| // Copyright 2012 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use core::prelude::*; |
| |
| use metadata::csearch; |
| use middle::astencode; |
| use middle::ty; |
| use middle; |
| |
| use syntax::{ast, ast_map, ast_util, visit}; |
| use syntax::ast::*; |
| |
| use core::hashmap::{HashMap, HashSet}; |
| |
| // |
| // This pass classifies expressions by their constant-ness. |
| // |
| // Constant-ness comes in 3 flavours: |
| // |
| // - Integer-constants: can be evaluated by the frontend all the way down |
| // to their actual value. They are used in a few places (enum |
| // discriminants, switch arms) and are a subset of |
| // general-constants. They cover all the integer and integer-ish |
| // literals (nil, bool, int, uint, char, iNN, uNN) and all integer |
| // operators and copies applied to them. |
| // |
| // - General-constants: can be evaluated by LLVM but not necessarily by |
| // the frontend; usually due to reliance on target-specific stuff such |
| // as "where in memory the value goes" or "what floating point mode the |
| // target uses". This _includes_ integer-constants, plus the following |
| // constructors: |
| // |
| // fixed-size vectors and strings: [] and ""/_ |
| // vector and string slices: &[] and &"" |
| // tuples: (,) |
| // records: {...} |
| // enums: foo(...) |
| // floating point literals and operators |
| // & and * pointers |
| // copies of general constants |
| // |
| // (in theory, probably not at first: if/match on integer-const |
| // conditions / descriminants) |
| // |
| // - Non-constants: everything else. |
| // |
| |
| pub enum constness { |
| integral_const, |
| general_const, |
| non_const |
| } |
| |
| pub fn join(a: constness, b: constness) -> constness { |
| match (a, b) { |
| (integral_const, integral_const) => integral_const, |
| (integral_const, general_const) |
| | (general_const, integral_const) |
| | (general_const, general_const) => general_const, |
| _ => non_const |
| } |
| } |
| |
| pub fn join_all(cs: &[constness]) -> constness { |
| vec::foldl(integral_const, cs, |a, b| join(a, *b)) |
| } |
| |
| pub fn classify(e: @expr, |
| tcx: ty::ctxt) |
| -> constness { |
| let did = ast_util::local_def(e.id); |
| match tcx.ccache.find(&did) { |
| Some(&x) => x, |
| None => { |
| let cn = |
| match e.node { |
| ast::expr_lit(lit) => { |
| match lit.node { |
| ast::lit_str(*) | |
| ast::lit_float(*) => general_const, |
| _ => integral_const |
| } |
| } |
| |
| ast::expr_copy(inner) | |
| ast::expr_unary(_, inner) | |
| ast::expr_paren(inner) => { |
| classify(inner, tcx) |
| } |
| |
| ast::expr_binary(_, a, b) => { |
| join(classify(a, tcx), |
| classify(b, tcx)) |
| } |
| |
| ast::expr_tup(ref es) | |
| ast::expr_vec(ref es, ast::m_imm) => { |
| join_all(vec::map(*es, |e| classify(*e, tcx))) |
| } |
| |
| ast::expr_vstore(e, vstore) => { |
| match vstore { |
| ast::expr_vstore_slice => classify(e, tcx), |
| ast::expr_vstore_uniq | |
| ast::expr_vstore_box | |
| ast::expr_vstore_mut_box | |
| ast::expr_vstore_mut_slice => non_const |
| } |
| } |
| |
| ast::expr_struct(_, ref fs, None) => { |
| let cs = do vec::map((*fs)) |f| { |
| if f.node.mutbl == ast::m_imm { |
| classify(f.node.expr, tcx) |
| } else { |
| non_const |
| } |
| }; |
| join_all(cs) |
| } |
| |
