//: Spaces help isolate recipes from each other. You can create them at will,
//: and all addresses in arguments are implicitly based on the 'default-space'
//: (unless they have the /raw property)
//:
//: Spaces are often called 'scopes' in other languages. Stack frames are a
//: limited form of space that can't outlive callers.
//:
//: Warning: messing with 'default-space' can corrupt memory. Don't share
//: default-space between recipes. Later we'll see how to chain spaces safely.
//: Under the hood, a space is an array of locations in memory.
:(before "End Mu Types Initialization")
put(Type_abbreviations, "space", new_type_tree("address:array:location"));
:(scenario set_default_space)
# if default-space is 10, and if an array of 5 locals lies from location 12 to 16 (inclusive),
# then local 0 is really location 12, local 1 is really location 13, and so on.
def main [
# pretend address:array:location; in practice we'll use 'new'
10:num <- copy 5 # length
default-space:space <- copy 10/unsafe
1:num <- copy 23
]
+mem: storing 23 in location 12
:(scenario lookup_sidesteps_default_space)
def main [
# pretend pointer from outside
2000:num <- copy 34
# pretend address:array:location; in practice we'll use 'new'
1000:num <- copy 5 # length
# actual start of this recipe
default-space:space <- copy 1000/unsafe
1:&:num <- copy 2000/unsafe # even local variables always contain raw addresses
8:num/raw <- copy *1:&:num
]
+mem: storing 34 in location 8
//: precondition: disable name conversion for 'default-space'
:(scenario convert_names_passes_default_space)
% Hide_errors = true;
def main [
default-space:num, x:num <- copy 0, 1
]
+name: assign x 1
-name: assign default-space 1
:(before "End is_disqualified Special-cases")
if (x.name == "default-space")
x.initialized = true;
:(before "End is_special_name Special-cases")
if (s == "default-space") return true;
//: core implementation
:(before "End call Fields")
int default_space;
:(before "End call Constructor")
default_space = 0;
:(before "Begin canonize(x) Lookups")
absolutize(x);
:(code)
void absolutize(reagent& x) {
if (is_raw(x) || is_dummy(x)) return;
if (x.name == "default-space") return;
if (!x.initialized)
raise << to_original_string(current_instruction()) << ": reagent not initialized: '" << x.original_string << "'\n" << end();
x.set_value(address(x.value, space_base(x)));
x.properties.push_back(pair<string, string_tree*>("raw", NULL));
assert(is_raw(x));
}
//: hook replaced in a later layer
int space_base(const reagent& x) {
return current_call().default_space ? current_call().default_space : 0;
}
int address(int offset, int base) {
assert(offset >= 0);
if (base == 0) return offset; // raw
int size = get_or_insert(Memory, base);
if (offset >= size) {
// todo: test
raise << current_recipe_name() << ": location " << offset << " is out of bounds " << size << " at " << base << '\n' << end();
DUMP("");
exit(1);
return 0;
}
return base + /*skip length*/1 + offset;
}
//: reads and writes to the 'default-space' variable have special behavior
:(after "Begin Preprocess write_memory(x, data)")
if (x.name == "default-space") {
if (!scalar(data) || !is_mu_space(x))
raise << maybe(current_recipe_name()) << "'default-space' should be of type address:array:location, but is " << to_string(x.type) << '\n' << end();
current_call().default_space = data.at(0);
return;
}
:(code)
bool is_mu_space(reagent/*copy*/ x) {
canonize_type(x);
if (!is_compound_type_starting_with(x.type, "address")) return false;
drop_from_type(x, "address");
if (!is_compound_type_starting_with(x.type, "array")) return false;
drop_from_type(x, "array");
return x.type && x.type->atom && x.type->name == "location";
}
:(scenario get_default_space)
def main [
default-space:space <- copy 10/unsafe
1:space/raw <- copy default-space:space
]
+mem: storing 10 in location 1
:(after "Begin Preprocess read_memory(x)")
if (x.name == "default-space") {
vector<double> result;
result.push_back(current_call().default_space);
return result;
}
//:: fix 'get'
:(scenario lookup_sidesteps_default_space_in_get)
def main [
# pretend pointer to container from outside
2000:num <- copy 34
2001:num <- copy 35
# pretend address:array:location; in practice we'll use 'new'
1000:num <- copy 5 # length
# actual start of this recipe
default-space:space <- copy 1000/unsafe
1:&:point <- copy 2000/unsafe
9:num/raw <- get *1:&:point, 1:offset
]
+mem: storing 35 in location 9
:(before "Read element" following "case GET:")
element.properties.push_back(pair<string, string_tree*>("raw", NULL));
