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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/8081] ICE with variably sized types returned from nested functions
Date: Thu, 12 Jan 2012 10:23:00 -0000 [thread overview]
Message-ID: <bug-8081-4-GgJG9GGyZh@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-8081-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8081
--- Comment #24 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-12 10:23:05 UTC ---
Created attachment 26306
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26306
A patch for using by-reference passing
(In reply to comment #23)
> as alternative to rejecting this case we can lower returning variable-size
> types during un-nesting to explicit passing of a return slot and using
> memcpy, making the nested function return nothing.
It's of course not that easy as we gimplify before un-nesting. The frontend
would be responsible to arrange things that way, similar to how we pass
a return slot in the C++ frontend (DECL_BY_REFERENCE on the DECL_RESULT
variable). Like for the attached patch. Passes
extern void abort (void);
int
main (int argc, char **argv)
{
int size = 10;
typedef struct
{
char val[size];
}
block;
block a, b;
block __attribute__((noinline))
retframe_block ()
{
return *(block *) &b;
}
b.val[0] = -1;
b.val[1] = -2;
a=retframe_block ();
if (a.val[0] != -1
|| a.val[1] != -2)
abort ();
return 0;
}
I'm not sure if one can construct a testcase where using return-slot
optimization causes wrong-code generation. Alternatively checking
DECL_BY_REFERENCE on the callees DECL_RESULT instead of applying it to
all VLA types could work (though not for indirect calls).
next prev parent reply other threads:[~2012-01-12 10:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-8081-4@http.gcc.gnu.org/bugzilla/>
2012-01-11 15:56 ` [Bug middle-end/8081] ICE with variably sized types and " rguenth at gcc dot gnu.org
2012-01-11 15:58 ` [Bug c/8081] ICE with variably sized types returned from " rguenth at gcc dot gnu.org
2012-01-12 10:23 ` rguenth at gcc dot gnu.org [this message]
2012-01-13 8:55 ` ebotcazou at gcc dot gnu.org
2012-01-13 9:28 ` rguenther at suse dot de
2012-01-13 10:19 ` rguenth at gcc dot gnu.org
2012-01-13 11:37 ` ebotcazou at gcc dot gnu.org
2012-01-13 11:54 ` rguenth at gcc dot gnu.org
2012-01-13 12:08 ` rguenth at gcc dot gnu.org
2012-01-13 12:10 ` rguenth at gcc dot gnu.org
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