| ast::expr_cast(base, _) => { |
| let ty = ty::expr_ty(tcx, e); |
| let base = classify(base, tcx); |
| if ty::type_is_integral(ty) { |
| join(integral_const, base) |
| } else if ty::type_is_fp(ty) { |
| join(general_const, base) |
| } else { |
| non_const |
| } |
| } |
| |
| ast::expr_field(base, _, _) => { |
| classify(base, tcx) |
| } |
| |
| ast::expr_index(base, idx) => { |
| join(classify(base, tcx), |
| classify(idx, tcx)) |
| } |
| |
| ast::expr_addr_of(ast::m_imm, base) => { |
| classify(base, tcx) |
| } |
| |
| // FIXME: (#3728) we can probably do something CCI-ish |
| // surrounding nonlocal constants. But we don't yet. |
| ast::expr_path(_) => { |
| lookup_constness(tcx, e) |
| } |
| |
| _ => non_const |
| }; |
| tcx.ccache.insert(did, cn); |
| cn |
| } |
| } |
| } |
| |
| pub fn lookup_const(tcx: ty::ctxt, e: @expr) -> Option<@expr> { |
| match tcx.def_map.find(&e.id) { |
| Some(&ast::def_const(def_id)) => lookup_const_by_id(tcx, def_id), |
| _ => None |
| } |
| } |
| |
| pub fn lookup_const_by_id(tcx: ty::ctxt, |
| def_id: ast::def_id) |
| -> Option<@expr> { |
| if ast_util::is_local(def_id) { |
| match tcx.items.find(&def_id.node) { |
| None => None, |
| Some(&ast_map::node_item(it, _)) => match it.node { |
| item_const(_, const_expr) => Some(const_expr), |
| _ => None |
| }, |
| Some(_) => None |
| } |
| } else { |
| let maps = astencode::Maps { |
| root_map: @mut HashMap::new(), |
| method_map: @mut HashMap::new(), |
| vtable_map: @mut HashMap::new(), |
| write_guard_map: @mut HashSet::new(), |
| moves_map: @mut HashSet::new(), |
| capture_map: @mut HashMap::new() |
| }; |
| match csearch::maybe_get_item_ast(tcx, def_id, |
| |a, b, c, d| astencode::decode_inlined_item(a, b, maps, /*bar*/ copy c, d)) { |
| csearch::found(ast::ii_item(item)) => match item.node { |
| item_const(_, const_expr) => Some(const_expr), |
| _ => None |
| }, |
| _ => None |
| } |
| } |
| } |
| |
| pub fn lookup_constness(tcx: ty::ctxt, e: @expr) -> constness { |
| match lookup_const(tcx, e) { |
| Some(rhs) => { |
| let ty = ty::expr_ty(tcx, rhs); |
| if ty::type_is_integral(ty) { |
| integral_const |
| } else { |
| general_const |
| } |
| } |
| None => non_const |
| } |
| } |
| |
| pub fn process_crate(crate: @ast::crate, |
| tcx: ty::ctxt) { |
| let v = visit::mk_simple_visitor(@visit::SimpleVisitor { |
| visit_expr_post: |e| { classify(e, tcx); }, |
| .. *visit::default_simple_visitor() |
| }); |
| visit::visit_crate(crate, (), v); |
| tcx.sess.abort_if_errors(); |
| } |
| |
| |
| // FIXME (#33): this doesn't handle big integer/float literals correctly |
| // (nor does the rest of our literal handling). |
| #[deriving(Eq)] |
| pub enum const_val { |
| const_float(f64), |
| const_int(i64), |
| const_uint(u64), |
| const_str(~str), |
| const_bool(bool) |
| } |
| |
| pub fn eval_const_expr(tcx: middle::ty::ctxt, e: @expr) -> const_val { |
| match eval_const_expr_partial(tcx, e) { |
| Ok(ref r) => (/*bad*/copy *r), |
| Err(ref s) => fail!(/*bad*/copy *s) |
| } |
| } |
| |
| pub fn eval_const_expr_partial(tcx: middle::ty::ctxt, e: @expr) |
| -> Result<const_val, ~str> { |
| use middle::ty; |
| fn fromb(b: bool) -> Result<const_val, ~str> { Ok(const_int(b as i64)) } |
| match e.node { |
| expr_unary(neg, inner) => { |
| match eval_const_expr_partial(tcx, inner) { |
