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remove now-unused mono files

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This commit is contained in:
Folkert 2020-08-06 21:17:25 +02:00
parent 378fe1d5d1
commit 9dbce40a55
6 changed files with 321 additions and 4598 deletions
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465
compiler/mono/src/decision_tree.rs
View File

@ -1,6 +1,6 @@
use crate::expr::{DestructType, Env, Expr, Pattern};
use crate::exhaustive::{Ctor, RenderAs, TagId, Union};
use crate::ir::{DestructType, Env, Expr, JoinPointId, Literal, Pattern, Stmt};
use crate::layout::{Builtin, Layout};
use crate::pattern::{Ctor, RenderAs, TagId, Union};
use bumpalo::Bump;
use roc_collections::all::{MutMap, MutSet};
use roc_module::ident::TagName;
@ -31,8 +31,12 @@ pub fn compile<'a>(raw_branches: Vec<(Guard<'a>, Pattern<'a>, u64)>) -> Decision
pub enum Guard<'a> {
NoGuard,
Guard {
stores: &'a [(Symbol, Layout<'a>, Expr<'a>)],
expr: Expr<'a>,
/// Symbol that stores a boolean
/// when true this branch is picked, otherwise skipped
symbol: Symbol,
/// after assigning to symbol, the stmt jumps to this label
id: JoinPointId,
stmt: Stmt<'a>,
},
}
@ -57,7 +61,7 @@ pub enum Test<'a> {
IsCtor {
tag_id: u8,
tag_name: TagName,
union: crate::pattern::Union,
union: crate::exhaustive::Union,
arguments: Vec<(Pattern<'a>, Layout<'a>)>,
},
IsInt(i64),
@ -72,8 +76,12 @@ pub enum Test<'a> {
// A pattern that always succeeds (like `_`) can still have a guard
Guarded {
opt_test: Option<Box<Test<'a>>>,
stores: &'a [(Symbol, Layout<'a>, Expr<'a>)],
expr: Expr<'a>,
/// Symbol that stores a boolean
/// when true this branch is picked, otherwise skipped
symbol: Symbol,
/// after assigning to symbol, the stmt jumps to this label
id: JoinPointId,
stmt: Stmt<'a>,
},
}
use std::hash::{Hash, Hasher};
@ -353,11 +361,12 @@ fn test_at_path<'a>(selected_path: &Path, branch: Branch<'a>, all_tests: &mut Ve
None => {}
Some((_, guard, pattern)) => {
let guarded = |test| {
if let Guard::Guard { stores, expr } = guard {
if let Guard::Guard { symbol, id, stmt } = guard {
Guarded {
opt_test: Some(Box::new(test)),
stores,
expr: expr.clone(),
stmt: stmt.clone(),
symbol: *symbol,
id: *id,
}
} else {
test
@ -367,11 +376,12 @@ fn test_at_path<'a>(selected_path: &Path, branch: Branch<'a>, all_tests: &mut Ve
match pattern {
// TODO use guard!
Identifier(_) | Underscore | Shadowed(_, _) | UnsupportedPattern(_) => {
if let Guard::Guard { stores, expr } = guard {
if let Guard::Guard { symbol, id, stmt } = guard {
all_tests.push(Guarded {
opt_test: None,
stores,
expr: expr.clone(),
stmt: stmt.clone(),
symbol: *symbol,
id: *id,
});
}
}
@ -575,6 +585,8 @@ fn to_relevant_branch_help<'a>(
start.push((Path::Unbox(Box::new(path.clone())), guard, arg.0));
start.extend(end);
}
} else if union.alternatives.len() == 1 {
todo!("this should need a special index, right?")
