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rustc: Switch from storing nullary tags as constants to storing their discriminants

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This commit is contained in:
Patrick Walton 2011-03-01 12:41:41 -08:00
parent 8d8b3d985a
commit f239ecb5f2
1 changed files with 31 additions and 22 deletions
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53
src/comp/middle/trans.rs
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@ -59,7 +59,11 @@ type glue_fns = rec(ValueRef activate_glue,
ValueRef memcpy_glue,
ValueRef bzero_glue);
type tag_info = rec(type_handle th, mutable uint size);
type tag_info = rec(
type_handle th,
mutable uint size,
mutable @hashmap[ast.def_id,ValueRef] lldiscrims
);
state type crate_ctxt = rec(session.session sess,
ModuleRef llmod,
@ -2774,9 +2778,23 @@ fn trans_path(@block_ctxt cx, &ast.path p, &option.t[ast.def] dopt,
}
ret lval_generic_fn(cx, tup(params, fty), vid, ann);
} else {
// Nullary variants are just scalar constants.
check (cx.fcx.ccx.item_ids.contains_key(vid));
ret lval_val(cx, cx.fcx.ccx.item_ids.get(vid));
// Nullary variant.
auto tag_ty = node_ann_type(cx.fcx.ccx, ann);
auto info = cx.fcx.ccx.tags.get(tag_ty);
check (info.lldiscrims.contains_key(vid));
auto lldiscrim_gv = info.lldiscrims.get(vid);
auto lldiscrim = cx.build.Load(lldiscrim_gv);
auto alloc_result = alloc_ty(cx, tag_ty);
auto lltagblob = alloc_result.val;
auto lltagptr = alloc_result.bcx.build.PointerCast(
lltagblob, T_ptr(type_of(cx.fcx.ccx, tag_ty)));
auto lldiscrimptr = alloc_result.bcx.build.GEP(
lltagptr, vec(C_int(0), C_int(0)));
alloc_result.bcx.build.Store(lldiscrim, lldiscrimptr);
ret lval_val(alloc_result.bcx, lltagptr);
}
}
case (ast.def_const(?did)) {
@ -4637,8 +4655,14 @@ fn collect_item(&@crate_ctxt cx, @ast.item i) -> @crate_ctxt {
case (ast.item_tag(_, ?variants, ?tps, ?tag_id)) {
auto vi = new_def_hash[uint]();
auto navi = new_def_hash[uint]();
cx.tags.insert(mk_plain_tag(tag_id), @rec(th=mk_type_handle(),
mutable size=0u));
auto info = @rec(
th=mk_type_handle(),
mutable size=0u,
mutable lldiscrims=@new_def_hash[ValueRef]()
);
cx.tags.insert(mk_plain_tag(tag_id), info);
cx.items.insert(tag_id, i);
}
@ -4772,22 +4796,7 @@ fn trans_constant(&@crate_ctxt cx, @ast.item it) -> @crate_ctxt {
llvm.LLVMSetLinkage(discrim_gvar, lib.llvm.LLVMPrivateLinkage
as llvm.Linkage);
if (_vec.len[ast.variant_arg](variant.args) == 0u) {
// Nullary tags become constants. (N-ary tags are treated
// as functions and generated later.)
auto union_val = C_zero_byte_arr(info.size as uint);
auto val = C_struct(vec(discrim_val, union_val));
// FIXME: better name
auto gvar = llvm.LLVMAddGlobal(cx.llmod, val_ty(val),
_str.buf("tag"));
llvm.LLVMSetInitializer(gvar, val);
llvm.LLVMSetGlobalConstant(gvar, True);
llvm.LLVMSetLinkage(gvar, lib.llvm.LLVMPrivateLinkage
as llvm.Linkage);
cx.item_ids.insert(variant.id, gvar);
}
info.lldiscrims.insert(variant.id, discrim_gvar);
i += 1u;
}