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Micro optimization for iterating over array ranges

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This commit is contained in:
Bruce Hill 2024-07-20 17:13:15 -04:00
parent fb95bbb1d4
commit 279cd23143
2 changed files with 38 additions and 8 deletions
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40
compile.c
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@ -822,17 +822,41 @@ CORD compile_statement(env_t *env, ast_t *ast)
}
}
CORD array = is_idempotent(for_->iter) ? compile(env, for_->iter) : "arr";
CORD loop = CORD_all("ARRAY_INCREF(", array, ");\n"
"for (int64_t ", index, " = 1; ", index, " <= ", array, ".length; ++", index, ") {\n",
ast_t *array = for_->iter;
CORD array_code, for_code;
// Micro-optimization: inline the logic for iterating over
// `array:from(i)` and `array:to(i)` because these happen inside
// hot path inner loops and can actually meaningfully affect
// performance:
if (for_->iter->tag == MethodCall && streq(Match(for_->iter, MethodCall)->name, "to")
&& value_type(get_type(env, Match(for_->iter, MethodCall)->self))->tag == ArrayType) {
array = Match(for_->iter, MethodCall)->self;
array_code = is_idempotent(array) ? compile(env, array) : "arr";
CORD limit = compile_arguments(env, for_->iter, new(arg_t, .type=Type(IntType, .bits=64), .name="last"), Match(for_->iter, MethodCall)->args);
for_code = CORD_all("for (int64_t ", index, " = 1, raw_limit = ", limit,
", limit = raw_limit < 0 ? ", array_code, ".length + raw_limit + 1 : raw_limit; ",
index, " <= limit; ++", index, ")");
} else if (for_->iter->tag == MethodCall && streq(Match(for_->iter, MethodCall)->name, "from")
&& value_type(get_type(env, Match(for_->iter, MethodCall)->self))->tag == ArrayType) {
array = Match(for_->iter, MethodCall)->self;
array_code = is_idempotent(array) ? compile(env, array) : "arr";
CORD first = compile_arguments(env, for_->iter, new(arg_t, .type=Type(IntType, .bits=64), .name="last"), Match(for_->iter, MethodCall)->args);
for_code = CORD_all("for (int64_t ", index, " = ", first, "; ", index, " <= ", array_code, ".length; ++", index, ")");
} else {
array_code = is_idempotent(array) ? compile(env, array) : "arr";
for_code = CORD_all("for (int64_t ", index, " = 1; ", index, " <= ", array_code, ".length; ++", index, ")");
}
CORD loop = CORD_all("ARRAY_INCREF(", array_code, ");\n",
for_code, "{\n",
compile_type(item_t), " ", value,
" = *(", compile_type(item_t), "*)(", array, ".data + (",index,"-1)*", array, ".stride);\n",
" = *(", compile_type(item_t), "*)(", array_code, ".data + (",index,"-1)*", array_code, ".stride);\n",
body, "\n}");
if (for_->empty)
loop = CORD_all("if (", array, ".length > 0) {\n", loop, "\n} else ", compile_statement(env, for_->empty));
loop = CORD_all(loop, stop, "\nARRAY_DECREF(", array, ");\n");
if (!is_idempotent(for_->iter))
loop = CORD_all("{\narray_t ",array," = ", compile(env, for_->iter), ";\n", loop, "\n}");
loop = CORD_all("if (", array_code, ".length > 0) {\n", loop, "\n} else ", compile_statement(env, for_->empty));
loop = CORD_all(loop, stop, "\nARRAY_DECREF(", array_code, ");\n");
if (!is_idempotent(array))
loop = CORD_all("{\narray_t ",array_code," = ", compile(env, array), ";\n", loop, "\n}");
return loop;
}
case TableType: {

6
test/arrays.tm
View File

@ -143,3 +143,9 @@ func main():
>> [i*10 for i in 10]:by(2):by(-1)
= [90, 70, 50, 30, 10]
// Test iterating over array:from() and array:to()
xs := ["A", "B", "C", "D"]
for i,x in xs:to(-2):
for y in xs:from(i+1):
say("{x}{y}")