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Incrementing index loop helper, deleted some comments, refactored List.concat to avoid some duplicate code work

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This commit is contained in:
Chad Stearns 2020-08-10 00:45:29 -04:00
parent 9662ca6bd6
commit e65c0cafbb
1 changed files with 392 additions and 598 deletions
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608
compiler/gen/src/llvm/build_list.rs
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@ -328,12 +328,7 @@ pub fn list_join<'a, 'ctx, 'env>(
// outer_list_len > 0 // outer_list_len > 0
// We do this check to avoid allocating memory. If the input // We do this check to avoid allocating memory. If the input
// list is empty, then we can just return an empty list. // list is empty, then we can just return an empty list.
let comparison = builder.build_int_compare( let comparison = list_is_not_empty(builder, ctx, outer_list_len);
IntPredicate::UGT,
outer_list_len,
ctx.i64_type().const_int(0, false),
"greaterthanzero",
);
let build_then = || { let build_then = || {
let list_len_sum_name = "#listslengthsum"; let list_len_sum_name = "#listslengthsum";
@ -342,33 +337,9 @@ pub fn list_join<'a, 'ctx, 'env>(
builder.build_store(list_len_sum_alloca, ctx.i64_type().const_int(0, false)); builder.build_store(list_len_sum_alloca, ctx.i64_type().const_int(0, false));
// List Sum Loop // List Sum Loop
{ let sum_loop = |sum_index| {
let index_name = "#index";
let index_alloca = builder.build_alloca(ctx.i64_type(), index_name);
// index in the outer list, pointing to a inner list
let outer_list_index = ctx.i64_type().const_int(0, false);
builder.build_store(index_alloca, outer_list_index);
let outer_loop_bb = ctx.append_basic_block(parent, "loop");
builder.build_unconditional_branch(outer_loop_bb);
builder.position_at_end(outer_loop_bb);
// #index = #index + 1
let curr_index = builder
.build_load(index_alloca, index_name)
.into_int_value();
let next_index = builder.build_int_add(
curr_index,
ctx.i64_type().const_int(1, false),
"nextindex",
);
builder.build_store(index_alloca, next_index);
let inner_list_wrapper_ptr = unsafe { let inner_list_wrapper_ptr = unsafe {
builder.build_in_bounds_gep(outer_list_ptr, &[curr_index], "load_index") builder.build_in_bounds_gep(outer_list_ptr, &[sum_index], "load_index")
}; };
let inner_list = builder.build_load(inner_list_wrapper_ptr, "inner_list"); let inner_list = builder.build_load(inner_list_wrapper_ptr, "inner_list");
@ -383,20 +354,18 @@ pub fn list_join<'a, 'ctx, 'env>(
); );
builder.build_store(list_len_sum_alloca, next_list_sum); builder.build_store(list_len_sum_alloca, next_list_sum);
};
// #index < outer_list_len incrementing_index_loop(
let outer_loop_end_cond = builder,
bounds_check_comparison(builder, next_index, outer_list_len); parent,
ctx,
let after_outer_loop_bb = ctx.append_basic_block(parent, "after_outer_loop"); outer_list_len,
"#sum_index",
builder.build_conditional_branch( None,
outer_loop_end_cond, sum_loop,
outer_loop_bb,
after_outer_loop_bb,
); );
builder.position_at_end(after_outer_loop_bb);
}
let final_list_sum = builder let final_list_sum = builder
.build_load(list_len_sum_alloca, list_len_sum_name) .build_load(list_len_sum_alloca, list_len_sum_name)
.into_int_value(); .into_int_value();
@ -409,32 +378,8 @@ pub fn list_join<'a, 'ctx, 'env>(
builder.build_store(dest_elem_ptr_alloca, final_list_ptr); builder.build_store(dest_elem_ptr_alloca, final_list_ptr);
// Element inserting loop // Inner List Loop
{ let inner_list_loop = |curr_index| {
let index_name = "#index";
let index_alloca = builder.build_alloca(ctx.i64_type(), index_name);
// index in the outer list, pointing to a inner list
