roc/compiler/mono/src/code_gen_help.rs
Brian Carroll 9fb7048de0 Rename rec_ptr_layout -> recursive_union
I kept thinking it was of type Layout but it's not
2021-12-26 10:45:23 +00:00

1238 lines
44 KiB
Rust

use bumpalo::collections::vec::Vec;
use bumpalo::Bump;
use roc_builtins::bitcode::IntWidth;
use roc_module::ident::Ident;
use roc_module::low_level::LowLevel;
use roc_module::symbol::{IdentIds, ModuleId, Symbol};
use crate::ir::{
BranchInfo, Call, CallSpecId, CallType, Expr, HostExposedLayouts, JoinPointId, Literal,
ModifyRc, Param, Proc, ProcLayout, SelfRecursive, Stmt, UpdateModeId,
};
use crate::layout::{Builtin, Layout, UnionLayout};
const LAYOUT_BOOL: Layout = Layout::Builtin(Builtin::Bool);
const LAYOUT_UNIT: Layout = Layout::Struct(&[]);
const LAYOUT_PTR: Layout = Layout::RecursivePointer;
const LAYOUT_U32: Layout = Layout::Builtin(Builtin::Int(IntWidth::U32));
const ARG_1: Symbol = Symbol::ARG_1;
const ARG_2: Symbol = Symbol::ARG_2;
/// "Infinite" reference count, for static values
/// Ref counts are encoded as negative numbers where isize::MIN represents 1
pub const REFCOUNT_MAX: usize = 0;
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum HelperOp {
Inc,
Dec,
DecRef,
Eq,
}
impl From<&ModifyRc> for HelperOp {
fn from(modify: &ModifyRc) -> Self {
match modify {
ModifyRc::Inc(..) => Self::Inc,
ModifyRc::Dec(_) => Self::Dec,
ModifyRc::DecRef(_) => Self::DecRef,
}
}
}
#[derive(Debug)]
struct Specialization<'a> {
op: HelperOp,
layout: Layout<'a>,
symbol: Symbol,
}
#[derive(Debug)]
struct Context<'a> {
new_linker_data: Vec<'a, (Symbol, ProcLayout<'a>)>,
recursive_union: Option<UnionLayout<'a>>,
op: HelperOp,
}
/// Generate specialized helper procs for code gen
/// ----------------------------------------------
///
/// Some low level operations need specialized helper procs to traverse data structures at runtime.
/// This includes refcounting, hashing, and equality checks.
///
/// For example, when checking List equality, we need to visit each element and compare them.
/// Depending on the type of the list elements, we may need to recurse deeper into each element.
/// For tag unions, we may need branches for different tag IDs, etc.
///
/// This module creates specialized helper procs for all such operations and types used in the program.
///
/// The backend drives the process, in two steps:
/// 1) When it sees the relevant node, it calls CodeGenHelp to get the replacement IR.
/// CodeGenHelp returns IR for a call to the helper proc, and remembers the specialization.
/// 2) After the backend has generated code for all user procs, it takes the IR for all of the
/// specialized helpers procs, and generates target code for them too.
///
pub struct CodeGenHelp<'a> {
arena: &'a Bump,
home: ModuleId,
ptr_size: u32,
layout_isize: Layout<'a>,
specializations: Vec<'a, Specialization<'a>>,
procs: Vec<'a, Proc<'a>>,
debug_recursion_depth: usize,
}
impl<'a> CodeGenHelp<'a> {
pub fn new(arena: &'a Bump, intwidth_isize: IntWidth, home: ModuleId) -> Self {
CodeGenHelp {
arena,
home,
ptr_size: intwidth_isize.stack_size(),
layout_isize: Layout::Builtin(Builtin::Int(intwidth_isize)),
specializations: Vec::with_capacity_in(16, arena),
procs: Vec::with_capacity_in(16, arena),
debug_recursion_depth: 0,
}
}
pub fn take_procs(&mut self) -> Vec<'a, Proc<'a>> {
std::mem::replace(&mut self.procs, Vec::new_in(self.arena))
}
// ============================================================================
//
// CALL GENERATED PROCS
//
// ============================================================================
/// Expand a `Refcounting` node to a `Let` node that calls a specialized helper proc.
/// The helper procs themselves are to be generated later with `generate_procs`
pub fn expand_refcount_stmt(
&mut self,
ident_ids: &mut IdentIds,
layout: Layout<'a>,
modify: &ModifyRc,
following: &'a Stmt<'a>,
) -> (&'a Stmt<'a>, Vec<'a, (Symbol, ProcLayout<'a>)>) {
if !Self::is_rc_implemented_yet(&layout) {
// Just a warning, so we can decouple backend development from refcounting development.