} else {
let sub_positions =
arguments
@ -863,31 +875,29 @@ enum Decider<'a, T> {
#[derive(Clone, Debug, PartialEq)]
enum Choice<'a> {
Inline(Stores<'a>, Expr<'a>),
Inline(Stmt<'a>),
Jump(Label),
}
type Stores<'a> = &'a [(Symbol, Layout<'a>, Expr<'a>)];
type StoresVec<'a> = bumpalo::collections::Vec<'a, (Symbol, Layout<'a>, Expr<'a>)>;
pub fn optimize_when<'a>(
env: &mut Env<'a, '_>,
cond_symbol: Symbol,
cond_layout: Layout<'a>,
ret_layout: Layout<'a>,
opt_branches: Vec<(Pattern<'a>, Guard<'a>, Stores<'a>, Expr<'a>)>,
) -> Expr<'a> {
opt_branches: bumpalo::collections::Vec<'a, (Pattern<'a>, Guard<'a>, Stmt<'a>)>,
) -> Stmt<'a> {
let (patterns, _indexed_branches) = opt_branches
.into_iter()
.enumerate()
.map(|(index, (pattern, guard, stores, branch))| {
(
(guard, pattern, index as u64),
(index as u64, stores, branch),
)
.map(|(index, (pattern, guard, branch))| {
((guard, pattern, index as u64), (index as u64, branch))
})
.unzip();
let indexed_branches: Vec<(u64, Stores<'a>, Expr<'a>)> = _indexed_branches;
let indexed_branches: Vec<(u64, Stmt<'a>)> = _indexed_branches;
let decision_tree = compile(patterns);
let decider = tree_to_decider(decision_tree);
@ -896,9 +906,8 @@ pub fn optimize_when<'a>(
let mut choices = MutMap::default();
let mut jumps = Vec::new();
for (index, stores, branch) in indexed_branches.into_iter() {
let ((branch_index, choice), opt_jump) =
create_choices(&target_counts, index, stores, branch);
for (index, branch) in indexed_branches.into_iter() {
let ((branch_index, choice), opt_jump) = create_choices(&target_counts, index, branch);
if let Some(jump) = opt_jump {
jumps.push(jump);
@ -909,7 +918,7 @@ pub fn optimize_when<'a>(
let choice_decider = insert_choices(&choices, decider);
let (stores, expr) = decide_to_branching(
let expr = decide_to_branching(
env,
cond_symbol,
cond_layout,
@ -921,7 +930,7 @@ pub fn optimize_when<'a>(
// increase the jump counter by the number of jumps in this branching structure
*env.jump_counter += jumps.len() as u64;
Expr::Store(stores, env.arena.alloc(expr))
expr
}
fn path_to_expr<'a>(
@ -929,47 +938,62 @@ fn path_to_expr<'a>(
symbol: Symbol,
path: &Path,
layout: &Layout<'a>,
) -> Expr<'a> {
path_to_expr_help(env, symbol, path, layout.clone()).0
) -> (StoresVec<'a>, Symbol) {
let (symbol, stores, _) = path_to_expr_help2(env, symbol, path, layout.clone());
(stores, symbol)
}
fn path_to_expr_help<'a>(
fn path_to_expr_help2<'a>(
env: &mut Env<'a, '_>,
symbol: Symbol,
path: &Path,
layout: Layout<'a>,
) -> (Expr<'a>, Layout<'a>) {
match path {
Path::Unbox(unboxed) => path_to_expr_help(env, symbol, unboxed, layout),
Path::Empty => (Expr::Load(symbol), layout),
mut symbol: Symbol,
mut path: &Path,
mut layout: Layout<'a>,
) -> (Symbol, StoresVec<'a>, Layout<'a>) {
let mut stores = bumpalo::collections::Vec::new_in(env.arena);
Path::Index {
index,
tag_id,
path: nested,
} => {
let (outer_expr, outer_layout) = path_to_expr_help(env, symbol, nested, layout);
loop {
match path {
Path::Unbox(unboxed) => {
path = unboxed;
}
Path::Empty => break,
let (is_unwrapped, field_layouts) = match outer_layout {
Layout::Union(layouts) => (layouts.is_empty(), layouts[*tag_id as usize].to_vec()),
Layout::Struct(layouts) => (true, layouts.to_vec()),
other => (true, vec![other]),
};
Path::Index {
index,
tag_id,
path: nested,
} => {
let (is_unwrapped, field_layouts) = match layout.clone() {
Layout::Union(layouts) => {
(layouts.is_empty(), layouts[*tag_id as usize].to_vec())
}
Layout::Struct(layouts) => (true, layouts.to_vec()),
other => (true, vec![other]),
};
debug_assert!(*index < field_layouts.len() as u64);
debug_assert!(*index < field_layouts.len() as u64);
let inner_layout = field_layouts[*index as usize].clone();
let inner_layout = field_layouts[*index as usize].clone();
let inner_expr = Expr::AccessAtIndex {
index: *index,
field_layouts: env.arena.alloc(field_layouts),