let outer_list_index = ctx.i64_type().const_int(0, false);
builder.build_store(index_alloca, outer_list_index);
let outer_loop_bb = ctx.append_basic_block(parent, "loop");
builder.build_unconditional_branch(outer_loop_bb);
builder.position_at_end(outer_loop_bb);
// #index = #index + 1
let curr_index = builder
.build_load(index_alloca, index_name)
.into_int_value();
let next_index = builder.build_int_add(
curr_index,
ctx.i64_type().const_int(1, false),
"nextindex",
);
builder.build_store(index_alloca, next_index);
let inner_list_wrapper = { let inner_list_wrapper = {
let wrapper_ptr = unsafe { let wrapper_ptr = unsafe {
builder.build_in_bounds_gep(outer_list_ptr, &[curr_index], "load_index") builder.build_in_bounds_gep(outer_list_ptr, &[curr_index], "load_index")
@ -445,16 +390,12 @@ pub fn list_join<'a, 'ctx, 'env>(
.into_struct_value() .into_struct_value()
}; };
// Inner Loop
{
let inner_list_len = list_len(builder, inner_list_wrapper); let inner_list_len = list_len(builder, inner_list_wrapper);
// inner_list_len > 0 // inner_list_len > 0
let inner_list_comparison = list_is_not_empty(builder, ctx, inner_list_len); let inner_list_comparison = list_is_not_empty(builder, ctx, inner_list_len);
let inner_list_non_empty_block = let inner_list_non_empty_block =
ctx.append_basic_block(parent, "inner_list_non_empty"); ctx.append_basic_block(parent, "inner_list_non_empty");
let after_inner_list_non_empty_block = let after_inner_list_non_empty_block =
ctx.append_basic_block(parent, "branchcont"); ctx.append_basic_block(parent, "branchcont");
@ -465,36 +406,15 @@ pub fn list_join<'a, 'ctx, 'env>(
); );
builder.position_at_end(inner_list_non_empty_block); builder.position_at_end(inner_list_non_empty_block);
let inner_index_name = "#inner_index"; // Element Inserting Loop
let inner_index_alloca = let inner_elem_loop = |inner_index| {
builder.build_alloca(ctx.i64_type(), inner_index_name);
let inner_list_index = ctx.i64_type().const_int(0, false);
builder.build_store(inner_index_alloca, inner_list_index);
let inner_loop_bb = ctx.append_basic_block(parent, "loop");
builder.build_unconditional_branch(inner_loop_bb);
builder.position_at_end(inner_loop_bb);
// #index = #index + 1
let curr_inner_index = builder
.build_load(inner_index_alloca, inner_index_name)
.into_int_value();
let next_inner_index = builder.build_int_add(
curr_inner_index,
ctx.i64_type().const_int(1, false),
"nextindex",
);
builder.build_store(inner_index_alloca, next_inner_index);
let src_elem_ptr = unsafe { let src_elem_ptr = unsafe {
let inner_list_ptr = let inner_list_ptr =
load_list_ptr(builder, inner_list_wrapper, elem_ptr_type); load_list_ptr(builder, inner_list_wrapper, elem_ptr_type);
builder.build_in_bounds_gep( builder.build_in_bounds_gep(
inner_list_ptr, inner_list_ptr,
&[curr_inner_index], &[inner_index],
"load_index", "load_index",
) )
}; };
@ -517,36 +437,31 @@ pub fn list_join<'a, 'ctx, 'env>(
}); });
builder.build_store(dest_elem_ptr_alloca, inc_dest_elem_ptr); builder.build_store(dest_elem_ptr_alloca, inc_dest_elem_ptr);
};
let inner_loop_end_cond = incrementing_index_loop(
bounds_check_comparison(builder, next_inner_index, inner_list_len); builder,
parent,
let after_inner_loop_bb = ctx,
ctx.append_basic_block(parent, "after_inner_loop"); inner_list_len,
"#inner_index",
builder.build_conditional_branch( None,
inner_loop_end_cond, inner_elem_loop,
inner_loop_bb,
after_inner_loop_bb,
); );
builder.position_at_end(after_inner_loop_bb);
builder.build_unconditional_branch(after_inner_list_non_empty_block); builder.build_unconditional_branch(after_inner_list_non_empty_block);
builder.position_at_end(after_inner_list_non_empty_block); builder.position_at_end(after_inner_list_non_empty_block);
} };
// #index < outer_list_len incrementing_index_loop(