| Ok(const_float(f)) => Ok(const_float(-f)), |
| Ok(const_int(i)) => Ok(const_int(-i)), |
| Ok(const_uint(i)) => Ok(const_uint(-i)), |
| Ok(const_str(_)) => Err(~"Negate on string"), |
| Ok(const_bool(_)) => Err(~"Negate on boolean"), |
| ref err => (/*bad*/copy *err) |
| } |
| } |
| expr_unary(not, inner) => { |
| match eval_const_expr_partial(tcx, inner) { |
| Ok(const_int(i)) => Ok(const_int(!i)), |
| Ok(const_uint(i)) => Ok(const_uint(!i)), |
| Ok(const_bool(b)) => Ok(const_bool(!b)), |
| _ => Err(~"Not on float or string") |
| } |
| } |
| expr_binary(op, a, b) => { |
| match (eval_const_expr_partial(tcx, a), |
| eval_const_expr_partial(tcx, b)) { |
| (Ok(const_float(a)), Ok(const_float(b))) => { |
| match op { |
| add => Ok(const_float(a + b)), |
| subtract => Ok(const_float(a - b)), |
| mul => Ok(const_float(a * b)), |
| div => Ok(const_float(a / b)), |
| rem => Ok(const_float(a % b)), |
| eq => fromb(a == b), |
| lt => fromb(a < b), |
| le => fromb(a <= b), |
| ne => fromb(a != b), |
| ge => fromb(a >= b), |
| gt => fromb(a > b), |
| _ => Err(~"Can't do this op on floats") |
| } |
| } |
| (Ok(const_int(a)), Ok(const_int(b))) => { |
| match op { |
| add => Ok(const_int(a + b)), |
| subtract => Ok(const_int(a - b)), |
| mul => Ok(const_int(a * b)), |
| div if b == 0 => Err(~"attempted to divide by zero"), |
| div => Ok(const_int(a / b)), |
| rem if b == 0 => Err(~"attempted remainder with a divisor of zero"), |
| rem => Ok(const_int(a % b)), |
| and | bitand => Ok(const_int(a & b)), |
| or | bitor => Ok(const_int(a | b)), |
| bitxor => Ok(const_int(a ^ b)), |
| shl => Ok(const_int(a << b)), |
| shr => Ok(const_int(a >> b)), |
| eq => fromb(a == b), |
| lt => fromb(a < b), |
| le => fromb(a <= b), |
| ne => fromb(a != b), |
| ge => fromb(a >= b), |
| gt => fromb(a > b) |
| } |
| } |
| (Ok(const_uint(a)), Ok(const_uint(b))) => { |
| match op { |
| add => Ok(const_uint(a + b)), |
| subtract => Ok(const_uint(a - b)), |
| mul => Ok(const_uint(a * b)), |
| div if b == 0 => Err(~"attempted to divide by zero"), |
| div => Ok(const_uint(a / b)), |
| rem if b == 0 => Err(~"attempted remainder with a divisor of zero"), |
| rem => Ok(const_uint(a % b)), |
| and | bitand => Ok(const_uint(a & b)), |
| or | bitor => Ok(const_uint(a | b)), |
| bitxor => Ok(const_uint(a ^ b)), |
| shl => Ok(const_uint(a << b)), |
| shr => Ok(const_uint(a >> b)), |
| eq => fromb(a == b), |
| lt => fromb(a < b), |
| le => fromb(a <= b), |
| ne => fromb(a != b), |
| ge => fromb(a >= b), |
| gt => fromb(a > b), |
| } |
| } |
| // shifts can have any integral type as their rhs |
| (Ok(const_int(a)), Ok(const_uint(b))) => { |
| match op { |
| shl => Ok(const_int(a << b)), |
| shr => Ok(const_int(a >> b)), |
| _ => Err(~"Can't do this op on an int and uint") |
| } |
| } |
| (Ok(const_uint(a)), Ok(const_int(b))) => { |
| match op { |
| shl => Ok(const_uint(a << b)), |
| shr => Ok(const_uint(a >> b)), |
| _ => Err(~"Can't do this op on a uint and int") |
| } |
| } |
| (Ok(const_bool(a)), Ok(const_bool(b))) => { |
| Ok(const_bool(match op { |
| and => a && b, |
| or => a || b, |
| bitxor => a ^ b, |
| bitand => a & b, |
| bitor => a | b, |
| eq => a == b, |
| ne => a != b, |
| _ => return Err(~"Can't do this op on bools") |
| })) |
| } |
