rust/src/librustc/middle/trans/reflect.rs

// 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 back::link::mangle_internal_name_by_path_and_seq;
use llvm::{ValueRef, get_param};
use middle::trans::adt;
use middle::trans::base::*;
use middle::trans::build::*;
use middle::trans::callee::ArgVals;
use middle::trans::callee;
use middle::trans::common::*;
use middle::trans::datum::*;
use middle::trans::glue;
use middle::trans::machine;
use middle::trans::meth;
use middle::trans::type_::Type;
use middle::trans::type_of::*;
use middle::ty;
use util::ppaux::ty_to_string;

use arena::TypedArena;
use libc::c_uint;
use syntax::ast::DefId;
use syntax::ast;
use syntax::ast_map;
use syntax::parse::token::{InternedString, special_idents};
use syntax::parse::token;

pub struct Reflector<'a, 'blk, 'tcx: 'blk> {
    visitor_val: ValueRef,
    visitor_items: &'a [ty::ImplOrTraitItem],
    final_bcx: Block<'blk, 'tcx>,
    tydesc_ty: Type,
    bcx: Block<'blk, 'tcx>
}

impl<'a, 'blk, 'tcx> Reflector<'a, 'blk, 'tcx> {
    pub fn c_uint(&mut self, u: uint) -> ValueRef {
        C_uint(self.bcx.ccx(), u)
    }

    pub fn c_bool(&mut self, b: bool) -> ValueRef {
        C_bool(self.bcx.ccx(), b)
    }

    pub fn c_slice(&mut self, s: InternedString) -> ValueRef {
        // We're careful to not use first class aggregates here because that
        // will kick us off fast isel. (Issue #4352.)
        let bcx = self.bcx;
        let str_ty = ty::mk_str_slice(bcx.tcx(), ty::ReStatic, ast::MutImmutable);
        let scratch = rvalue_scratch_datum(bcx, str_ty, "");
        let len = C_uint(bcx.ccx(), s.get().len());
        let c_str = PointerCast(bcx, C_cstr(bcx.ccx(), s, false), Type::i8p(bcx.ccx()));
        Store(bcx, c_str, GEPi(bcx, scratch.val, [ 0, 0 ]));
        Store(bcx, len, GEPi(bcx, scratch.val, [ 0, 1 ]));
        scratch.val
    }

    pub fn c_size_and_align(&mut self, t: ty::t) -> Vec<ValueRef> {
        let tr = type_of(self.bcx.ccx(), t);
        let s = machine::llsize_of_real(self.bcx.ccx(), tr);
        let a = align_of(self.bcx.ccx(), t);
        return vec!(self.c_uint(s as uint),
             self.c_uint(a as uint));
    }

    pub fn c_tydesc(&mut self, t: ty::t) -> ValueRef {
        let bcx = self.bcx;
        let static_ti = get_tydesc(bcx.ccx(), t);
        glue::lazily_emit_visit_glue(bcx.ccx(), &*static_ti);
        PointerCast(bcx, static_ti.tydesc, self.tydesc_ty.ptr_to())
    }

    pub fn c_mt(&mut self, mt: &ty::mt) -> Vec<ValueRef> {
        vec!(self.c_uint(mt.mutbl as uint),
          self.c_tydesc(mt.ty))
    }

    pub fn visit(&mut self, ty_name: &str, args: &[ValueRef]) {
        let fcx = self.bcx.fcx;
        let tcx = self.bcx.tcx();
        let mth_idx = ty::impl_or_trait_item_idx(token::str_to_ident(format!(
                        "visit_{}", ty_name).as_slice()),
                                     self.visitor_items.as_slice()).expect(
                format!("couldn't find visit method for {}", ty_name).as_slice());
        let method = match self.visitor_items[mth_idx] {
            ty::MethodTraitItem(ref method) => (*method).clone(),
        };
        let mth_ty = ty::mk_bare_fn(tcx, method.fty.clone());
        debug!("Emit call visit method: visit_{}: {}", ty_name, ty_to_string(tcx, mth_ty));
        let v = self.visitor_val;
        debug!("passing {} args:", args.len());
        let mut bcx = self.bcx;
        for (i, a) in args.iter().enumerate() {
            debug!("arg {}: {}", i, bcx.val_to_string(*a));
        }
        let result = unpack_result!(bcx, callee::trans_call_inner(
            self.bcx, None, mth_ty,
            |bcx, _| meth::trans_trait_callee_from_llval(bcx,
                                                         mth_ty,
                                                         mth_idx,
                                                         v),
            ArgVals(args), None));
        let next_bcx = fcx.new_temp_block("next");
        CondBr(bcx, result, next_bcx.llbb, self.final_bcx.llbb);
        self.bcx = next_bcx
    }

