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large_assignments: Lint on specific large args passed to functions

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This commit is contained in:
Martin Nordholts 2023-10-07 14:34:29 +02:00 committed by Martin Nordholts
parent 16ba56c242
commit 8f440f06c6
5 changed files with 134 additions and 41 deletions
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12
compiler/rustc_middle/src/mir/tcx.rs
View File

@ -229,6 +229,18 @@ pub fn ty<D: ?Sized>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>
Operand::Constant(c) => c.const_.ty(),
}
}
pub fn span<D: ?Sized>(&self, local_decls: &D) -> Span
where
D: HasLocalDecls<'tcx>,
{
match self {
&Operand::Copy(ref l) | &Operand::Move(ref l) => {
local_decls.local_decls()[l.local].source_info.span
}
Operand::Constant(c) => c.span,
}
}
}
impl<'tcx> BinOp {

104
compiler/rustc_monomorphize/src/collector.rs
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@ -614,8 +614,8 @@ pub fn monomorphize<T>(&self, value: T) -> T
}
fn check_operand_move_size(&mut self, operand: &mir::Operand<'tcx>, location: Location) {
let limit = self.tcx.move_size_limit().0;
if limit == 0 {
let limit = self.tcx.move_size_limit();
if limit.0 == 0 {
return;
}
@ -627,48 +627,19 @@ fn check_operand_move_size(&mut self, operand: &mir::Operand<'tcx>, location: Lo
return;
}
let limit = Size::from_bytes(limit);
let ty = operand.ty(self.body, self.tcx);
let ty = self.monomorphize(ty);
let Ok(layout) = self.tcx.layout_of(ty::ParamEnv::reveal_all().and(ty)) else { return };
if layout.size <= limit {
return;
}
debug!(?layout);
let source_info = self.body.source_info(location);
debug!(?source_info);
for span in &self.move_size_spans {
if span.overlaps(source_info.span) {
return;
}
}
let lint_root = source_info.scope.lint_root(&self.body.source_scopes);
debug!(?lint_root);
let Some(lint_root) = lint_root else {
// This happens when the issue is in a function from a foreign crate that
// we monomorphized in the current crate. We can't get a `HirId` for things
// in other crates.
// FIXME: Find out where to report the lint on. Maybe simply crate-level lint root
// but correct span? This would make the lint at least accept crate-level lint attributes.
return;
if let Some(too_large_size) = self.operand_size_if_too_large(limit, operand) {
self.lint_large_assignment(limit.0, too_large_size, location, source_info.span);
};
self.tcx.emit_spanned_lint(
LARGE_ASSIGNMENTS,
lint_root,
source_info.span,
LargeAssignmentsLint {
span: source_info.span,
size: layout.size.bytes(),
limit: limit.bytes(),
},
);
self.move_size_spans.push(source_info.span);
}
fn check_fn_args_move_size(
&mut self,
callee_ty: Ty<'tcx>,
args: &[Spanned<mir::Operand<'tcx>>],
fn_span: Span,
location: Location,
) {
let limit = self.tcx.move_size_limit();
@ -692,10 +663,65 @@ fn check_fn_args_move_size(
return;
}
debug!(?def_id, ?fn_span);
for arg in args {
self.check_operand_move_size(&arg.node, location);
if let Some(too_large_size) = self.operand_size_if_too_large(limit, &arg.node) {
self.lint_large_assignment(limit.0, too_large_size, location, arg.span);
};
}
}
fn operand_size_if_too_large(
&mut self,
limit: Limit,
operand: &mir::Operand<'tcx>,
) -> Option<Size> {
let ty = operand.ty(self.body, self.tcx);
let ty = self.monomorphize(ty);
let Ok(layout) = self.tcx.layout_of(ty::ParamEnv::reveal_all().and(ty)) else {
return None;
};
if layout.size.bytes_usize() > limit.0 {
debug!(?layout);
Some(layout.size)
} else {
None
}
}
fn lint_large_assignment(
&mut self,
limit: usize,
too_large_size: Size,
location: Location,
span: Span,
) {
let source_info = self.body.source_info(location);
debug!(?source_info);
for reported_span in &self.move_size_spans {
if reported_span.overlaps(span) {
return;
}
}
let lint_root = source_info.scope.lint_root(&self.body.source_scopes);
debug!(?lint_root);
let Some(lint_root) = lint_root else {
// This happens when the issue is in a function from a foreign crate that
// we monomorphized in the current crate. We can't get a `HirId` for things
// in other crates.
// FIXME: Find out where to report the lint on. Maybe simply crate-level lint root
// but correct span? This would make the lint at least accept crate-level lint attributes.
return;
};
self.tcx.emit_spanned_lint(
LARGE_ASSIGNMENTS,
lint_root,
span,
LargeAssignmentsLint { span, size: too_large_size.bytes(), limit: limit as u64 },
);
self.move_size_spans.push(span);
}
}
impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
@ -813,11 +839,11 @@ fn visit_terminator(&mut self, terminator: &mir::Terminator<'tcx>, location: Loc
};
match terminator.kind {
mir::TerminatorKind::Call { ref func, ref args, .. } => {
mir::TerminatorKind::Call { ref func, ref args, ref fn_span, .. } => {
let callee_ty = func.ty(self.body, tcx);
let callee_ty = self.monomorphize(callee_ty);
self.check_fn_args_move_size(callee_ty, args, location);
visit_fn_use(self.tcx, callee_ty, true, source, self.output)
self.check_fn_args_move_size(callee_ty, args, *fn_span, location);
visit_fn_use(self.tcx, callee_ty, true, source, &mut self.output)
}
mir::TerminatorKind::Drop { ref place, .. } => {
let ty = place.ty(self.body, self.tcx).ty;

