[m-dev.] tests/hard_coded/ho_solns.m

[Fergus Henderson]

I wrote:
 
> Hi Tyson,
> 
> tests/hard_coded/ho_solns.m breaks in grade `fast';
> it gets a seg fault in deep_copy().
> 
> Can you please investigate this?

It's OK, I've found and fixed this one.  The problem was that you
forgot the calls to save/restore_transient_regs() around the second
call to deep_copy().

library/std_util.m:
	Make sure that we save/restore_transient_regs() before/after
	both calls to deep_copy().

Index: std_util.m
===================================================================
RCS file: /home/staff/zs/imp/mercury/library/std_util.m,v
retrieving revision 1.70
diff -u -r1.70 std_util.m
--- std_util.m	1997/02/13 16:41:15	1.70
+++ std_util.m	1997/02/16 12:44:35
@@ -325,14 +325,14 @@
 	/* set heap to solutions heap */
 	hp = (Word) solutions_heap_pointer;
 
-	/* to be safe, save the registers before the call */
+	/*
+	** deep_copy() it to the solutions heap, up to the saved_hp.
+	** Note that we need to save/restore the hp register, if it
+	** is transient, before/after calling deep_copy().
+	*/
 	save_transient_registers();
-
-	/* deep copy it to the solutions heap, up to the saved_hp */
 	r3 = deep_copy(r1, (Word *) type_info_fv, (Word *) saved_hp_fv, 
 		heap_zone->top);
-
-	/* restore the registers */
 	restore_transient_registers();
 
 	/* create a cons cell on the solutions heap */
@@ -364,12 +364,17 @@
 	  	&mercury_data_mercury_builtin__base_type_info_list_1;
 	  new_type_info[1] = (Word *) type_info_fv;
 
-		/* deep_copy the list to the mercury heap, copying
-		 * everything between where we started on the solutions
-		 * heap, and the top of the solutions heap 
-		 */
+	  /*
+	  ** deep_copy() the list to the mercury heap, copying
+	  ** everything between where we started on the solutions
+	  ** heap, and the top of the solutions heap.
+	  ** Note that we need to save/restore the hp register, if it
+	  ** is transient, before/after calling deep_copy().
+	  */
+	  save_transient_registers();
 	  solutions_output = deep_copy(list_fv, (Word *) new_type_info,
 		(Word *) saved_solhp_fv, solutions_heap_zone->top);
+	  restore_transient_registers();
 	}
 
 	/* reset solutions heap to where it was before call to solutions  */

-- 
Fergus Henderson <fjh at cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3         |     -- the last words of T. S. Garp.