481 lines
16 KiB
C++
481 lines
16 KiB
C++
//: Spaces help isolate recipes from each other. You can create them at will,
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//: and all addresses in arguments are implicitly based on the 'default-space'
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//: (unless they have the /raw property)
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//:
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//: Spaces are often called 'scopes' in other languages. Stack frames are a
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//: limited form of space that can't outlive callers.
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//:
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//: Warning: messing with 'default-space' can corrupt memory. Don't share
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//: default-space between recipes. Later we'll see how to chain spaces safely.
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//: Under the hood, a space is an array of locations in memory.
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:(before "End Mu Types Initialization")
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put(Type_abbreviations, "space", new_type_tree("address:array:location"));
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:(scenario set_default_space)
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# if default-space is 10, and if an array of 5 locals lies from location 12 to 16 (inclusive),
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# then local 0 is really location 12, local 1 is really location 13, and so on.
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def main [
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# pretend address:array:location; in practice we'll use 'new'
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10:num <- copy 0 # refcount
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11:num <- copy 5 # length
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default-space:space <- copy 10/unsafe
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1:num <- copy 23
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]
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+mem: storing 23 in location 13
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:(scenario lookup_sidesteps_default_space)
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def main [
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# pretend pointer from outside (2000 reserved for refcount)
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2001:num <- copy 34
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# pretend address:array:location; in practice we'll use 'new'
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1000:num <- copy 0 # refcount
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1001:num <- copy 5 # length
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# actual start of this recipe
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default-space:space <- copy 1000/unsafe
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1:&:num <- copy 2000/unsafe # even local variables always contain raw addresses
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8:num/raw <- copy *1:&:num
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]
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+mem: storing 34 in location 8
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//: precondition: disable name conversion for 'default-space'
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:(scenario convert_names_passes_default_space)
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% Hide_errors = true;
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def main [
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default-space:num, x:num <- copy 0, 1
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]
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+name: assign x 1
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-name: assign default-space 1
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:(before "End is_disqualified Special-cases")
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if (x.name == "default-space")
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x.initialized = true;
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:(before "End is_special_name Special-cases")
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if (s == "default-space") return true;
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//: core implementation
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:(before "End call Fields")
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int default_space;
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:(before "End call Constructor")
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default_space = 0;
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:(before "Begin canonize(x) Lookups")
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absolutize(x);
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:(code)
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void absolutize(reagent& x) {
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if (is_raw(x) || is_dummy(x)) return;
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if (x.name == "default-space") return;
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if (!x.initialized)
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raise << to_original_string(current_instruction()) << ": reagent not initialized: '" << x.original_string << "'\n" << end();
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x.set_value(address(x.value, space_base(x)));
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x.properties.push_back(pair<string, string_tree*>("raw", NULL));
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assert(is_raw(x));
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}
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//: hook replaced in a later layer
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int space_base(const reagent& x) {
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return current_call().default_space ? (current_call().default_space+/*skip refcount*/1) : 0;
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}
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int address(int offset, int base) {
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assert(offset >= 0);
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if (base == 0) return offset; // raw
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int size = get_or_insert(Memory, base);
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if (offset >= size) {
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// todo: test
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raise << current_recipe_name() << ": location " << offset << " is out of bounds " << size << " at " << base << '\n' << end();
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DUMP("");
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exit(1);
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return 0;
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}
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return base + /*skip length*/1 + offset;
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}
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//: reads and writes to the 'default-space' variable have special behavior
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:(after "Begin Preprocess write_memory(x, data)")
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if (x.name == "default-space") {
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if (!scalar(data) || !is_mu_space(x))
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raise << maybe(current_recipe_name()) << "'default-space' should be of type address:array:location, but is " << to_string(x.type) << '\n' << end();
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current_call().default_space = data.at(0);
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return;
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}
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:(code)
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bool is_mu_space(reagent/*copy*/ x) {
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canonize_type(x);
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if (!is_compound_type_starting_with(x.type, "address")) return false;
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drop_from_type(x, "address");
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if (!is_compound_type_starting_with(x.type, "array")) return false;
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drop_from_type(x, "array");
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return x.type && x.type->atom && x.type->name == "location";
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}
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:(scenario get_default_space)
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def main [
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default-space:space <- copy 10/unsafe
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1:space/raw <- copy default-space:space
