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Merged
nunoplopes merged 2 commits into from
May 20, 2026
Merged

Rewrite compound assignment in a single expression #120

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204f3bb
Rewrite compound assignment in a single expression
lucic71 May 18, 2026
a676434
Hoist _ptr to save one clone
lucic71 May 18, 2026
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10 changes: 5 additions & 5 deletions cpp2rust/converter/models/converter_refcount.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1796,13 +1796,13 @@ void ConverterRefCount::ConvertAssignment(clang::Expr *lhs, clang::Expr *rhs,
auto lhs_str = ConvertLValue(lhs);
if (!pending_deref_.empty()) {
auto ptr = pending_deref_.take();
// *ptr += val => { let __ptr = ptr.clone(); let __tmp = __ptr.read() +
// val;
// __ptr.write(__tmp) }
auto op = assign_operator;
op.remove_suffix(1); // remove '='
StrCat("{ let __ptr = ", ptr, ".clone(); let __tmp = __ptr.read() ", op,
" ", rhs_as_string, "; __ptr.write(__tmp) }");
{
PushBrace brace(*this);
StrCat(std::format("let _ptr = {}.clone();", ptr));
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@nunoplopes nunoplopes May 18, 2026

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why doesn't this use the emitFreshPointer functionality instead of always doing a clone?

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@lucic71 lucic71 May 18, 2026

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No good reason. I will replace with ConvertFreshPointer

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@lucic71 lucic71 May 18, 2026

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I took a closer look and it's not trivial to replace with ConvertFreshPointer. This path uses the pending_deref_ mechanism. pending_deref_ is generally used for rewriting mutable method receivers to use Ptr::with_mut. Or more generally, to convert pointer dereferences in AddrOf/LValue contexts.

pending_deref_ is triggered inside ConvertLValue, line 1796 above, so every user of ConvertLValue must also check pending_deref_.