// When we are closer to completion, we can change it to a panic.
println!(
"WARNING! MEMORY LEAK! Refcounting not yet implemented for Layout {:?}",
layout
);
return (following, Vec::new_in(self.arena));
}
let arena = self.arena;
let mut ctx = Context {
new_linker_data: Vec::new_in(self.arena),
recursive_union: None,
op: HelperOp::from(modify),
};
match modify {
ModifyRc::Inc(structure, amount) => {
let layout_isize = self.layout_isize;
// Define a constant for the amount to increment
let amount_sym = self.create_symbol(ident_ids, "amount");
let amount_expr = Expr::Literal(Literal::Int(*amount as i128));
let amount_stmt = |next| Stmt::Let(amount_sym, amount_expr, layout_isize, next);
// Call helper proc, passing the Roc structure and constant amount
let call_result_empty = self.create_symbol(ident_ids, "call_result_empty");
let call_expr = self.call_specialized_op(
ident_ids,
&mut ctx,
layout,
arena.alloc([*structure, amount_sym]),
);
let call_stmt = Stmt::Let(call_result_empty, call_expr, LAYOUT_UNIT, following);
let rc_stmt = arena.alloc(amount_stmt(arena.alloc(call_stmt)));
(rc_stmt, ctx.new_linker_data)
}
ModifyRc::Dec(structure) => {
// Call helper proc, passing the Roc structure
let call_result_empty = self.create_symbol(ident_ids, "call_result_empty");
let call_expr = self.call_specialized_op(
ident_ids,
&mut ctx,
layout,
arena.alloc([*structure]),
);
let rc_stmt = arena.alloc(Stmt::Let(
call_result_empty,
call_expr,
LAYOUT_UNIT,
following,
));
(rc_stmt, ctx.new_linker_data)
}
ModifyRc::DecRef(structure) => {
// No generated procs for DecRef, just lowlevel ops
let rc_ptr_sym = self.create_symbol(ident_ids, "rc_ptr");
// Pass the refcount pointer to the lowlevel call (see utils.zig)
let call_result_empty = self.create_symbol(ident_ids, "call_result_empty");
let call_expr = Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::RefCountDec,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: arena.alloc([rc_ptr_sym]),
});
let call_stmt = Stmt::Let(call_result_empty, call_expr, LAYOUT_UNIT, following);
let rc_stmt = arena.alloc(self.rc_ptr_from_struct(
ident_ids,
*structure,
rc_ptr_sym,
arena.alloc(call_stmt),
));
(rc_stmt, ctx.new_linker_data)
}
}
}
// Check if refcounting is implemented yet. In the long term, this will be deleted.
// In the short term, it helps us to skip refcounting and let it leak, so we can make
// progress incrementally. Kept in sync with generate_procs using assertions.
fn is_rc_implemented_yet(layout: &Layout) -> bool {
matches!(layout, Layout::Builtin(Builtin::Str))
}
/// Replace a generic `Lowlevel::Eq` call with a specialized helper proc.
/// The helper procs themselves are to be generated later with `generate_procs`
pub fn call_specialized_equals(
&mut self,
ident_ids: &mut IdentIds,
layout: &Layout<'a>,
arguments: &'a [Symbol],
) -> (Expr<'a>, Vec<'a, (Symbol, ProcLayout<'a>)>) {
let mut ctx = Context {
new_linker_data: Vec::new_in(self.arena),
recursive_union: None,
op: HelperOp::Eq,
};
let expr = self.call_specialized_op(ident_ids, &mut ctx, *layout, arguments);
(expr, ctx.new_linker_data)
}
// ============================================================================
//
// CALL SPECIALIZED OP
//
// ============================================================================
fn call_specialized_op(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
called_layout: Layout<'a>,
arguments: &[Symbol],
) -> Expr<'a> {
use HelperOp::*;
debug_assert!(self.debug_recursion_depth < 10);
self.debug_recursion_depth += 1;
let layout = if matches!(called_layout, Layout::RecursivePointer) {
let union_layout = ctx.recursive_union.unwrap();
Layout::Union(union_layout)
} else {
called_layout
};
if layout_needs_helper_proc(&layout, ctx.op) {
let proc_name = self.find_or_create_proc(ident_ids, ctx, layout);
let (ret_layout, arg_layouts): (&'a Layout<'a>, &'a [Layout<'a>]) = {
match ctx.op {
Dec | DecRef => (&LAYOUT_UNIT, self.arena.alloc([layout])),
Inc => (&LAYOUT_UNIT, self.arena.alloc([layout, self.layout_isize])),
