Merge from rustc

Author: RalfJung

src/diagnostics.rs

@@ -473,14 +473,14 @@ pub fn report_leaks<'tcx>(
     leaks: Vec<(AllocId, MemoryKind, Allocation<Provenance, AllocExtra<'tcx>, MiriAllocBytes>)>,
 ) {
     let mut any_pruned = false;
-    for (id, kind, mut alloc) in leaks {
+    for (id, kind, alloc) in leaks {
         let mut title = format!(
             "memory leaked: {id:?} ({}, size: {:?}, align: {:?})",
             kind,
             alloc.size().bytes(),
             alloc.align.bytes()
         );
-        let Some(backtrace) = alloc.extra.backtrace.take() else {
+        let Some(backtrace) = alloc.extra.backtrace else {
             ecx.tcx.dcx().err(title);
             continue;
         };

src/eval.rs

@@ -473,7 +473,7 @@ pub fn eval_entry<'tcx>(
         }
         // Check for memory leaks.
         info!("Additional static roots: {:?}", ecx.machine.static_roots);
-        let leaks = ecx.find_leaked_allocations(&ecx.machine.static_roots);
+        let leaks = ecx.take_leaked_allocations(|ecx| &ecx.machine.static_roots);
         if !leaks.is_empty() {
             report_leaks(&ecx, leaks);
             tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check");

src/intrinsics/mod.rs

@@ -295,6 +295,37 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 this.write_scalar(res, dest)?;
             }
 
+            "fmuladdf32" => {
+                let [a, b, c] = check_arg_count(args)?;
+                let a = this.read_scalar(a)?.to_f32()?;
+                let b = this.read_scalar(b)?.to_f32()?;
+                let c = this.read_scalar(c)?.to_f32()?;
+                let fuse: bool = this.machine.rng.get_mut().gen();
+                let res = if fuse {
+                    // FIXME: Using host floats, to work around https://github.com/rust-lang/rustc_apfloat/issues/11
+                    a.to_host().mul_add(b.to_host(), c.to_host()).to_soft()
+                } else {
+                    ((a * b).value + c).value
+                };
+                let res = this.adjust_nan(res, &[a, b, c]);
+                this.write_scalar(res, dest)?;
+            }
+            "fmuladdf64" => {
+                let [a, b, c] = check_arg_count(args)?;
+                let a = this.read_scalar(a)?.to_f64()?;
+                let b = this.read_scalar(b)?.to_f64()?;
+                let c = this.read_scalar(c)?.to_f64()?;
+                let fuse: bool = this.machine.rng.get_mut().gen();
+                let res = if fuse {
+                    // FIXME: Using host floats, to work around https://github.com/rust-lang/rustc_apfloat/issues/11
+                    a.to_host().mul_add(b.to_host(), c.to_host()).to_soft()
+                } else {
+                    ((a * b).value + c).value
+                };
+                let res = this.adjust_nan(res, &[a, b, c]);
+                this.write_scalar(res, dest)?;
+            }
+
             "powf32" => {
                 let [f1, f2] = check_arg_count(args)?;
                 let f1 = this.read_scalar(f1)?.to_f32()?;

src/lib.rs

@@ -1,6 +1,5 @@
 #![feature(rustc_private)]
 #![feature(cell_update)]
-#![feature(const_option)]
 #![feature(float_gamma)]
 #![feature(map_try_insert)]
 #![feature(never_type)]

src/machine.rs

@@ -321,7 +321,7 @@ impl ProvenanceExtra {
 }
 
 /// Extra per-allocation data
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct AllocExtra<'tcx> {
     /// Global state of the borrow tracker, if enabled.
     pub borrow_tracker: Option<borrow_tracker::AllocState>,
@@ -338,6 +338,14 @@ pub struct AllocExtra<'tcx> {
     pub backtrace: Option<Vec<FrameInfo<'tcx>>>,
 }
 
+// We need a `Clone` impl because the machine passes `Allocation` through `Cow`...
+// but that should never end up actually cloning our `AllocExtra`.
+impl<'tcx> Clone for AllocExtra<'tcx> {
+    fn clone(&self) -> Self {
+        panic!("our allocations should never be cloned");
+    }
+}
+
 impl VisitProvenance for AllocExtra<'_> {
     fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
         let AllocExtra { borrow_tracker, data_race, weak_memory, backtrace: _ } = self;

tests/pass/float.rs

@@ -30,6 +30,7 @@ fn main() {
     libm();
     test_fast();
     test_algebraic();
+    test_fmuladd();
 }
 
 trait Float: Copy + PartialEq + Debug {
@@ -1041,3 +1042,20 @@ fn test_algebraic() {
     test_operations_f32(11., 2.);
     test_operations_f32(10., 15.);
 }
+
+fn test_fmuladd() {
+    use std::intrinsics::{fmuladdf32, fmuladdf64};
+
+    #[inline(never)]
+    pub fn test_operations_f32(a: f32, b: f32, c: f32) {
+        assert_approx_eq!(unsafe { fmuladdf32(a, b, c) }, a * b + c);
+    }
+
+    #[inline(never)]
+    pub fn test_operations_f64(a: f64, b: f64, c: f64) {
+        assert_approx_eq!(unsafe { fmuladdf64(a, b, c) }, a * b + c);
+    }
+
+    test_operations_f32(0.1, 0.2, 0.3);
+    test_operations_f64(1.1, 1.2, 1.3);
+}

