possible change to ZIR for functions

patch.diff

--- a/src/Zir.zig
+++ b/src/Zir.zig
     /// Trailing:
     /// 0. lib_name: u32, // null terminated string index, if has_lib_name is set
-    /// 1. cc: Ref, // if has_cc is set
-    /// 2. align: Ref, // if has_align is set
-    /// 3. return_type: Index // for each ret_body_len
-    /// 4. body: Index // for each body_len
-    /// 5. src_locs: Func.SrcLocs // if body_len != 0
-    pub const ExtendedFunc = struct {
-        /// If this is 0 it means a void return type.
-        ret_body_len: u32,
+    /// if (has_cc_ref) {
+    ///   1. cc: Ref,
+    /// }
+    /// if (has_cc_body) {
+    ///   2. cc_body_len: u32
+    ///   3. cc_body: u32 // for each cc_body_len
+    /// }
+    /// if (has_align_ref) {
+    ///   4. align: Ref,
+    /// }
+    /// if (has_align_body) {
+    ///   5. align_body_len: u32
+    ///   6. align_body: u32 // for each align_body_len
+    /// }
+    /// if (has_ret_ty_ref) {
+    ///   7. ret_ty: Ref,
+    /// }
+    /// if (has_ret_ty_body) {
+    ///   8. ret_ty_body_len: u32
+    ///   9. ret_ty_body: u32 // for each ret_ty_body_len
+    /// }
+    /// if (has_section_ref) {
+    ///   10. section: Ref,
+    /// }
+    /// if (has_section_body) {
+    ///   11. section_body_len: u32
+    ///   12. section_body: u32 // for each section_body_len
+    /// }
+    /// if (has_addrspace_ref) {
+    ///   13. addrspace: Ref,
+    /// }
+    /// if (has_addrspace_body) {
+    ///   14. addrspace_body_len: u32
+    ///   15. addrspace_body: u32 // for each addrspace_body_len
+    /// }
+    /// 16. body: Index // for each body_len
+    /// 17. src_locs: Func.SrcLocs // if body_len != 0
+    pub const FuncFancy = struct {
         /// Points to the block that contains the param instructions for this function.
         param_block: Index,
         body_len: u32,
         bits: Bits,
 
+        /// If both has_cc_ref and has_cc_body are false, it means auto calling convention.
+        /// If both has_align_ref and has_align_body are false, it means default alignment.
+        /// If both has_ret_ty_ref and has_ret_ty_body are false, it means void return type.
+        /// If both has_section_ref and has_section_body are false, it means default section.
+        /// If both has_addrspace_ref and has_addrspace_body are false, it means default addrspace.
         pub const Bits = packed struct {
             is_var_args: bool,
             is_inferred_error: bool,
-            has_lib_name: bool,
-            has_cc: bool,
-            has_align: bool,
             is_test: bool,
             is_extern: bool,
-            _: u25 = undefined,
+            has_cc_ref: bool,
+            has_cc_body: bool,
+            has_align_ref: bool,
+            has_align_body: bool,
+            has_ret_ty_ref: bool,
+            has_ret_ty_body: bool,
+            has_section_ref: bool,
+            has_section_body: bool,
+            has_addrspace_ref: bool,
+            has_addrspace_body: bool,
+            has_lib_name: bool,
+            _: u17 = undefined,
         };
     };