Eq => (&LAYOUT_BOOL, self.arena.alloc([layout, layout])),
}
};
Expr::Call(Call {
call_type: CallType::ByName {
name: proc_name,
ret_layout,
arg_layouts,
specialization_id: CallSpecId::BACKEND_DUMMY,
},
arguments: self.arena.alloc_slice_copy(arguments),
})
} else {
Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::Eq,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc_slice_copy(arguments),
})
}
}
fn find_or_create_proc(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
layout: Layout<'a>,
) -> Symbol {
use HelperOp::*;
let found = self
.specializations
.iter()
.find(|spec| spec.op == ctx.op && spec.layout == layout);
if let Some(spec) = found {
return spec.symbol;
}
// Create the specialization before recursing
let (proc_symbol, proc_layout) = self.create_proc_symbol(ident_ids, ctx, &layout);
ctx.new_linker_data.push((proc_symbol, proc_layout));
self.specializations.push(Specialization {
op: ctx.op,
layout,
symbol: proc_symbol,
});
// Recursively generate the body of the Proc and sub-procs
let (ret_layout, body) = match ctx.op {
Inc | Dec | DecRef => (LAYOUT_UNIT, self.refcount_generic(ident_ids, ctx, layout)),
Eq => (LAYOUT_BOOL, self.eq_generic(ident_ids, ctx, layout)),
};
let args: &'a [(Layout<'a>, Symbol)] = {
let roc_value = (layout, ARG_1);
match ctx.op {
Inc => {
let inc_amount = (self.layout_isize, ARG_2);
self.arena.alloc([roc_value, inc_amount])
}
Dec | DecRef => self.arena.alloc([roc_value]),
Eq => self.arena.alloc([roc_value, (layout, ARG_2)]),
}
};
self.procs.push(Proc {
name: proc_symbol,
args,
body,
closure_data_layout: None,
ret_layout,
is_self_recursive: SelfRecursive::NotSelfRecursive,
must_own_arguments: false,
host_exposed_layouts: HostExposedLayouts::NotHostExposed,
});
proc_symbol
}
fn create_proc_symbol(
&self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
layout: &Layout<'a>,
) -> (Symbol, ProcLayout<'a>) {
let debug_name = format!(
"#help{}_{:?}_{:?}",
self.specializations.len(),
ctx.op,
layout
)
.replace("Builtin", "");
let proc_symbol: Symbol = self.create_symbol(ident_ids, &debug_name);
let proc_layout = match ctx.op {
HelperOp::Inc => ProcLayout {
arguments: self.arena.alloc([*layout, self.layout_isize]),
result: LAYOUT_UNIT,
},
HelperOp::Dec => ProcLayout {
arguments: self.arena.alloc([*layout]),
result: LAYOUT_UNIT,
},
HelperOp::DecRef => unreachable!("No generated Proc for DecRef"),
HelperOp::Eq => ProcLayout {
arguments: self.arena.alloc([*layout, *layout]),
result: LAYOUT_BOOL,
},
};
(proc_symbol, proc_layout)
}
fn create_symbol(&self, ident_ids: &mut IdentIds, debug_name: &str) -> Symbol {
let ident_id = ident_ids.add(Ident::from(debug_name));
Symbol::new(self.home, ident_id)
}
// ============================================================================
//
// GENERATE REFCOUNTING
//
// ============================================================================
fn refcount_generic(
&self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
layout: Layout<'a>,
) -> Stmt<'a> {
debug_assert!(Self::is_rc_implemented_yet(&layout));
let rc_todo = || todo!("Please update is_rc_implemented_yet for `{:?}`", layout);
match layout {
Layout::Builtin(
Builtin::Int(_) | Builtin::Float(_) | Builtin::Bool | Builtin::Decimal,
) => unreachable!("Not refcounted: {:?}", layout),
Layout::Builtin(Builtin::Str) => self.refcount_str(ident_ids, ctx),
Layout::Builtin(Builtin::Dict(_, _) | Builtin::Set(_) | Builtin::List(_)) => rc_todo(),
Layout::Struct(_) => rc_todo(),
Layout::Union(_) => rc_todo(),
Layout::LambdaSet(_) => {
unreachable!("Refcounting on LambdaSet is invalid. Should be a Union at runtime.")
}
Layout::RecursivePointer => rc_todo(),
}
}
fn return_unit(&self, ident_ids: &mut IdentIds) -> Stmt<'a> {
let unit = self.create_symbol(ident_ids, "unit");
let ret_stmt = self.arena.alloc(Stmt::Ret(unit));
Stmt::Let(unit, Expr::Struct(&[]), LAYOUT_UNIT, ret_stmt)
}
// Subtract a constant from a pointer to find the refcount
// Also does some type casting, so that we have different Symbols and Layouts
// for the 'pointer' and 'integer' versions of the address.
