Auto merge of rust-lang#117332 - saethlin:panic-immediate-abort, r=wo…

…rkingjubilee Increase the reach of panic_immediate_abort I wanted to use/abuse this recently as part of another project, and I was surprised how many panic-related things were left in my binaries if I built a large crate with the feature enabled along with LTO. These changes get all the panic-related symbols that I could find out of my set of locally installed Rust utilities.
RalfJung · Oct 30, 2023 · bcb5798 · bcb5798
2 parents 608e968 + 2e7364a
commit bcb5798
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Showing 9 changed files with 87 additions and 10 deletions.
diff --git a/library/alloc/Cargo.toml b/library/alloc/Cargo.toml
@@ -36,3 +36,5 @@ compiler-builtins-c = ["compiler_builtins/c"]
 compiler-builtins-no-asm = ["compiler_builtins/no-asm"]
 compiler-builtins-mangled-names = ["compiler_builtins/mangled-names"]
 compiler-builtins-weak-intrinsics = ["compiler_builtins/weak-intrinsics"]
+# Make panics and failed asserts immediately abort without formatting any message
+panic_immediate_abort = []
diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs
@@ -377,13 +377,20 @@ pub const fn handle_alloc_error(layout: Layout) -> ! {
         panic!("allocation failed");
     }
 
+    #[inline]
     fn rt_error(layout: Layout) -> ! {
         unsafe {
             __rust_alloc_error_handler(layout.size(), layout.align());
         }
     }
 
-    unsafe { core::intrinsics::const_eval_select((layout,), ct_error, rt_error) }
+    #[cfg(not(feature = "panic_immediate_abort"))]
+    unsafe {
+        core::intrinsics::const_eval_select((layout,), ct_error, rt_error)
+    }
+
+    #[cfg(feature = "panic_immediate_abort")]
+    ct_error(layout)
 }
 
 // For alloc test `std::alloc::handle_alloc_error` can be used directly.

diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs
@@ -530,7 +530,7 @@ fn alloc_guard(alloc_size: usize) -> Result<(), TryReserveError> {
 // ensure that the code generation related to these panics is minimal as there's
 // only one location which panics rather than a bunch throughout the module.
 #[cfg(not(no_global_oom_handling))]
-#[inline(never)]
+#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
 fn capacity_overflow() -> ! {
     panic!("capacity overflow");
 }
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
@@ -1447,7 +1447,8 @@ impl<T, A: Allocator> Vec<T, A> {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn swap_remove(&mut self, index: usize) -> T {
         #[cold]
-        #[inline(never)]
+        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
+        #[track_caller]
         fn assert_failed(index: usize, len: usize) -> ! {
             panic!("swap_remove index (is {index}) should be < len (is {len})");
         }
@@ -1488,7 +1489,8 @@ impl<T, A: Allocator> Vec<T, A> {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn insert(&mut self, index: usize, element: T) {
         #[cold]
-        #[inline(never)]
+        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
+        #[track_caller]
         fn assert_failed(index: usize, len: usize) -> ! {
             panic!("insertion index (is {index}) should be <= len (is {len})");
         }
@@ -1549,7 +1551,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[track_caller]
     pub fn remove(&mut self, index: usize) -> T {
         #[cold]
-        #[inline(never)]
+        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
         #[track_caller]
         fn assert_failed(index: usize, len: usize) -> ! {
             panic!("removal index (is {index}) should be < len (is {len})");
@@ -2148,7 +2150,8 @@ impl<T, A: Allocator> Vec<T, A> {
         A: Clone,
     {
         #[cold]
-        #[inline(never)]
+        #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
+        #[track_caller]
         fn assert_failed(at: usize, len: usize) -> ! {
             panic!("`at` split index (is {at}) should be <= len (is {len})");
         }

diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
@@ -755,15 +755,15 @@ impl Display for BorrowMutError {
 }
 
 // This ensures the panicking code is outlined from `borrow_mut` for `RefCell`.
-#[inline(never)]
+#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
 #[track_caller]
 #[cold]
 fn panic_already_borrowed(err: BorrowMutError) -> ! {
     panic!("already borrowed: {:?}", err)
 }
 
 // This ensures the panicking code is outlined from `borrow` for `RefCell`.
-#[inline(never)]
+#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
 #[track_caller]
 #[cold]
 fn panic_already_mutably_borrowed(err: BorrowError) -> ! {

diff --git a/library/core/src/panic/unwind_safe.rs b/library/core/src/panic/unwind_safe.rs
@@ -267,6 +267,7 @@ impl<T> DerefMut for AssertUnwindSafe<T> {
 impl<R, F: FnOnce() -> R> FnOnce<()> for AssertUnwindSafe<F> {
     type Output = R;
 