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]
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+mem: storing 10 in location 1
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:(after "Begin Preprocess read_memory(x)")
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if (x.name == "default-space") {
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vector<double> result;
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result.push_back(current_call().default_space);
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return result;
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}
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//:: fix 'get'
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:(scenario lookup_sidesteps_default_space_in_get)
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def main [
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# pretend pointer to container from outside (2000 reserved for refcount)
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2001:num <- copy 34
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2002:num <- copy 35
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# pretend address:array:location; in practice we'll use 'new'
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1000:num <- copy 0 # refcount
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1001:num <- copy 5 # length
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# actual start of this recipe
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default-space:space <- copy 1000/unsafe
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1:&:point <- copy 2000/unsafe
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9:num/raw <- get *1:&:point, 1:offset
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]
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+mem: storing 35 in location 9
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:(before "Read element" following "case GET:")
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element.properties.push_back(pair<string, string_tree*>("raw", NULL));
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//:: fix 'index'
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:(scenario lookup_sidesteps_default_space_in_index)
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def main [
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# pretend pointer to array from outside (2000 reserved for refcount)
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2001:num <- copy 2 # length
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2002:num <- copy 34
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2003:num <- copy 35
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# pretend address:array:location; in practice we'll use 'new'
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1000:num <- copy 0 # refcount
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1001:num <- copy 5 # length
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# actual start of this recipe
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default-space:space <- copy 1000/unsafe
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1:&:@:num <- copy 2000/unsafe
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9:num/raw <- index *1:&:@:num, 1
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]
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+mem: storing 35 in location 9
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:(before "Read element" following "case INDEX:")
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element.properties.push_back(pair<string, string_tree*>("raw", NULL));
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//:: 'local-scope' is a convenience operation to automatically deduce
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//:: the amount of space to allocate in a default space with names
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:(scenario local_scope)
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def main [
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local-scope
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x:num <- copy 0
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y:num <- copy 3
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]
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# allocate space for x and y, as well as the chaining slot at 0
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+mem: array length is 3
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:(before "End is_disqualified Special-cases")
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if (x.name == "number-of-locals")
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x.initialized = true;
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:(before "End is_special_name Special-cases")
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if (s == "number-of-locals") return true;
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:(before "End Rewrite Instruction(curr, recipe result)")
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// rewrite 'local-scope' to
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// ```
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// default-space:space <- new location:type, number-of-locals:literal
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// ```
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// where number-of-locals is Name[recipe][""]
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if (curr.name == "local-scope") {
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rewrite_default_space_instruction(curr);
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}
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:(code)
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void rewrite_default_space_instruction(instruction& curr) {
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if (!curr.ingredients.empty())
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raise << "'" << to_original_string(curr) << "' can't take any ingredients\n" << end();
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curr.name = "new";
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curr.ingredients.push_back(reagent("location:type"));
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curr.ingredients.push_back(reagent("number-of-locals:literal"));
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if (!curr.products.empty())
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raise << "new-default-space can't take any results\n" << end();
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curr.products.push_back(reagent("default-space:space"));
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}
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:(after "Begin Preprocess read_memory(x)")
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if (x.name == "number-of-locals") {
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vector<double> result;
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result.push_back(Name[get(Recipe_ordinal, current_recipe_name())][""]);
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if (result.back() == 0)
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raise << "no space allocated for default-space in recipe " << current_recipe_name() << "; are you using names?\n" << end();
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return result;
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}
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:(after "Begin Preprocess write_memory(x, data)")
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if (x.name == "number-of-locals") {
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raise << maybe(current_recipe_name()) << "can't write to special name 'number-of-locals'\n" << end();
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return;
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}
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//:: try to reclaim the default-space when a recipe returns
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:(scenario local_scope_reclaimed_on_return)
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def main [
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1:num <- foo
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2:num <- foo
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3:bool <- equal 1:num, 2:num
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]
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def foo [
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local-scope
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result:num <- copy default-space:space
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return result:num
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]
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# both calls to foo should have received the same default-space
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+mem: storing 1 in location 3
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//: todo: do this in a transform, rather than magically in the 'return' instruction
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:(after "Falling Through End Of Recipe")
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reclaim_default_space();