// This helps to avoid issues with the backends Symbol->Layout mapping.
fn rc_ptr_from_struct(
&self,
ident_ids: &mut IdentIds,
structure: Symbol,
rc_ptr_sym: Symbol,
following: &'a Stmt<'a>,
) -> Stmt<'a> {
// Typecast the structure pointer to an integer
// Backends expect a number Layout to choose the right "subtract" instruction
let addr_sym = self.create_symbol(ident_ids, "addr");
let addr_expr = Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::PtrCast,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([structure]),
});
let addr_stmt = |next| Stmt::Let(addr_sym, addr_expr, self.layout_isize, next);
// Pointer size constant
let ptr_size_sym = self.create_symbol(ident_ids, "ptr_size");
let ptr_size_expr = Expr::Literal(Literal::Int(self.ptr_size as i128));
let ptr_size_stmt = |next| Stmt::Let(ptr_size_sym, ptr_size_expr, self.layout_isize, next);
// Refcount address
let rc_addr_sym = self.create_symbol(ident_ids, "rc_addr");
let rc_addr_expr = Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::NumSub,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([structure, ptr_size_sym]),
});
let rc_addr_stmt = |next| Stmt::Let(rc_addr_sym, rc_addr_expr, self.layout_isize, next);
// Typecast the refcount address from integer to pointer
let rc_ptr_expr = Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::PtrCast,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([rc_addr_sym]),
});
let rc_ptr_stmt = |next| Stmt::Let(rc_ptr_sym, rc_ptr_expr, LAYOUT_PTR, next);
addr_stmt(self.arena.alloc(
//
ptr_size_stmt(self.arena.alloc(
//
rc_addr_stmt(self.arena.alloc(
//
rc_ptr_stmt(self.arena.alloc(
//
following,
)),
)),
)),
))
}
/// Generate a procedure to modify the reference count of a Str
fn refcount_str(&self, ident_ids: &mut IdentIds, ctx: &mut Context<'a>) -> Stmt<'a> {
let op = ctx.op;
let string = ARG_1;
let layout_isize = self.layout_isize;
// Get the string length as a signed int
let len = self.create_symbol(ident_ids, "len");
let len_expr = Expr::StructAtIndex {
index: 1,
field_layouts: self.arena.alloc([LAYOUT_PTR, layout_isize]),
structure: string,
};
let len_stmt = |next| Stmt::Let(len, len_expr, layout_isize, next);
// Zero
let zero = self.create_symbol(ident_ids, "zero");
let zero_expr = Expr::Literal(Literal::Int(0));
let zero_stmt = |next| Stmt::Let(zero, zero_expr, layout_isize, next);
// is_big_str = (len >= 0);
// Treat len as isize so that the small string flag is the same as the sign bit
let is_big_str = self.create_symbol(ident_ids, "is_big_str");
let is_big_str_expr = Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::NumGte,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([len, zero]),
});
let is_big_str_stmt = |next| Stmt::Let(is_big_str, is_big_str_expr, LAYOUT_BOOL, next);
// Get the pointer to the string elements
let elements = self.create_symbol(ident_ids, "elements");
let elements_expr = Expr::StructAtIndex {
index: 0,
field_layouts: self.arena.alloc([LAYOUT_PTR, layout_isize]),
structure: string,
};
let elements_stmt = |next| Stmt::Let(elements, elements_expr, layout_isize, next);
// A pointer to the refcount value itself
let rc_ptr = self.create_symbol(ident_ids, "rc_ptr");
// Alignment constant (same value as ptr_size but different layout)
let alignment = self.create_symbol(ident_ids, "alignment");
let alignment_expr = Expr::Literal(Literal::Int(self.ptr_size as i128));
let alignment_stmt = |next| Stmt::Let(alignment, alignment_expr, LAYOUT_U32, next);
// Call the relevant Zig lowlevel to actually modify the refcount
let zig_call_result = self.create_symbol(ident_ids, "zig_call_result");
let zig_call_expr = match op {
HelperOp::Inc => Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::RefCountInc,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([rc_ptr, ARG_2]),
}),
HelperOp::Dec | HelperOp::DecRef => Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::RefCountDec,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([rc_ptr, alignment]),
}),
_ => unreachable!(),
};
let zig_call_stmt = |next| Stmt::Let(zig_call_result, zig_call_expr, LAYOUT_UNIT, next);
// Generate an `if` to skip small strings but modify big strings
let then_branch = elements_stmt(self.arena.alloc(
//
self.rc_ptr_from_struct(
ident_ids,
elements,
rc_ptr,
self.arena.alloc(
//
alignment_stmt(self.arena.alloc(
//
zig_call_stmt(self.arena.alloc(
//
Stmt::Ret(zig_call_result),
)),
)),
),
),
));
let if_stmt = Stmt::Switch {
cond_symbol: is_big_str,
cond_layout: LAYOUT_BOOL,
branches: self.arena.alloc([(1, BranchInfo::None, then_branch)]),
default_branch: (
BranchInfo::None,
self.arena.alloc(self.return_unit(ident_ids)),
),
ret_layout: LAYOUT_UNIT,
};
// Combine the statements in sequence
len_stmt(self.arena.alloc(
//
zero_stmt(self.arena.alloc(
//
is_big_str_stmt(self.arena.alloc(
//
if_stmt,
)),
)),
))
}
// ============================================================================
//
// GENERATE EQUALS
//
// ============================================================================
fn eq_generic(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
layout: Layout<'a>,
) -> Stmt<'a> {
let eq_todo = || todo!("Specialized `==` operator for `{:?}`", layout);
let main_body = match layout {
Layout::Builtin(
Builtin::Int(_) | Builtin::Float(_) | Builtin::Bool | Builtin::Decimal,
) => unreachable!(
"No generated proc for `==`. Use direct code gen for {:?}",
layout
),
Layout::Builtin(Builtin::Str) => {
unreachable!("No generated helper proc for `==` on Str. Use Zig function.")