StrCat(std::format("_ptr.write(_ptr.read() {} {})", op, rhs_as_string));
}
} else {
StrCat(lhs_str, assign_operator, rhs_as_string);
}
Expand Down
30 changes: 12 additions & 18 deletions tests/unit/out/refcount/borrow_mut_opt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -68,45 +68,39 @@ pub fn convert_with_rhs_1() {
(*arr.borrow_mut())[(0) as usize] = __rhs;
let __rhs = (*x.borrow());
{
let __ptr = z.clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = z.clone();
_ptr.write(_ptr.read() + __rhs)
};
let __rhs = (*y.borrow());
{
let __ptr = z.clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = z.clone();
_ptr.write(_ptr.read() + __rhs)
};
let __rhs = ((*p.borrow()).read());
{
let __ptr = z.clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = z.clone();
_ptr.write(_ptr.read() + __rhs)
};
let __rhs = ((*y.borrow()) + (*x.borrow()));
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + __rhs)
};
let __rhs = {
let _lhs = (*x.borrow());
_lhs + (z.read())
};
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + __rhs)
};
let __rhs = {
let _lhs = (*y.borrow());
_lhs + (z.read())
};
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + __rhs)
};
}
pub fn main() {
Expand Down
35 changes: 14 additions & 21 deletions tests/unit/out/refcount/complex_function.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -140,15 +140,13 @@ fn main_0() -> i32 {
});
let __rhs = (*x1.borrow());
{
let __ptr = r2.clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = r2.clone();
_ptr.write(_ptr.read() + __rhs)
};
let __rhs = (r1.read());
{
let __ptr = r3.clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = r3.clone();
_ptr.write(_ptr.read() + __rhs)
};
let x4: Value<i32> = Rc::new(RefCell::new(
((({
Expand Down Expand Up @@ -231,13 +229,12 @@ fn main_0() -> i32 {
.borrow()),
));
{
let __ptr = ({
let _ptr = ({
let _x: Ptr<i32> = x1.as_pointer();
bar_2(_x)
})
.clone();
let __tmp = __ptr.read() + 10;
__ptr.write(__tmp)
_ptr.write(_ptr.read() + 10)
};
({
let _x: Ptr<i32> = x1.as_pointer();
Expand Down Expand Up @@ -283,7 +280,7 @@ fn main_0() -> i32 {
}))
+ 1);
{
let __ptr = ({
let _ptr = ({
let _x: Ptr<i32> = (*({
(*({ (*({ (*d.borrow()).get() }).upgrade().deref()).get() })
.upgrade()
Expand All @@ -297,8 +294,7 @@ fn main_0() -> i32 {
bar_2(_x)
})
.clone();
let __tmp = __ptr.read() + 10;
__ptr.write(__tmp)
_ptr.write(_ptr.read() + 10)
};
({
let _x: Ptr<i32> = (*({
Expand Down Expand Up @@ -350,13 +346,12 @@ fn main_0() -> i32 {
})
.with_mut(|__v| __v.prefix_inc());
{
let __ptr = ({
let _ptr = ({
let _x: Ptr<i32> = (x1.as_pointer());
ptr_1(_x)
})
.clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
_ptr.write(_ptr.read() + 1)
};
({
let _x: Ptr<i32> = ((*({
Expand All @@ -373,7 +368,7 @@ fn main_0() -> i32 {
})
.with_mut(|__v| __v.prefix_inc());
{
let __ptr = ({
let _ptr = ({
let _x: Ptr<i32> = ((*({
(*({ (*({ (*d.borrow()).get() }).upgrade().deref()).get() })
.upgrade()
Expand All @@ -387,11 +382,10 @@ fn main_0() -> i32 {
ptr_1(_x)
})
.clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
_ptr.write(_ptr.read() + 1)
};
{
let __ptr = ({
let _ptr = ({
let _x: Ptr<i32> = ((*({
(*({ (*({ (*d.borrow()).get() }).upgrade().deref()).get() })
.upgrade()
Expand All @@ -405,8 +399,7 @@ fn main_0() -> i32 {
ptr_1(_x)
})
.clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
_ptr.write(_ptr.read() + 1)
};
let ptr1: Value<i32> = Rc::new(RefCell::new(
({
Expand Down
20 changes: 8 additions & 12 deletions tests/unit/out/refcount/fatorial.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,8 @@ pub fn fatorial_0(n: i32) -> i32 {
pub fn fatorial_by_ref_1(n: Ptr<i32>) {
if ((n.read()) == 1) {
{
let __ptr = n.clone();
let __tmp = __ptr.read() * 1;
__ptr.write(__tmp)
let _ptr = n.clone();
_ptr.write(_ptr.read() * 1)
};
return;
}
Expand All @@ -33,18 +32,16 @@ pub fn fatorial_by_ref_1(n: Ptr<i32>) {
});
let __rhs = (*n_1.borrow());
{
let __ptr = n.clone();
let __tmp = __ptr.read() * __rhs;
__ptr.write(__tmp)
let _ptr = n.clone();
_ptr.write(_ptr.read() * __rhs)
};
}
pub fn fatorial_by_ptr_2(n: Ptr<i32>) {
let n: Value<Ptr<i32>> = Rc::new(RefCell::new(n));
if (((*n.borrow()).read()) == 1) {
{
let __ptr = (*n.borrow()).clone();
let __tmp = __ptr.read() * 1;
__ptr.write(__tmp)
let _ptr = (*n.borrow()).clone();
_ptr.write(_ptr.read() * 1)
};
return;
}
Expand All @@ -55,9 +52,8 @@ pub fn fatorial_by_ptr_2(n: Ptr<i32>) {
});
let __rhs = (*n_1.borrow());
{
let __ptr = (*n.borrow()).clone();
let __tmp = __ptr.read() * __rhs;
__ptr.write(__tmp)
let _ptr = (*n.borrow()).clone();
_ptr.write(_ptr.read() * __rhs)
};
}
pub fn main() {
Expand Down
5 changes: 2 additions & 3 deletions tests/unit/out/refcount/fn_ptr_as_condition.rs
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Expand Up @@ -9,9 +9,8 @@ use std::rc::{Rc, Weak};
pub fn double_it_0(x: Ptr<i32>) {
