static struct ast_node* stmt(void *opaque) { struct ast_node *node; token_t prev_token; prev_token = current_token; if (match(TOKEN_FUNCTION)) node = process_function(opaque); else if (match(TOKEN_LOCAL)) node = process_local_declaration(opaque); else if (match(TOKEN_IF)) node = if_expr(opaque); else if (match(TOKEN_FOR)) node = for_expr(opaque); else if (match(TOKEN_WHILE)) node = while_expr(opaque); else if (match(TOKEN_BREAK)) node = break_expr(opaque); else if (match(TOKEN_CONTINUE)) node = continue_expr(opaque); else if (match(TOKEN_RETURN)) node = process_return_node(opaque); else if (match(TOKEN_LBRACE)) node = process_scope(opaque); else if (match(TOKEN_RBRACE)) node = end_scope_expr(opaque); else if (match(TOKEN_UNKNOWN)) node = unknown_expr(opaque); else node = other_expr(opaque); return node; }
bool simplify_exprt::simplify_index(exprt &expr) { bool result=true; // extra arithmetic optimizations const exprt &index=to_index_expr(expr).index(); const exprt &array=to_index_expr(expr).array(); if(index.id()==ID_div && index.operands().size()==2) { if(index.op0().id()==ID_mult && index.op0().operands().size()==2 && index.op0().op1()==index.op1()) { exprt tmp=index.op0().op0(); expr.op1()=tmp; result=false; } else if(index.op0().id()==ID_mult && index.op0().operands().size()==2 && index.op0().op0()==index.op1()) { exprt tmp=index.op0().op1(); expr.op1()=tmp; result=false; } } if(array.id()==ID_lambda) { // simplify (lambda i: e)(x) to e[i/x] const exprt &lambda_expr=array; if(lambda_expr.operands().size()!=2) return true; if(expr.op1().type()==lambda_expr.op0().type()) { exprt tmp=lambda_expr.op1(); replace_expr(lambda_expr.op0(), expr.op1(), tmp); expr.swap(tmp); return false; } } else if(array.id()==ID_with) { // we have (a WITH [i:=e])[j] const exprt &with_expr=array; if(with_expr.operands().size()!=3) return true; if(with_expr.op1()==expr.op1()) { // simplify (e with [i:=v])[i] to v exprt tmp=with_expr.op2(); expr.swap(tmp); return false; } else { // Turn (a with i:=x)[j] into (i==j)?x:a[j]. // watch out that the type of i and j might be different. equal_exprt equality_expr(expr.op1(), with_expr.op1()); if(equality_expr.lhs().type()!=equality_expr.rhs().type()) equality_expr.rhs().make_typecast(equality_expr.lhs().type()); simplify_inequality(equality_expr); index_exprt new_index_expr; new_index_expr.type()=expr.type(); new_index_expr.array()=with_expr.op0(); new_index_expr.index()=expr.op1(); simplify_index(new_index_expr); // recursive call if(equality_expr.is_true()) { expr=with_expr.op2(); return false; } else if(equality_expr.is_false()) { expr.swap(new_index_expr); return false; } if_exprt if_expr(equality_expr, with_expr.op2(), new_index_expr); simplify_if(if_expr); expr.swap(if_expr); return false; } } else if(array.id()==ID_constant || array.id()==ID_array) { mp_integer i; if(to_integer(expr.op1(), i)) { } else if(i<0 || i>=array.operands().size()) { // out of bounds } else { // ok exprt tmp=array.operands()[integer2size_t(i)]; expr.swap(tmp); return false; } } else if(array.id()==ID_string_constant) { mp_integer i; const irep_idt &value=array.get(ID_value); if(to_integer(expr.op1(), i)) { } else if(i<0 || i>value.size()) { // out of bounds } else { // terminating zero? char v=(i==value.size())?0:value[integer2size_t(i)]; exprt tmp=from_integer(v, expr.type()); expr.swap(tmp); return false; } } else if(array.id()==ID_array_of) { if(array.operands().size()==1) { exprt tmp=array.op0(); expr.swap(tmp); return false; } } else if(array.id()=="array-list") { // These are index/value pairs, alternating. for(size_t i=0; i<array.operands().size()/2; i++) { exprt tmp_index=array.operands()[i*2]; tmp_index.make_typecast(index.type()); simplify(tmp_index); if(tmp_index==index) { exprt tmp=array.operands()[i*2+1]; expr.swap(tmp); return false; } } } else if(array.id()==ID_byte_extract_little_endian || array.id()==ID_byte_extract_big_endian) { const typet &array_type=ns.follow(array.type()); if(array_type.id()==ID_array) { // This rewrites byte_extract(s, o, array_type)[i] // to byte_extract(s, o+offset, sub_type) mp_integer sub_size=pointer_offset_size(array_type.subtype(), ns); if(sub_size==-1) return true; // add offset to index mult_exprt offset(from_integer(sub_size, array.op1().type()), index); plus_exprt final_offset(array.op1(), offset); simplify_node(final_offset); exprt result(array.id(), expr.type()); result.copy_to_operands(array.op0(), final_offset); expr.swap(result); simplify_rec(expr); return false; } } else if(array.id()==ID_if) { const if_exprt &if_expr=to_if_expr(array); exprt cond=if_expr.cond(); index_exprt idx_false=to_index_expr(expr); idx_false.array()=if_expr.false_case(); to_index_expr(expr).array()=if_expr.true_case(); expr=if_exprt(cond, expr, idx_false, expr.type()); simplify_rec(expr); return false; } return result; }