Skip to content

Commit 8fb67fb

Browse files
borsbors
committedFeb 9, 2024
Auto merge of #120594 - saethlin:delayed-debug-asserts, r=oli-obk
Toggle assert_unsafe_precondition in codegen instead of expansion The goal of this PR is to make some of the unsafe precondition checks in the standard library available in debug builds. Some UI tests are included to verify that it does that. The diff is large, but most of it is blessing mir-opt tests and I've also split up this PR so it can be reviewed commit-by-commit. This PR: 1. Adds a new intrinsic, `debug_assertions` which is lowered to a new MIR NullOp, and only to a constant after monomorphization 2. Rewrites `assume_unsafe_precondition` to check the new intrinsic, and be monomorphic. 3. Skips codegen of the `assume` intrinsic in unoptimized builds, because that was silly before but with these checks it's *very* silly 4. The checks with the most overhead are `ptr::read`/`ptr::write` and `NonNull::new_unchecked`. I've simply added `#[cfg(debug_assertions)]` to the checks for `ptr::read`/`ptr::write` because I was unable to come up with any (good) ideas for decreasing their impact. But for `NonNull::new_unchecked` I found that the majority of callers can use a different function, often a safe one. Yes, this PR slows down the compile time of some programs. But in our benchmark suite it's never more than 1% icount, and the average icount change in debug-full programs is 0.22%. I think that is acceptable for such an improvement in developer experience. #120539 (comment)
2 parents 972452c + dbf817b commit 8fb67fb

File tree

65 files changed

+1439
-1252
lines changed

Some content is hidden

Large Commits have some content hidden by default. Use the searchbox below for content that may be hidden.

65 files changed

+1439
-1252
lines changed
 

Diff for: ‎compiler/rustc_borrowck/src/type_check/mod.rs

+1
Original file line numberDiff line numberDiff line change
@@ -1983,6 +1983,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
19831983
ConstraintCategory::SizedBound,
19841984
);
19851985
}
1986+
&Rvalue::NullaryOp(NullOp::DebugAssertions, _) => {}
19861987

19871988
Rvalue::ShallowInitBox(operand, ty) => {
19881989
self.check_operand(operand, location);

Diff for: ‎compiler/rustc_codegen_cranelift/src/base.rs

+9
Original file line numberDiff line numberDiff line change
@@ -767,6 +767,15 @@ fn codegen_stmt<'tcx>(
767767
NullOp::OffsetOf(fields) => {
768768
layout.offset_of_subfield(fx, fields.iter()).bytes()
769769
}
770+
NullOp::DebugAssertions => {
771+
let val = fx.tcx.sess.opts.debug_assertions;
772+
let val = CValue::by_val(
773+
fx.bcx.ins().iconst(types::I8, i64::try_from(val).unwrap()),
774+
fx.layout_of(fx.tcx.types.bool),
775+
);
776+
lval.write_cvalue(fx, val);
777+
return;
778+
}
770779
};
771780
let val = CValue::by_val(
772781
fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(val).unwrap()),

0 commit comments

Comments
 (0)