//:: fix 'index'
:(scenario lookup_sidesteps_default_space_in_index)
def main [
# pretend pointer to array from outside
2000:num <- copy 2 # length
2001:num <- copy 34
2002:num <- copy 35
# pretend address:array:location; in practice we'll use 'new'
1000:num <- copy 5 # length
# actual start of this recipe
default-space:space <- copy 1000/unsafe
1:&:@:num <- copy 2000/unsafe
9:num/raw <- index *1:&:@:num, 1
]
+mem: storing 35 in location 9
:(before "Read element" following "case INDEX:")
element.properties.push_back(pair<string, string_tree*>("raw", NULL));
//:: 'local-scope' is a convenience operation to automatically deduce
//:: the amount of space to allocate in a default space with names
:(scenario local_scope)
def main [
local-scope
x:num <- copy 0
y:num <- copy 3
]
# allocate space for x and y, as well as the chaining slot at 0
+mem: array length is 3
:(before "End is_disqualified Special-cases")
if (x.name == "number-of-locals")
x.initialized = true;
:(before "End is_special_name Special-cases")
if (s == "number-of-locals") return true;
:(before "End Rewrite Instruction(curr, recipe result)")
// rewrite 'local-scope' to
// ```
// default-space:space <- new location:type, number-of-locals:literal
// ```
// where number-of-locals is Name[recipe][""]
if (curr.name == "local-scope") {
rewrite_default_space_instruction(curr);
}
:(code)
void rewrite_default_space_instruction(instruction& curr) {
if (!curr.ingredients.empty())
raise << "'" << to_original_string(curr) << "' can't take any ingredients\n" << end();
curr.name = "new";
curr.ingredients.push_back(reagent("location:type"));
curr.ingredients.push_back(reagent("number-of-locals:literal"));
if (!curr.products.empty())
raise << "local-scope can't take any results\n" << end();
curr.products.push_back(reagent("default-space:space"));
}
:(after "Begin Preprocess read_memory(x)")
if (x.name == "number-of-locals") {
vector<double> result;
result.push_back(Name[get(Recipe_ordinal, current_recipe_name())][""]);
if (result.back() == 0)
raise << "no space allocated for default-space in recipe " << current_recipe_name() << "; are you using names?\n" << end();
return result;
}
:(after "Begin Preprocess write_memory(x, data)")
if (x.name == "number-of-locals") {
raise << maybe(current_recipe_name()) << "can't write to special name 'number-of-locals'\n" << end();
return;
}
//:: all recipes must set default-space one way or another
:(before "End Globals")
bool Hide_missing_default_space_errors = true;
:(before "End Checks")
Transform.push_back(check_default_space); // idempotent
:(code)
void check_default_space(const recipe_ordinal r) {
if (Hide_missing_default_space_errors) return; // skip previous core tests; this is only for Mu code
const recipe& caller = get(Recipe, r);
// End check_default_space Special-cases
// assume recipes with only numeric addresses know what they're doing (usually tests)
if (!contains_non_special_name(r)) return;
trace(9991, "transform") << "--- check that recipe " << caller.name << " sets default-space" << end();
if (caller.steps.empty()) return;
if (!starts_by_setting_default_space(caller))
raise << caller.name << " does not seem to start with 'local-scope' or 'default-space'\n" << end();
}
bool starts_by_setting_default_space(const recipe& r) {
return !r.steps.empty()
&& !r.steps.at(0).products.empty()
&& r.steps.at(0).products.at(0).name == "default-space";
}
:(after "Load Mu Prelude")
Hide_missing_default_space_errors = false;
:(after "Test Runs")
Hide_missing_default_space_errors = true;
:(after "Running Main")
Hide_missing_default_space_errors = false;
:(code)
bool contains_non_special_name(const recipe_ordinal r) {
for (map<string, int>::iterator p = Name[r].begin(); p != Name[r].end(); ++p) {
if (p->first.empty()) continue;
if (p->first.find("stash_") == 0) continue; // generated by rewrite_stashes_to_text (cross-layer)
if (!is_special_name(p->first))
return true;
}
return false;
}
// reagent comparison -- only between reagents in a single recipe
bool operator==(const reagent& a, const reagent& b) {
if (a.name != b.name) return false;
if (property(a, "space") != property(b, "space")) return false;
return true;
}
bool operator<(const reagent& a, const reagent& b) {
int aspace = 0, bspace = 0;
if (has_property(a, "space")) aspace = to_integer(property(a, "space")->value);
if (has_property(b, "space")) bspace = to_integer(property(b, "space")->value);
if (aspace != bspace) return aspace < bspace;
return a.name < b.name;
}