let x: Value<Ptr<i32>> = Rc::new(RefCell::new(x));
{
let __ptr = (*x.borrow()).clone();
let __tmp = __ptr.read() * 2;
__ptr.write(__tmp)
let _ptr = (*x.borrow()).clone();
_ptr.write(_ptr.read() * 2)
};
}
pub fn maybe_call_1(cb: FnPtr<fn(Ptr<i32>)>, x: Ptr<i32>) {
Expand Down
5 changes: 2 additions & 3 deletions tests/unit/out/refcount/foreach_mut.rs
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Expand Up @@ -38,9 +38,8 @@ fn main_0() -> i32 {
'loop_: for mut p in v2.as_pointer() as Ptr<Ptr<i32>> {
let p: Value<Ptr<i32>> = Rc::new(RefCell::new(p.read().clone()));
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + 5;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + 5)
};
}
'loop_: for p in v2.as_pointer() as Ptr<Ptr<i32>> {
Expand Down
25 changes: 10 additions & 15 deletions tests/unit/out/refcount/pointer_arithmetic.rs
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Expand Up @@ -13,38 +13,33 @@ fn main_0() -> i32 {
let x: Value<i32> = Rc::new(RefCell::new(1));
let p: Value<Ptr<i32>> = Rc::new(RefCell::new((x.as_pointer())));
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + 1)
};
if ((*x.borrow()) == 2) {
let a: Value<Box<[i32]>> = Rc::new(RefCell::new(Box::new([1, 2])));
(*p.borrow_mut()) = ((a.as_pointer() as Ptr<i32>).offset(1 as isize));
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + 1)
};
if ((*a.borrow())[(0) as usize] == 1) && ((*a.borrow())[(1) as usize] == 3) {
(*p.borrow_mut()).prefix_dec();
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + 1)
};
if ((*a.borrow())[(0) as usize] == 2) && ((*a.borrow())[(1) as usize] == 3) {
(*p.borrow_mut()) = (x.as_pointer());
{
let __ptr = (*p.borrow()).clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
let _ptr = (*p.borrow()).clone();
_ptr.write(_ptr.read() + 1)
};
if ((*x.borrow()) == 3) {
let p2: Value<Ptr<i32>> = Rc::new(RefCell::new((*p.borrow()).clone()));
{
let __ptr = (*p2.borrow()).clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
let _ptr = (*p2.borrow()).clone();
_ptr.write(_ptr.read() + 1)
};
return (((*x.borrow()) == 4) as i32);
}
Expand Down
5 changes: 2 additions & 3 deletions tests/unit/out/refcount/pointer_array.rs
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Expand Up @@ -34,9 +34,8 @@ pub fn IncrementAll_0(s: Ptr<StackArray>) {
let i: Value<i32> = Rc::new(RefCell::new(0));
'loop_: while ((*i.borrow()) < 3) {
{
let __ptr = (*(*s.upgrade().deref()).arr.borrow())[(*i.borrow()) as usize].clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
let _ptr = (*(*s.upgrade().deref()).arr.borrow())[(*i.borrow()) as usize].clone();
_ptr.write(_ptr.read() + 1)
};
(*i.borrow_mut()).prefix_inc();
}
Expand Down
5 changes: 2 additions & 3 deletions tests/unit/out/refcount/pointers.rs
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Expand Up @@ -71,9 +71,8 @@ fn main_0() -> i32 {
(*t3.borrow_mut()) = (*t2.borrow()).clone();
(*(*(*t3.borrow()).upgrade().deref()).x.borrow_mut()) = 15;
{
let __ptr = ({ (*(*t3.borrow()).upgrade().deref()).as_ptr() }).clone();
let __tmp = __ptr.read() + 10;
__ptr.write(__tmp)
let _ptr = ({ (*(*t3.borrow()).upgrade().deref()).as_ptr() }).clone();
_ptr.write(_ptr.read() + 10)
};
return {
let _lhs = {
Expand Down
5 changes: 2 additions & 3 deletions tests/unit/out/refcount/refs_as_args.rs
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Expand Up @@ -36,9 +36,8 @@ pub fn more_refs_0(x1: i32, x2: i32, r1: Ptr<i32>, r2: Ptr<i32>) {
_lhs + (r.read())
};
{
let __ptr = rx2.clone();
let __tmp = __ptr.read() + __rhs;
__ptr.write(__tmp)
let _ptr = rx2.clone();
_ptr.write(_ptr.read() + __rhs)
};
let __rhs = (rx2.read());
r1.write(__rhs);
Expand Down
5 changes: 2 additions & 3 deletions tests/unit/out/refcount/unique_ptr.rs
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Expand Up @@ -58,9 +58,8 @@ pub fn DoStuffWithSafePointer_0(safe_ptr: Ptr<Option<Value<SafePointer>>>) {
(*x4.borrow_mut()) = (*x3.borrow_mut()).take();
let raw_ptr2: Value<Ptr<i32>> = Rc::new(RefCell::new(((*x4.borrow()).as_pointer())));
{
let __ptr = (*raw_ptr2.borrow()).clone();
let __tmp = __ptr.read() + 1;
__ptr.write(__tmp)
let _ptr = (*raw_ptr2.borrow()).clone();
_ptr.write(_ptr.read() + 1)
};
let pair: Value<Option<Value<Pair>>> =
Rc::new(RefCell::new(Some(Rc::new(RefCell::new(Pair {
Expand Down
5 changes: 2 additions & 3 deletions tests/unit/out/refcount/vector.rs
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Expand Up @@ -211,9 +211,8 @@ fn main_0() -> i32 {
let ref1: Ptr<f64> =
(v6.as_pointer() as Ptr<f64>).offset((*s2.borrow()).wrapping_sub(1_u64) as isize);
{
let __ptr = ref1.clone();
let __tmp = __ptr.read() + 1.5E+0;
__ptr.write(__tmp)
let _ptr = ref1.clone();
_ptr.write(_ptr.read() + 1.5E+0)
};
assert!(
(((v6.as_pointer() as Ptr<f64>)
Expand Down
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