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Revert "Attempt a mono/ approach for List.get"

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This reverts commit f0b76f41da.
This commit is contained in:
Richard Feldman 2020-04-25 06:19:10 -04:00
parent f0b76f41da
commit d97e16de7e
2 changed files with 5 additions and 147 deletions
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147
compiler/mono/src/expr.rs
View File

@ -480,7 +480,7 @@ fn from_can<'a>(
Expr::FunctionPointer(symbol)
}
Call(boxed, mut loc_args, _) => {
Call(boxed, loc_args, _) => {
use IntOrFloat::*;
let (fn_var, loc_expr, ret_var) = *boxed;
@ -555,106 +555,6 @@ fn from_can<'a>(
};
match from_can(env, loc_expr.value, procs, None) {
Expr::Load(Symbol::LIST_GET) => {
// Expand to a bounds check around List.getUnsafe.
//
// We do this during monomorphization instead of code gen
// because it returns an open union around `Err` and
// we discard tag names prior to code gen. This means that
// (for example) if this `Err` ends up unifying to
// [ Foo, OutOfBounds ], then code gen won't know what
// integer discriminant OutOfBounds corresponds to anymore,
// so it won't know what integer to return.
//
// At this stage we still have tag names to work with,
// so we can return Err OutOfBounds and let the subsequent
// stages turn it into the appropriate integer discriminant.
let arena = env.arena;
let list_symbol = env.fresh_symbol();
// We need owned versions of the arguments' Expr values
// for later. We obtain them using .drain() because the
// alternative of calling .remove(0) twice would result in
// wasted work shifting around the remaining Vec elements.
let ((list_expr, list_layout), (index_expr, index_layout)) = {
let mut opt_arg0 = None;
let mut opt_arg1 = None;
for (index, (var, loc_expr)) in loc_args.drain(..).enumerate() {
let mono_expr = from_can(env, loc_expr.value, procs, None);
let layout =
Layout::from_var(env.arena, var, env.subs, env.pointer_size)
.expect("invalid arg layout when converting List.get");
match index {
0 => opt_arg0 = Some((mono_expr, layout)),
1 => opt_arg1 = Some((mono_expr, layout)),
_ => unreachable!(),
}
}
(opt_arg0.unwrap(), opt_arg1.unwrap())
};
let ret_layout =
Layout::from_var(env.arena, ret_var, env.subs, env.pointer_size)
.expect("invalid ret_layout");
let cond = Expr::CallByName(
Symbol::LIST_IS_EMPTY, // TODO FIXME proper bounds check instead of just isEmpty
bumpalo::vec![in arena; (Expr::Load(list_symbol), list_layout.clone())]
.into_bump_slice(),
);
let (ok_layout, err_layout) = match ret_layout {
// Err comes before Ok because they're sorted alphabetically
Layout::Union([[_err_discrim, err_layout], [_ok_discrim, ok_layout]]) => {
(ok_layout, err_layout)
}
_ => {
unreachable!("Invalid ret_layout for Result");
}
};
let then_branch = {
let payload_expr = Expr::CallByName(
Symbol::LIST_GET_UNSAFE,
bumpalo::vec![in arena;
(Expr::Load(list_symbol), list_layout.clone()),
(index_expr, index_layout),
]
.into_bump_slice(),
);
build_ok(arena, ret_layout.clone(), payload_expr, ok_layout.clone())
};
let else_branch = {
// OutOfBounds is zero-sized
// TODO FIXME this isn't always zero-sized! Could be an int if union is nonempty.
let payload_expr = Expr::Struct(&[]);
build_err(arena, ret_layout.clone(), payload_expr, err_layout.clone())
};
let branch_symbol = env.fresh_symbol();
let cond_expr = Expr::Cond {
cond_symbol: branch_symbol,
branch_symbol,
cond_layout: Layout::Builtin(Builtin::Bool),
pass: (&[], arena.alloc(then_branch)),
fail: (&[], arena.alloc(else_branch)),
ret_layout,
};
Expr::Store(
bumpalo::vec![in &arena;
(list_symbol, list_layout, list_expr),
(branch_symbol, Layout::Builtin(Builtin::Bool), cond)
]
.into_bump_slice(),
env.arena.alloc(cond_expr),
)
}
Expr::Load(proc_name) => {
// Some functions can potentially mutate in-place.
// If we have one of those, switch to the in-place version if appropriate.
@ -733,7 +633,8 @@ fn from_can<'a>(
};
expr = Expr::Store(
bumpalo::vec![in env.arena; (branch_symbol, Layout::Builtin(Builtin::Bool), cond)].into_bump_slice(),
env.arena
.alloc(vec![(branch_symbol, Layout::Builtin(Builtin::Bool), cond)]),
env.arena.alloc(cond_expr),
);
}
@ -1800,45 +1701,3 @@ pub fn specialize_equality<'a>(
arena.alloc([(lhs, layout.clone()), (rhs, layout.clone())]),
)
}
// Discriminant is always 0, and Err is alphabetically before Ok
const ERR_TAG_ID: u8 = 1;
const OK_TAG_ID: u8 = 2;
fn build_ok<'a>(
arena: &'a Bump,
result_layout: Layout<'a>,
payload_expr: Expr<'a>,
payload_layout: Layout<'a>,
) -> Expr<'a> {
let mut arguments = Vec::with_capacity_in(1, arena);
arguments.push((payload_expr, payload_layout));
Expr::Tag {
tag_layout: result_layout,
tag_name: TagName::Global("Ok".into()),
tag_id: OK_TAG_ID,
union_size: 2,
arguments: arguments.into_bump_slice(),
}
}
fn build_err<'a>(
arena: &'a Bump,
result_layout: Layout<'a>,
payload_expr: Expr<'a>,
payload_layout: Layout<'a>,
) -> Expr<'a> {
let mut arguments = Vec::with_capacity_in(1, arena);
arguments.push((payload_expr, payload_layout));
Expr::Tag {
tag_layout: result_layout,
tag_name: TagName::Global("Err".into()),
tag_id: ERR_TAG_ID,
union_size: 2,
arguments: arguments.into_bump_slice(),
}
}

5
compiler/mono/src/layout.rs
View File

@ -420,10 +420,10 @@ fn union_sorted_tags_help<'a>(
let mut result = Vec::with_capacity_in(tags_vec.len(), arena);
for (tag_name, arguments) in tags_vec {
// +1 to reserve space for the discriminant
// resverse space for the tag discriminant
let mut arg_layouts = Vec::with_capacity_in(arguments.len() + 1, arena);
// add the discriminant
// add the tag discriminant
arg_layouts.push(Layout::Builtin(Builtin::Int64));
for var in arguments {
@ -434,7 +434,6 @@ fn union_sorted_tags_help<'a>(
result.push((tag_name, arg_layouts.into_bump_slice()));
}
UnionVariant::Wrapped(result)
}
}