Remove eh_unwind_resume lang item

Author: Amanieu

Cargo.lock

@@ -2308,7 +2308,6 @@ dependencies = [
 name = "panic_abort"
 version = "0.0.0"
 dependencies = [
- "cfg-if",
  "compiler_builtins",
  "core",
  "libc",

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.
+  `panic` and `panic_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) -> ! {
@@ -211,10 +198,8 @@ compiler. When a panic happens, this controls the message that's displayed on
 the screen. While the language item's name is `panic_impl`, the symbol name is
 `rust_begin_panic`.
 
-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`.
+Finally, a `eh_catch_typeinfo` static is needed for certain targets which
+implement Rust panics on top of C++ exceptions.
 
 ## List of all language items
 
@@ -247,7 +232,6 @@ 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)
   - `panic`: `libcore/panicking.rs`
   - `panic_bounds_check`: `libcore/panicking.rs`

src/libpanic_abort/Cargo.toml

@@ -14,4 +14,3 @@ doc = false
 core = { path = "../libcore" }
 libc = { version = "0.2", default-features = false }
 compiler_builtins = "0.1.0"
-cfg-if = "0.1.8"

src/libpanic_abort/lib.rs

@@ -115,7 +115,7 @@ pub mod personalities {
     // Note that we don't execute landing pads, so this is never called, so it's
     // body is empty.
     #[no_mangle]
-    #[cfg(all(target_os = "windows", target_env = "gnu"))]
+    #[cfg(all(bootstrap, target_os = "windows", target_env = "gnu"))]
     pub extern "C" fn rust_eh_unwind_resume() {}
 
     // These two are called by our startup objects on i686-pc-windows-gnu, but

src/libpanic_unwind/gcc.rs

@@ -35,14 +35,6 @@
 //!
 //! Once stack has been unwound down to the handler frame level, unwinding stops
 //! and the last personality routine transfers control to the catch block.
-//!
-//! ## `eh_personality` and `eh_unwind_resume`
-//!
-//! These language items are used by the compiler when generating unwind info.
-//! The first one is the personality routine described above. The second one
-//! allows compilation target to customize the process of resuming unwind at the
-//! end of the landing pads. `eh_unwind_resume` is used only if
-//! `custom_unwind_resume` flag in the target options is set.
 
 #![allow(private_no_mangle_fns)]
 
@@ -324,8 +316,8 @@ unsafe fn find_eh_action(
     eh::find_eh_action(lsda, &eh_context, foreign_exception)
 }
 
-// See docs in the `unwind` module.
 #[cfg(all(
+    bootstrap,
     target_os = "windows",
     any(target_arch = "x86", target_arch = "x86_64"),
     target_env = "gnu"

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

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
     }

src/librustc_codegen_ssa/mir/block.rs

@@ -178,15 +178,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             let lp1 = bx.load_operand(lp1).immediate();
             slot.storage_dead(&mut bx);
 
-            if !bx.sess().target.target.options.custom_unwind_resume {
-                let mut lp = bx.const_undef(self.landing_pad_type());
-                lp = bx.insert_value(lp, lp0, 0);
-                lp = bx.insert_value(lp, lp1, 1);
-                bx.resume(lp);
-            } else {
-                bx.call(bx.eh_unwind_resume(), &[lp0], helper.funclet(self));
-                bx.unreachable();
-            }
+            let mut lp = bx.const_undef(self.landing_pad_type());
+            lp = bx.insert_value(lp, lp0, 0);
+            lp = bx.insert_value(lp, lp1, 1);
+            bx.resume(lp);
         }
     }
 

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>>;

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;