}
Layout::Builtin(Builtin::Dict(_, _) | Builtin::Set(_)) => eq_todo(),
Layout::Builtin(Builtin::List(elem_layout)) => {
self.eq_list(ident_ids, ctx, elem_layout)
}
Layout::Struct(field_layouts) => self.eq_struct(ident_ids, ctx, field_layouts),
Layout::Union(union_layout) => self.eq_tag_union(ident_ids, ctx, union_layout),
Layout::LambdaSet(_) => unreachable!("`==` is not defined on functions"),
Layout::RecursivePointer => eq_todo(),
};
Stmt::Let(
Symbol::BOOL_TRUE,
Expr::Literal(Literal::Int(1)),
LAYOUT_BOOL,
self.arena.alloc(Stmt::Let(
Symbol::BOOL_FALSE,
Expr::Literal(Literal::Int(0)),
LAYOUT_BOOL,
self.arena.alloc(main_body),
)),
)
}
fn if_pointers_equal_return_true(
&self,
ident_ids: &mut IdentIds,
following: &'a Stmt<'a>,
) -> Stmt<'a> {
let ptr1_addr = self.create_symbol(ident_ids, "addr1");
let ptr2_addr = self.create_symbol(ident_ids, "addr2");
let ptr_eq = self.create_symbol(ident_ids, "eq_addr");
Stmt::Let(
ptr1_addr,
Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::PtrCast,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([ARG_1]),
}),
self.layout_isize,
self.arena.alloc(Stmt::Let(
ptr2_addr,
Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::PtrCast,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([ARG_2]),
}),
self.layout_isize,
self.arena.alloc(Stmt::Let(
ptr_eq,
Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::Eq,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([ptr1_addr, ptr2_addr]),
}),
LAYOUT_BOOL,
self.arena.alloc(Stmt::Switch {
cond_symbol: ptr_eq,
cond_layout: LAYOUT_BOOL,
branches: self.arena.alloc([(
1,
BranchInfo::None,
Stmt::Ret(Symbol::BOOL_TRUE),
)]),
default_branch: (BranchInfo::None, following),
ret_layout: LAYOUT_BOOL,
}),
)),
)),
)
}
fn if_false_return_false(&self, symbol: Symbol, following: &'a Stmt<'a>) -> Stmt<'a> {
Stmt::Switch {
cond_symbol: symbol,
cond_layout: LAYOUT_BOOL,
branches: self
.arena
.alloc([(0, BranchInfo::None, Stmt::Ret(Symbol::BOOL_FALSE))]),
default_branch: (BranchInfo::None, following),
ret_layout: LAYOUT_BOOL,
}
}
fn eq_struct(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
field_layouts: &'a [Layout<'a>],
) -> Stmt<'a> {
let else_clause = self.eq_fields(ident_ids, ctx, 0, field_layouts);
self.if_pointers_equal_return_true(ident_ids, self.arena.alloc(else_clause))
}
fn eq_fields(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
tag_id: u64,
field_layouts: &'a [Layout<'a>],
) -> Stmt<'a> {
let mut stmt = Stmt::Ret(Symbol::BOOL_TRUE);
for (i, layout) in field_layouts.iter().enumerate().rev() {
let field1_sym = self.create_symbol(ident_ids, &format!("field_1_{}_{}", tag_id, i));
let field1_expr = Expr::StructAtIndex {
index: i as u64,
field_layouts,
structure: ARG_1,
};
let field1_stmt = |next| Stmt::Let(field1_sym, field1_expr, *layout, next);
let field2_sym = self.create_symbol(ident_ids, &format!("field_2_{}_{}", tag_id, i));
let field2_expr = Expr::StructAtIndex {
index: i as u64,
field_layouts,
structure: ARG_2,
};
let field2_stmt = |next| Stmt::Let(field2_sym, field2_expr, *layout, next);
let eq_call_expr = self.call_specialized_op(
ident_ids,
ctx,
*layout,
self.arena.alloc([field1_sym, field2_sym]),
);
let eq_call_name = format!("eq_call_{}", i);
let eq_call_sym = self.create_symbol(ident_ids, &eq_call_name);
let eq_call_stmt = |next| Stmt::Let(eq_call_sym, eq_call_expr, LAYOUT_BOOL, next);
stmt = field1_stmt(self.arena.alloc(
//
field2_stmt(self.arena.alloc(
//
eq_call_stmt(self.arena.alloc(
//
self.if_false_return_false(eq_call_sym, self.arena.alloc(stmt)),
