Move the signature_ids field first.

lib/environ/src/func_environ.rs

@@ -59,6 +59,9 @@ pub struct FuncEnvironment<'module_environment> {
     /// The Cranelift global holding the vmctx address.
     vmctx: Option<ir::GlobalValue>,
 
+    /// The Cranelift global holding the base address of the signature IDs vector.
+    signature_ids_base: Option<ir::GlobalValue>,
+
     /// The Cranelift global holding the base address of the imported functions table.
     imported_functions_base: Option<ir::GlobalValue>,
 
@@ -80,9 +83,6 @@ pub struct FuncEnvironment<'module_environment> {
     /// The Cranelift global holding the base address of the globals vector.
     globals_base: Option<ir::GlobalValue>,
 
-    /// The Cranelift global holding the base address of the signature IDs vector.
-    signature_ids_base: Option<ir::GlobalValue>,
-
     /// The external function declaration for implementing wasm's `memory.size`
     /// for locally-defined 32-bit memories.
     memory32_size_extfunc: Option<FuncRef>,
@@ -109,6 +109,7 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
             target_config,
             module,
             vmctx: None,
+            signature_ids_base: None,
             imported_functions_base: None,
             imported_tables_base: None,
             imported_memories_base: None,
@@ -116,7 +117,6 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
             tables_base: None,
             memories_base: None,
             globals_base: None,
-            signature_ids_base: None,
             memory32_size_extfunc: None,
             imported_memory32_size_extfunc: None,
             memory_grow_extfunc: None,

lib/environ/src/vmoffsets.rs

@@ -207,45 +207,45 @@ impl VMOffsets {
 
 /// Offsets for `VMContext`.
 impl VMOffsets {
+    /// The offset of the `signature_ids` field.
+    pub fn vmctx_signature_ids(&self) -> u8 {
+        0 * self.pointer_size
+    }
+
     /// The offset of the `tables` field.
     #[allow(clippy::erasing_op)]
     pub fn vmctx_imported_functions(&self) -> u8 {
-        0 * self.pointer_size
+        1 * self.pointer_size
     }
 
     /// The offset of the `tables` field.
     #[allow(clippy::identity_op)]
     pub fn vmctx_imported_tables(&self) -> u8 {
-        1 * self.pointer_size
+        2 * self.pointer_size
     }
 
     /// The offset of the `memories` field.
     pub fn vmctx_imported_memories(&self) -> u8 {
-        2 * self.pointer_size
+        3 * self.pointer_size
     }
 
     /// The offset of the `globals` field.
     pub fn vmctx_imported_globals(&self) -> u8 {
-        3 * self.pointer_size
+        4 * self.pointer_size
     }
 
     /// The offset of the `tables` field.
     pub fn vmctx_tables(&self) -> u8 {
-        4 * self.pointer_size
+        5 * self.pointer_size
     }
 
     /// The offset of the `memories` field.
     pub fn vmctx_memories(&self) -> u8 {
-        5 * self.pointer_size
+        6 * self.pointer_size
     }
 
     /// The offset of the `globals` field.
     pub fn vmctx_globals(&self) -> u8 {
-        6 * self.pointer_size
-    }
-
-    /// The offset of the `signature_ids` field.
-    pub fn vmctx_signature_ids(&self) -> u8 {
         7 * self.pointer_size
     }
 

lib/runtime/src/vmcontext.rs

@@ -469,6 +469,9 @@ impl Default for VMCallerCheckedAnyfunc {
 #[derive(Debug)]
 #[repr(C)]
 pub struct VMContext {
+    /// Signature identifiers for signature-checking indirect calls.
+    signature_ids: *mut VMSharedSignatureIndex,
+
     /// A pointer to an array of `*const VMFunctionBody` instances, indexed by `FuncIndex`.
     imported_functions: *const VMFunctionImport,
 
@@ -492,9 +495,6 @@ pub struct VMContext {
     /// A pointer to an array of locally-defined `VMGlobalDefinition` instances,
     /// indexed by `DefinedGlobalIndex`.
     globals: *mut VMGlobalDefinition,
-
-    /// Signature identifiers for signature-checking indirect calls.
-    signature_ids: *mut VMSharedSignatureIndex,
     // If more elements are added here, remember to add offset_of tests below!
 }
 
@@ -509,20 +509,36 @@ mod test {
         let offsets = VMOffsets::new(size_of::<*mut u8>() as u8);
         assert_eq!(size_of::<VMContext>(), usize::from(offsets.size_of_vmctx()));
         assert_eq!(
-            offset_of!(VMContext, memories),
+            offset_of!(VMContext, signature_ids),
-            usize::from(offsets.vmctx_memories())
+            usize::from(offsets.vmctx_signature_ids())
         );
         assert_eq!(
-            offset_of!(VMContext, globals),
+            offset_of!(VMContext, imported_functions),
-            usize::from(offsets.vmctx_globals())
+            usize::from(offsets.vmctx_imported_functions())
+        );
+        assert_eq!(
+            offset_of!(VMContext, imported_tables),
+            usize::from(offsets.vmctx_imported_tables())
+        );
+        assert_eq!(
+            offset_of!(VMContext, imported_memories),
+            usize::from(offsets.vmctx_imported_memories())
+        );
+        assert_eq!(
+            offset_of!(VMContext, imported_globals),
+            usize::from(offsets.vmctx_imported_globals())
         );
         assert_eq!(
             offset_of!(VMContext, tables),
             usize::from(offsets.vmctx_tables())
         );
         assert_eq!(
-            offset_of!(VMContext, signature_ids),
+            offset_of!(VMContext, memories),
-            usize::from(offsets.vmctx_signature_ids())
+            usize::from(offsets.vmctx_memories())
+        );
+        assert_eq!(
+            offset_of!(VMContext, globals),
+            usize::from(offsets.vmctx_globals())
         );
     }
 }