tests/pass/intrinsics/fmuladd_nondeterministic.rs

@@ -0,0 +1,44 @@
+#![feature(core_intrinsics)]
+use std::intrinsics::{fmuladdf32, fmuladdf64};
+
+fn main() {
+    let mut saw_zero = false;
+    let mut saw_nonzero = false;
+    for _ in 0..50 {
+        let a = std::hint::black_box(0.1_f64);
+        let b = std::hint::black_box(0.2);
+        let c = std::hint::black_box(-a * b);
+        // It is unspecified whether the following operation is fused or not. The
+        // following evaluates to 0.0 if unfused, and nonzero (-1.66e-18) if fused.
+        let x = unsafe { fmuladdf64(a, b, c) };
+        if x == 0.0 {
+            saw_zero = true;
+        } else {
+            saw_nonzero = true;
+        }
+    }
+    assert!(
+        saw_zero && saw_nonzero,
+        "`fmuladdf64` failed to be evaluated as both fused and unfused"
+    );
+
+    let mut saw_zero = false;
+    let mut saw_nonzero = false;
+    for _ in 0..50 {
+        let a = std::hint::black_box(0.1_f32);
+        let b = std::hint::black_box(0.2);
+        let c = std::hint::black_box(-a * b);
+        // It is unspecified whether the following operation is fused or not. The
+        // following evaluates to 0.0 if unfused, and nonzero (-8.1956386e-10) if fused.
+        let x = unsafe { fmuladdf32(a, b, c) };
+        if x == 0.0 {
+            saw_zero = true;
+        } else {
+            saw_nonzero = true;
+        }
+    }
+    assert!(
+        saw_zero && saw_nonzero,
+        "`fmuladdf32` failed to be evaluated as both fused and unfused"
+    );
+}

tests/pass/underscore_pattern.rs

@@ -1,5 +1,7 @@
 // Various tests ensuring that underscore patterns really just construct the place, but don't check its contents.
 #![feature(strict_provenance)]
+#![feature(never_type)]
+
 use std::ptr;
 
 fn main() {
@@ -9,6 +11,7 @@ fn main() {
     invalid_let();
     dangling_let_type_annotation();
     invalid_let_type_annotation();
+    never();
 }
 
 fn dangling_match() {
@@ -34,13 +37,25 @@ fn invalid_match() {
             _ => {}
         }
     }
+
+    unsafe {
+        let x: Uninit<!> = Uninit { uninit: () };
+        match x.value {
+            _ => {}
+        }
+    }
 }
 
 fn dangling_let() {
     unsafe {
         let ptr = ptr::without_provenance::<bool>(0x40);
         let _ = *ptr;
     }
+
+    unsafe {
+        let ptr = ptr::without_provenance::<!>(0x40);
+        let _ = *ptr;
+    }
 }
 
 fn invalid_let() {
@@ -49,6 +64,12 @@ fn invalid_let() {
         let ptr = ptr::addr_of!(val).cast::<bool>();
         let _ = *ptr;
     }
+
+    unsafe {
+        let val = 3u8;
+        let ptr = ptr::addr_of!(val).cast::<!>();
+        let _ = *ptr;
+    }
 }
 
 // Adding a type annotation used to change how MIR is generated, make sure we cover both cases.
@@ -57,6 +78,11 @@ fn dangling_let_type_annotation() {
         let ptr = ptr::without_provenance::<bool>(0x40);
         let _: bool = *ptr;
     }
+
+    unsafe {
+        let ptr = ptr::without_provenance::<!>(0x40);
+        let _: ! = *ptr;
+    }
 }
 
 fn invalid_let_type_annotation() {
@@ -65,7 +91,28 @@ fn invalid_let_type_annotation() {
         let ptr = ptr::addr_of!(val).cast::<bool>();
         let _: bool = *ptr;
     }
+
+    unsafe {
+        let val = 3u8;
+        let ptr = ptr::addr_of!(val).cast::<!>();
+        let _: ! = *ptr;
+    }
 }
 
-// FIXME: we should also test `!`, not just `bool` -- but that s currently buggy:
-// https://github.com/rust-lang/rust/issues/117288
+// Regression test from <https://github.com/rust-lang/rust/issues/117288>.
+fn never() {
+    unsafe {
+        let x = 3u8;
+        let x: *const ! = &x as *const u8 as *const _;
+        let _: ! = *x;
+    }
+
+    // Without a type annotation, make sure we don't implicitly coerce `!` to `()`
+    // when we do the noop `*x` (as that would require a `!` *value*, creating
+    // which is UB).
+    unsafe {
+        let x = 3u8;
+        let x: *const ! = &x as *const u8 as *const _;
+        let _ = *x;
+    }
+}