expr: env.arena.alloc(outer_expr),
is_unwrapped,
};
let inner_expr = Expr::AccessAtIndex {
index: *index,
field_layouts: env.arena.alloc(field_layouts),
//structure: env.arena.alloc(outer_expr),
structure: symbol,
is_unwrapped,
};
(inner_expr, inner_layout)
symbol = env.unique_symbol();
stores.push((symbol, inner_layout.clone(), inner_expr));
layout = inner_layout;
path = nested;
}
}
}
(symbol, stores, layout)
}
fn test_to_equality<'a>(
@ -978,8 +1002,7 @@ fn test_to_equality<'a>(
cond_layout: &Layout<'a>,
path: &Path,
test: Test<'a>,
tests: &mut Vec<(Expr<'a>, Expr<'a>, Layout<'a>)>,
) {
) -> (StoresVec<'a>, Symbol, Symbol, Layout<'a>) {
match test {
Test::IsCtor {
tag_id,
@ -991,7 +1014,7 @@ fn test_to_equality<'a>(
// (e.g. record pattern guard matches)
debug_assert!(union.alternatives.len() > 1);
let lhs = Expr::Int(tag_id as i64);
let lhs = Expr::Literal(Literal::Int(tag_id as i64));
let mut field_layouts =
bumpalo::collections::Vec::with_capacity_in(arguments.len(), env.arena);
@ -1006,65 +1029,101 @@ fn test_to_equality<'a>(
let rhs = Expr::AccessAtIndex {
index: 0,
field_layouts: field_layouts.into_bump_slice(),
expr: env.arena.alloc(Expr::Load(cond_symbol)),
structure: cond_symbol,
is_unwrapped: union.alternatives.len() == 1,
};
tests.push((lhs, rhs, Layout::Builtin(Builtin::Int64)));
let lhs_symbol = env.unique_symbol();
let rhs_symbol = env.unique_symbol();
let mut stores = bumpalo::collections::Vec::with_capacity_in(2, env.arena);
stores.push((lhs_symbol, Layout::Builtin(Builtin::Int64), lhs));
stores.push((rhs_symbol, Layout::Builtin(Builtin::Int64), rhs));
(
stores,
lhs_symbol,
rhs_symbol,
Layout::Builtin(Builtin::Int64),
)
}
Test::IsInt(test_int) => {
let lhs = Expr::Int(test_int);
let rhs = path_to_expr(env, cond_symbol, &path, &cond_layout);
let lhs = Expr::Literal(Literal::Int(test_int));
let lhs_symbol = env.unique_symbol();
let (mut stores, rhs_symbol) = path_to_expr(env, cond_symbol, &path, &cond_layout);
stores.push((lhs_symbol, Layout::Builtin(Builtin::Int64), lhs));
tests.push((lhs, rhs, Layout::Builtin(Builtin::Int64)));
(
stores,
lhs_symbol,
rhs_symbol,
Layout::Builtin(Builtin::Int64),
)
}
Test::IsFloat(test_int) => {
// TODO maybe we can actually use i64 comparison here?
let test_float = f64::from_bits(test_int as u64);
let lhs = Expr::Float(test_float);
let rhs = path_to_expr(env, cond_symbol, &path, &cond_layout);
let lhs = Expr::Literal(Literal::Float(test_float));
let lhs_symbol = env.unique_symbol();
let (mut stores, rhs_symbol) = path_to_expr(env, cond_symbol, &path, &cond_layout);
stores.push((lhs_symbol, Layout::Builtin(Builtin::Float64), lhs));
tests.push((lhs, rhs, Layout::Builtin(Builtin::Float64)));
(
stores,
lhs_symbol,
rhs_symbol,
Layout::Builtin(Builtin::Float64),
)
}
Test::IsByte {
tag_id: test_byte, ..
} => {
let lhs = Expr::Byte(test_byte);
let rhs = path_to_expr(env, cond_symbol, &path, &cond_layout);
let lhs = Expr::Literal(Literal::Byte(test_byte));
let lhs_symbol = env.unique_symbol();
let (mut stores, rhs_symbol) = path_to_expr(env, cond_symbol, &path, &cond_layout);
stores.push((lhs_symbol, Layout::Builtin(Builtin::Int8), lhs));
tests.push((lhs, rhs, Layout::Builtin(Builtin::Int8)));
(
stores,
lhs_symbol,
rhs_symbol,
Layout::Builtin(Builtin::Int8),
)
}
Test::IsBit(test_bit) => {
let lhs = Expr::Bool(test_bit);
let rhs = path_to_expr(env, cond_symbol, &path, &cond_layout);
let lhs = Expr::Literal(Literal::Bool(test_bit));
let lhs_symbol = env.unique_symbol();
let (mut stores, rhs_symbol) = path_to_expr(env, cond_symbol, &path, &cond_layout);
stores.push((lhs_symbol, Layout::Builtin(Builtin::Int1), lhs));
tests.push((lhs, rhs, Layout::Builtin(Builtin::Int1)));
(
stores,
lhs_symbol,
rhs_symbol,
Layout::Builtin(Builtin::Int1),
)
}
Test::IsStr(test_str) => {
let lhs = Expr::Str(env.arena.alloc(test_str));
let rhs = path_to_expr(env, cond_symbol, &path, &cond_layout);