+    #[inline]
     extern "rust-call" fn call_once(self, _args: ()) -> R {
         (self.0)()
     }

diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
@@ -81,6 +81,7 @@ use iter::{MatchesInternal, SplitNInternal};
 #[cold]
 #[track_caller]
 #[rustc_allow_const_fn_unstable(const_eval_select)]
+#[cfg(not(feature = "panic_immediate_abort"))]
 const fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
     // SAFETY: panics for both branches
     unsafe {
@@ -92,6 +93,11 @@ const fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
     }
 }
 
+#[cfg(feature = "panic_immediate_abort")]
+const fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
+    slice_error_fail_ct(s, begin, end)
+}
+
 #[track_caller]
 const fn slice_error_fail_ct(_: &str, _: usize, _: usize) -> ! {
     panic!("failed to slice string");

diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
@@ -72,7 +72,7 @@ llvm-libunwind = ["unwind/llvm-libunwind"]
 system-llvm-libunwind = ["unwind/system-llvm-libunwind"]
 
 # Make panics and failed asserts immediately abort without formatting any message
-panic_immediate_abort = ["core/panic_immediate_abort"]
+panic_immediate_abort = ["core/panic_immediate_abort", "alloc/panic_immediate_abort"]
 
 # Enable std_detect default features for stdarch/crates/std_detect:
 # https://github.com/rust-lang/stdarch/blob/master/crates/std_detect/Cargo.toml

diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
@@ -295,12 +295,53 @@ fn default_hook(info: &PanicInfo<'_>) {
 
 #[cfg(not(test))]
 #[doc(hidden)]
+#[cfg(feature = "panic_immediate_abort")]
+#[unstable(feature = "update_panic_count", issue = "none")]
+pub mod panic_count {
+    /// A reason for forcing an immediate abort on panic.
+    #[derive(Debug)]
+    pub enum MustAbort {
+        AlwaysAbort,
+        PanicInHook,
+    }
+
+    #[inline]
+    pub fn increase(run_panic_hook: bool) -> Option<MustAbort> {
+        None
+    }
+
+    #[inline]
+    pub fn finished_panic_hook() {}
+
+    #[inline]
+    pub fn decrease() {}
+
+    #[inline]
+    pub fn set_always_abort() {}
+
+    // Disregards ALWAYS_ABORT_FLAG
+    #[inline]
+    #[must_use]
+    pub fn get_count() -> usize {
+        0
+    }
+
+    #[must_use]
+    #[inline]
+    pub fn count_is_zero() -> bool {
+        true
+    }
+}
+
+#[cfg(not(test))]
+#[doc(hidden)]
+#[cfg(not(feature = "panic_immediate_abort"))]
 #[unstable(feature = "update_panic_count", issue = "none")]
 pub mod panic_count {
     use crate::cell::Cell;
     use crate::sync::atomic::{AtomicUsize, Ordering};
 
-    pub const ALWAYS_ABORT_FLAG: usize = 1 << (usize::BITS - 1);
+    const ALWAYS_ABORT_FLAG: usize = 1 << (usize::BITS - 1);
 
     /// A reason for forcing an immediate abort on panic.
     #[derive(Debug)]
@@ -421,6 +462,13 @@ pub mod panic_count {
 pub use realstd::rt::panic_count;
 
 /// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
+#[cfg(feature = "panic_immediate_abort")]
+pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
+    Ok(f())
+}
+
+/// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
+#[cfg(not(feature = "panic_immediate_abort"))]
 pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
     union Data<F, R> {
         f: ManuallyDrop<F>,
@@ -755,6 +803,7 @@ fn rust_panic_with_hook(
 
 /// This is the entry point for `resume_unwind`.
 /// It just forwards the payload to the panic runtime.
+#[cfg_attr(feature = "panic_immediate_abort", inline)]
 pub fn rust_panic_without_hook(payload: Box<dyn Any + Send>) -> ! {
     panic_count::increase(false);
 
@@ -777,7 +826,16 @@ pub fn rust_panic_without_hook(payload: Box<dyn Any + Send>) -> ! {
 /// yer breakpoints.
 #[inline(never)]
 #[cfg_attr(not(test), rustc_std_internal_symbol)]
+#[cfg(not(feature = "panic_immediate_abort"))]
 fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
     let code = unsafe { __rust_start_panic(msg) };
     rtabort!("failed to initiate panic, error {code}")
 }
+
+#[cfg_attr(not(test), rustc_std_internal_symbol)]
+#[cfg(feature = "panic_immediate_abort")]
+fn rust_panic(_: &mut dyn PanicPayload) -> ! {
+    unsafe {
+        crate::intrinsics::abort();
+    }
+}