Remove custom frame info registration on i686-pc-windows-gnu

The indirection is no longer needed since we always link to libgcc
even when the panic_abort runtime is used. Instead we can just call
the libgcc functions directly.

library/panic_abort/src/lib.rs

@@ -123,13 +123,4 @@ pub mod personalities {
     #[allow(non_upper_case_globals)]
     #[cfg(target_os = "emscripten")]
     static rust_eh_catch_typeinfo: [usize; 2] = [0; 2];
-
-    // These two are called by our startup objects on i686-pc-windows-gnu, but
-    // they don't need to do anything so the bodies are nops.
-    #[rustc_std_internal_symbol]
-    #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))]
-    pub extern "C" fn rust_eh_register_frames() {}
-    #[rustc_std_internal_symbol]
-    #[cfg(all(target_os = "windows", target_env = "gnu", target_arch = "x86"))]
-    pub extern "C" fn rust_eh_unregister_frames() {}
 }

library/panic_unwind/src/gcc.rs

@@ -87,37 +87,3 @@ fn rust_exception_class() -> uw::_Unwind_Exception_Class {
     // M O Z \0  R U S T -- vendor, language
     0x4d4f5a_00_52555354
 }
-
-// Frame unwind info registration
-//
-// Each module's image contains a frame unwind info section (usually
-// ".eh_frame").  When a module is loaded/unloaded into the process, the
-// unwinder must be informed about the location of this section in memory. The
-// methods of achieving that vary by the platform.  On some (e.g., Linux), the
-// unwinder can discover unwind info sections on its own (by dynamically
-// enumerating currently loaded modules via the dl_iterate_phdr() API and
-// finding their ".eh_frame" sections); Others, like Windows, require modules
-// to actively register their unwind info sections via unwinder API.
-//
-// This module defines two symbols which are referenced and called from
-// rsbegin.rs to register our information with the GCC runtime. The
-// implementation of stack unwinding is (for now) deferred to libgcc_eh, however
-// Rust crates use these Rust-specific entry points to avoid potential clashes
-// with any GCC runtime.
-#[cfg(all(target_os = "windows", target_arch = "x86", target_env = "gnu"))]
-pub mod eh_frame_registry {
-    extern "C" {
-        fn __register_frame_info(eh_frame_begin: *const u8, object: *mut u8);
-        fn __deregister_frame_info(eh_frame_begin: *const u8, object: *mut u8);
-    }
-
-    #[rustc_std_internal_symbol]
-    pub unsafe extern "C" fn rust_eh_register_frames(eh_frame_begin: *const u8, object: *mut u8) {
-        __register_frame_info(eh_frame_begin, object);
-    }
-
-    #[rustc_std_internal_symbol]
-    pub unsafe extern "C" fn rust_eh_unregister_frames(eh_frame_begin: *const u8, object: *mut u8) {
-        __deregister_frame_info(eh_frame_begin, object);
-    }
-}

library/panic_unwind/src/lib.rs

@@ -52,9 +52,6 @@ cfg_if::cfg_if! {
         all(target_family = "unix", not(target_os = "espidf")),
         all(target_vendor = "fortanix", target_env = "sgx"),
     ))] {
-        // Rust runtime's startup objects depend on these symbols, so make them public.
-        #[cfg(all(target_os="windows", target_arch = "x86", target_env="gnu"))]
-        pub use real_imp::eh_frame_registry::*;
         #[path = "gcc.rs"]
         mod real_imp;
     } else {

library/rtstartup/rsbegin.rs

@@ -35,6 +35,16 @@ pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
     drop_in_place(to_drop);
 }
 
+// Frame unwind info registration
+//
+// Each module's image contains a frame unwind info section (usually
+// ".eh_frame").  When a module is loaded/unloaded into the process, the
+// unwinder must be informed about the location of this section in memory. The
+// methods of achieving that vary by the platform.  On some (e.g., Linux), the
+// unwinder can discover unwind info sections on its own (by dynamically
+// enumerating currently loaded modules via the dl_iterate_phdr() API and
+// finding their ".eh_frame" sections); Others, like Windows, require modules
+// to actively register their unwind info sections via unwinder API.
 #[cfg(all(target_os = "windows", target_arch = "x86", target_env = "gnu"))]
 pub mod eh_frames {
     #[no_mangle]
@@ -62,20 +72,19 @@ pub mod eh_frames {
     }
 
     // Unwind info registration/deregistration routines.
-    // See the docs of libpanic_unwind.
     extern "C" {
-        fn rust_eh_register_frames(eh_frame_begin: *const u8, object: *mut u8);
-        fn rust_eh_unregister_frames(eh_frame_begin: *const u8, object: *mut u8);
+        fn __register_frame_info(eh_frame_begin: *const u8, object: *mut u8);
+        fn __deregister_frame_info(eh_frame_begin: *const u8, object: *mut u8);
     }
 
     unsafe extern "C" fn init() {
         // register unwind info on module startup
-        rust_eh_register_frames(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8);
+        __register_frame_info(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8);
     }
 
     unsafe extern "C" fn uninit() {
         // unregister on shutdown
-        rust_eh_unregister_frames(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8);
+        __deregister_frame_info(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8);
     }
 
     // MinGW-specific init/uninit routine registration