let lhs = Expr::Literal(Literal::Str(env.arena.alloc(test_str)));
let lhs_symbol = env.unique_symbol();
let (mut stores, rhs_symbol) = path_to_expr(env, cond_symbol, &path, &cond_layout);
tests.push((lhs, rhs, Layout::Builtin(Builtin::Str)));
stores.push((lhs_symbol, Layout::Builtin(Builtin::Str), lhs));
(
stores,
lhs_symbol,
rhs_symbol,
Layout::Builtin(Builtin::Str),
)
}
Test::Guarded {
opt_test,
stores,
expr,
} => {
if let Some(nested) = opt_test {
test_to_equality(env, cond_symbol, cond_layout, path, *nested, tests);
}
let lhs = Expr::Bool(true);
let rhs = Expr::Store(stores, env.arena.alloc(expr));
tests.push((lhs, rhs, Layout::Builtin(Builtin::Int1)));
}
Test::Guarded { .. } => unreachable!("should be handled elsewhere"),
}
}
@ -1074,21 +1133,21 @@ fn decide_to_branching<'a>(
cond_layout: Layout<'a>,
ret_layout: Layout<'a>,
decider: Decider<'a, Choice<'a>>,
jumps: &Vec<(u64, Stores<'a>, Expr<'a>)>,
) -> (Stores<'a>, Expr<'a>) {
jumps: &Vec<(u64, Stmt<'a>)>,
) -> Stmt<'a> {
use Choice::*;
use Decider::*;
match decider {
Leaf(Jump(label)) => {
// we currently inline the jumps: does fewer jumps but produces a larger artifact
let (_, stores, expr) = jumps
let (_, expr) = jumps
.iter()
.find(|(l, _, _)| l == &label)
.find(|(l, _)| l == &label)
.expect("jump not in list of jumps");
(stores, expr.clone())
expr.clone()
}
Leaf(Inline(stores, expr)) => (stores, expr),
Leaf(Inline(expr)) => expr,
Chain {
test_chain,
success,
@ -1096,13 +1155,7 @@ fn decide_to_branching<'a>(
} => {
// generate a switch based on the test chain
let mut tests = Vec::with_capacity(test_chain.len());
for (path, test) in test_chain {
test_to_equality(env, cond_symbol, &cond_layout, &path, test, &mut tests);
}
let (pass_stores, pass_expr) = decide_to_branching(
let pass_expr = decide_to_branching(
env,
cond_symbol,
cond_layout.clone(),
@ -1111,7 +1164,7 @@ fn decide_to_branching<'a>(
jumps,
);
let (fail_stores, fail_expr) = decide_to_branching(
let fail_expr = decide_to_branching(
env,
cond_symbol,
cond_layout.clone(),
@ -1120,31 +1173,148 @@ fn decide_to_branching<'a>(
jumps,
);
let fail = (fail_stores, &*env.arena.alloc(fail_expr));
let pass = (pass_stores, &*env.arena.alloc(pass_expr));
let fail = &*env.arena.alloc(fail_expr);
let pass = &*env.arena.alloc(pass_expr);
let condition = boolean_all(env.arena, tests);
// TODO totally wrong
let condition = Expr::Literal(Literal::Int(42));
let branching_symbol = env.unique_symbol();
let stores = [(branching_symbol, Layout::Builtin(Builtin::Int1), condition)];
let branching_layout = Layout::Builtin(Builtin::Int1);
(
env.arena.alloc(stores),
Expr::Store(
&[],
env.arena.alloc(Expr::Cond {
let mut cond = Stmt::Cond {
cond_symbol,
cond_layout: cond_layout.clone(),
branching_symbol,
branching_layout,
pass,
fail,
ret_layout,
};
let true_symbol = env.unique_symbol();
let mut tests = Vec::with_capacity(test_chain.len());
let mut guard = None;
// Assumption: there is at most 1 guard, and it is the outer layer.
for (path, test) in test_chain {
match test {
Test::Guarded {
opt_test,
id,
symbol,
stmt,
} => {
if let Some(nested) = opt_test {
tests.push(test_to_equality(
env,
cond_symbol,
&cond_layout,
&path,
*nested,
));
}
// let (stores, rhs_symbol) = path_to_expr(env, cond_symbol, &path, &cond_layout);
guard = Some((symbol, id, stmt));
}
_ => tests.push(test_to_equality(
env,
cond_symbol,
cond_layout,
branching_symbol,
branching_layout,
pass,
fail,
ret_layout,
}),
),
)
&cond_layout,
&path,
test,
)),
}
}
let mut current_symbol = branching_symbol;
// TODO There must be some way to remove this iterator/loop
let nr = (tests.len() as i64) - 1 + (guard.is_some() as i64);
let accum_symbols = std::iter::once(true_symbol)
.chain((0..nr).map(|_| env.unique_symbol()))
.rev()
.collect::<Vec<_>>();
let mut accum_it = accum_symbols.into_iter();
// the guard is the final thing that we check, so needs to be layered on first!
