Replace GlobalAlloc::oom with a lang item

Author: sfackler

src/liballoc/alloc.rs

@@ -48,9 +48,6 @@ extern "Rust" {
     #[allocator]
     #[rustc_allocator_nounwind]
     fn __rust_alloc(size: usize, align: usize) -> *mut u8;
-    #[cold]
-    #[rustc_allocator_nounwind]
-    fn __rust_oom() -> !;
     #[rustc_allocator_nounwind]
     fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize);
     #[rustc_allocator_nounwind]
@@ -107,16 +104,6 @@ unsafe impl GlobalAlloc for Global {
         let ptr = __rust_alloc_zeroed(layout.size(), layout.align(), &mut 0);
         ptr as *mut Opaque
     }
-
-    #[inline]
-    fn oom(&self) -> ! {
-        unsafe {
-            #[cfg(not(stage0))]
-            __rust_oom();
-            #[cfg(stage0)]
-            __rust_oom(&mut 0);
-        }
-    }
 }
 
 unsafe impl Alloc for Global {
@@ -147,7 +134,7 @@ unsafe impl Alloc for Global {
 
     #[inline]
     fn oom(&mut self) -> ! {
-        GlobalAlloc::oom(self)
+        oom()
     }
 }
 
@@ -165,7 +152,7 @@ unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
         if !ptr.is_null() {
             ptr as *mut u8
         } else {
-            Global.oom()
+            oom()
         }
     }
 }
@@ -182,19 +169,33 @@ pub(crate) unsafe fn box_free<T: ?Sized>(ptr: *mut T) {
     }
 }
 
+#[cfg(stage0)]
+pub fn oom() -> ! {
+    unsafe { ::core::intrinsics::abort() }
+}
+
+#[cfg(not(stage0))]
+pub fn oom() -> ! {
+    extern {
+        #[lang = "oom"]
+        fn oom_impl() -> !;
+    }
+    unsafe { oom_impl() }
+}
+
 #[cfg(test)]
 mod tests {
     extern crate test;
     use self::test::Bencher;
     use boxed::Box;
-    use alloc::{Global, Alloc, Layout};
+    use alloc::{Global, Alloc, Layout, oom};
 
     #[test]
     fn allocate_zeroed() {
         unsafe {
             let layout = Layout::from_size_align(1024, 1).unwrap();
             let ptr = Global.alloc_zeroed(layout.clone())
-                .unwrap_or_else(|_| Global.oom());
+                .unwrap_or_else(|_| oom());
 
             let mut i = ptr.cast::<u8>().as_ptr();
             let end = i.offset(layout.size() as isize);

src/liballoc/arc.rs

@@ -31,7 +31,7 @@ use core::hash::{Hash, Hasher};
 use core::{isize, usize};
 use core::convert::From;
 
-use alloc::{Global, Alloc, Layout, box_free};
+use alloc::{Global, Alloc, Layout, box_free, oom};
 use boxed::Box;
 use string::String;
 use vec::Vec;
@@ -553,7 +553,7 @@ impl<T: ?Sized> Arc<T> {
         let layout = Layout::for_value(&*fake_ptr);
 
         let mem = Global.alloc(layout)
-            .unwrap_or_else(|_| Global.oom());
+            .unwrap_or_else(|_| oom());
 
         // Initialize the real ArcInner
         let inner = set_data_ptr(ptr as *mut T, mem.as_ptr() as *mut u8) as *mut ArcInner<T>;

src/liballoc/rc.rs

@@ -259,7 +259,7 @@ use core::ops::CoerceUnsized;
 use core::ptr::{self, NonNull};
 use core::convert::From;
 
-use alloc::{Global, Alloc, Layout, Opaque, box_free};
+use alloc::{Global, Alloc, Layout, Opaque, box_free, oom};
 use string::String;
 use vec::Vec;
 
@@ -668,7 +668,7 @@ impl<T: ?Sized> Rc<T> {
         let layout = Layout::for_value(&*fake_ptr);
 
         let mem = Global.alloc(layout)
-            .unwrap_or_else(|_| Global.oom());
+            .unwrap_or_else(|_| oom());
 
         // Initialize the real RcBox
         let inner = set_data_ptr(ptr as *mut T, mem.as_ptr() as *mut u8) as *mut RcBox<T>;

src/liballoc_jemalloc/lib.rs

@@ -30,8 +30,6 @@ extern crate libc;
 pub use contents::*;
 #[cfg(not(dummy_jemalloc))]
 mod contents {
-    use core::alloc::GlobalAlloc;
-    use alloc_system::System;
     use libc::{c_int, c_void, size_t};
 