let outer_loop_end_cond = builder,
bounds_check_comparison(builder, next_index, outer_list_len); parent,
ctx,
let after_outer_loop_bb = ctx.append_basic_block(parent, "after_outer_loop"); outer_list_len,
"#inner_list_index",
builder.build_conditional_branch( None,
outer_loop_end_cond, inner_list_loop,
outer_loop_bb,
after_outer_loop_bb,
); );
builder.position_at_end(after_outer_loop_bb);
let ptr_bytes = env.ptr_bytes; let ptr_bytes = env.ptr_bytes;
let int_type = ptr_int(ctx, ptr_bytes); let int_type = ptr_int(ctx, ptr_bytes);
@ -581,7 +496,6 @@ pub fn list_join<'a, 'ctx, 'env>(
collection(ctx, ptr_bytes), collection(ctx, ptr_bytes),
"cast_collection", "cast_collection",
) )
}
}; };
let build_else = || empty_list(env); let build_else = || empty_list(env);
@ -604,75 +518,6 @@ pub fn list_join<'a, 'ctx, 'env>(
} }
} }
fn clone_nonempty_list<'a, 'ctx, 'env>(
env: &Env<'a, 'ctx, 'env>,
list_len: IntValue<'ctx>,
elems_ptr: PointerValue<'ctx>,
elem_layout: &Layout<'_>,
) -> (StructValue<'ctx>, PointerValue<'ctx>) {
let builder = env.builder;
let ctx = env.context;
let ptr_bytes = env.ptr_bytes;
// Calculate the number of bytes we'll need to allocate.
let elem_bytes = env
.ptr_int()
.const_int(elem_layout.stack_size(env.ptr_bytes) as u64, false);
let size = env
.builder
.build_int_mul(elem_bytes, list_len, "mul_len_by_elem_bytes");
// Allocate space for the new array that we'll copy into.
let elem_type = basic_type_from_layout(env.arena, ctx, elem_layout, env.ptr_bytes);
let clone_ptr = builder
.build_array_malloc(elem_type, list_len, "list_ptr")
.unwrap();
let int_type = ptr_int(ctx, ptr_bytes);
let ptr_as_int = builder.build_ptr_to_int(clone_ptr, int_type, "list_cast_ptr");
// TODO check if malloc returned null; if so, runtime error for OOM!
// Either memcpy or deep clone the array elements
if elem_layout.safe_to_memcpy() {
// Copy the bytes from the original array into the new
// one we just malloc'd.
//
// TODO how do we decide when to do the small memcpy vs the normal one?
builder.build_memcpy(clone_ptr, ptr_bytes, elems_ptr, ptr_bytes, size);
} else {
panic!("TODO Cranelift currently only knows how to clone list elements that are Copy.");
}
// Create a fresh wrapper struct for the newly populated array
let struct_type = collection(ctx, env.ptr_bytes);
let mut struct_val;
// Store the pointer
struct_val = builder
.build_insert_value(
struct_type.get_undef(),
ptr_as_int,
Builtin::WRAPPER_PTR,
"insert_ptr",
)
.unwrap();
// Store the length
struct_val = builder
.build_insert_value(struct_val, list_len, Builtin::WRAPPER_LEN, "insert_len")
.unwrap();
let answer = builder
.build_bitcast(
struct_val.into_struct_value(),
collection(ctx, ptr_bytes),
"cast_collection",
)
.into_struct_value();
(answer, clone_ptr)
}
/// List.reverse : List elem -> List elem /// List.reverse : List elem -> List elem
pub fn list_reverse<'a, 'ctx, 'env>( pub fn list_reverse<'a, 'ctx, 'env>(
env: &Env<'a, 'ctx, 'env>, env: &Env<'a, 'ctx, 'env>,
@ -1046,58 +891,35 @@ pub fn list_concat<'a, 'ctx, 'env>(
) -> BasicValueEnum<'ctx> { ) -> BasicValueEnum<'ctx> {
debug_assert_eq!(args.len(), 2); debug_assert_eq!(args.len(), 2);
// This implementation is quite long, let me explain what is complicating it. Here are our
// contraints:
//
// constraint 1. lists might be empty because they have the layout `EmptyList`, or they might
// be empty because they have a `List` layout, but happen to be empty, such as in this code:
//
// list : List Int
// list =
// []
//
// So we have two sources of truth for emptiness.
//
// constraint 2. iterating over a non-empty list involves allocating memory for a index and
// a loop, and allocating memory is costly, so we dont want to even try to iterate over empty
// lists.
