es && es->value == e); + assert(current_expr && current_expr->value == e); if (session.verbose>2) clog << "Creating if statement from unused logical-and " @@ -2388,8 +2398,9 @@ void_statement_reducer::visit_logical_and_expr (logical_and_expr* e) is->elseblock = 0; is->condition = e->left; *current_stmt = is; + current_expr = NULL; - // NB: reusing the expr_statement for the thenblock + expr_statement *es = new expr_statement; es->value = e->right; es->tok = es->value->tok; is->thenblock = es; @@ -2404,8 +2415,7 @@ void_statement_reducer::visit_ternary_expression (ternary_expression* e) // In void context, the evaluation of "a ? b : c" is exactly like // "if (a) b else c", so let's do that instead. - expr_statement *es = dynamic_cast<expr_statement *>(*current_stmt); - assert(es && es->value == e); + assert(current_expr && current_expr->value == e); if (session.verbose>2) clog << "Creating if statement from unused ternary expression " @@ -2415,8 +2425,9 @@ void_statement_reducer::visit_ternary_expression (ternary_expression* e) is->tok = e->tok; is->condition = e->cond; *current_stmt = is; + current_expr = NULL; - // NB: reusing the expr_statement for the thenblock + expr_statement *es = new expr_statement; es->value = e->truevalue; es->tok = es->value->tok; is->thenblock = es; @@ -2436,17 +2447,17 @@ void_statement_reducer::visit_binary_expression (binary_expression* e) // When the result of a binary operation isn't needed, it's just as good to // evaluate the operands as sequential statements in a block. - expr_statement *es = dynamic_cast<expr_statement *>(*current_stmt); - assert(es && es->value == e); + assert(current_expr && current_expr->value == e); if (session.verbose>2) clog << "Eliding unused binary " << *e->tok << endl; block *b = new block; - b->tok = es->tok; + b->tok = current_expr->tok; *current_stmt = b; + current_expr = NULL; - // NB: reusing the existing expr_statement for the first one... + expr_statement *es = new expr_statement; es->value = e->left; es->tok = es->value->tok; b->statements.push_back(es); @@ -2466,15 +2477,14 @@ void_statement_reducer::visit_unary_expression (unary_expression* e) // When the result of a unary operation isn't needed, it's just as good to // evaluate the operand directly - expr_statement *es = dynamic_cast<expr_statement *>(*current_stmt); - assert(es && es->value == e); + assert(current_expr && current_expr->value == e); if (session.verbose>2) clog << "Eliding unused unary " << *e->tok << endl; - es->value = e->operand; - es->tok = es->value->tok; - es->value->visit(this); + current_expr->value = e->operand; + current_expr->tok = current_expr->value->tok; + current_expr->value->visit(this); relaxed_p = false; } @@ -2507,34 +2517,25 @@ void_statement_reducer::visit_functioncall (functioncall* e) if (!vut.side_effect_free_wrt (focal_vars)) return; - expr_statement *es = dynamic_cast<expr_statement *>(*current_stmt); - assert(es && es->value == e); + assert(current_expr && current_expr->value == e); if (session.verbose>2) clog << "Eliding side-effect-free function call " << *e->tok << endl; - // NB: reusing the existing expr_statement for the first arg... - es->value = e->args[0]; - es->tok = es->value->tok; + block *b = new block; + b->tok = e->tok; + *current_stmt = b; + current_expr = NULL; - if (e->args.size() > 1) + for (unsigned i=0; i<e->args.size(); i++ ) { - block *b = new block; - b->tok = es->tok; - *current_stmt = b; - + expr_statement *es = new expr_statement; + es->value = e->args[i]; + es->tok = es->value->tok; b->statements.push_back(es); - - for (unsigned i=1; i<e->args.size(); i++ ) - { - es = new expr_statement; - es->value = e->args[i]; - es->tok = es->value->tok; - b->statements.push_back(es); - } } - (*current_stmt)->visit(this); + b->visit(this); relaxed_p = false; } @@ -2547,34 +2548,25 @@ void_statement_reducer::visit_print_format (print_format* e) if (e->print_to_stream || !e->args.size()) return; - expr_statement *es = dynamic_cast<expr_statement *>(*current_stmt); - assert(es && es->value == e); + assert(current_expr && current_expr->value == e); if (session.verbose>2) clog << "Eliding unused print " << *e->tok << endl; - // NB: reusing the existing expr_statement for the first arg... - es->value = e->args[0]; - es->tok = es->value->tok; + block *b = new block; + b->tok = e->tok; + *current_stmt = b; + current_expr = NULL; - if (e->args.size() > 1) + for (unsigned i=0; i<e->args.size(); i++ ) { - block *b = new block; - b->tok = es->tok; - *current_stmt = b; - + expr_statement *es = new expr_statement; + es->value = e->args[i]; + es->tok = es->value->tok; b->statements.push_back(es); - - for (unsigned i=1; i<e->args.size(); i++ ) - { - es = new expr_statement; - es->value = e->args[i]; - es->tok = es->value->tok; - b->statements.push_back(es); - } } - (*current_stmt)->visit(this); + b->visit(this); relaxed_p = false; } |