    pub fn bracketed(&mut self,
                     bracket_name: &str,
                     extra: &[ValueRef],
                     inner: |&mut Reflector|) {
        self.visit(format!("enter_{}", bracket_name).as_slice(), extra);
        inner(self);
        self.visit(format!("leave_{}", bracket_name).as_slice(), extra);
    }

    pub fn leaf(&mut self, name: &str) {
        self.visit(name, []);
    }

    // Entrypoint
    pub fn visit_ty(&mut self, t: ty::t) {
        let bcx = self.bcx;
        let tcx = bcx.tcx();
        debug!("reflect::visit_ty {}", ty_to_string(bcx.tcx(), t));

        match ty::get(t).sty {
          ty::ty_bot => self.leaf("bot"),
          ty::ty_nil => self.leaf("nil"),
          ty::ty_bool => self.leaf("bool"),
          ty::ty_char => self.leaf("char"),
          ty::ty_int(ast::TyI) => self.leaf("int"),
          ty::ty_int(ast::TyI8) => self.leaf("i8"),
          ty::ty_int(ast::TyI16) => self.leaf("i16"),
          ty::ty_int(ast::TyI32) => self.leaf("i32"),
          ty::ty_int(ast::TyI64) => self.leaf("i64"),
          ty::ty_uint(ast::TyU) => self.leaf("uint"),
          ty::ty_uint(ast::TyU8) => self.leaf("u8"),
          ty::ty_uint(ast::TyU16) => self.leaf("u16"),
          ty::ty_uint(ast::TyU32) => self.leaf("u32"),
          ty::ty_uint(ast::TyU64) => self.leaf("u64"),
          ty::ty_float(ast::TyF32) => self.leaf("f32"),
          ty::ty_float(ast::TyF64) => self.leaf("f64"),

          ty::ty_open(_) | ty::ty_str | ty::ty_vec(_, None) | ty::ty_trait(..) => {
              // Unfortunately we can't do anything here because at runtime we
              // pass around the value by pointer (*u8). But unsized pointers are
              // fat and so we can't just cast them to *u8 and back. So we have
              // to work with the pointer directly (see ty_ptr/ty_rptr/ty_uniq).
              fail!("Can't reflect unsized type")
          }
          // FIXME(15049) Reflection for unsized structs.
          ty::ty_struct(..) if !ty::type_is_sized(bcx.tcx(), t) => {
              fail!("Can't reflect unsized type")
          }

          // Should rename to vec_*.
          ty::ty_vec(ty, Some(sz)) => {
              let mut extra = (vec!(self.c_uint(sz))).append(self.c_size_and_align(t).as_slice());
              extra.push(self.c_tydesc(ty));
              self.visit("evec_fixed", extra.as_slice())
          }
          // Should remove mt from box and uniq.
          ty::ty_box(typ) => {
              let extra = self.c_mt(&ty::mt {
                  ty: typ,
                  mutbl: ast::MutImmutable,
              });
              self.visit("box", extra.as_slice())
          }
          ty::ty_ptr(ref mt) => {
              match ty::get(mt.ty).sty {
                  ty::ty_vec(ty, None) => {
                      let extra = self.c_mt(&ty::mt{ty: ty, mutbl: mt.mutbl});
                      self.visit("evec_slice", extra.as_slice())
                  }
                  ty::ty_str => self.visit("estr_slice", &[]),
                  ty::ty_trait(..) => {
                      let extra = [
                          self.c_slice(token::intern_and_get_ident(
                                  ty_to_string(tcx, t).as_slice()))
                      ];
                      self.visit("trait", extra);
                  }
                  _ => {
                      let extra = self.c_mt(mt);
                      self.visit("ptr", extra.as_slice())
                  }
              }
          }
          ty::ty_uniq(typ) => {
              match ty::get(typ).sty {
                  ty::ty_trait(..) => {
                      let extra = [
                          self.c_slice(token::intern_and_get_ident(
                                  ty_to_string(tcx, t).as_slice()))
                      ];
                      self.visit("trait", extra);
                  }
                  // FIXME(15049) allow reflection of Box<[T]>. You'll need to
                  // restore visit_evec_uniq.
                  ty::ty_vec(_, None) => {
                      fail!("Box<[T]> theoretically doesn't exist, so don't try to reflect it")
                  }
                  ty::ty_str => fail!("Can't reflect Box<str> which shouldn't be used anyway"),
                  _ => {
                      let extra = self.c_mt(&ty::mt {
                          ty: typ,
                          mutbl: ast::MutImmutable,
                      });
                      self.visit("uniq", extra.as_slice())
                  }
              }
          }
          ty::ty_rptr(_, ref mt) => {
              match ty::get(mt.ty).sty {
                  ty::ty_vec(ty, None) => {
                      let extra = self.c_mt(&ty::mt{ty: ty, mutbl: mt.mutbl});
                      self.visit("evec_slice", extra.as_slice())
                  }
                  ty::ty_str => self.visit("estr_slice", &[]),
                  ty::ty_trait(..) => {
                      let extra = [
                          self.c_slice(token::intern_and_get_ident(
                                  ty_to_string(tcx, t).as_slice()))
                      ];
                      self.visit("trait", extra);
                  }
                  _ => {
                      let extra = self.c_mt(mt);
                      self.visit("rptr", extra.as_slice())
                  }
              }
          }