//
// Accounting for all the possibilities in the two constraints above gives us 9 code paths:
//
// first list EmptyList List(list) List(list)
// second list where list.length = 0 where list.length > 0
// ---------------------------------------------------------------------
// EmptyList | [] | [] | clone(1st_list) |
// ---------------------------------------------------------------------
// List(list) | [] | [] | clone(1st_list) |
// where list.length = 0 | | | |
// ---------------------------------------------------------------------
// List(list) | clone(2nd_list) | clone(2nd_list) | 2nd_list ++ 1st_list |
// where list.length > 0 | | | |
// ---------------------------------------------------------------------
//
let builder = env.builder; let builder = env.builder;
let ctx = env.context; let ctx = env.context;
let (first_list, first_list_layout) = &args[0]; let (first_list, list_layout) = &args[0];
let (second_list, second_list_layout) = &args[1]; let (second_list, _) = &args[1];
let second_list_wrapper = let second_list_wrapper =
build_expr(env, layout_ids, scope, parent, second_list).into_struct_value(); build_expr(env, layout_ids, scope, parent, second_list).into_struct_value();
let second_list_len = list_len(builder, second_list_wrapper); let second_list_len = list_len(builder, second_list_wrapper);
match first_list_layout { // We only match on the first lists layout
Layout::Builtin(Builtin::EmptyList) => { // because the first and second input lists
match second_list_layout { // necessarily have the same layout
match list_layout {
Layout::Builtin(Builtin::EmptyList) => empty_list(env), Layout::Builtin(Builtin::EmptyList) => empty_list(env),
Layout::Builtin(Builtin::List(elem_layout)) => { Layout::Builtin(Builtin::List(elem_layout)) => {
// THIS IS A COPY AND PASTE let first_list_wrapper =
// All the code under the Layout::Builtin(Builtin::List()) match branch build_expr(env, layout_ids, scope, parent, first_list).into_struct_value();
// is the same as what is under `if_first_list_is_empty`. Re-using
// `if_first_list_is_empty` here however, creates memory problems.
let first_list_len = list_len(builder, first_list_wrapper);
// first_list_len > 0
// We do this check to avoid allocating memory. If the first input
// list is empty, then we can just return the second list cloned
let first_list_length_comparison = list_is_not_empty(builder, ctx, first_list_len);
let if_first_list_is_empty = || {
// second_list_len > 0 // second_list_len > 0
// We do this check to avoid allocating memory. If the second input // We do this check to avoid allocating memory. If the second input
// list is empty, then we can just return the first list cloned // list is empty, then we can just return the first list cloned
@ -1129,25 +951,7 @@ pub fn list_concat<'a, 'ctx, 'env>(
build_second_list_else, build_second_list_else,
BasicTypeEnum::StructType(collection(ctx, env.ptr_bytes)), BasicTypeEnum::StructType(collection(ctx, env.ptr_bytes)),
) )
} };
_ => {
unreachable!(
"Invalid List layout for second input list of List.concat: {:?}",
second_list_layout
);
}
}
}
Layout::Builtin(Builtin::List(elem_layout)) => {
let first_list_wrapper =
build_expr(env, layout_ids, scope, parent, first_list).into_struct_value();
let first_list_len = list_len(builder, first_list_wrapper);
// first_list_len > 0
// We do this check to avoid allocating memory. If the first input
// list is empty, then we can just return the second list cloned
let first_list_length_comparison = list_is_not_empty(builder, ctx, first_list_len);
let if_first_list_is_not_empty = || { let if_first_list_is_not_empty = || {
let elem_type = basic_type_from_layout(env.arena, ctx, elem_layout, env.ptr_bytes); let elem_type = basic_type_from_layout(env.arena, ctx, elem_layout, env.ptr_bytes);
@ -1166,18 +970,6 @@ pub fn list_concat<'a, 'ctx, 'env>(
BasicValueEnum::StructValue(new_wrapper) BasicValueEnum::StructValue(new_wrapper)
}; };
match second_list_layout {
Layout::Builtin(Builtin::EmptyList) => {
let (new_wrapper, _) = clone_nonempty_list(
env,
first_list_len,
load_list_ptr(builder, first_list_wrapper, ptr_type),
elem_layout,
);
BasicValueEnum::StructValue(new_wrapper)
}