4
tests/ui/lint/large_assignments/box_rc_arc_allowed.stderr
View File

@ -1,8 +1,8 @@
error: moving 9999 bytes
--> $DIR/box_rc_arc_allowed.rs:16:13
--> $DIR/box_rc_arc_allowed.rs:16:25
|
LL | let _ = NotBox::new([0; 9999]);
| ^^^^^^^^^^^^^^^^^^^^^^ value moved from here
| ^^^^^^^^^ value moved from here
|
= note: The current maximum size is 1000, but it can be customized with the move_size_limit attribute: `#![move_size_limit = "..."]`
note: the lint level is defined here

24
tests/ui/lint/large_assignments/copy_into_fn.rs Normal file
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@ -0,0 +1,24 @@
// build-fail
#![feature(large_assignments)]
#![move_size_limit = "1000"]
#![deny(large_assignments)]
#![allow(unused)]
// We want copy semantics, because moving data into functions generally do not
// translate to actual `memcpy`s.
#[derive(Copy, Clone)]
struct Data([u8; 9999]);
fn main() {
one_arg(Data([0; 9999])); //~ ERROR large_assignments
// each individual large arg shall have its own span
many_args(Data([0; 9999]), true, Data([0; 9999]));
//~^ ERROR large_assignments
//~| ERROR large_assignments
}
fn one_arg(a: Data) {}
fn many_args(a: Data, b: bool, c: Data) {}

31
tests/ui/lint/large_assignments/copy_into_fn.stderr Normal file
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@ -0,0 +1,31 @@
error: moving 9999 bytes
--> $DIR/copy_into_fn.rs:14:13
|
LL | one_arg(Data([0; 9999]));
| ^^^^^^^^^^^^^^^ value moved from here
|
= note: The current maximum size is 1000, but it can be customized with the move_size_limit attribute: `#![move_size_limit = "..."]`
note: the lint level is defined here
--> $DIR/copy_into_fn.rs:5:9
|
LL | #![deny(large_assignments)]
| ^^^^^^^^^^^^^^^^^
error: moving 9999 bytes
--> $DIR/copy_into_fn.rs:17:15
|
LL | many_args(Data([0; 9999]), true, Data([0; 9999]));
| ^^^^^^^^^^^^^^^ value moved from here
|
= note: The current maximum size is 1000, but it can be customized with the move_size_limit attribute: `#![move_size_limit = "..."]`
error: moving 9999 bytes
--> $DIR/copy_into_fn.rs:17:38
|
LL | many_args(Data([0; 9999]), true, Data([0; 9999]));
| ^^^^^^^^^^^^^^^ value moved from here
|
= note: The current maximum size is 1000, but it can be customized with the move_size_limit attribute: `#![move_size_limit = "..."]`
error: aborting due to 3 previous errors