          ty::ty_tup(ref tys) => {
              let extra = (vec!(self.c_uint(tys.len())))
                          .append(self.c_size_and_align(t).as_slice());
              self.bracketed("tup", extra.as_slice(), |this| {
                  for (i, t) in tys.iter().enumerate() {
                      let extra = vec!(this.c_uint(i), this.c_tydesc(*t));
                      this.visit("tup_field", extra.as_slice());
                  }
              })
          }

          // FIXME (#2594): fetch constants out of intrinsic
          // FIXME (#4809): visitor should break out bare fns from other fns
          ty::ty_closure(ref fty) => {
            let pureval = ast_fn_style_constant(fty.fn_style);
            let sigilval = match fty.store {
                ty::UniqTraitStore => 2u,
                ty::RegionTraitStore(..) => 4u,
            };
            let retval = if ty::type_is_bot(fty.sig.output) {0u} else {1u};
            let extra = vec!(self.c_uint(pureval),
                          self.c_uint(sigilval),
                          self.c_uint(fty.sig.inputs.len()),
                          self.c_uint(retval));
            self.visit("enter_fn", extra.as_slice());
            self.visit_sig(retval, &fty.sig);
            self.visit("leave_fn", extra.as_slice());
          }

          // FIXME (#2594): fetch constants out of intrinsic:: for the
          // numbers.
          ty::ty_bare_fn(ref fty) => {
            let pureval = ast_fn_style_constant(fty.fn_style);
            let sigilval = 0u;
            let retval = if ty::type_is_bot(fty.sig.output) {0u} else {1u};
            let extra = vec!(self.c_uint(pureval),
                          self.c_uint(sigilval),
                          self.c_uint(fty.sig.inputs.len()),
                          self.c_uint(retval));
            self.visit("enter_fn", extra.as_slice());
            self.visit_sig(retval, &fty.sig);
            self.visit("leave_fn", extra.as_slice());
          }

          ty::ty_struct(did, ref substs) => {
              let fields = ty::struct_fields(tcx, did, substs);
              let mut named_fields = false;
              if !fields.is_empty() {
                  named_fields = fields.get(0).ident.name !=
                      special_idents::unnamed_field.name;
              }

              // This and the type_is_sized check on individual field types are
              // because we cannot reflect unsized types (see note above). We
              // just pretend the unsized field does not exist and print nothing.
              // This is sub-optimal.
              let len = fields.len();

              let extra = (vec!(
                  self.c_slice(
                      token::intern_and_get_ident(ty_to_string(tcx,
                                                            t).as_slice())),
                  self.c_bool(named_fields),
                  self.c_uint(len)
              )).append(self.c_size_and_align(t).as_slice());
              self.bracketed("class", extra.as_slice(), |this| {
                  for (i, field) in fields.iter().enumerate() {
                      let extra = (vec!(
                        this.c_uint(i),
                        this.c_slice(token::get_ident(field.ident)),
                        this.c_bool(named_fields)
                      )).append(this.c_mt(&field.mt).as_slice());
                      this.visit("class_field", extra.as_slice());
                  }
              })
          }

          // FIXME (#2595): visiting all the variants in turn is probably
          // not ideal. It'll work but will get costly on big enums. Maybe
          // let the visitor tell us if it wants to visit only a particular
          // variant?
          ty::ty_enum(did, ref substs) => {
            let ccx = bcx.ccx();
            let repr = adt::represent_type(bcx.ccx(), t);
            let variants = ty::substd_enum_variants(ccx.tcx(), did, substs);
            let llptrty = type_of(ccx, t).ptr_to();
            let opaquety = ty::get_opaque_ty(ccx.tcx()).unwrap();
            let opaqueptrty = ty::mk_ptr(ccx.tcx(), ty::mt { ty: opaquety,
                                                           mutbl: ast::MutImmutable });