Layout::Builtin(Builtin::List(_)) => {
// second_list_len > 0 // second_list_len > 0
// We do this check to avoid allocating memory. If the second input // We do this check to avoid allocating memory. If the second input
// list is empty, then we can just return the first list cloned // list is empty, then we can just return the first list cloned
@ -1185,11 +977,8 @@ pub fn list_concat<'a, 'ctx, 'env>(
list_is_not_empty(builder, ctx, second_list_len); list_is_not_empty(builder, ctx, second_list_len);
let if_second_list_is_not_empty = || { let if_second_list_is_not_empty = || {
let combined_list_len = builder.build_int_add( let combined_list_len =
first_list_len, builder.build_int_add(first_list_len, second_list_len, "add_list_lengths");
second_list_len,
"add_list_lengths",
);
let combined_list_ptr = env let combined_list_ptr = env
.builder .builder
@ -1200,26 +989,9 @@ pub fn list_concat<'a, 'ctx, 'env>(
) )
.unwrap(); .unwrap();
let index_name = "#index";
let index_alloca = builder.build_alloca(ctx.i64_type(), index_name);
// The index variable begins at 0 and increments
// on each iteration of the loop
builder.build_store(index_alloca, ctx.i64_type().const_int(0, false));
// FIRST LOOP // FIRST LOOP
{ let first_loop = |curr_first_loop_index| {
let first_loop_bb = let first_list_ptr = load_list_ptr(builder, first_list_wrapper, ptr_type);
ctx.append_basic_block(parent, "first_list_concat_loop");
builder.build_unconditional_branch(first_loop_bb);
builder.position_at_end(first_loop_bb);
let curr_first_loop_index = builder
.build_load(index_alloca, index_name)
.into_int_value();
let first_list_ptr =
load_list_ptr(builder, first_list_wrapper, ptr_type);
// The pointer to the element in the first list // The pointer to the element in the first list
let first_list_elem_ptr = unsafe { let first_list_elem_ptr = unsafe {
@ -1239,57 +1011,30 @@ pub fn list_concat<'a, 'ctx, 'env>(
) )
}; };
let first_list_elem = let first_list_elem = builder.build_load(first_list_elem_ptr, "get_elem");
builder.build_load(first_list_elem_ptr, "get_elem");
// Mutate the new array in-place to change the element. // Mutate the new array in-place to change the element.
builder.build_store(combined_list_elem_ptr, first_list_elem); builder.build_store(combined_list_elem_ptr, first_list_elem);
};
// #index = #index + 1 let index_name = "#index";
let next_first_loop_index = builder.build_int_add(
curr_first_loop_index,
ctx.i64_type().const_int(1, false),
"nextindex",
);
builder.build_store(index_alloca, next_first_loop_index); let index_alloca = incrementing_index_loop(
// #index < first_list_len
let first_loop_end_cond = bounds_check_comparison(
builder, builder,
next_first_loop_index, parent,
ctx,
first_list_len, first_list_len,
index_name,
None,
first_loop,
); );
let after_first_loop_bb =
ctx.append_basic_block(parent, "after_first_loop");
builder.build_conditional_branch(
first_loop_end_cond,
first_loop_bb,
after_first_loop_bb,
);
builder.position_at_end(after_first_loop_bb);
}
// Reset the index variable to 0 // Reset the index variable to 0
builder.build_store(index_alloca, ctx.i64_type().const_int(0, false)); builder.build_store(index_alloca, ctx.i64_type().const_int(0, false));
// SECOND LOOP // SECOND LOOP
{ let second_loop = |curr_second_index| {
let second_loop_bb = let second_list_ptr = load_list_ptr(builder, second_list_wrapper, ptr_type);
ctx.append_basic_block(parent, "second_list_concat_loop");
builder.build_unconditional_branch(second_loop_bb);
builder.position_at_end(second_loop_bb);
let curr_second_index = builder
.build_load(index_alloca, index_name)
.into_int_value();
let second_list_ptr =
load_list_ptr(builder, second_list_wrapper, ptr_type);
// The pointer to the element in the second list // The pointer to the element in the second list
let second_list_elem_ptr = unsafe { let second_list_elem_ptr = unsafe {
@ -1322,45 +1067,27 @@ pub fn list_concat<'a, 'ctx, 'env>(
) )
}; };
let second_list_elem = let second_list_elem = builder.build_load(second_list_elem_ptr, "get_elem");
builder.build_load(second_list_elem_ptr, "get_elem");
// Mutate the new array in-place to change the element. // Mutate the new array in-place to change the element.
