Remove eh_unwind_resume lang item

Author: Amanieu

Diff for: src/doc/unstable-book/src/language-features/lang-items.md

@@ -52,7 +52,6 @@ fn main(_argc: isize, _argv: *const *const u8) -> isize {
 
 #[lang = "eh_personality"] extern fn rust_eh_personality() {}
 #[lang = "panic_impl"] extern fn rust_begin_panic(info: &PanicInfo) -> ! { unsafe { intrinsics::abort() } }
-#[lang = "eh_unwind_resume"] extern fn rust_eh_unwind_resume() {}
 #[no_mangle] pub extern fn rust_eh_register_frames () {}
 #[no_mangle] pub extern fn rust_eh_unregister_frames () {}
 ```
@@ -67,7 +66,7 @@ Other features provided by lang items include:
   marked with lang items; those specific four are `eq`, `ord`,
   `deref`, and `add` respectively.
 - stack unwinding and general failure; the `eh_personality`,
-  `eh_unwind_resume`, `fail` and `fail_bounds_checks` lang items.
+  `fail` and `fail_bounds_checks` lang items.
 - the traits in `std::marker` used to indicate types of
   various kinds; lang items `send`, `sync` and `copy`.
 - the marker types and variance indicators found in
@@ -130,12 +129,6 @@ fn start(_argc: isize, _argv: *const *const u8) -> isize {
 pub extern fn rust_eh_personality() {
 }
 
-// This function may be needed based on the compilation target.
-#[lang = "eh_unwind_resume"]
-#[no_mangle]
-pub extern fn rust_eh_unwind_resume() {
-}
-
 #[lang = "panic_impl"]
 #[no_mangle]
 pub extern fn rust_begin_panic(info: &PanicInfo) -> ! {
@@ -173,12 +166,6 @@ pub extern fn main(_argc: i32, _argv: *const *const u8) -> i32 {
 pub extern fn rust_eh_personality() {
 }
 
-// This function may be needed based on the compilation target.
-#[lang = "eh_unwind_resume"]
-#[no_mangle]
-pub extern fn rust_eh_unwind_resume() {
-}
-
 #[lang = "panic_impl"]
 #[no_mangle]
 pub extern fn rust_begin_panic(info: &PanicInfo) -> ! {
@@ -213,8 +200,8 @@ the screen. While the language item's name is `panic_impl`, the symbol name is
 
 A third function, `rust_eh_unwind_resume`, is also needed if the `custom_unwind_resume`
 flag is set in the options of the compilation target. It allows customizing the
-process of resuming unwind at the end of the landing pads. The language item's name
-is `eh_unwind_resume`.
+process of resuming unwind at the end of the landing pads. Since this function
+must be defined in assembly code it does not have an associated language item.
 
 ## List of all language items
 
@@ -247,8 +234,8 @@ the source code.
   - `eh_personality`: `libpanic_unwind/emcc.rs` (EMCC)
   - `eh_personality`: `libpanic_unwind/gcc.rs` (GNU)
   - `eh_personality`: `libpanic_unwind/seh.rs` (SEH)
-  - `eh_unwind_resume`: `libpanic_unwind/gcc.rs` (GCC)
   - `eh_catch_typeinfo`: `libpanic_unwind/emcc.rs` (EMCC)
+  - `rust_eh_unwind_resume`: `libpanic_unwind/gcc.rs` (GCC)
   - `panic`: `libcore/panicking.rs`
   - `panic_bounds_check`: `libcore/panicking.rs`
   - `panic_impl`: `libcore/panicking.rs`

Diff for: src/librustc/middle/lang_items.rs

@@ -57,8 +57,7 @@ pub fn whitelisted(tcx: TyCtxt<'_>, lang_item: LangItem) -> bool {
     // symbols. Other panic runtimes ensure that the relevant symbols are
     // available to link things together, but they're never exercised.