if let Some((_, id, stmt)) = guard {
let accum = accum_it.next().unwrap();
let test_symbol = env.unique_symbol();
let and_expr =
Expr::RunLowLevel(LowLevel::And, env.arena.alloc([test_symbol, accum]));
// write to the branching symbol
cond = Stmt::Let(
current_symbol,
and_expr,
Layout::Builtin(Builtin::Int1),
env.arena.alloc(cond),
);
// calculate the guard value
cond = Stmt::Join {
id,
arguments: env
.arena
.alloc([(test_symbol, Layout::Builtin(Builtin::Int1))]),
remainder: env.arena.alloc(stmt),
continuation: env.arena.alloc(cond),
};
current_symbol = accum;
}
for ((new_stores, lhs, rhs, layout), accum) in tests.into_iter().rev().zip(accum_it) {
let test_symbol = env.unique_symbol();
let test = Expr::RunLowLevel(
LowLevel::Eq,
bumpalo::vec![in env.arena; lhs, rhs].into_bump_slice(),
);
let and_expr =
Expr::RunLowLevel(LowLevel::And, env.arena.alloc([test_symbol, accum]));
// write to the branching symbol
cond = Stmt::Let(
current_symbol,
and_expr,
Layout::Builtin(Builtin::Int1),
env.arena.alloc(cond),
);
// write to the test symbol
cond = Stmt::Let(
test_symbol,
test,
Layout::Builtin(Builtin::Int1),
env.arena.alloc(cond),
);
for (symbol, layout, expr) in new_stores.into_iter() {
cond = Stmt::Let(symbol, expr, layout, env.arena.alloc(cond));
}
current_symbol = accum;
}
cond = Stmt::Let(
true_symbol,
Expr::Literal(Literal::Bool(true)),
Layout::Builtin(Builtin::Int1),
env.arena.alloc(cond),
);
// (env.arena.alloc(stores), cond)
cond
}
FanOut {
path,
@ -1153,9 +1323,11 @@ fn decide_to_branching<'a>(
} => {
// the cond_layout can change in the process. E.g. if the cond is a Tag, we actually
// switch on the tag discriminant (currently an i64 value)
let (cond, cond_layout) = path_to_expr_help(env, cond_symbol, &path, cond_layout);
// NOTE the tag discriminant is not actually loaded, `cond` can point to a tag
let (cond, cond_stores_vec, cond_layout) =
path_to_expr_help2(env, cond_symbol, &path, cond_layout);
let (default_stores, default_expr) = decide_to_branching(
let default_branch = decide_to_branching(
env,
cond_symbol,
cond_layout.clone(),
@ -1163,12 +1335,11 @@ fn decide_to_branching<'a>(
*fallback,
jumps,
);
let default_branch = (default_stores, &*env.arena.alloc(default_expr));
let mut branches = bumpalo::collections::Vec::with_capacity_in(tests.len(), env.arena);
for (test, decider) in tests {
let (stores, branch) = decide_to_branching(
let branch = decide_to_branching(
env,
cond_symbol,
cond_layout.clone(),
@ -1186,25 +1357,28 @@ fn decide_to_branching<'a>(
other => todo!("other {:?}", other),
};
branches.push((tag, stores, branch));
branches.push((tag, branch));
}
let mut switch = Stmt::Switch {
cond_layout,
cond_symbol: cond,
branches: branches.into_bump_slice(),
default_branch: env.arena.alloc(default_branch),
ret_layout,
};
for (symbol, layout, expr) in cond_stores_vec.into_iter() {
switch = Stmt::Let(symbol, expr, layout, env.arena.alloc(switch));
}
// make a jump table based on the tests
(
&[],
Expr::Switch {
cond: env.arena.alloc(cond),
cond_layout,
cond_symbol,
branches: branches.into_bump_slice(),
default_branch,
ret_layout,
},
)
switch
}
}
}
/*
fn boolean_all<'a>(arena: &'a Bump, tests: Vec<(Expr<'a>, Expr<'a>, Layout<'a>)>) -> Expr<'a> {
let mut expr = Expr::Bool(true);
@ -1225,6 +1399,7 @@ fn boolean_all<'a>(arena: &'a Bump, tests: Vec<(Expr<'a>, Expr<'a>, Layout<'a>)>
expr
}
*/
/// TREE TO DECIDER
///
@ -1398,19 +1573,15 @@ fn count_targets_help(decision_tree: &Decider<u64>, targets: &mut MutMap<u64, u6
fn create_choices<'a>(
target_counts: &MutMap<u64, u64>,
target: u64,
stores: Stores<'a>,
branch: Expr<'a>,
) -> ((u64, Choice<'a>), Option<(u64, Stores<'a>, Expr<'a>)>) {
branch: Stmt<'a>,
) -> ((u64, Choice<'a>), Option<(u64, Stmt<'a>)>) {
match target_counts.get(&target) {
None => unreachable!(
"this should never happen: {:?} not in {:?}",
target, target_counts
),
Some(1) => ((target, Choice::Inline(stores, branch)), None),
Some(_) => (
(target, Choice::Jump(target)),
Some((target, stores, branch)),
),
Some(1) => ((target, Choice::Inline(branch)), None),
Some(_) => ((target, Choice::Jump(target)), Some((target, branch))),
}
}

1625
compiler/mono/src/decision_tree2.rs
View File

File diff suppressed because it is too large Load Diff

2288
compiler/mono/src/expr.rs
View File

File diff suppressed because it is too large Load Diff

4