)),
)),
))
}
stmt
}
fn eq_tag_union(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
union_layout: UnionLayout<'a>,
) -> Stmt<'a> {
use UnionLayout::*;
let parent_rec_ptr_layout = ctx.recursive_union;
if !matches!(union_layout, NonRecursive(_)) {
ctx.recursive_union = Some(union_layout);
}
let main_stmt = match union_layout {
NonRecursive(tags) => self.eq_tag_union_help(ident_ids, ctx, union_layout, tags, None),
Recursive(tags) => self.eq_tag_union_help(ident_ids, ctx, union_layout, tags, None),
NonNullableUnwrapped(field_layouts) => self.eq_fields(ident_ids, ctx, 0, field_layouts),
NullableWrapped {
other_tags,
nullable_id,
} => {
self.eq_tag_union_help(ident_ids, ctx, union_layout, other_tags, Some(nullable_id))
}
NullableUnwrapped {
other_fields,
nullable_id: n,
} => self.eq_tag_union_help(
ident_ids,
ctx,
union_layout,
self.arena.alloc([other_fields]),
Some(n as u16),
),
};
ctx.recursive_union = parent_rec_ptr_layout;
self.if_pointers_equal_return_true(ident_ids, self.arena.alloc(main_stmt))
}
fn eq_tag_union_help(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
union_layout: UnionLayout<'a>,
tag_layouts: &'a [&'a [Layout<'a>]],
nullable_id: Option<u16>,
) -> Stmt<'a> {
let tag_id_layout = union_layout.tag_id_layout();
let tag_id_a = self.create_symbol(ident_ids, "tag_id_a");
let tag_id_a_stmt = |next| {
Stmt::Let(
tag_id_a,
Expr::GetTagId {
structure: ARG_1,
union_layout,
},
tag_id_layout,
next,
)
};
let tag_id_b = self.create_symbol(ident_ids, "tag_id_b");
let tag_id_b_stmt = |next| {
Stmt::Let(
tag_id_b,
Expr::GetTagId {
structure: ARG_2,
union_layout,
},
tag_id_layout,
next,
)
};
let tag_ids_eq = self.create_symbol(ident_ids, "tag_ids_eq");
let tag_ids_expr = Expr::Call(Call {
call_type: CallType::LowLevel {
op: LowLevel::Eq,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: self.arena.alloc([tag_id_a, tag_id_b]),
});
let tag_ids_eq_stmt = |next| Stmt::Let(tag_ids_eq, tag_ids_expr, LAYOUT_BOOL, next);
let if_equal_ids_branches =
self.arena
.alloc([(0, BranchInfo::None, Stmt::Ret(Symbol::BOOL_FALSE))]);
//
// Switch statement by tag ID
//
let mut tag_branches = Vec::with_capacity_in(tag_layouts.len(), self.arena);
// If there's a null tag, check it first. We might not need to load any data from memory.
if let Some(id) = nullable_id {
tag_branches.push((id as u64, BranchInfo::None, Stmt::Ret(Symbol::BOOL_TRUE)))
}
let mut tag_id: u64 = 0;
for field_layouts in tag_layouts.iter().take(tag_layouts.len() - 1) {
if let Some(null_id) = nullable_id {
if tag_id == null_id as u64 {
tag_id += 1;
}
}
let tag_stmt = self.eq_fields(ident_ids, ctx, tag_id, field_layouts);
tag_branches.push((tag_id, BranchInfo::None, tag_stmt));
tag_id += 1;
}
let tag_switch_stmt = Stmt::Switch {
cond_symbol: tag_id_a,
cond_layout: tag_id_layout,
branches: tag_branches.into_bump_slice(),
default_branch: (
BranchInfo::None,
self.arena.alloc(self.eq_fields(
ident_ids,
ctx,
tag_id,
tag_layouts.last().unwrap(),
)),
),
ret_layout: LAYOUT_BOOL,
};
let if_equal_ids_stmt = Stmt::Switch {
cond_symbol: tag_ids_eq,
cond_layout: LAYOUT_BOOL,
branches: if_equal_ids_branches,
default_branch: (BranchInfo::None, self.arena.alloc(tag_switch_stmt)),
ret_layout: LAYOUT_BOOL,
};
//
// combine all the statments
//
tag_id_a_stmt(self.arena.alloc(
//
tag_id_b_stmt(self.arena.alloc(
//
tag_ids_eq_stmt(self.arena.alloc(
//
if_equal_ids_stmt,
)),
)),
))
}
/// List equality
/// We can't use `ListGetUnsafe` because it increments the refcount, and we don't want that.