     if tcx.sess.panic_strategy() != PanicStrategy::Unwind {
-        return lang_item == LangItem::EhPersonalityLangItem
-            || lang_item == LangItem::EhUnwindResumeLangItem;
+        return lang_item == LangItem::EhPersonalityLangItem;
     }
 
     false

Diff for: src/librustc_codegen_llvm/context.rs

@@ -1,4 +1,3 @@
-use crate::abi::FnAbi;
 use crate::attributes;
 use crate::debuginfo;
 use crate::llvm;
@@ -15,23 +14,20 @@ use rustc::mir::mono::CodegenUnit;
 use rustc::session::config::{self, CFGuard, DebugInfo};
 use rustc::session::Session;
 use rustc::ty::layout::{
-    FnAbiExt, HasParamEnv, LayoutError, LayoutOf, PointeeInfo, Size, TyLayout, VariantIdx,
+    HasParamEnv, LayoutError, LayoutOf, PointeeInfo, Size, TyLayout, VariantIdx,
 };
 use rustc::ty::{self, Instance, Ty, TyCtxt};
 use rustc_codegen_ssa::base::wants_msvc_seh;
 use rustc_data_structures::base_n;
 use rustc_data_structures::const_cstr;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::small_c_str::SmallCStr;
-use rustc_hir::Unsafety;
 use rustc_target::spec::{HasTargetSpec, Target};
 
-use crate::abi::Abi;
 use rustc_span::source_map::{Span, DUMMY_SP};
 use rustc_span::symbol::Symbol;
 use std::cell::{Cell, RefCell};
 use std::ffi::CStr;
-use std::iter;
 use std::str;
 use std::sync::Arc;
 
@@ -87,7 +83,6 @@ pub struct CodegenCx<'ll, 'tcx> {
     pub dbg_cx: Option<debuginfo::CrateDebugContext<'ll, 'tcx>>,
 
     eh_personality: Cell<Option<&'ll Value>>,
-    eh_unwind_resume: Cell<Option<&'ll Value>>,
     pub rust_try_fn: Cell<Option<&'ll Value>>,
 
     intrinsics: RefCell<FxHashMap<&'static str, &'ll Value>>,
@@ -328,7 +323,6 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
             isize_ty,
             dbg_cx,
             eh_personality: Cell::new(None),
-            eh_unwind_resume: Cell::new(None),
             rust_try_fn: Cell::new(None),
             intrinsics: Default::default(),
             local_gen_sym_counter: Cell::new(0),
@@ -406,45 +400,6 @@ impl MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         llfn
     }
 
-    // Returns a Value of the "eh_unwind_resume" lang item if one is defined,
-    // otherwise declares it as an external function.
-    fn eh_unwind_resume(&self) -> &'ll Value {
-        let unwresume = &self.eh_unwind_resume;
-        if let Some(llfn) = unwresume.get() {
-            return llfn;
-        }
-
-        let tcx = self.tcx;
-        assert!(self.sess().target.target.options.custom_unwind_resume);
-        if let Some(def_id) = tcx.lang_items().eh_unwind_resume() {
-            let llfn = self.get_fn_addr(
-                ty::Instance::resolve(
-                    tcx,
-                    ty::ParamEnv::reveal_all(),
-                    def_id,
-                    tcx.intern_substs(&[]),
-                )
-                .unwrap(),
-            );
-            unwresume.set(Some(llfn));
-            return llfn;
-        }
-
-        let sig = ty::Binder::bind(tcx.mk_fn_sig(
-            iter::once(tcx.mk_mut_ptr(tcx.types.u8)),
-            tcx.types.never,
-            false,
-            Unsafety::Unsafe,
-            Abi::C,
-        ));
-
-        let fn_abi = FnAbi::of_fn_ptr(self, sig, &[]);
-        let llfn = self.declare_fn("rust_eh_unwind_resume", &fn_abi);
-        attributes::apply_target_cpu_attr(self, llfn);
-        unwresume.set(Some(llfn));
-        llfn
-    }
-
     fn sess(&self) -> &Session {
         &self.tcx.sess
     }

Diff for: src/librustc_codegen_ssa/traits/misc.rs

@@ -14,7 +14,6 @@ pub trait MiscMethods<'tcx>: BackendTypes {
     fn get_fn(&self, instance: Instance<'tcx>) -> Self::Function;
     fn get_fn_addr(&self, instance: Instance<'tcx>) -> Self::Value;
     fn eh_personality(&self) -> Self::Value;
-    fn eh_unwind_resume(&self) -> Self::Value;
     fn sess(&self) -> &Session;
     fn codegen_unit(&self) -> &Arc<CodegenUnit<'tcx>>;
     fn used_statics(&self) -> &RefCell<Vec<Self::Value>>;

Diff for: src/librustc_hir/lang_items.rs

@@ -240,7 +240,6 @@ language_item_table! {
     StartFnLangItem,             "start",              start_fn,                Target::Fn;
 
