Emit gc glue and rearrange crate glue offsets slightly to have a regular order.

src/boot/be/abi.ml

@@ -145,6 +145,7 @@ type abi =
     abi_activate: (Il.emitter -> unit);
     abi_yield: (Il.emitter -> unit);
     abi_unwind: (Il.emitter -> Common.nabi -> Common.fixup -> unit);
+    abi_gc: (Il.emitter -> unit);
     abi_get_next_pc_thunk:
       ((Il.reg                   (* output            *)
         * Common.fixup           (* thunk in objfile  *)

src/boot/be/x86.ml

@@ -1627,6 +1627,7 @@ let (abi:Abi.abi) =
     Abi.abi_activate = activate_glue;
     Abi.abi_yield = yield_glue;
     Abi.abi_unwind = unwind_glue;
+    Abi.abi_gc = gc_glue;
     Abi.abi_get_next_pc_thunk = Some get_next_pc_thunk;
 
     Abi.abi_sp_reg = (Il.Hreg esp);

src/boot/llvm/llabi.ml

@@ -23,9 +23,10 @@ let declare_abi (llctx:Llvm.llcontext) (llmod:Llvm.llmodule) : abi =
         i32;                              (* ptrdiff_t debug_info_off *)
         i32;                              (* size_t debug_info_sz *)
         i32;                              (* size_t activate_glue_off *)
-        i32;                              (* size_t main_exit_task_glue_off *)
-        i32;                              (* size_t unwind_glue_off *)
         i32;                              (* size_t yield_glue_off *)
+        i32;                              (* size_t unwind_glue_off *)
+        i32;                              (* size_t gc_glue_off *)
+        i32;                              (* size_t main_exit_task_glue_off *)
         i32;                              (* int n_rust_syms *)
         i32;                              (* int n_c_syms *)
         i32                               (* int n_libs *)

src/boot/llvm/llfinal.ml

@@ -53,9 +53,10 @@ let finalize_module
       Llvm.const_int i32 0;             (* ptrdiff_t debug_info_off *)
       Llvm.const_int i32 0;             (* size_t debug_info_sz *)
       activate_glue_off;                (* size_t activate_glue_off *)
-      exit_task_glue_off;               (* size_t main_exit_task_glue_off *)
-      Llvm.const_int i32 0;             (* size_t unwind_glue_off *)
       yield_glue_off;                   (* size_t yield_glue_off *)
+      Llvm.const_int i32 0;             (* size_t unwind_glue_off *)
+      Llvm.const_int i32 0;             (* size_t gc_glue_off *)
+      exit_task_glue_off;               (* size_t main_exit_task_glue_off *)
       Llvm.const_int i32 rust_fn_count; (* int n_rust_syms *)
       Llvm.const_int i32 c_fn_count;    (* int n_c_syms *)
       Llvm.const_int i32 0              (* int n_libs *)

src/boot/me/semant.ml

@@ -30,6 +30,7 @@ type glue =
   | GLUE_write of Ast.ty
   | GLUE_read of Ast.ty
   | GLUE_unwind
+  | GLUE_gc
   | GLUE_get_next_pc
   | GLUE_mark_frame of node_id    (* node is the frame                 *)
   | GLUE_drop_frame of node_id    (* node is the frame                 *)
@@ -135,6 +136,7 @@ type ctxt =
       ctxt_spill_fixups: (node_id,fixup) Hashtbl.t;
       ctxt_abi: Abi.abi;
       ctxt_activate_fixup: fixup;
+      ctxt_gc_fixup: fixup;
       ctxt_yield_fixup: fixup;
       ctxt_unwind_fixup: fixup;
       ctxt_exit_task_fixup: fixup;
@@ -218,6 +220,7 @@ let new_ctxt sess abi crate =
     ctxt_activate_fixup = new_fixup "activate glue";
     ctxt_yield_fixup = new_fixup "yield glue";
     ctxt_unwind_fixup = new_fixup "unwind glue";
+    ctxt_gc_fixup = new_fixup "gc glue";
     ctxt_exit_task_fixup = new_fixup "exit-task glue";
 
     ctxt_debug_aranges_fixup = new_fixup "debug_aranges section";
@@ -1989,6 +1992,7 @@ let glue_str (cx:ctxt) (g:glue) : string =
     | GLUE_write ty -> "glue$write$" ^ (ty_str ty)
     | GLUE_read ty -> "glue$read$" ^ (ty_str ty)
     | GLUE_unwind -> "glue$unwind"
+    | GLUE_gc -> "glue$gc"
     | GLUE_get_next_pc -> "glue$get_next_pc"
     | GLUE_mark_frame i -> "glue$mark_frame$" ^ (item_str cx i)
     | GLUE_drop_frame i -> "glue$drop_frame$" ^ (item_str cx i)

src/boot/me/trans.ml

@@ -4891,9 +4891,10 @@ let trans_visitor
             Asm.WORD (word_ty_mach, Asm.M_SZ cx.ctxt_debug_info_fixup);
 
             crate_rel_word cx.ctxt_activate_fixup;
-            crate_rel_word cx.ctxt_exit_task_fixup;
-            crate_rel_word cx.ctxt_unwind_fixup;
             crate_rel_word cx.ctxt_yield_fixup;
+            crate_rel_word cx.ctxt_unwind_fixup;
+            crate_rel_word cx.ctxt_gc_fixup;
+            crate_rel_word cx.ctxt_exit_task_fixup;
 
             tab_sz cx.ctxt_required_rust_sym_num;
             tab_sz cx.ctxt_required_c_sym_num;
@@ -4915,6 +4916,10 @@ let trans_visitor
         (fun e -> abi.Abi.abi_unwind
            e nabi_rust (upcall_fixup "upcall_exit"));
 
+      emit_aux_global_glue cx GLUE_gc
+        cx.ctxt_gc_fixup
+        abi.Abi.abi_gc;
+
       ignore (get_exit_task_glue ());
 
       begin

src/rt/rust_internal.h

@@ -263,9 +263,10 @@ rust_crate
     size_t debug_info_sz;         // Size of .debug_info.
 
     ptrdiff_t activate_glue_off;
-    ptrdiff_t exit_task_glue_off;
-    ptrdiff_t unwind_glue_off;
     ptrdiff_t yield_glue_off;
+    ptrdiff_t unwind_glue_off;
+    ptrdiff_t gc_glue_off;
+    ptrdiff_t exit_task_glue_off;
 
 public:
 
@@ -278,9 +279,11 @@ public:
     uintptr_t get_image_base() const;
     ptrdiff_t get_relocation_diff() const;
     activate_glue_ty get_activate_glue() const;
-    uintptr_t get_exit_task_glue() const;
-    uintptr_t get_unwind_glue() const;
     uintptr_t get_yield_glue() const;
+    uintptr_t get_unwind_glue() const;
+    uintptr_t get_gc_glue() const;
+    uintptr_t get_exit_task_glue() const;
+
     struct mem_area
     {
       rust_dom *dom;