Add support for table.copy

This adds support for the `table.copy` instruction from the bulk memory
proposal. It also supports multiple tables, which were introduced by the
reference types proposal.

Part of #928

crates/runtime/src/traphandlers.rs

@@ -73,6 +73,20 @@ pub unsafe fn raise_user_trap(data: Box<dyn Error + Send + Sync>) -> ! {
     tls::with(|info| info.unwrap().unwind_with(UnwindReason::UserTrap(data)))
 }
 
+/// Raises a trap from inside library code immediately.
+///
+/// This function performs as-if a wasm trap was just executed. This trap
+/// payload is then returned from `wasmtime_call` and `wasmtime_call_trampoline`
+/// below.
+///
+/// # Safety
+///
+/// Only safe to call when wasm code is on the stack, aka `wasmtime_call` or
+/// `wasmtime_call_trampoline` must have been previously called.
+pub unsafe fn raise_lib_trap(trap: Trap) -> ! {
+    tls::with(|info| info.unwrap().unwind_with(UnwindReason::LibTrap(trap)))
+}
+
 /// Carries a Rust panic across wasm code and resumes the panic on the other
 /// side.
 ///
@@ -192,6 +206,7 @@ enum UnwindReason {
     None,
     Panic(Box<dyn Any + Send>),
     UserTrap(Box<dyn Error + Send + Sync>),
+    LibTrap(Trap),
     Trap { backtrace: Backtrace, pc: usize },
 }
 
@@ -219,6 +234,7 @@ impl CallThreadState {
                     debug_assert_eq!(ret, 0);
                     Err(Trap::User(data))
                 }
+                UnwindReason::LibTrap(trap) => Err(trap),
                 UnwindReason::Trap { backtrace, pc } => {
                     debug_assert_eq!(ret, 0);
                     let instance = unsafe { InstanceHandle::from_vmctx(self.vmctx) };