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:(after "Begin Return")
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reclaim_default_space();
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:(code)
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void reclaim_default_space() {
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if (!Reclaim_memory) return;
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reagent default_space("default-space:address:array:location");
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decrement_any_refcounts(default_space);
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}
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:(after "Begin Decrement Refcounts(canonized_x)")
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if (is_mu_space(canonized_x)) {
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int space_address = (canonized_x.name == "default-space") ? current_call().default_space : get_or_insert(Memory, canonized_x.value);
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if (space_address == 0) return;
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// this branch relies on global state
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string recipe_name;
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if (has_property(canonized_x, "names")) {
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assert(property(canonized_x, "names")->atom);
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recipe_name = property(canonized_x, "names")->value;
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}
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else {
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if (canonized_x.name != "default-space")
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cerr << current_recipe_name() << ": " << to_string(canonized_x) << '\n';
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assert(canonized_x.name == "default-space");
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recipe_name = current_recipe_name();
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}
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const recipe_ordinal space_recipe_ordinal = get(Recipe_ordinal, recipe_name);
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const recipe& space_recipe = get(Recipe, space_recipe_ordinal);
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if (canonized_x.name == "default-space" && !has_property(canonized_x, "names") && !starts_by_setting_default_space(space_recipe)) return;
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// Reclaim Space(space_address, space_recipe_ordinal, space_recipe)
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decrement_refcount(space_address, canonized_x.type->right,
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/*refcount*/1 + /*array length*/1 + /*number-of-locals*/Name[space_recipe_ordinal][""]);
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return;
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}
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:(code)
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bool starts_by_setting_default_space(const recipe& r) {
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return !r.steps.empty()
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&& !r.steps.at(0).products.empty()
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&& r.steps.at(0).products.at(0).name == "default-space";
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}
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//:
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:(scenario local_scope_reclaims_locals)
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def main [
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local-scope
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x:text <- new [abc]
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]
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# x
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+mem: automatically abandoning 1004
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# local-scope
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+mem: automatically abandoning 1000
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:(before "Reclaim Space(space_address, space_recipe_ordinal, space_recipe)")
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if (get_or_insert(Memory, space_address) <= 1) {
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set<string> reclaimed_locals;
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trace("mem") << "trying to reclaim locals" << end();
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// update any refcounts for variables in the space -- in the context of the space
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call_stack calls_stash = save_call_stack(space_address, space_recipe_ordinal);
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Current_routine->calls.swap(calls_stash);
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// no early returns until we restore 'calls' below
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for (int i = /*leave default space for last*/1; i < SIZE(space_recipe.steps); ++i) {
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const instruction& inst = space_recipe.steps.at(i);
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for (int i = 0; i < SIZE(inst.products); ++i) {
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reagent/*copy*/ product = inst.products.at(i);
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if (reclaimed_locals.find(product.name) != reclaimed_locals.end()) continue;
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reclaimed_locals.insert(product.name);
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// local variables only
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if (has_property(product, "lookup")) continue;
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if (has_property(product, "raw")) continue; // tests often want to check such locations after they run
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// End Checks For Reclaiming Locals
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trace("mem") << "trying to reclaim local " << product.original_string << end();
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canonize(product);
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decrement_any_refcounts(product);
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}
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}
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Current_routine->calls.swap(calls_stash); // restore
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}
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:(code)
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call_stack save_call_stack(int space_address, recipe_ordinal space_recipe_ordinal) {
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call dummy_call(space_recipe_ordinal);
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dummy_call.default_space = space_address;
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call_stack result;
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result.push_front(dummy_call);
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return result;
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}
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:(scenario local_variables_can_outlive_call)
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def main [
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local-scope
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x:&:num <- new num:type
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y:space <- copy default-space:space
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]
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-mem: automatically abandoning 1005
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//:
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:(scenario local_scope_does_not_reclaim_escaping_locals)
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def main [
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1:text <- foo
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]
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def foo [
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local-scope
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x:text <- new [abc]
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return x:text
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]
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# local-scope
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+mem: automatically abandoning 1000
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# x
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-mem: automatically abandoning 1004
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:(after "Begin Return") // before reclaiming default-space
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increment_refcounts_of_return_ingredients(ingredients);
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:(code)
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void increment_refcounts_of_return_ingredients(const vector<vector<double> >& ingredients) {