/// Another way to dereference a heap pointer is to use `Expr::UnionAtIndex`.
/// To achieve this we use `PtrCast` to cast the element pointer to a "Box" layout.
/// Then we can increment the Box pointer in a loop, dereferencing it each time.
/// (An alternative approach would be to create a new lowlevel like ListPeekUnsafe.)
fn eq_list(
&mut self,
ident_ids: &mut IdentIds,
ctx: &mut Context<'a>,
elem_layout: &Layout<'a>,
) -> Stmt<'a> {
use LowLevel::*;
let layout_isize = self.layout_isize;
let arena = self.arena;
// A "Box" layout (heap pointer to a single list element)
let box_union_layout = UnionLayout::NonNullableUnwrapped(self.arena.alloc([*elem_layout]));
let box_layout = Layout::Union(box_union_layout);
// Compare lengths
let len_1 = self.create_symbol(ident_ids, "len_1");
let len_2 = self.create_symbol(ident_ids, "len_2");
let len_1_stmt = |next| let_lowlevel(arena, layout_isize, len_1, ListLen, &[ARG_1], next);
let len_2_stmt = |next| let_lowlevel(arena, layout_isize, len_2, ListLen, &[ARG_2], next);
let eq_len = self.create_symbol(ident_ids, "eq_len");
let eq_len_stmt =
|next| let_lowlevel(arena, LAYOUT_BOOL, eq_len, Eq, &[len_1, len_2], next);
// if lengths are equal...
// get element pointers
let elements_1 = self.create_symbol(ident_ids, "elements_1");
let elements_2 = self.create_symbol(ident_ids, "elements_2");
let elements_1_expr = Expr::StructAtIndex {
index: 0,
field_layouts: self.arena.alloc([box_layout, layout_isize]),
structure: ARG_1,
};
let elements_2_expr = Expr::StructAtIndex {
index: 0,
field_layouts: self.arena.alloc([box_layout, layout_isize]),
structure: ARG_2,
};
let elements_1_stmt = |next| Stmt::Let(elements_1, elements_1_expr, box_layout, next);
let elements_2_stmt = |next| Stmt::Let(elements_2, elements_2_expr, box_layout, next);
// Cast to integers
let start_1 = self.create_symbol(ident_ids, "start_1");
let start_2 = self.create_symbol(ident_ids, "start_2");
let start_1_stmt =
|next| let_lowlevel(arena, layout_isize, start_1, PtrCast, &[elements_1], next);
let start_2_stmt =
|next| let_lowlevel(arena, layout_isize, start_2, PtrCast, &[elements_2], next);
//
// Loop initialisation
//
// let size = literal int
let size = self.create_symbol(ident_ids, "size");
let size_expr = Expr::Literal(Literal::Int(elem_layout.stack_size(self.ptr_size) as i128));
let size_stmt = |next| Stmt::Let(size, size_expr, layout_isize, next);
// let list_size = len_1 * size
let list_size = self.create_symbol(ident_ids, "list_size");
let list_size_stmt =
|next| let_lowlevel(arena, layout_isize, list_size, NumMul, &[len_1, size], next);
// let end_1 = start_1 + list_size
let end_1 = self.create_symbol(ident_ids, "end_1");
let end_1_stmt = |next| {
let_lowlevel(
arena,
layout_isize,
end_1,
NumAdd,
&[start_1, list_size],
next,
)
};
//
// Loop name & parameters
//
let elems_loop = JoinPointId(self.create_symbol(ident_ids, "elems_loop"));
let addr1 = self.create_symbol(ident_ids, "addr1");
let addr2 = self.create_symbol(ident_ids, "addr2");
let param_addr1 = Param {
symbol: addr1,
borrow: false,
layout: layout_isize,
};
let param_addr2 = Param {
symbol: addr2,
borrow: false,
layout: layout_isize,
};
//
// if we haven't reached the end yet...
