Add str(int) and repr(int) fast path using i64 conversion

youknowone · youknowone · commit 872a6e0f8ec1 · 2026-03-02T00:58:35.000+09:00
- Skip __str__ method resolution for exact PyInt in PyObject::str()
- Use i64::to_string() for small integers, BigInt::to_string() for large ones
- ~36% improvement in str(int) benchmarks
diff --git a/crates/vm/src/builtins/int.rs b/crates/vm/src/builtins/int.rs
@@ -603,7 +603,10 @@ impl Comparable for PyInt {
 impl Representable for PyInt {
     #[inline]
     fn repr_str(zelf: &Py<Self>, _vm: &VirtualMachine) -> PyResult<String> {
-        Ok(zelf.value.to_string())
+        Ok(match zelf.value.to_i64() {
+            Some(i) => i.to_string(),
+            None => zelf.value.to_string(),
+        })
     }
 }
 
diff --git a/crates/vm/src/protocol/object.rs b/crates/vm/src/protocol/object.rs
@@ -15,6 +15,7 @@ use crate::{
     protocol::PyIter,
     types::{Constructor, PyComparisonOp},
 };
+use num_traits::ToPrimitive;
 
 // RustPython doesn't need these items
 // PyObject *Py_NotImplemented
@@ -375,6 +376,17 @@ impl PyObject {
             Ok(s) => return Ok(s.into_pyref()),
             Err(obj) => obj,
         };
+        // Fast path for exact int: skip __str__ method resolution
+        let obj = match obj.downcast_exact::<PyInt>(vm) {
+            Ok(int) => {
+                let s = match int.as_bigint().to_i64() {
+                    Some(i) => i.to_string(),
+                    None => int.as_bigint().to_string(),
+                };
+                return Ok(vm.ctx.new_str(s));
+            }
+            Err(obj) => obj,
+        };
         // TODO: replace to obj.class().slots.str
         let str_method = match vm.get_special_method(&obj, identifier!(vm, __str__))? {
             Some(str_method) => str_method,

Original file line number	Diff line number	Diff line change
`@@ -603,7 +603,10 @@ impl Comparable for PyInt {`
`603`	`603`	`impl Representable for PyInt {`
`604`	`604`	`#[inline]`
`605`	`605`	`fn repr_str(zelf: &Py<Self>, _vm: &VirtualMachine) -> PyResult<String> {`
`606`		`- Ok(zelf.value.to_string())`
	`606`	`+ Ok(match zelf.value.to_i64() {`
	`607`	`+ Some(i) => i.to_string(),`
	`608`	`+ None => zelf.value.to_string(),`
	`609`	`+ })`
`607`	`610`	`}`
`608`	`611`	`}`
`609`	`612`