Rewrite emscripten unwinding to use libcxx

src/libpanic_unwind/Cargo.lock

@@ -5,6 +5,7 @@ dependencies = [
  "alloc 0.0.0",
  "core 0.0.0",
  "libc 0.0.0",
+ "unwind 0.0.0",
 ]
 
 [[package]]
@@ -25,3 +26,11 @@ dependencies = [
  "core 0.0.0",
 ]
 
+[[package]]
+name = "unwind"
+version = "0.0.0"
+dependencies = [
+ "core 0.0.0",
+ "libc 0.0.0",
+]
+

src/libpanic_unwind/emcc.rs

@@ -0,0 +1,76 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(private_no_mangle_fns)]
+
+use core::any::Any;
+use core::ptr;
+use alloc::boxed::Box;
+use libc::{self, c_int};
+use unwind as uw;
+use core::mem;
+
+pub fn payload() -> *mut u8 {
+    ptr::null_mut()
+}
+
+pub unsafe fn cleanup(ptr: *mut u8) -> Box<Any + Send> {
+    assert!(!ptr.is_null());
+    let ex = ptr::read(ptr as *mut _);
+    __cxa_free_exception(ptr as *mut _);
+    ex
+}
+
+pub unsafe fn panic(data: Box<Any + Send>) -> u32 {
+    let sz = mem::size_of_val(&data);
+    let exception = __cxa_allocate_exception(sz);
+    if exception == ptr::null_mut() {
+        return uw::_URC_FATAL_PHASE1_ERROR as u32;
+    }
+    let exception = exception as *mut Box<Any + Send>;
+    ptr::write(exception, data);
+    __cxa_throw(exception as *mut _, ptr::null_mut(), ptr::null_mut());
+
+    unreachable!()
+}
+
+#[lang = "eh_personality"]
+#[no_mangle]
+unsafe extern "C" fn rust_eh_personality(version: c_int,
+                                         actions: uw::_Unwind_Action,
+                                         exception_class: uw::_Unwind_Exception_Class,
+                                         exception_object: *mut uw::_Unwind_Exception,
+                                         context: *mut uw::_Unwind_Context)
+                                         -> uw::_Unwind_Reason_Code {
+    __gxx_personality_v0(version, actions,
+                         exception_class,
+                         exception_object,
+                         context)
+}
+
+#[lang = "eh_unwind_resume"]
+#[unwind]
+unsafe extern "C" fn rust_eh_unwind_resume(panic_ctx: *mut u8) -> ! {
+    uw::_Unwind_Resume(panic_ctx as *mut uw::_Unwind_Exception);
+}
+
+extern {
+    fn __cxa_allocate_exception(thrown_size: libc::size_t) -> *mut libc::c_void;
+    fn __cxa_free_exception(thrown_exception: *mut libc::c_void);
+    fn __cxa_throw(thrown_exception: *mut libc::c_void,
+                   tinfo: *mut libc::c_void,
+                   dest: *mut libc::c_void);
+    fn __gxx_personality_v0(version: c_int,
+                            actions: uw::_Unwind_Action,
+                            exception_class: uw::_Unwind_Exception_Class,
+                            exception_object: *mut uw::_Unwind_Exception,
+                            context: *mut uw::_Unwind_Context)
+                            -> uw::_Unwind_Reason_Code;
+}

src/libpanic_unwind/gcc.rs

@@ -133,16 +133,6 @@ const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4 / X3, X4
 #[cfg(target_arch = "s390x")]
 const UNWIND_DATA_REG: (i32, i32) = (6, 7); // R6, R7
 
-// FIXME: This is completely and utterly wrong.
-// I copy'n'pasted the x86 thing just to see if asmjs-unknown-emscripten compiles at all
-// (the happy path)
-#[cfg(target_arch = "asmjs")]
-const UNWIND_DATA_REG: (i32, i32) = (0, 2); // EAX, EDX
-
-// FIXME: Ditto the above
-#[cfg(target_arch = "wasm32")]
-const UNWIND_DATA_REG: (i32, i32) = (0, 2); // EAX, EDX
-
 // The following code is based on GCC's C and C++ personality routines.  For reference, see:
 // https://github.com/gcc-mirror/gcc/blob/master/libstdc++-v3/libsupc++/eh_personality.cc
 // https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c

src/libpanic_unwind/lib.rs

@@ -68,10 +68,16 @@ mod imp;
 mod imp;
 
 // i686-pc-windows-gnu and all others
-#[cfg(any(unix, all(windows, target_arch = "x86", target_env = "gnu")))]
+#[cfg(any(all(unix, not(target_os = "emscripten")),
+          all(windows, target_arch = "x86", target_env = "gnu")))]
 #[path = "gcc.rs"]
 mod imp;
 
+// emscripten
+#[cfg(target_os = "emscripten")]
+#[path = "emcc.rs"]
+mod imp;
+
 mod dwarf;
 mod windows;
 

src/libunwind/libunwind.rs

@@ -65,7 +65,7 @@ pub const unwinder_private_data_size: usize = 2;
 #[cfg(target_arch = "s390x")]
 pub const unwinder_private_data_size: usize = 2;
 
-#[cfg(any(target_arch = "asmjs", target_arch = "wasm32"))]
+#[cfg(target_os = "emscripten")]
 pub const unwinder_private_data_size: usize = 20;
 
 #[repr(C)]