builder.build_store(combined_list_elem_ptr, second_list_elem); builder.build_store(combined_list_elem_ptr, second_list_elem);
};
// #index = #index + 1 incrementing_index_loop(
let next_second_index = builder.build_int_add(
curr_second_index,
ctx.i64_type().const_int(1, false),
"increment_index",
);
builder.build_store(index_alloca, next_second_index);
// #index < second_list_len
let second_loop_end_cond = bounds_check_comparison(
builder, builder,
next_second_index, parent,
ctx,
second_list_len, second_list_len,
index_name,
Some(index_alloca),
second_loop,
); );
let after_second_loop_bb =
ctx.append_basic_block(parent, "after_second_loop");
builder.build_conditional_branch(
second_loop_end_cond,
second_loop_bb,
after_second_loop_bb,
);
builder.position_at_end(after_second_loop_bb);
let ptr_bytes = env.ptr_bytes; let ptr_bytes = env.ptr_bytes;
let int_type = ptr_int(ctx, ptr_bytes); let int_type = ptr_int(ctx, ptr_bytes);
let ptr_as_int = builder.build_ptr_to_int( let ptr_as_int =
combined_list_ptr, builder.build_ptr_to_int(combined_list_ptr, int_type, "list_cast_ptr");
int_type,
"list_cast_ptr",
);
let struct_type = collection(ctx, ptr_bytes); let struct_type = collection(ctx, ptr_bytes);
let mut struct_val; let mut struct_val;
@ -1390,7 +1117,6 @@ pub fn list_concat<'a, 'ctx, 'env>(
collection(ctx, ptr_bytes), collection(ctx, ptr_bytes),
"cast_collection", "cast_collection",
) )
}
}; };
build_basic_phi2( build_basic_phi2(
@ -1401,59 +1127,6 @@ pub fn list_concat<'a, 'ctx, 'env>(
if_second_list_is_empty, if_second_list_is_empty,
BasicTypeEnum::StructType(collection(ctx, env.ptr_bytes)), BasicTypeEnum::StructType(collection(ctx, env.ptr_bytes)),
) )
}
_ => {
unreachable!(
"Invalid List layout for second input list of List.concat: {:?}",
second_list_layout
);
}
}
};
let if_first_list_is_empty = || {
match second_list_layout {
Layout::Builtin(Builtin::EmptyList) => empty_list(env),
Layout::Builtin(Builtin::List(elem_layout)) => {
// second_list_len > 0
// We do this check to avoid allocating memory. If the second input
// list is empty, then we can just return the first list cloned
let second_list_length_comparison =
list_is_not_empty(builder, ctx, second_list_len);
let build_second_list_then = || {
let elem_type =
basic_type_from_layout(env.arena, ctx, elem_layout, env.ptr_bytes);
let ptr_type = get_ptr_type(&elem_type, AddressSpace::Generic);
let (new_wrapper, _) = clone_nonempty_list(
env,
second_list_len,
load_list_ptr(builder, second_list_wrapper, ptr_type),
elem_layout,
);
BasicValueEnum::StructValue(new_wrapper)
};
let build_second_list_else = || empty_list(env);
build_basic_phi2(
env,
parent,
second_list_length_comparison,
build_second_list_then,
build_second_list_else,
BasicTypeEnum::StructType(collection(ctx, env.ptr_bytes)),
)
}
_ => {
unreachable!(
"Invalid List layout for second input list of List.concat: {:?}",
second_list_layout
);
}
}
}; };
build_basic_phi2( build_basic_phi2(
@ -1468,12 +1141,64 @@ pub fn list_concat<'a, 'ctx, 'env>(
_ => { _ => {
unreachable!( unreachable!(
"Invalid List layout for first list in List.concat : {:?}", "Invalid List layout for first list in List.concat : {:?}",
first_list_layout list_layout
); );
} }
} }
} }
// This helper simulates a basic for loop, where
// and index increments up from 0 to some end value
fn incrementing_index_loop<'ctx, LoopFn>(
builder: &Builder<'ctx>,
parent: FunctionValue<'ctx>,
ctx: &'ctx Context,
end: IntValue<'ctx>,
index_name: &str,
// allocating memory for an index is costly, so sometimes
// we want to reuse an index if multiple loops happen in a
// series, such as the case in List.concat. A memory
// allocation cab be passed in to be used, and the memory
// allocation that _is_ used is the return value.