compiler/mono/src/ir.rs
View File

@ -1971,7 +1971,7 @@ fn from_can_when<'a>(
}
};
use crate::decision_tree2::Guard;
use crate::decision_tree::Guard;
match res_stores {
Ok(_) => {
for (symbol, layout, expr) in stores.iter().rev() {
@ -2008,7 +2008,7 @@ fn from_can_when<'a>(
});
let mono_branches = Vec::from_iter_in(it, arena);
crate::decision_tree2::optimize_when(
crate::decision_tree::optimize_when(
env,
cond_symbol,
cond_layout.clone(),

2
compiler/mono/src/lib.rs
View File

@ -19,6 +19,6 @@ pub mod layout;
//#[allow(clippy::ptr_arg)]
//pub mod decision_tree;
#[allow(clippy::ptr_arg)]
pub mod decision_tree2;
pub mod decision_tree;
#[allow(clippy::ptr_arg)]
pub mod exhaustive;

535
compiler/mono/src/pattern.rs
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@ -1,535 +0,0 @@
use crate::expr::DestructType;
use roc_collections::all::{Index, MutMap};
use roc_module::ident::{Lowercase, TagName};
use roc_region::all::{Located, Region};
use self::Pattern::*;
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct Union {
pub alternatives: Vec<Ctor>,
pub render_as: RenderAs,
}
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub enum RenderAs {
Tag,
Record(Vec<Lowercase>),
Guard,
}
#[derive(Clone, Debug, PartialEq, Eq, Hash, Copy)]
pub struct TagId(pub u8);
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct Ctor {
pub name: TagName,
pub tag_id: TagId,
pub arity: usize,
}
#[derive(Clone, Debug, PartialEq)]
pub enum Pattern {
Anything,
Literal(Literal),
Ctor(Union, TagId, std::vec::Vec<Pattern>),
}
#[derive(Clone, Debug, PartialEq)]
pub enum Literal {
Int(i64),
Bit(bool),
Byte(u8),
Float(u64),
Str(Box<str>),
}
fn simplify<'a>(pattern: &crate::expr::Pattern<'a>) -> Pattern {
use crate::expr::Pattern::*;
match pattern {
IntLiteral(v) => Literal(Literal::Int(*v)),
FloatLiteral(v) => Literal(Literal::Float(*v)),
StrLiteral(v) => Literal(Literal::Str(v.clone())),
// To make sure these are exhaustive, we have to "fake" a union here
// TODO: use the hash or some other integer to discriminate between constructors
BitLiteral { value, union, .. } => Ctor(union.clone(), TagId(*value as u8), vec![]),
EnumLiteral { tag_id, union, .. } => Ctor(union.clone(), TagId(*tag_id), vec![]),
Underscore => Anything,
Identifier(_) => Anything,
RecordDestructure(destructures, _) => {
let tag_id = TagId(0);
let mut patterns = std::vec::Vec::with_capacity(destructures.len());
let mut field_names = std::vec::Vec::with_capacity(destructures.len());
for destruct in destructures {
field_names.push(destruct.label.clone());
match &destruct.typ {
DestructType::Required | DestructType::Optional(_) => patterns.push(Anything),
DestructType::Guard(guard) => patterns.push(simplify(guard)),
}
}
let union = Union {
render_as: RenderAs::Record(field_names),
alternatives: vec![Ctor {
name: TagName::Global("#Record".into()),
tag_id,
arity: destructures.len(),
}],
};
Ctor(union, tag_id, patterns)
}
Shadowed(_region, _ident) => {
// Treat as an Anything
// code-gen will make a runtime error out of the branch
Anything
}
UnsupportedPattern(_region) => {
// Treat as an Anything
// code-gen will make a runtime error out of the branch
Anything
}
AppliedTag {
tag_id,
arguments,
union,
..
} => {
let simplified_args: std::vec::Vec<_> =
arguments.iter().map(|v| simplify(&v.0)).collect();
Ctor(union.clone(), TagId(*tag_id), simplified_args)
}
}
}
/// Error
#[derive(Clone, Debug, PartialEq)]
pub enum Error {
Incomplete(Region, Context, Vec<Pattern>),
Redundant {
overall_region: Region,
branch_region: Region,
index: Index,
},
}
#[derive(Clone, Debug, PartialEq)]
pub enum Context {
BadArg,
BadDestruct,
BadCase,
}
#[derive(Clone, Debug, PartialEq)]
pub enum Guard {
HasGuard,
NoGuard,
}
/// Check
pub fn check<'a>(
region: Region,
patterns: &[(Located<crate::expr::Pattern<'a>>, Guard)],
context: Context,
) -> Result<(), Vec<Error>> {
let mut errors = Vec::new();
check_patterns(region, context, patterns, &mut errors);
if errors.is_empty() {
Ok(())
} else {
Err(errors)
}
}
pub fn check_patterns<'a>(
region: Region,
context: Context,
patterns: &[(Located<crate::expr::Pattern<'a>>, Guard)],
errors: &mut Vec<Error>,
) {
match to_nonredundant_rows(region, patterns) {
Err(err) => errors.push(err),
Ok(matrix) => {
let bad_patterns = is_exhaustive(&matrix, 1);
if !bad_patterns.is_empty() {
// TODO i suspect this is like a concat in in practice? code below can panic
