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//: Support jumps to labels.
//: We'll also treat 'break' and 'loop' as jumps. The choice of name is
//: just documentation about intent; use 'break' to indicate you're exiting
//: one or more loop nests, and 'loop' to indicate you're skipping to the next
//: iteration of some containing loop nest.
:(scenario jump_to_label)
recipe main [
jump +target:label
1:number <- copy 0
+target
]
-mem: storing 0 in location 1
:(before "End Mu Types Initialization")
Type_ordinal["label"] = 0;
:(after "int main")
Transform.push_back(transform_labels);
:(code)
void transform_labels(const recipe_ordinal r) {
map<string, long long int> offset;
for (long long int i = 0; i < SIZE(Recipe[r].steps); ++i) {
const instruction& inst = Recipe[r].steps.at(i);
if (!inst.label.empty()) offset[inst.label] = i;
}
for (long long int i = 0; i < SIZE(Recipe[r].steps); ++i) {
instruction& inst = Recipe[r].steps.at(i);
if (inst.operation == Recipe_ordinal["jump"]) {
replace_offset(inst.ingredients.at(0), offset, i, r);
}
if (inst.operation == Recipe_ordinal["jump-if"] || inst.operation == Recipe_ordinal["jump-unless"]) {
replace_offset(inst.ingredients.at(1), offset, i, r);
}
if ((inst.operation == Recipe_ordinal["loop"] || inst.operation == Recipe_ordinal["break"])
&& SIZE(inst.ingredients) == 1) {
replace_offset(inst.ingredients.at(0), offset, i, r);
}
if ((inst.operation == Recipe_ordinal["loop-if"] || inst.operation == Recipe_ordinal["loop-unless"]
|| inst.operation == Recipe_ordinal["break-if"] || inst.operation == Recipe_ordinal["break-unless"])
&& SIZE(inst.ingredients) == 2) {
replace_offset(inst.ingredients.at(1), offset, i, r);
}
}
}
:(code)
void replace_offset(reagent& x, /*const*/ map<string, long long int>& offset, const long long int current_offset, const recipe_ordinal r) {
if (!is_literal(x)) {
raise << Recipe[r].name << ": jump target must be offset or label but is " << x.original_string << '\n' << end();
return;
}
assert(!x.initialized);
if (is_integer(x.name)) return; // non-labels will be handled like other number operands
if (offset.find(x.name) == offset.end())
raise << Recipe[r].name << ": can't find label " << x.name << '\n' << end();
x.set_value(offset[x.name]-current_offset);
}
:(scenario break_to_label)
recipe main [
#? $print [aaa]
{
{
break +target:label
1:number <- copy 0
}
}
+target
]
-mem: storing 0 in location 1
:(scenario jump_if_to_label)
recipe main [
{
{
jump-if 1, +target:label
1:number <- copy 0
}
}
+target
]
-mem: storing 0 in location 1
:(scenario loop_unless_to_label)
recipe main [
{
{
loop-unless 0, +target:label # loop/break with a label don't care about braces
1:number <- copy 0
}
}
+target
]
-mem: storing 0 in location 1
:(scenario jump_runs_code_after_label)
recipe main [
# first a few lines of padding to exercise the offset computation
1:number <- copy 0
2:number <- copy 0
3:number <- copy 0
jump +target:label
4:number <- copy 0
+target
5:number <- copy 0
]
+mem: storing 0 in location 5
-mem: storing 0 in location 4
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