maybe_alloca: Option<PointerValue<'ctx>>,
mut loop_fn: LoopFn,
) -> PointerValue<'ctx>
where
LoopFn: FnMut(IntValue<'ctx>) -> (),
{
let index_alloca = match maybe_alloca {
None => builder.build_alloca(ctx.i64_type(), index_name),
Some(alloca) => alloca,
};
builder.build_store(index_alloca, ctx.i64_type().const_int(0, false));
let loop_bb = ctx.append_basic_block(parent, "loop");
builder.build_unconditional_branch(loop_bb);
builder.position_at_end(loop_bb);
let curr_index = builder
.build_load(index_alloca, index_name)
.into_int_value();
let next_index =
builder.build_int_add(curr_index, ctx.i64_type().const_int(1, false), "nextindex");
builder.build_store(index_alloca, next_index);
// The body of the loop
loop_fn(curr_index);
// #index < end
let loop_end_cond = bounds_check_comparison(builder, next_index, end);
let after_loop_bb = ctx.append_basic_block(parent, "after_outer_loop");
builder.build_conditional_branch(loop_end_cond, loop_bb, after_loop_bb);
builder.position_at_end(after_loop_bb);
index_alloca
}
fn build_basic_phi2<'a, 'ctx, 'env, PassFn, FailFn>( fn build_basic_phi2<'a, 'ctx, 'env, PassFn, FailFn>(
env: &Env<'a, 'ctx, 'env>, env: &Env<'a, 'ctx, 'env>,
parent: FunctionValue<'ctx>, parent: FunctionValue<'ctx>,
@ -1555,3 +1280,72 @@ fn load_list_ptr<'ctx>(
builder.build_int_to_ptr(ptr_as_int, ptr_type, "list_cast_ptr") builder.build_int_to_ptr(ptr_as_int, ptr_type, "list_cast_ptr")
} }
fn clone_nonempty_list<'a, 'ctx, 'env>(
env: &Env<'a, 'ctx, 'env>,
list_len: IntValue<'ctx>,
elems_ptr: PointerValue<'ctx>,
elem_layout: &Layout<'_>,
) -> (StructValue<'ctx>, PointerValue<'ctx>) {
let builder = env.builder;
let ctx = env.context;
let ptr_bytes = env.ptr_bytes;
// Calculate the number of bytes we'll need to allocate.
let elem_bytes = env
.ptr_int()
.const_int(elem_layout.stack_size(env.ptr_bytes) as u64, false);
let size = env
.builder
.build_int_mul(elem_bytes, list_len, "mul_len_by_elem_bytes");
// Allocate space for the new array that we'll copy into.
let elem_type = basic_type_from_layout(env.arena, ctx, elem_layout, env.ptr_bytes);
let clone_ptr = builder
.build_array_malloc(elem_type, list_len, "list_ptr")
.unwrap();
let int_type = ptr_int(ctx, ptr_bytes);
let ptr_as_int = builder.build_ptr_to_int(clone_ptr, int_type, "list_cast_ptr");
// TODO check if malloc returned null; if so, runtime error for OOM!
// Either memcpy or deep clone the array elements
if elem_layout.safe_to_memcpy() {
// Copy the bytes from the original array into the new
// one we just malloc'd.
//
// TODO how do we decide when to do the small memcpy vs the normal one?
builder.build_memcpy(clone_ptr, ptr_bytes, elems_ptr, ptr_bytes, size);
} else {
panic!("TODO Cranelift currently only knows how to clone list elements that are Copy.");
}
// Create a fresh wrapper struct for the newly populated array
let struct_type = collection(ctx, env.ptr_bytes);
let mut struct_val;
// Store the pointer
struct_val = builder
.build_insert_value(
struct_type.get_undef(),
ptr_as_int,
Builtin::WRAPPER_PTR,
"insert_ptr",
)
.unwrap();
// Store the length
struct_val = builder
.build_insert_value(struct_val, list_len, Builtin::WRAPPER_LEN, "insert_len")
.unwrap();
let answer = builder
.build_bitcast(
struct_val.into_struct_value(),
collection(ctx, ptr_bytes),
"cast_collection",
)
.into_struct_value();
(answer, clone_ptr)
}