| _ => Err(~"Bad operands for binary") |
| } |
| } |
| expr_cast(base, _) => { |
| let ety = ty::expr_ty(tcx, e); |
| let base = eval_const_expr_partial(tcx, base); |
| match /*bad*/copy base { |
| Err(_) => base, |
| Ok(val) => { |
| match ty::get(ety).sty { |
| ty::ty_float(_) => match val { |
| const_uint(u) => Ok(const_float(u as f64)), |
| const_int(i) => Ok(const_float(i as f64)), |
| const_float(_) => base, |
| _ => Err(~"Can't cast float to str"), |
| }, |
| ty::ty_uint(_) => match val { |
| const_uint(_) => base, |
| const_int(i) => Ok(const_uint(i as u64)), |
| const_float(f) => Ok(const_uint(f as u64)), |
| _ => Err(~"Can't cast str to uint"), |
| }, |
| ty::ty_int(_) | ty::ty_bool => match val { |
| const_uint(u) => Ok(const_int(u as i64)), |
| const_int(_) => base, |
| const_float(f) => Ok(const_int(f as i64)), |
| _ => Err(~"Can't cast str to int"), |
| }, |
| _ => Err(~"Can't cast this type") |
| } |
| } |
| } |
| } |
| expr_path(_) => { |
| match lookup_const(tcx, e) { |
| Some(actual_e) => eval_const_expr_partial(tcx, actual_e), |
| None => Err(~"Non-constant path in constant expr") |
| } |
| } |
| expr_lit(lit) => Ok(lit_to_const(lit)), |
| // If we have a vstore, just keep going; it has to be a string |
| expr_vstore(e, _) => eval_const_expr_partial(tcx, e), |
| expr_paren(e) => eval_const_expr_partial(tcx, e), |
| _ => Err(~"Unsupported constant expr") |
| } |
| } |
| |
| pub fn lit_to_const(lit: @lit) -> const_val { |
| match lit.node { |
| lit_str(s) => const_str(/*bad*/copy *s), |
| lit_int(n, _) => const_int(n), |
| lit_uint(n, _) => const_uint(n), |
| lit_int_unsuffixed(n) => const_int(n), |
| lit_float(n, _) => const_float(float::from_str(*n).get() as f64), |
| lit_float_unsuffixed(n) => |
| const_float(float::from_str(*n).get() as f64), |
| lit_nil => const_int(0i64), |
| lit_bool(b) => const_bool(b) |
| } |
| } |
| |
| pub fn compare_const_vals(a: &const_val, b: &const_val) -> Option<int> { |
| match (a, b) { |
| (&const_int(a), &const_int(b)) => { |
| if a == b { |
| Some(0) |
| } else if a < b { |
| Some(-1) |
| } else { |
| Some(1) |
| } |
| } |
| (&const_uint(a), &const_uint(b)) => { |
| if a == b { |
| Some(0) |
| } else if a < b { |
| Some(-1) |
| } else { |
| Some(1) |
| } |
| } |
| (&const_float(a), &const_float(b)) => { |
| if a == b { |
| Some(0) |
| } else if a < b { |
| Some(-1) |
| } else { |
| Some(1) |
| } |
| } |
| (&const_str(ref a), &const_str(ref b)) => { |
| if (*a) == (*b) { |
| Some(0) |
| } else if (*a) < (*b) { |
| Some(-1) |
| } else { |
| Some(1) |
| } |
| } |
| (&const_bool(a), &const_bool(b)) => { |
| if a == b { |
| Some(0) |
| } else if a < b { |
| Some(-1) |
| } else { |
| Some(1) |
| } |
| } |
| _ => { |
| None |
| } |
| } |
| } |
| |
| pub fn compare_lit_exprs(tcx: middle::ty::ctxt, a: @expr, b: @expr) -> Option<int> { |
| compare_const_vals(&eval_const_expr(tcx, a), &eval_const_expr(tcx, b)) |
| } |
| |
| pub fn lit_expr_eq(tcx: middle::ty::ctxt, a: @expr, b: @expr) -> Option<bool> { |
| match compare_lit_exprs(tcx, a, b) { |
| Some(val) => Some(val == 0), |
| None => None, |
| } |
| } |
| |
| pub fn lit_eq(a: @lit, b: @lit) -> Option<bool> { |
| match compare_const_vals(&lit_to_const(a), &lit_to_const(b)) { |
| Some(val) => Some(val == 0), |
| None => None, |
| } |
| } |