     EhPersonalityLangItem,       "eh_personality",     eh_personality,          Target::Fn;
-    EhUnwindResumeLangItem,      "eh_unwind_resume",   eh_unwind_resume,        Target::Fn;
     EhCatchTypeinfoLangItem,     "eh_catch_typeinfo",  eh_catch_typeinfo,       Target::Static;
 
     OwnedBoxLangItem,            "owned_box",          owned_box,               Target::Struct;

Diff for: src/librustc_hir/weak_lang_items.rs

@@ -43,6 +43,5 @@ impl LanguageItems {
 weak_lang_items! {
     panic_impl,         PanicImplLangItem,          rust_begin_unwind;
     eh_personality,     EhPersonalityLangItem,      rust_eh_personality;
-    eh_unwind_resume,   EhUnwindResumeLangItem,     rust_eh_unwind_resume;
     oom,                OomLangItem,                rust_oom;
 }

Diff for: src/librustc_passes/weak_lang_items.rs

@@ -28,9 +28,6 @@ pub fn check_crate<'tcx>(tcx: TyCtxt<'tcx>, items: &mut lang_items::LanguageItem
     if items.eh_personality().is_none() {
         items.missing.push(lang_items::EhPersonalityLangItem);
     }
-    if tcx.sess.target.target.options.custom_unwind_resume & items.eh_unwind_resume().is_none() {
-        items.missing.push(lang_items::EhUnwindResumeLangItem);
-    }
 
     {
         let mut cx = Context { tcx, items };

Diff for: src/librustc_span/symbol.rs

@@ -287,7 +287,6 @@ symbols! {
         dylib,
         dyn_trait,
         eh_personality,
-        eh_unwind_resume,
         enable,
         Encodable,
         env,
@@ -663,7 +662,6 @@ symbols! {
         rustc_variance,
         rustfmt,
         rust_eh_personality,
-        rust_eh_unwind_resume,
         rust_oom,
         rvalue_static_promotion,
         sanitize,

Diff for: src/librustc_target/spec/mod.rs

@@ -695,7 +695,7 @@ pub struct TargetOptions {
     /// Whether the target uses a custom unwind resumption routine.
     /// By default LLVM lowers `resume` instructions into calls to `_Unwind_Resume`
     /// defined in libgcc. If this option is enabled, the target must provide
-    /// `eh_unwind_resume` lang item.
+    /// a `rust_eh_unwind_resume` symbol.
     pub custom_unwind_resume: bool,
     /// Whether the runtime startup code requires the `main` function be passed
     /// `argc` and `argv` values.

Diff for: src/test/compile-fail/auxiliary/panic-runtime-lang-items.rs

@@ -11,5 +11,3 @@ use core::panic::PanicInfo;
 fn panic_impl(info: &PanicInfo) -> ! { loop {} }
 #[lang = "eh_personality"]
 fn eh_personality() {}
-#[lang = "eh_unwind_resume"]
-fn eh_unwind_resume() {}

Diff for: src/test/ui/consts/const-eval/const_panic_libcore_main.rs

@@ -17,8 +17,6 @@ const X: () = unimplemented!();
 
 #[lang = "eh_personality"]
 fn eh() {}
-#[lang = "eh_unwind_resume"]
-fn eh_unwind_resume() {}
 
 #[panic_handler]
 fn panic(_info: &PanicInfo) -> ! {

Diff for: src/test/ui/macros/macro-comma-behavior.rs

@@ -9,7 +9,6 @@
 #[cfg(std)] use std::fmt;
 #[cfg(core)] use core::fmt;
 #[cfg(core)] #[lang = "eh_personality"] fn eh_personality() {}
-#[cfg(core)] #[lang = "eh_unwind_resume"] fn eh_unwind_resume() {}
 #[cfg(core)] #[lang = "panic_impl"] fn panic_impl(panic: &core::panic::PanicInfo) -> ! { loop {} }
 
 // (see documentation of the similarly-named test in run-pass)

Diff for: src/test/ui/no_owned_box_lang_item.rs

@@ -12,5 +12,4 @@ fn main() {
 }
 
 #[lang = "eh_personality"] extern fn eh_personality() {}
-#[lang = "eh_unwind_resume"] extern fn eh_unwind_resume() {}
 #[lang = "panic_impl"] fn panic_impl(panic: &PanicInfo) -> ! { loop {} }

Diff for: src/test/ui/panic-runtime/auxiliary/panic-runtime-lang-items.rs

@@ -11,5 +11,3 @@ use core::panic::PanicInfo;
 fn panic_impl(info: &PanicInfo) -> ! { loop {} }
 #[lang = "eh_personality"]
 fn eh_personality() {}
-#[lang = "eh_unwind_resume"]
-fn eh_unwind_resume() {}

Diff for: src/test/ui/range/issue-54505-no-std.rs

@@ -15,10 +15,6 @@ use core::ops::RangeBounds;
 #[lang = "eh_personality"]
 extern fn eh_personality() {}
 
-#[cfg(target_os = "windows")]
-#[lang = "eh_unwind_resume"]
-extern fn eh_unwind_resume() {}
-
 
 // take a reference to any built-in range
 fn take_range(_r: &impl RangeBounds<i8>) {}