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[Bug middle-end/52478] -ftrapv calls the wrong functions in libgcc
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 05 Mar 2012 12:01:23 +0000
- Subject: [Bug middle-end/52478] -ftrapv calls the wrong functions in libgcc
- Auto-submitted: auto-generated
- References: <bug-52478-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52478
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |NEW
AssignedTo|rguenth at gcc dot gnu.org |unassigned at gcc dot
| |gnu.org
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-03-05 12:01:23 UTC ---
This seems to be by design, libgcc only provides >= word_mode trapping ops.
Which
means we'd need to expand this all using inline code:
/* Like gen_libfunc, but verify that integer operation is involved. */
static void
gen_int_libfunc (optab optable, const char *opname, char suffix,
enum machine_mode mode)
{
int maxsize = 2 * BITS_PER_WORD;
if (GET_MODE_CLASS (mode) != MODE_INT)
return;
if (maxsize < LONG_LONG_TYPE_SIZE)
maxsize = LONG_LONG_TYPE_SIZE;
if (GET_MODE_CLASS (mode) != MODE_INT
|| mode < word_mode || GET_MODE_BITSIZE (mode) > maxsize)
return;
oops.
Otherwise a simple
Index: gcc/expr.c
===================================================================
--- gcc/expr.c (revision 184918)
+++ gcc/expr.c (working copy)
@@ -8938,7 +8938,9 @@ expand_expr_real_2 (sepops ops, rtx targ
if (modifier == EXPAND_STACK_PARM)
target = 0;
temp = expand_binop (mode, this_optab, op0, op1, target,
- unsignedp, OPTAB_LIB_WIDEN);
+ unsignedp,
+ trapv_binoptab_p (this_optab)
+ ? OPTAB_LIB : OPTAB_LIB_WIDEN);
gcc_assert (temp);
/* Bitwise operations do not need bitfield reduction as we expect their
operands being properly truncated. */
should have worked.
So, it's a "not implemented thing" currently ... unlike to change until
somebody implements the ftrapv proposal from Joseph.