[m-rev.] for review: increase default detstack size

[Mark Brown]

Hi,

Bootchecking fails on saturn in grade asm_fast.gc.tr.debug because of a
detstack overflow in stage3.  One solution is to double the default size,
which is not unreasonable since 64-bit machines are becoming more common.
Is this a good idea?  It will come with a performance penalty (see the
comments in runtime/mercury_wrapper.c).  This is what the diff below does.

One alternative is to leave the default as is, but specify a higher limit
in the bootcheck script when in a debug grade.  Another alternative is for
the default size to be specified in words rather than kB, so that the size
will naturally be doubled on 64-bit machines.  Any comments?

Cheers,
Mark.

Estimated hours taken: 0.1
Branches: main

runtime/mercury_wrapper.c:
	Double the default detstack size.  We run out of detstack when
	bootchecking in grade asm_fast.gc.tr.debug on x86_64.

doc/user_guide.texi:
	Update the documentation corresponding to this.

Index: doc/user_guide.texi
===================================================================
RCS file: /home/mercury1/repository/mercury/doc/user_guide.texi,v
retrieving revision 1.451
diff -u -r1.451 user_guide.texi
--- doc/user_guide.texi	24 Aug 2005 09:07:09 -0000	1.451
+++ doc/user_guide.texi	30 Aug 2005 15:05:49 -0000
@@ -421,7 +421,7 @@
 @c XXX FIXME This is wrong for the case when --high-level-code is enabled.
 The det stack and the nondet stack
 are allocated fixed sizes at program start-up.
-The default size is 4096k for the det stack and 128k for the nondet stack,
+The default size is 8192k for the det stack and 128k for the nondet stack,
 but these can be overridden with the
 @samp{--detstack-size} and @samp{--nondetstack-size} options,
 @findex --detstack-size
Index: runtime/mercury_wrapper.c
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_wrapper.c,v
retrieving revision 1.151
diff -u -r1.151 mercury_wrapper.c
--- runtime/mercury_wrapper.c	29 Aug 2005 15:44:28 -0000	1.151
+++ runtime/mercury_wrapper.c	30 Aug 2005 15:12:41 -0000
@@ -85,7 +85,7 @@
 #else
   size_t	MR_heap_size =		       32768; /* 32 Mb */
 #endif
-size_t		MR_detstack_size =		4096;
+size_t		MR_detstack_size =		8192;
 size_t		MR_nondstack_size =	 	 256;
 size_t		MR_solutions_heap_size =	1024;
 size_t		MR_global_heap_size =		1024;
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