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Default struct member reordering for minimal size

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Rule: largest members to smallest; if same size, order in source order
This commit is contained in:
Ginger Bill
2016-09-10 11:24:50 +01:00
parent 6979678ff9
commit 7509cdceb8
7 changed files with 66 additions and 35 deletions
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45
src/checker/expr.cpp
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@@ -357,14 +357,15 @@ void check_fields(Checker *c, AstNode *node, AstNodeArray decls,
AstNode *name = vd->names[name_index];
Token name_token = name->Ident;
Entity *e = make_entity_field(c->allocator, c->context.scope, name_token, type, vd->is_using);
Entity *e = make_entity_field(c->allocator, c->context.scope, name_token, type, vd->is_using, cast(i32)field_index);
HashKey key = hash_string(name_token.string);
if (map_get(&entity_map, key) != NULL) {
// TODO(bill): Scope checking already checks the declaration
error(&c->error_collector, name_token, "`%.*s` is already declared in this type", LIT(name_token.string));
} else {
map_set(&entity_map, key, e);
fields[field_index++] = e;
fields[field_index] = e;
field_index++;
add_entity(c, c->context.scope, name, e);
}
add_entity_use(&c->info, name, e);
@@ -391,13 +392,19 @@ gb_global BaseTypeSizes __checker_sizes = {};
gb_global gbAllocator __checker_allocator = {};
GB_COMPARE_PROC(cmp_struct_entity_size) {
// NOTE(bill): Biggest to smallest
// Rule: Biggest to smallest
// if same size, order by order in source
Entity *x = *(Entity **)a;
Entity *y = *(Entity **)b;
GB_ASSERT(x != NULL);
GB_ASSERT(y != NULL);
GB_ASSERT(x->kind == Entity_Variable);
GB_ASSERT(y->kind == Entity_Variable);
i64 xs = type_size_of(__checker_sizes, __checker_allocator, x->type);
i64 ys = type_size_of(__checker_sizes, __checker_allocator, y->type);
if (xs == ys) {
return string_cmp(&x->token.string, &y->token.string);
i32 diff = x->Variable.field_index - y->Variable.field_index;
return diff < 0 ? -1 : diff > 0;
}
return xs > ys ? -1 : xs < ys;
}
@@ -430,24 +437,36 @@ void check_struct_type(Checker *c, Type *struct_type, AstNode *node, CycleChecke
check_fields(c, node, st->decls, fields, field_count, other_fields, other_field_count, cycle_checker, make_string("struct"));
struct_type->Record.struct_is_packed = st->is_packed;
struct_type->Record.struct_is_ordered = st->is_ordered;
struct_type->Record.fields = fields;
struct_type->Record.fields_in_src_order = fields;
struct_type->Record.field_count = field_count;
struct_type->Record.other_fields = other_fields;
struct_type->Record.other_field_count = other_field_count;
if (!st->is_packed && !st->is_ordered) {
// NOTE(bill): Reorder fields for reduced size/performance
Entity **reordered_fields = gb_alloc_array(c->allocator, Entity *, field_count);
for (isize i = 0; i < field_count; i++) {
reordered_fields[i] = struct_type->Record.fields_in_src_order[i];
}
// NOTE(bill): Hacky thing
__checker_sizes = c->sizes;
__checker_allocator = c->allocator;
// TODO(bill): Figure out rules more
// sorting rules
// compound literal order must match source not layout
// gb_sort_array(fields, field_count, cmp_struct_entity_size);
gb_sort_array(reordered_fields, field_count, cmp_struct_entity_size);
struct_type->Record.fields = reordered_fields;
}
struct_type->Record.struct_is_packed = st->is_packed;
struct_type->Record.struct_is_ordered = st->is_ordered;
struct_type->Record.fields = fields;
struct_type->Record.field_count = field_count;
struct_type->Record.other_fields = other_fields;
struct_type->Record.other_field_count = other_field_count;
}
void check_union_type(Checker *c, Type *union_type, AstNode *node, CycleChecker *cycle_checker) {
@@ -3097,7 +3116,7 @@ ExprKind check__expr_base(Checker *c, Operand *o, AstNode *node, Type *type_hint
"Mixture of `field = value` and value elements in a structure literal is not allowed");
continue;
}
Entity *field = t->Record.fields[index];
Entity *field = t->Record.fields_in_src_order[index];
check_expr(c, o, elem);
if (index >= field_count) {