[Bug c/37756] New: ICE building object file with -O3 and -combine

[Bug c/37756] New: ICE building object file with -O3 and -combine

[zlynx at acm dot org]

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# gcc *.i -combine -O3 -c -o udns.o
dia-submit/udns_init.c: In function ‘dns_set_srch_internal’:
dia-submit/udns_init.c:47: internal compiler error: in
get_addr_dereference_operands, at tree-ssa-operands.c:1698

Because it only appears to happen when building with multiple input files, I
have attached a tar of .i files that reproduce the problem (the udns async DNS
resolver library actually).

I have observed this ICE on i386 and x86_64 and IA64 builds of GCC 4.3.2.


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           Summary: ICE building object file with -O3 and -combine
           Product: gcc
           Version: 4.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zlynx at acm dot org
  GCC host triplet: i386-redhat-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37756

[Bug c/37756] ICE building object file with -O3 and -combine

[zlynx at acm dot org]

------- Comment #1 from zlynx at acm dot org  2008-10-06 21:25 -------
Created an attachment (id=16465)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=16465&action=view)
Gzipped Tar of .i files for bug reproduction


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37756

[Bug tree-optimization/37756] ICE building object file with -O3 and -combine

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2008-10-07 07:38 -------
Unlikely to be fixed.  -combine is an obscure feature.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37756

[Bug tree-optimization/37756] ICE building object file with -O3 and -combine

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2008-10-07 20:40 -------
(In reply to comment #2)
> Unlikely to be fixed.  -combine is an obscure feature.

Except it might not be a -combine issue :).  Until the bug gets
reduced/analyzed we cannot say it will unlikely be fixed. 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37756

[Bug tree-optimization/37756] ICE building object file with -O3 and -combine

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2008-10-08 00:29 -------
Reduced testcase.
FILE 1:
struct dns_ctx {
  int dnsc_serv[6];
  unsigned dnsc_nserv;
};
struct dns_ctx dns_defctx;
int dns_add_serv(int t) {
  struct dns_ctx *ctx = &dns_defctx;
  ctx->dnsc_serv[t] = 0;
}

--- CUT ---
FILE 2:
extern struct dns_ctx dns_defctx;

--- CUT ---
Though I am still figuring out if this is valid code or not really,
dns_defctx's type is incomplete.


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-10-08 00:29:07
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37756

[Bug tree-optimization/37756] ICE building object file with -O3 and -combine

[zlynx at acm dot org]

------- Comment #5 from zlynx at acm dot org  2008-10-08 00:54 -------
I think you missed some of your explanation.  

Do you mean that it may not be valid to take the address of a global struct
with partial definition? For example in udns_init.c which does not define
dns_defctx, but has this code:

int dns_init(struct dns_ctx *ctx, int do_open) {
  if (!ctx)
    ctx = &dns_defctx;
[...]


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37756

[Bug tree-optimization/37756] ICE building object file with -O3 and -combine

[rguenth at gcc dot gnu dot org]

------- Comment #6 from rguenth at gcc dot gnu dot org  2010-09-17 09:06 -------
-combine has been removed from GCC 4.6 in favor of LTO, closing as WONTFIX.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WONTFIX


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37756