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assert(current_instruction().operation == RETURN);
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if (SIZE(Current_routine->calls) == 1) // no caller to receive result
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return;
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const instruction& caller_instruction = to_instruction(*++Current_routine->calls.begin());
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for (int i = 0; i < min(SIZE(current_instruction().ingredients), SIZE(caller_instruction.products)); ++i) {
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if (!is_dummy(caller_instruction.products.at(i))) {
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// no need to canonize ingredient because we ignore its value
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increment_any_refcounts(current_instruction().ingredients.at(i), ingredients.at(i));
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}
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}
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}
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//:
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:(scenario local_scope_frees_up_addresses_inside_containers)
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container foo [
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x:num
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y:&:num
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]
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def main [
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local-scope
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x:&:num <- new number:type
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y:foo <- merge 34, x:&:num
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# x and y are both cleared when main returns
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]
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+mem: automatically abandoning 1006
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:(scenario local_scope_returns_addresses_inside_containers)
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container foo [
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x:num
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y:&:num
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]
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def f [
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local-scope
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x:&:num <- new number:type
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*x:&:num <- copy 12
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y:foo <- merge 34, x:&:num
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# since y is 'escaping' f, it should not be cleared
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return y:foo
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]
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def main [
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1:foo <- f
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3:num <- get 1:foo, x:offset
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4:&:num <- get 1:foo, y:offset
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5:num <- copy *4:&:num
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1:foo <- put 1:foo, y:offset, 0
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4:&:num <- copy 0
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]
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+mem: storing 34 in location 1
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+mem: storing 1006 in location 2
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+mem: storing 34 in location 3
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# refcount of 1:foo shouldn't include any stray ones from f
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+run: {4: ("address" "number")} <- get {1: "foo"}, {y: "offset"}
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+mem: incrementing refcount of 1006: 1 -> 2
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# 1:foo wasn't abandoned/cleared
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+run: {5: "number"} <- copy {4: ("address" "number"), "lookup": ()}
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+mem: storing 12 in location 5
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+run: {1: "foo"} <- put {1: "foo"}, {y: "offset"}, {0: "literal"}
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+mem: decrementing refcount of 1006: 2 -> 1
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+run: {4: ("address" "number")} <- copy {0: "literal"}
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+mem: decrementing refcount of 1006: 1 -> 0
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+mem: automatically abandoning 1006
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:(scenario local_scope_claims_return_values_when_not_saved)
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def f [
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local-scope
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x:&:num <- new number:type
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return x:&:num
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]
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def main [
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f # doesn't save result
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]
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# x reclaimed
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+mem: automatically abandoning 1004
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# f's local scope reclaimed
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+mem: automatically abandoning 1000
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//:: all recipes must set default-space one way or another
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:(before "End Globals")
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bool Hide_missing_default_space_errors = true;
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:(before "End Checks")
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Transform.push_back(check_default_space); // idempotent
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:(code)
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void check_default_space(const recipe_ordinal r) {
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if (Hide_missing_default_space_errors) return; // skip previous core tests; this is only for Mu code
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const recipe& caller = get(Recipe, r);
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// End check_default_space Special-cases
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// assume recipes with only numeric addresses know what they're doing (usually tests)
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if (!contains_non_special_name(r)) return;
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trace(9991, "transform") << "--- check that recipe " << caller.name << " sets default-space" << end();
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if (caller.steps.empty()) return;
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if (!starts_by_setting_default_space(caller))
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raise << caller.name << " does not seem to start with 'local-scope' or 'default-space'\n" << end();
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}
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:(after "Load Mu Prelude")
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Hide_missing_default_space_errors = false;
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:(after "Test Runs")
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Hide_missing_default_space_errors = true;
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:(after "Running Main")
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Hide_missing_default_space_errors = false;
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:(code)
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bool contains_non_special_name(const recipe_ordinal r) {
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for (map<string, int>::iterator p = Name[r].begin(); p != Name[r].end(); ++p) {
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if (p->first.empty()) continue;
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if (p->first.find("stash_") == 0) continue; // generated by rewrite_stashes_to_text (cross-layer)
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if (!is_special_name(p->first))
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return true;
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}
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return false;
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}
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// reagent comparison -- only between reagents in a single recipe
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bool operator==(const reagent& a, const reagent& b) {
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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;
|
|
}
|