Don't save disabled FPU registers

GDB binary seems to need 2

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "unwinding"
-version = "0.1.4"
+version = "0.1.5"
 authors = ["Gary Guo <gary@garyguo.net>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"

src/abi.rs

@@ -137,7 +137,7 @@ binding! {
     extern "C-unwind" fn _Unwind_RaiseException(
         exception: &mut UnwindException,
     ) -> UnwindReasonCode;
-    extern "C-unwind" fn _Unwind_ForceUnwind(
+    extern "C-unwind" fn _Unwind_ForcedUnwind(
         exception: &mut UnwindException,
         stop: UnwindStopFn,
         stop_arg: *mut c_void,

src/panic.rs

@@ -8,15 +8,15 @@ pub use crate::panic_handler::*;
 use crate::panicking::Exception;
 
 #[repr(transparent)]
-struct RustPanic(Box<dyn Any + Send>, ForeignGuard);
+struct RustPanic(Box<dyn Any + Send>, DropGuard);
 
-struct ForeignGuard;
+struct DropGuard;
 
-impl Drop for ForeignGuard {
+impl Drop for DropGuard {
     fn drop(&mut self) {
         #[cfg(feature = "panic-handler")]
         {
-            foreign_exception();
+            drop_panic();
         }
         core::intrinsics::abort();
     }
@@ -45,7 +45,7 @@ unsafe impl Exception for RustPanic {
 }
 
 pub fn begin_panic(payload: Box<dyn Any + Send>) -> UnwindReasonCode {
-    crate::panicking::begin_panic(RustPanic(payload, ForeignGuard))
+    crate::panicking::begin_panic(RustPanic(payload, DropGuard))
 }
 
 pub fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
@@ -55,7 +55,7 @@ pub fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
             None => {
                 #[cfg(feature = "panic-handler")]
                 {
-                    drop_panic();
+                    foreign_exception();
                 }
                 core::intrinsics::abort();
             }

src/unwinder/arch/x86_64.rs

@@ -77,7 +77,7 @@ pub extern "C-unwind" fn save_context() -> Context {
             mov [rax + 0x78], r15
             mov rdx, [rsp]
             mov [rax + 0x80], rdx
-            stmxcsr [rax + 0x88]
+            /* stmxcsr [rax + 0x88] */
             fnstcw [rax + 0x90]
             ret
             ",
@@ -95,7 +95,7 @@ pub unsafe extern "C" fn restore_context(ctx: &Context) -> ! {
             mov rsp, [rdi + 0x38]
 
             /* Restore callee-saved control registers */
-            ldmxcsr [rdi + 0x88]
+            /* ldmxcsr [rdi + 0x88] */
             fldcw [rdi + 0x90]
 
             /* Restore return address */

src/unwinder/frame.rs

@@ -27,7 +27,7 @@ const fn next_value(x: usize) -> usize {
 
 impl<R: gimli::Reader> gimli::UnwindContextStorage<R> for StoreOnStack {
     type Rules = [(Register, RegisterRule<R>); next_value(MAX_REG_RULES)];
-    type Stack = [UnwindTableRow<R, Self>; 1];
+    type Stack = [UnwindTableRow<R, Self>; 2];
 }
 
 #[cfg(feature = "dwarf-expr")]

src/unwinder/mod.rs

@@ -217,7 +217,7 @@ fn raise_exception_phase2(
 
 #[inline(never)]
 #[no_mangle]
-pub extern "C-unwind" fn _Unwind_ForceUnwind(
+pub extern "C-unwind" fn _Unwind_ForcedUnwind(
     exception: &mut UnwindException,
     stop: UnwindStopFn,
     stop_arg: *mut c_void,