Fix table64 initialization when bulk memory is disabled (#12894)

* Fix table64 initialization when bulk memory is disabled

This commit fixes a panic in the host during instantiation when the
`bulk_memory` wasm feature is disabled. In this mode the initialization
of tables/memories is slightly different and a refactoring for 64-bit
support wasn't applied to this code path, meaning that it resulted in a
panic instead of properly handling 64-bit tables.

* Fix clippy

Author: alexcrichton

crates/wasmtime/src/runtime/vm/instance/allocator.rs

@@ -508,12 +508,12 @@ fn check_table_init_bounds(
         let start = const_evaluator
             .eval_int(&mut store, context, &segment.offset)
             .expect("const expression should be valid");
-        let start = usize::try_from(start.unwrap_i32().cast_unsigned()).unwrap();
-        let end = start.checked_add(usize::try_from(segment.elements.len()).unwrap());
+        let start = get_index(start, module.tables[segment.table_index].idx_type);
+        let end = start.checked_add(segment.elements.len());
 
         let table = store.instance_mut(instance).get_table(segment.table_index);
         match end {
-            Some(end) if end <= table.size() => {
+            Some(end) if end <= u64::try_from(table.size())? => {
                 // Initializer is in bounds
             }
             _ => {
@@ -564,10 +564,7 @@ async fn initialize_tables(
         let start = const_evaluator
             .eval_int(&mut store, context, &segment.offset)
             .expect("const expression should be valid");
-        let start = get_index(
-            start,
-            store.instance(context.instance).env_module().tables[segment.table_index].idx_type,
-        );
+        let start = get_index(start, module.tables[segment.table_index].idx_type);
         Instance::table_init_segment(
             &mut store,
             limiter.as_deref_mut(),

tests/misc_testsuite/memory64/tables-without-bulk-memory.wast

@@ -0,0 +1,13 @@
+;;! memory64 = true
+;;! reference_types = true
+;;! bulk_memory = false
+
+(module $A
+  (table (export "table") i64 1 funcref)
+)
+
+(module
+  (import "A" "table" (table $t i64 1 funcref))
+  (func $f)
+  (elem (i64.const 0) func $f)
+)