[Bug c/42991] New: cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[Bug c/42991] New: cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[dcb314 at hotmail dot com]

I just tried to compile the Linux kernel 2.6.33-rc6 under valgrind
with the C compiler version 4.5 snapshot 20100128 and valgrind said

==17102== Conditional jump or move depends on uninitialised value(s)
==17102==    at 0x56D105: expand_debug_expr (cfgexpand.c:2487)
==17102==    by 0x56C912: expand_debug_expr (cfgexpand.c:2876)
==17102==    by 0x570D54: gimple_expand_cfg (cfgexpand.c:2981)
==17102==    by 0x722ECA: execute_one_pass (passes.c:1561)
==17102==    by 0x723154: execute_pass_list (passes.c:1616)
==17102==    by 0x818C94: tree_rest_of_compilation (tree-optimize.c:413)
==17102==    by 0x99A420: cgraph_expand_function (cgraphunit.c:1543)
==17102==    by 0x99CE44: cgraph_optimize (cgraphunit.c:1622)
==17102==    by 0x99D3A4: cgraph_finalize_compilation_unit (cgraphunit.c:1093)
==17102==    by 0x4B0602: c_write_global_declarations (c-decl.c:9537)
==17102==    by 0x7C7AFB: toplev_main (toplev.c:1065)
==17102==    by 0x6568A7C: (below main) (in /lib64/libc-2.10.1.so)
==17102==

Line 2487 of cfgexpand.c is

        if (bitsize == 0)
          return NULL;

Preprocessed source code attached. Flags -Os -g required.


-- 
           Summary: cfgexpand.c:2487: Conditional jump or move depends on
                    uninitialised value(s)
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dcb314 at hotmail dot com
  GCC host triplet: x86_64-suse-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42991

[Bug c/42991] cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[dcb314 at hotmail dot com]

------- Comment #1 from dcb314 at hotmail dot com  2010-02-07 10:25 -------
Created an attachment (id=19817)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19817&action=view)
C source code


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42991

[Bug debug/42991] [4.5 Regression] cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2010-02-07 10:58 -------
Which means that likely DEBUG_DECLs do not have DECL_SIZE set properly.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aoliva at gcc dot gnu dot
                   |                            |org
           Keywords|                            |wrong-debug
            Summary|cfgexpand.c:2487:           |[4.5 Regression]
                   |Conditional jump or move    |cfgexpand.c:2487:
                   |depends on uninitialised    |Conditional jump or move
                   |value(s)                    |depends on uninitialised
                   |                            |value(s)
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42991

[Bug debug/42991] [4.5 Regression] cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2010-02-07 15:22 -------
No, this is not really debug-expr related.  We have

struct crypto_tfm {
...
 void *__crt_ctx[] __attribute__ ((__aligned__(__alignof__(unsigned long
long))));
};

and the FIELD_DECL for __crt_ctx has DECL_SIZE == 0, so get_inner_reference
on a COMPONENT_REF of __crt_ctx will leave us with *pbitsize uninitialized.

I have a patch.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-02-07 15:22:59
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42991

[Bug debug/42991] [4.5 Regression] cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2010-02-07 15:29 -------
*** Bug 42993 has been marked as a duplicate of this bug. ***


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42991

[Bug debug/42991] [4.5 Regression] cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2010-02-07 17:18 -------
Subject: Bug 42991

Author: rguenth
Date: Sun Feb  7 17:18:22 2010
New Revision: 156575

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=156575
Log:
2010-02-07  Richard Guenther  <rguenther@suse.de>

        PR middle-end/42991
        * expr.c (get_inner_reference): Always initialize *pbitsize.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/expr.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42991

[Bug debug/42991] [4.5 Regression] cfgexpand.c:2487: Conditional jump or move depends on uninitialised value(s)

[rguenth at gcc dot gnu dot org]

------- Comment #6 from rguenth at gcc dot gnu dot org  2010-02-07 17:18 -------
Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42991