//
// Cast integers to box pointers
let box1 = self.create_symbol(ident_ids, "box1");
let box2 = self.create_symbol(ident_ids, "box2");
let box1_stmt = |next| let_lowlevel(arena, box_layout, box1, PtrCast, &[addr1], next);
let box2_stmt = |next| let_lowlevel(arena, box_layout, box2, PtrCast, &[addr2], next);
// Dereference the box pointers to get the current elements
let elem1 = self.create_symbol(ident_ids, "elem1");
let elem2 = self.create_symbol(ident_ids, "elem2");
let elem1_expr = Expr::UnionAtIndex {
structure: box1,
union_layout: box_union_layout,
tag_id: 0,
index: 0,
};
let elem2_expr = Expr::UnionAtIndex {
structure: box2,
union_layout: box_union_layout,
tag_id: 0,
index: 0,
};
let elem1_stmt = |next| Stmt::Let(elem1, elem1_expr, *elem_layout, next);
let elem2_stmt = |next| Stmt::Let(elem2, elem2_expr, *elem_layout, next);
// Compare the two current elements
let eq_elems = self.create_symbol(ident_ids, "eq_elems");
let eq_elems_expr = self.call_specialized_op(ident_ids, ctx, *elem_layout, &[elem1, elem2]);
let eq_elems_stmt = |next| Stmt::Let(eq_elems, eq_elems_expr, LAYOUT_BOOL, next);
// If current elements are equal, loop back again
let next_1 = self.create_symbol(ident_ids, "next_1");
let next_2 = self.create_symbol(ident_ids, "next_2");
let next_1_stmt =
|next| let_lowlevel(arena, layout_isize, next_1, NumAdd, &[addr1, size], next);
let next_2_stmt =
|next| let_lowlevel(arena, layout_isize, next_2, NumAdd, &[addr2, size], next);
let jump_back = Stmt::Jump(elems_loop, self.arena.alloc([next_1, next_2]));
//
// Control flow
//
let is_end = self.create_symbol(ident_ids, "is_end");
let is_end_stmt =
|next| let_lowlevel(arena, LAYOUT_BOOL, is_end, NumGte, &[addr1, end_1], next);
let if_elems_not_equal = self.if_false_return_false(
eq_elems,
// else
self.arena.alloc(
//
next_1_stmt(self.arena.alloc(
//
next_2_stmt(self.arena.alloc(
//
jump_back,
)),
)),
),
);
let if_end_of_list = Stmt::Switch {
cond_symbol: is_end,
cond_layout: LAYOUT_BOOL,
ret_layout: LAYOUT_BOOL,
branches: self
.arena
.alloc([(1, BranchInfo::None, Stmt::Ret(Symbol::BOOL_TRUE))]),
default_branch: (
BranchInfo::None,
self.arena.alloc(
//
box1_stmt(self.arena.alloc(
//
box2_stmt(self.arena.alloc(
//
elem1_stmt(self.arena.alloc(
//
elem2_stmt(self.arena.alloc(
//
eq_elems_stmt(self.arena.alloc(
//
if_elems_not_equal,
)),
)),
)),
)),
)),
),
),
};
let joinpoint_loop = Stmt::Join {
id: elems_loop,
parameters: self.arena.alloc([param_addr1, param_addr2]),
body: self.arena.alloc(
//
is_end_stmt(
//
self.arena.alloc(if_end_of_list),
),
),
remainder: self
.arena
.alloc(Stmt::Jump(elems_loop, self.arena.alloc([start_1, start_2]))),
};
let if_different_lengths = self.if_false_return_false(
eq_len,
// else
self.arena.alloc(
//
elements_1_stmt(self.arena.alloc(
//
elements_2_stmt(self.arena.alloc(
//
start_1_stmt(self.arena.alloc(
//
start_2_stmt(self.arena.alloc(
//
size_stmt(self.arena.alloc(
//
list_size_stmt(self.arena.alloc(
//
end_1_stmt(self.arena.alloc(
//
joinpoint_loop,
)),
)),
)),
)),
)),
)),
)),
),
);
let pointers_else = len_1_stmt(self.arena.alloc(
//
len_2_stmt(self.arena.alloc(
//
eq_len_stmt(self.arena.alloc(
//
if_different_lengths,
)),
)),
));
self.if_pointers_equal_return_true(ident_ids, self.arena.alloc(pointers_else))
}
}
fn let_lowlevel<'a>(
arena: &'a Bump,
result_layout: Layout<'a>,
result: Symbol,
op: LowLevel,
arguments: &[Symbol],
next: &'a Stmt<'a>,
) -> Stmt<'a> {
Stmt::Let(
result,
Expr::Call(Call {
call_type: CallType::LowLevel {
op,
update_mode: UpdateModeId::BACKEND_DUMMY,
},
arguments: arena.alloc_slice_copy(arguments),
}),
result_layout,
next,
)
}
fn layout_needs_helper_proc(layout: &Layout, op: HelperOp) -> bool {
match layout {
Layout::Builtin(Builtin::Int(_) | Builtin::Float(_) | Builtin::Bool | Builtin::Decimal) => {
false
}
Layout::Builtin(Builtin::Str) => {
// Str type can use either Zig functions or generated IR, since it's not generic.
// Eq uses a Zig function, refcount uses generated IR.
// Both are fine, they were just developed at different times.
matches!(op, HelperOp::Inc | HelperOp::Dec | HelperOp::DecRef)
}
Layout::Builtin(Builtin::Dict(_, _) | Builtin::Set(_) | Builtin::List(_)) => true,
Layout::Struct(fields) => !fields.is_empty(),
Layout::Union(UnionLayout::NonRecursive(tags)) => !tags.is_empty(),
Layout::Union(_) => true,
Layout::LambdaSet(_) | Layout::RecursivePointer => false,
}
}