            let make_get_disr = || {
                let sym = mangle_internal_name_by_path_and_seq(
                    ast_map::Values([].iter()).chain(None), "get_disr");

                let fn_ty = ty::mk_ctor_fn(ccx.tcx(), ast::DUMMY_NODE_ID,
                                           [opaqueptrty], ty::mk_u64());
                let llfdecl = decl_internal_rust_fn(ccx,
                                                    fn_ty,
                                                    sym.as_slice());
                let arena = TypedArena::new();
                let empty_param_substs = param_substs::empty();
                let fcx = new_fn_ctxt(ccx, llfdecl, ast::DUMMY_NODE_ID, false,
                                      ty::mk_u64(), &empty_param_substs,
                                      None, &arena);
                let bcx = init_function(&fcx, false, ty::mk_u64());

                // we know the return type of llfdecl is an int here, so
                // no need for a special check to see if the return type
                // is immediate.
                let arg = get_param(llfdecl, fcx.arg_pos(0u) as c_uint);
                let arg = BitCast(bcx, arg, llptrty);
                let ret = adt::trans_get_discr(bcx, &*repr, arg, Some(Type::i64(ccx)));
                assert!(!fcx.needs_ret_allocas);
                let ret_slot = fcx.get_ret_slot(bcx, ty::mk_u64(), "ret_slot");
                Store(bcx, ret, ret_slot);
                match fcx.llreturn.get() {
                    Some(llreturn) => Br(bcx, llreturn),
                    None => {}
                };
                finish_fn(&fcx, bcx, ty::mk_u64());
                llfdecl
            };

            let enum_args = (vec!(self.c_uint(variants.len()), make_get_disr()))
                            .append(self.c_size_and_align(t).as_slice());
            self.bracketed("enum", enum_args.as_slice(), |this| {
                for (i, v) in variants.iter().enumerate() {
                    let name = token::get_ident(v.name);
                    let variant_args = [this.c_uint(i),
                                         C_u64(ccx, v.disr_val),
                                         this.c_uint(v.args.len()),
                                         this.c_slice(name)];
                    this.bracketed("enum_variant",
                                   variant_args,
                                   |this| {
                        for (j, a) in v.args.iter().enumerate() {
                            let bcx = this.bcx;
                            let null = C_null(llptrty);
                            let ptr = adt::trans_field_ptr(bcx, &*repr, null, v.disr_val, j);
                            let offset = p2i(ccx, ptr);
                            let field_args = [this.c_uint(j),
                                               offset,
                                               this.c_tydesc(*a)];
                            this.visit("enum_variant_field",
                                       field_args);
                        }
                    })
                }
            })
          }

          // Miscellaneous extra types
          ty::ty_infer(_) => self.leaf("infer"),
          ty::ty_err => self.leaf("err"),
          ty::ty_unboxed_closure(..) => self.leaf("err"),
          ty::ty_param(ref p) => {
              let extra = vec!(self.c_uint(p.idx));
              self.visit("param", extra.as_slice())
          }
        }
    }

    pub fn visit_sig(&mut self, retval: uint, sig: &ty::FnSig) {
        for (i, arg) in sig.inputs.iter().enumerate() {
            let modeval = 5u;   // "by copy"
            let extra = vec!(self.c_uint(i),
                         self.c_uint(modeval),
                         self.c_tydesc(*arg));
            self.visit("fn_input", extra.as_slice());
        }
        let extra = vec!(self.c_uint(retval),
                      self.c_bool(sig.variadic),
                      self.c_tydesc(sig.output));
        self.visit("fn_output", extra.as_slice());
    }
}

// Emit a sequence of calls to visit_ty::visit_foo
pub fn emit_calls_to_trait_visit_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                                                t: ty::t,
                                                visitor_val: ValueRef,
                                                visitor_trait_id: DefId)
                                                -> Block<'blk, 'tcx> {
    let fcx = bcx.fcx;
    let final = fcx.new_temp_block("final");
    let tydesc_ty = ty::get_tydesc_ty(bcx.tcx()).unwrap();
    let tydesc_ty = type_of(bcx.ccx(), tydesc_ty);
    let visitor_items = ty::trait_items(bcx.tcx(), visitor_trait_id);
    let mut r = Reflector {
        visitor_val: visitor_val,
        visitor_items: visitor_items.as_slice(),
        final_bcx: final,
        tydesc_ty: tydesc_ty,
        bcx: bcx
    };
    r.visit_ty(t);
    Br(r.bcx, final.llbb);
    return final;
}

pub fn ast_fn_style_constant(fn_style: ast::FnStyle) -> uint {
    match fn_style {
        ast::UnsafeFn => 1u,
        ast::NormalFn => 2u,
    }
}