WIP instr_size calculation fixes.

asmcomp/power/emit.mlp

@@ -372,8 +372,7 @@ let name_for_specific = function
   | _ -> Misc.fatal_error "Emit.Ispecific"
 
 (* Relaxation of branches that exceed the span of a relative branch. *)
-
-module BR = Branch_relaxation.Make (struct
+module Size = struct
   type distance = int
 
   module Cond_branch = struct
@@ -508,7 +507,9 @@ module BR = Branch_relaxation.Make (struct
   (* [classify_addr], above, never identifies these instructions as needing
      relaxing.  As such, these functions should never be called. *)
   let relax_specific_op _ = assert false
-end)
+end
+
+module BR = Branch_relaxation.Make (Size)
 
 (* Assembly code for inlined allocation *)
 
@@ -958,11 +959,37 @@ let emit_instr env i =
         end
 
 (* Emit a sequence of instructions *)
-
-let rec emit_all env i =
+(* for debugging instr_size errors *)
+let emit_instr_debug env i =
+  let lbl = new_label () in
+  `{emit_label lbl}:\n`;
+  emit_instr env i;
+  let sz = Size.instr_size env.f i.desc * 4 in
+  `	.ifne (. - {emit_label lbl}) - {emit_int sz}\n`;
+  `	.error \"Emit.instr_size: instruction length mismatch\"\n`;
+  `	.endif\n`
+
+let rec emit_all env lbl_start acc i =
   match i.desc with
-  | Lend -> ()
-  |  _   -> emit_instr env i; emit_all env i.next
+  | Lend ->
+     (* acc measures in units of 32-bit instructions *)
+     let sz = acc * 4 in
+     `	.ifne (. - {emit_label lbl_start}) - {emit_int sz}\n`;
+     `	.error \"Emit.instr_size: instruction length mismatch\"\n`;
+     `	.endif\n`;
+  | _ ->
+     let debug = false in
+     if debug then emit_instr_debug env i else emit_instr env i;
+     emit_all env lbl_start (acc + Size.instr_size env.f i.desc) i.next
+
+let emit_all env i =
+  let lbl = new_label () in
+  `{emit_label lbl}:\n`;
+  emit_all env lbl 0 i
+(* let rec emit_all env i = *)
+(*   match i.desc with *)
+(*   | Lend -> () *)
+(*   |  _   -> emit_instr env i; emit_all env i.next *)
 
 (* On this target, the possible "out of line" code blocks are:
    - a single "call GC" point, which comes immediately after the