     // Note that the symbols here are prefixed by default on macOS and Windows (we
@@ -100,10 +98,11 @@ mod contents {
         ptr
     }
 
+    #[cfg(stage0)]
     #[no_mangle]
     #[rustc_std_internal_symbol]
     pub unsafe extern fn __rde_oom() -> ! {
-        System.oom()
+        ::alloc_system::oom()
     }
 
     #[no_mangle]

src/liballoc_system/lib.rs

@@ -368,7 +368,7 @@ mod platform {
 }
 
 #[inline]
-fn oom() -> ! {
+pub fn oom() -> ! {
     write_to_stderr("fatal runtime error: memory allocation failed");
     unsafe {
         ::core::intrinsics::abort();

src/libcore/alloc.rs

@@ -451,17 +451,6 @@ pub unsafe trait GlobalAlloc {
         }
         new_ptr
     }
-
-    /// Aborts the thread or process, optionally performing
-    /// cleanup or logging diagnostic information before panicking or
-    /// aborting.
-    ///
-    /// `oom` is meant to be used by clients unable to cope with an
-    /// unsatisfied allocation request, and wish to abandon
-    /// computation rather than attempt to recover locally.
-    fn oom(&self) -> ! {
-        unsafe { ::intrinsics::abort() }
-    }
 }
 
 /// An implementation of `Alloc` can allocate, reallocate, and

src/librustc/middle/lang_items.rs

@@ -303,7 +303,8 @@ language_item_table! {
 
     ExchangeMallocFnLangItem,        "exchange_malloc",         exchange_malloc_fn;
     BoxFreeFnLangItem,               "box_free",                box_free_fn;
-    DropInPlaceFnLangItem,             "drop_in_place",           drop_in_place_fn;
+    DropInPlaceFnLangItem,           "drop_in_place",           drop_in_place_fn;
+    OomLangItem,                     "oom",                     oom;
 
     StartFnLangItem,                 "start",                   start_fn;
 

src/librustc/middle/weak_lang_items.rs

@@ -151,4 +151,5 @@ weak_lang_items! {
     panic_fmt,          PanicFmtLangItem,           rust_begin_unwind;
     eh_personality,     EhPersonalityLangItem,      rust_eh_personality;
     eh_unwind_resume,   EhUnwindResumeLangItem,     rust_eh_unwind_resume;
+    oom,                OomLangItem,                rust_oom;
 }

src/librustc_allocator/lib.rs

@@ -23,11 +23,6 @@ pub static ALLOCATOR_METHODS: &[AllocatorMethod] = &[
         inputs: &[AllocatorTy::Layout],
         output: AllocatorTy::ResultPtr,
     },
-    AllocatorMethod {
-        name: "oom",
-        inputs: &[],
-        output: AllocatorTy::Bang,
-    },
     AllocatorMethod {
         name: "dealloc",
         inputs: &[AllocatorTy::Ptr, AllocatorTy::Layout],

src/libstd/alloc.rs

@@ -13,10 +13,18 @@
 #![unstable(issue = "32838", feature = "allocator_api")]
 
 #[doc(inline)] #[allow(deprecated)] pub use alloc_crate::alloc::Heap;
-#[doc(inline)] pub use alloc_crate::alloc::Global;
+#[doc(inline)] pub use alloc_crate::alloc::{Global, oom};
 #[doc(inline)] pub use alloc_system::System;
 #[doc(inline)] pub use core::alloc::*;
 
+#[cfg(not(stage0))]
+#[cfg(not(test))]
+#[doc(hidden)]
+#[lang = "oom"]
+pub extern fn rust_oom() -> ! {
+    rtabort!("memory allocation failed");
+}
+
 #[cfg(not(test))]
 #[doc(hidden)]
 #[allow(unused_attributes)]
@@ -35,10 +43,11 @@ pub mod __default_lib_allocator {
         System.alloc(layout) as *mut u8
     }
 
+    #[cfg(stage0)]
     #[no_mangle]
     #[rustc_std_internal_symbol]
     pub unsafe extern fn __rdl_oom() -> ! {
-        System.oom()
+        super::oom()
     }
 
     #[no_mangle]