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Make sure simplify_type simplifies all pointer types

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This is needed to prevent infinite recursion when computing
the shape of an enum type that contains pointers to itself.

Closes #1821
This commit is contained in:
Marijn Haverbeke 2012-02-13 14:10:03 +01:00
parent 8309d50ff4
commit bcbe36b33b
1 changed files with 17 additions and 19 deletions
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36
src/comp/middle/shape.rs
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@ -666,7 +666,8 @@ fn static_size_of_enum(cx: @crate_ctxt, t: ty::t)
let max_size = 0u;
let variants = ty::enum_variants(cx.tcx, tid);
for variant: ty::variant_info in *variants {
let tup_ty = simplify_type(cx, ty::mk_tup(cx.tcx, variant.args));
let tup_ty = simplify_type(cx.tcx,
ty::mk_tup(cx.tcx, variant.args));
// Perform any type parameter substitutions.
tup_ty = ty::substitute_type_params(cx.tcx, subtys, tup_ty);
@ -776,29 +777,26 @@ fn dynamic_metrics(cx: @block_ctxt, t: ty::t) -> metrics {
// to have (a) the same size as the type that was passed in; (b) to be non-
// recursive. This is done by replacing all boxes in a type with boxed unit
// types.
fn simplify_type(ccx: @crate_ctxt, typ: ty::t) -> ty::t {
fn simplifier(ccx: @crate_ctxt, typ: ty::t) -> ty::t {
// This should reduce all pointers to some simple pointer type, to
// ensure that we don't recurse endlessly when computing the size of a
// nominal type that has pointers to itself in it.
fn simplify_type(tcx: ty::ctxt, typ: ty::t) -> ty::t {
fn nilptr(tcx: ty::ctxt) -> ty::t {
ty::mk_ptr(tcx, {ty: ty::mk_nil(tcx), mut: ast::imm})
}
fn simplifier(tcx: ty::ctxt, typ: ty::t) -> ty::t {
alt ty::get(typ).struct {
ty::ty_box(_) | ty::ty_opaque_box {
ret ty::mk_imm_box(ccx.tcx, ty::mk_nil(ccx.tcx));
}
ty::ty_uniq(_) {
ret ty::mk_imm_uniq(ccx.tcx, ty::mk_nil(ccx.tcx));
}
ty::ty_fn(_) {
ret ty::mk_tup(ccx.tcx,
[ty::mk_imm_box(ccx.tcx, ty::mk_nil(ccx.tcx)),
ty::mk_imm_box(ccx.tcx, ty::mk_nil(ccx.tcx))]);
}
ty::ty_box(_) | ty::ty_opaque_box | ty::ty_uniq(_) | ty::ty_vec(_) |
ty::ty_ptr(_) { nilptr(tcx) }
ty::ty_fn(_) { ty::mk_tup(tcx, [nilptr(tcx), nilptr(tcx)]) }
ty::ty_res(_, sub, tps) {
let sub1 = ty::substitute_type_params(ccx.tcx, tps, sub);
ret ty::mk_tup(ccx.tcx,
[ty::mk_int(ccx.tcx), simplify_type(ccx, sub1)]);
let sub1 = ty::substitute_type_params(tcx, tps, sub);
ty::mk_tup(tcx, [ty::mk_int(tcx), simplify_type(tcx, sub1)])
}
_ { ret typ; }
_ { typ }
}
}
ret ty::fold_ty(ccx.tcx, ty::fm_general(bind simplifier(ccx, _)), typ);
ty::fold_ty(tcx, ty::fm_general(bind simplifier(tcx, _)), typ)
}
// Given a tag type `ty`, returns the offset of the payload.