[Bug tree-optimization/83456] -Wrestrict false positive on a non-overlapping memcpy in an inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83456 Martin Sebor changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED --- Comment #6 from Martin Sebor --- Patch committed in r258455.
[Bug tree-optimization/83456] -Wrestrict false positive on a non-overlapping memcpy in an inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83456 --- Comment #5 from Martin Sebor --- Author: msebor Date: Mon Mar 12 18:04:16 2018 New Revision: 258455 URL: https://gcc.gnu.org/viewcvs?rev=258455=gcc=rev Log: PR tree-optimization/83456 - -Wrestrict false positive on a non-overlapping memcpy in an inline function gcc/ChangeLog: PR tree-optimization/83456 * gimple-fold.c (gimple_fold_builtin_memory_op): Avoid warning for perfectly overlapping calls to memcpy. (gimple_fold_builtin_memory_chk): Same. (gimple_fold_builtin_strcpy): Handle no-warning. (gimple_fold_builtin_stxcpy_chk): Same. * tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Handle no-warning. gcc/c-family/ChangeLog: PR tree-optimization/83456 * gcc/c-family/c-common.c (check_function_restrict): Return bool. Restore checking of bounded built-in functions. (check_function_arguments): Also return the result of warn_for_restrict. * gcc/c-family/c-common.c (check_function_restrict): Return bool. * gcc/c-family/c-warn.c (warn_for_restrict): Return bool. gcc/testsuite/ChangeLog: PR tree-optimization/83456 * c-c++-common/Wrestrict-2.c: Remove test cases. * c-c++-common/Wrestrict.c: Same. * gcc.dg/Wrestrict-12.c: New test. * gcc.dg/Wrestrict-14.c: New test. Added: trunk/gcc/testsuite/gcc.dg/Wrestrict-12.c trunk/gcc/testsuite/gcc.dg/Wrestrict-14.c Modified: trunk/gcc/ChangeLog trunk/gcc/c-family/ChangeLog trunk/gcc/c-family/c-common.c trunk/gcc/c-family/c-common.h trunk/gcc/c-family/c-warn.c trunk/gcc/gimple-fold.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/c-c++-common/Wrestrict-2.c trunk/gcc/testsuite/c-c++-common/Wrestrict.c trunk/gcc/tree-ssa-strlen.c
[Bug tree-optimization/83456] -Wrestrict false positive on a non-overlapping memcpy in an inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83456 Martin Sebor changed: What|Removed |Added Keywords||patch Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |msebor at gcc dot gnu.org --- Comment #4 from Martin Sebor --- Patch: https://gcc.gnu.org/ml/gcc-patches/2018-03/msg00358.html
[Bug tree-optimization/83456] -Wrestrict false positive on a non-overlapping memcpy in an inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83456
Martin Sebor changed:
What|Removed |Added
See Also||https://gcc.gnu.org/bugzill
||a/show_bug.cgi?id=32667
--- Comment #3 from Martin Sebor ---
See also bug 32667 for some background into GCC emitting perfectly overlapping
calls to memcpy for some aggregate assignments. The code that controls the
diagnostic tries to work around that bug:
/* If SRC and DEST are the same (and not volatile), return
DEST{,+LEN,+LEN-1}. */
if (operand_equal_p (src, dest, 0))
{
/* Avoid diagnosing exact overlap in calls to __builtin_memcpy.
It's safe and may even be emitted by GCC itself (see bug
32667). However, diagnose it in explicit calls to the memcpy
function. */
if (check_overlap && *IDENTIFIER_POINTER (DECL_NAME (func)) != '_')
warning_at (loc, OPT_Wrestrict,
"%qD source argument is the same as destination",
func);
[Bug tree-optimization/83456] -Wrestrict false positive on a non-overlapping memcpy in an inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83456
--- Comment #2 from Martin Sebor ---
And another test case from bug 84095 comment #9, also due to the check in
gimple-fold.c. This one seems closer to the first test case in comment #0.
$ cat t.c && gcc -O2 -S -Wall t.c
extern void* memcpy (void*, const void*, __SIZE_TYPE__);
struct netdevice {
void *priv;
};
struct ip_tunnel {
struct netdevice *dev;
int ip6rd[3];
};
struct sit_net {
struct netdevice *fb_tunnel_dev;
};
void ipip6_tunnel_clone_6rd (struct netdevice *dev, struct sit_net *sitn)
{
struct ip_tunnel *t = dev->priv;
if (t->dev == sitn->fb_tunnel_dev)
return;
struct ip_tunnel *t0 = sitn->fb_tunnel_dev->priv;
memcpy(>ip6rd, >ip6rd, sizeof(t->ip6rd));
}
void sit_init_net (struct sit_net *sitn, struct netdevice *fb_tunnel_dev)
{
sitn->fb_tunnel_dev = fb_tunnel_dev;
ipip6_tunnel_clone_6rd (sitn->fb_tunnel_dev, sitn);
}
t.c: In function ‘sit_init_net’:
t.c:23:3: warning: ‘memcpy’ source argument is the same as destination
[-Wrestrict]
memcpy(>ip6rd, >ip6rd, sizeof(t->ip6rd));
^~~
[Bug tree-optimization/83456] -Wrestrict false positive on a non-overlapping memcpy in an inline function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83456
Martin Sebor changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Last reconfirmed||2018-02-06
See Also||https://gcc.gnu.org/bugzill
||a/show_bug.cgi?id=84095
Ever confirmed|0 |1
--- Comment #1 from Martin Sebor ---
Here's a slightly different test case, this one from bug 84095 comment 14
(reduced from bug 84095 comment 17). I'll confirm this bug based on that one.
$ cat t.c && gcc -O2 -S -Wall t.c
extern void* memcpy (void*, const void*, __SIZE_TYPE__);
char a[4];
void f (unsigned n)
{
for (int i = 0; i < 1; i++)
{
if (!i)
continue;
memcpy (a, a, n);
}
}
t.c: In function ‘f’:
t.c:12:7: warning: ‘memcpy’ source argument is the same as destination
[-Wrestrict]
memcpy (a, a, n);
^~~~