// if this debug_assert! ever fails, the theory is disproven
debug_assert!(
bad_patterns.iter().map(|v| v.len()).sum::<usize>() == bad_patterns.len()
);
let heads = bad_patterns.into_iter().map(|mut v| v.remove(0)).collect();
errors.push(Error::Incomplete(region, context, heads));
}
}
}
}
/// EXHAUSTIVE PATTERNS
/// INVARIANTS:
///
/// The initial rows "matrix" are all of length 1
/// The initial count of items per row "n" is also 1
/// The resulting rows are examples of missing patterns
fn is_exhaustive(matrix: &PatternMatrix, n: usize) -> PatternMatrix {
if matrix.is_empty() {
vec![std::iter::repeat(Anything).take(n).collect()]
} else if n == 0 {
vec![]
} else {
let ctors = collect_ctors(matrix);
let num_seen = ctors.len();
if num_seen == 0 {
let new_matrix = matrix
.iter()
.filter_map(specialize_row_by_anything)
.collect();
let mut rest = is_exhaustive(&new_matrix, n - 1);
for row in rest.iter_mut() {
row.push(Anything);
}
rest
} else {
let alts = ctors.iter().next().unwrap().1;
let alt_list = &alts.alternatives;
let num_alts = alt_list.len();
if num_seen < num_alts {
let new_matrix = matrix
.iter()
.filter_map(specialize_row_by_anything)
.collect();
let rest: Vec<Vec<Pattern>> = is_exhaustive(&new_matrix, n - 1);
let last: _ = alt_list
.iter()
.filter_map(|r| is_missing(alts.clone(), ctors.clone(), r));
let mut result = Vec::new();
for last_option in last {
for mut row in rest.clone() {
row.push(last_option.clone());
result.push(row);
}
}
result
} else {
let is_alt_exhaustive = |Ctor { arity, tag_id, .. }| {
let new_matrix = matrix
.iter()
.filter_map(|r| specialize_row_by_ctor(tag_id, arity, r))
.collect();
let rest: Vec<Vec<Pattern>> = is_exhaustive(&new_matrix, arity + n - 1);
let mut result = Vec::with_capacity(rest.len());
for row in rest {
result.push(recover_ctor(alts.clone(), tag_id, arity, row));
}
result
};
alt_list
.iter()
.cloned()
.map(is_alt_exhaustive)
.flatten()
.collect()
}
}
}
}
fn is_missing<T>(union: Union, ctors: MutMap<TagId, T>, ctor: &Ctor) -> Option<Pattern> {
let Ctor { arity, tag_id, .. } = ctor;
if ctors.contains_key(tag_id) {
None
} else {
let anythings = std::iter::repeat(Anything).take(*arity).collect();
Some(Pattern::Ctor(union, *tag_id, anythings))
}
}
fn recover_ctor(
union: Union,
tag_id: TagId,
arity: usize,
mut patterns: Vec<Pattern>,
) -> Vec<Pattern> {
let mut rest = patterns.split_off(arity);
let args = patterns;
rest.push(Ctor(union, tag_id, args));
rest
}
/// REDUNDANT PATTERNS
/// INVARIANT: Produces a list of rows where (forall row. length row == 1)
fn to_nonredundant_rows<'a>(
overall_region: Region,
patterns: &[(Located<crate::expr::Pattern<'a>>, Guard)],
) -> Result<Vec<Vec<Pattern>>, Error> {
let mut checked_rows = Vec::with_capacity(patterns.len());
// If any of the branches has a guard, e.g.
//
// when x is
// y if y < 10 -> "foo"
// _ -> "bar"
//
// then we treat it as a pattern match on the pattern and a boolean, wrapped in the #Guard
// constructor. We can use this special constructor name to generate better error messages.
// This transformation of the pattern match only works because we only report exhaustiveness
// errors: the Pattern created in this file is not used for code gen.
//
// when x is
// #Guard y True -> "foo"
// #Guard _ _ -> "bar"
let any_has_guard = patterns.iter().any(|(_, guard)| guard == &Guard::HasGuard);
for (loc_pat, guard) in patterns {
let region = loc_pat.region;
let next_row = if any_has_guard {
let guard_pattern = match guard {
Guard::HasGuard => Pattern::Literal(Literal::Bit(true)),
Guard::NoGuard => Pattern::Anything,
};
let tag_id = TagId(0);
let union = Union {
render_as: RenderAs::Guard,
alternatives: vec![Ctor {
tag_id,
name: TagName::Global("#Guard".into()),
arity: 2,
}],
};
vec![Pattern::Ctor(
union,
tag_id,
vec![simplify(&loc_pat.value), guard_pattern],
)]
} else {
vec![simplify(&loc_pat.value)]
};
if is_useful(&checked_rows, &next_row) {
checked_rows.push(next_row);
} else {
return Err(Error::Redundant {
overall_region,
branch_region: region,
index: Index::zero_based(checked_rows.len()),
});
}
}
Ok(checked_rows)
}
/// Check if a new row "vector" is useful given previous rows "matrix"
fn is_useful(matrix: &PatternMatrix, vector: &Row) -> bool {
if matrix.is_empty() {
// No rows are the same as the new vector! The vector is useful!
