Jeff,
What you have for the "Make sure..." is wrong in the same way as the one
that was in rc1.
The problem is that the AC_COMPILE_IFELSE code tests too-few and
too-many args together.
Since xlc makes too many an error by default, we don't notice its
MISbehavior when given too few.
So, one needs to split the too-many and too-few tests as I did in the
patch I sent.
I don't think we should drop that AC_COMPILE_IFELSE entirely (or rather
we shouldn't drop the TWO once split).
If we were to encounter another Linux compiler that didn't STOP on
too-few arguments the binding code would get silently broken again.
I was also partial to the "structure" of my patch which needed to test
$hwloc_c_vendor only once.
This would allow adding compiler-specific logic in exactly one place if
other cases arise.
I *do* like the way you've run the AC_COMPILE_IFELSE test AFTER adding
the compiler-specific flag (thus confirming that it actually resolved
the problem). However, as noted above you will need to split the
too-few and too-many arg tests for that to be effective.
And regarding the "older, buggy" comment:
This is a recent XLC compiler, and this behavior is NOT a bug because
the C spec doesn't require a fatal error here.
That is why I commented (with <rant> delimiters) on the evils of
configure probes that try to determine how many arguments appear in a
prototype.
-Paul
On 2/9/2012 5:08 AM, Jeff Squyres wrote:
How's this patch (against v1.3, assuming
https://svn.open-mpi.org/trac/hwloc/changeset/4285)?
Is the test that checks to see if compilers error when the wrong number of
params are passed now mooot?
Index: config/hwloc.m4
===================================================================
--- config/hwloc.m4 (revision 4285)
+++ config/hwloc.m4 (working copy)
@@ -268,22 +268,24 @@
AS_IF([test "$HWLOC_VISIBILITY_CFLAGS" != ""],
[AC_MSG_WARN(["$HWLOC_VISIBILITY_CFLAGS" has been added to the
hwloc CFLAGS])])
- # make sure the compiler returns an error code when function arg count is
wrong,
- # otherwise sched_setaffinity checks may fail
+ # Make sure the compiler returns an error code when function arg
+ # count is wrong, otherwise sched_setaffinity checks may fail.
+ # For older, buggy versions of the xlc compilers, we need to set
+ # an additional compiler flag to catch these situations.
+ AS_IF([test "$hwloc_c_vendor" = "ibm"],
+ [HWLOC_CFLAGS_save=$CFLAGS
+ CFLAGS="$CFLAGS -qhalt=e"])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
extern int one_arg(int x);
extern int two_arg(int x, int y);
int foo(void) { return one_arg(1, 2) + two_arg(3); }
]])], [
AC_MSG_WARN([Your C compiler does not consider incorrect argument
counts to be a fatal error.])
- if test "$hwloc_check_compiler_vendor_result" = "ibm"; then
- AC_MSG_WARN([For XLC you may try appending '-qhalt=-e' to the
value of CFLAGS.])
- AC_MSG_WARN([Alternatively you may configure with a different
compiler.])
- else
- AC_MSG_WARN([Please report this failure, and configure using a
different C compiler if possible.])
- fi
AC_MSG_ERROR([Cannot continue.])
])
+ # Restore the CFLAGS if we modified them above
+ AS_IF([test "$hwloc_c_vendor" = "ibm"],
+ [CFLAGS=HWLOC_CFLAGS])
#
# Now detect support
@@ -387,6 +389,12 @@
AC_DEFINE_UNQUOTED(hwloc_thread_t, $hwloc_thread_t, [Define this to the
thread ID type])
fi
+ # For older, buggy versions of the xlc compilers, we need to set
+ # an additional compiler flag to catch cases where the wrong
+ # number of parameters are passed.
+ AS_IF([test "$hwloc_c_vendor" = "ibm"],
+ [HWLOC_CFLAGS_save=$CFLAGS
+ CFLAGS="$CFLAGS -qhalt=e"])
_HWLOC_CHECK_DECL([sched_setaffinity], [
AC_DEFINE([HWLOC_HAVE_SCHED_SETAFFINITY], [1], [Define to 1 if glibc
provides a prototype of sched_setaffinity()])
AC_MSG_CHECKING([for old prototype of sched_setaffinity])
@@ -403,6 +411,9 @@
#define _GNU_SOURCE
#include<sched.h>
]])
+ # Restore the CFLAGS if we modified them above
+ AS_IF([test "$hwloc_c_vendor" = "ibm"],
+ [CFLAGS=HWLOC_CFLAGS])
AC_MSG_CHECKING([for working CPU_SET])
AC_LINK_IFELSE([
On Feb 8, 2012, at 7:47 PM, Paul H. Hargrove wrote:
On 2/8/2012 4:41 PM, Paul H. Hargrove wrote:
I do agree w/ Samuel that the BEST solution is to apply "-qhalt=e" ONLY to the test(s)
where one expects the compiler to through errors (rather than warnings) for function calls with
argument counts which don't match the prototypes. At the moment, I am 90% certain that the
"old sched_setaffinity()" probe is the only one fitting that description.
I am hoping to be able contribute patch for this soon.
-Paul
--
Paul H. Hargrove phhargr...@lbl.gov
Future Technologies Group
HPC Research Department Tel: +1-510-495-2352
Lawrence Berkeley National Laboratory Fax: +1-510-486-6900
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--
Paul H. Hargrove phhargr...@lbl.gov
Future Technologies Group
HPC Research Department Tel: +1-510-495-2352
Lawrence Berkeley National Laboratory Fax: +1-510-486-6900
