Work around naked-function-plus-LTO issue (#11960) (#11972)

This is an attempt to apply a local fix for #11957 which works around
the upstream Rust issue mentioned in that issue.

Author: alexcrichton

crates/fiber/src/stackswitch/aarch64.rs

@@ -36,8 +36,13 @@ cfg_if::cfg_if! {
     }
 }
 
+#[inline(never)] // FIXME(rust-lang/rust#148307)
+pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8) {
+    unsafe { wasmtime_fiber_switch_(top_of_stack) }
+}
+
 #[unsafe(naked)]
-pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8 /* x0 */) {
+unsafe extern "C" fn wasmtime_fiber_switch_(top_of_stack: *mut u8 /* x0 */) {
     naked_asm!(concat!(
         "
             .cfi_startproc

crates/fiber/src/stackswitch/arm.rs

@@ -10,8 +10,13 @@
 
 use core::arch::naked_asm;
 
+#[inline(never)] // FIXME(rust-lang/rust#148307)
+pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8) {
+    unsafe { wasmtime_fiber_switch_(top_of_stack) }
+}
+
 #[unsafe(naked)]
-pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8 /* r0 */) {
+unsafe extern "C" fn wasmtime_fiber_switch_(top_of_stack: *mut u8 /* r0 */) {
     naked_asm!(
         "
         // Save callee-saved registers

crates/fiber/src/stackswitch/riscv64.rs

@@ -7,8 +7,13 @@
 
 use core::arch::naked_asm;
 
+#[inline(never)] // FIXME(rust-lang/rust#148307)
+pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8) {
+    unsafe { wasmtime_fiber_switch_(top_of_stack) }
+}
+
 #[unsafe(naked)]
-pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8 /* a0 */) {
+unsafe extern "C" fn wasmtime_fiber_switch_(top_of_stack: *mut u8 /* a0 */) {
     naked_asm!(
         "
       // See https://github.com/rust-lang/rust/issues/80608.

crates/fiber/src/stackswitch/s390x.rs

@@ -7,8 +7,13 @@
 
 use core::arch::naked_asm;
 
+#[inline(never)] // FIXME(rust-lang/rust#148307)
+pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8) {
+    unsafe { wasmtime_fiber_switch_(top_of_stack) }
+}
+
 #[unsafe(naked)]
-pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8 /* x0 */) {
+unsafe extern "C" fn wasmtime_fiber_switch_(top_of_stack: *mut u8 /* x0 */) {
     naked_asm!(
         "
         // Save all callee-saved registers on the stack since we're assuming

crates/fiber/src/stackswitch/x86.rs

@@ -12,8 +12,13 @@
 
 use core::arch::naked_asm;
 
-#[unsafe(naked)]
+#[inline(never)] // FIXME(rust-lang/rust#148307)
 pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8) {
+    unsafe { wasmtime_fiber_switch_(top_of_stack) }
+}
+
+#[unsafe(naked)]
+unsafe extern "C" fn wasmtime_fiber_switch_(top_of_stack: *mut u8) {
     naked_asm!(
         "
         // Load our stack-to-use

crates/fiber/src/stackswitch/x86_64.rs

@@ -7,8 +7,13 @@
 
 use core::arch::naked_asm;
 
+#[inline(never)] // FIXME(rust-lang/rust#148307)
+pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8) {
+    unsafe { wasmtime_fiber_switch_(top_of_stack) }
+}
+
 #[unsafe(naked)]
-pub(crate) unsafe extern "C" fn wasmtime_fiber_switch(top_of_stack: *mut u8 /* rdi */) {
+unsafe extern "C" fn wasmtime_fiber_switch_(top_of_stack: *mut u8 /* rdi */) {
     naked_asm!(
         "
         // We're switching to arbitrary code somewhere else, so pessimistically