true
} else if vector.is_empty() {
// There is nothing left in the new vector, but we still have
// rows that match the same things. This is not a useful vector!
false
} else {
// NOTE: if there are bugs in this code, look at the ordering of the row/matrix
let mut vector = vector.clone();
let first_pattern = vector.remove(0);
let patterns = vector;
match first_pattern {
// keep checking rows that start with this Ctor or Anything
Ctor(_, id, args) => {
let new_matrix: Vec<_> = matrix
.iter()
.filter_map(|r| specialize_row_by_ctor(id, args.len(), r))
.collect();
let mut new_row = Vec::new();
new_row.extend(patterns);
new_row.extend(args);
is_useful(&new_matrix, &new_row)
}
Anything => {
// check if all alts appear in matrix
match is_complete(matrix) {
Complete::No => {
// This Anything is useful because some Ctors are missing.
// But what if a previous row has an Anything?
// If so, this one is not useful.
let new_matrix: Vec<_> = matrix
.iter()
.filter_map(|r| specialize_row_by_anything(r))
.collect();
is_useful(&new_matrix, &patterns)
}
Complete::Yes(alts) => {
// All Ctors are covered, so this Anything is not needed for any
// of those. But what if some of those Ctors have subpatterns
// that make them less general? If so, this actually is useful!
let is_useful_alt = |Ctor { arity, tag_id, .. }| {
let new_matrix = matrix
.iter()
.filter_map(|r| specialize_row_by_ctor(tag_id, arity, r))
.collect();
let mut new_row: Vec<Pattern> =
std::iter::repeat(Anything).take(arity).collect::<Vec<_>>();
new_row.extend(patterns.clone());
is_useful(&new_matrix, &new_row)
};
alts.iter().cloned().any(is_useful_alt)
}
}
}
Literal(literal) => {
// keep checking rows that start with this Literal or Anything
let new_matrix = matrix
.iter()
.filter_map(|r| specialize_row_by_literal(&literal, r))
.collect();
is_useful(&new_matrix, &patterns)
}
}
}
}
/// INVARIANT: (length row == N) ==> (length result == arity + N - 1)
fn specialize_row_by_ctor(tag_id: TagId, arity: usize, row: &Row) -> Option<Row> {
let mut row = row.clone();
let head = row.pop();
let patterns = row;
match head {
Some(Ctor(_, id, args)) =>
if id == tag_id {
// TODO order!
let mut new_patterns = Vec::new();
new_patterns.extend(args);
new_patterns.extend(patterns);
Some(new_patterns)
} else {
None
}
Some(Anything) => {
// TODO order!
let new_patterns =
std::iter::repeat(Anything).take(arity).chain(patterns).collect();
Some(new_patterns)
}
Some(Literal(_)) => panic!( "Compiler bug! After type checking, constructors and literal should never align in pattern match exhaustiveness checks."),
None => panic!("Compiler error! Empty matrices should not get specialized."),
}
}
/// INVARIANT: (length row == N) ==> (length result == N-1)
fn specialize_row_by_literal(literal: &Literal, row: &Row) -> Option<Row> {
let mut row = row.clone();
let head = row.pop();
let patterns = row;
match head {
Some(Literal(lit)) => {
if &lit == literal {
Some(patterns)
} else {
None
}
}
Some(Anything) => Some(patterns),
Some(Ctor(_, _, _)) => panic!(
r#"Compiler bug! After type checking, constructors and literals should never align in pattern match exhaustiveness checks."#
),
None => panic!("Compiler error! Empty matrices should not get specialized."),
}
}
/// INVARIANT: (length row == N) ==> (length result == N-1)
fn specialize_row_by_anything(row: &Row) -> Option<Row> {
let mut row = row.clone();
match row.pop() {
Some(Anything) => Some(row),
_ => None,
}
}
/// ALL CONSTRUCTORS ARE PRESENT?
pub enum Complete {
Yes(Vec<Ctor>),
No,
}
fn is_complete(matrix: &PatternMatrix) -> Complete {
let ctors = collect_ctors(matrix);
let mut it = ctors.values();
match it.next() {
None => Complete::No,
Some(Union { alternatives, .. }) => {
if ctors.len() == alternatives.len() {
Complete::Yes(alternatives.to_vec())
} else {
Complete::No
}
}
}
}
/// COLLECT CTORS
type RefPatternMatrix = [Vec<Pattern>];
type PatternMatrix = Vec<Vec<Pattern>>;
type Row = Vec<Pattern>;
fn collect_ctors(matrix: &RefPatternMatrix) -> MutMap<TagId, Union> {
let mut ctors = MutMap::default();
for row in matrix {
if let Some(Ctor(union, id, _)) = row.get(row.len() - 1) {
ctors.insert(*id, union.clone());
}
}
ctors
}