[Bug middle-end/53790] New: ICE on dereferencing a extern union in asm statement

[Bug middle-end/53790] New: ICE on dereferencing a extern union in asm statement

[samueldotj at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

             Bug #: 53790
           Summary: ICE on dereferencing a extern union in asm statement
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: samueldotj@gmail.com


Created attachment 27713
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27713
Preprocessed sources

gcc-4.6.3 causes ICE when compiling program which dereferences a extern union
in asm().

It is avoided if the union's structure is made known to the compiler at compile
time.(Defined inside the c file or in an include file).
Removing optimization(-O0) also avoid this problem.

------------------------------
typedef long long uint64;

typedef struct s {
    uint64 value;
} s_t;

static inline uint64
do_some_asm(s_t const *var)
{
   uint64 value;

   __asm__ __volatile__(
      "xor %1, %0"
      : "=r" (value)
      : "r" (var->value)
   );

   return value;
}

typedef union u u_t;

int main()
{
    extern u_t extern_var;
    return do_some_asm((s_t *)&extern_var);
}

----------------------------

$gcc -v -save-temps -O3 sample.c
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.6.3/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ./configure
Thread model: posix
gcc version 4.6.3 (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-mtune=generic' '-march=x86-64'
 /usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.6.3/cc1 -E -quiet -v
sample.c -mtune=generic -march=x86-64 -O3 -fpch-preprocess -o sample.i
ignoring nonexistent directory
"/usr/local/lib/gcc/x86_64-unknown-linux-gnu/4.6.3/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/lib/gcc/x86_64-unknown-linux-gnu/4.6.3/include
 /usr/local/include
 /usr/local/lib/gcc/x86_64-unknown-linux-gnu/4.6.3/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-mtune=generic' '-march=x86-64'
 /usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.6.3/cc1 -fpreprocessed
sample.i -quiet -dumpbase sample.c -mtune=generic -march=x86-64 -auxbase sample
-O3 -version -o sample.s
GNU C (GCC) version 4.6.3 (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.6.3, GMP version 4.3.2, MPFR version
2.4.2-p1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C (GCC) version 4.6.3 (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.6.3, GMP version 4.3.2, MPFR version
2.4.2-p1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 4cf08a0fcb4b2719a02f394936c437ef
sample.c: In function ‘main’:
sample.c:15:17: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Currently I am working around this by applying the following patch.
diff -rupN gcc-4.6.3/gcc/expr.c gcc-4.6.3.new1/gcc/expr.c
--- gcc-4.6.3/gcc/expr.c        2012-02-09 09:28:22.000000000 -0800
+++ gcc-4.6.3.new1/gcc/expr.c   2012-06-20 22:53:10.613748645 -0700
@@ -9182,6 +9182,7 @@ expand_expr_real_1 (tree exp, rtx target
        orig_op0 = op0
          = expand_expr (tem,
                         (TREE_CODE (TREE_TYPE (tem)) == UNION_TYPE
+              && TYPE_SIZE (TREE_TYPE (tem))
                          && (TREE_CODE (TYPE_SIZE (TREE_TYPE (tem)))
                              != INTEGER_CST)
                          && modifier != EXPAND_STACK_PARM

[Bug middle-end/53790] ICE on dereferencing a extern union in asm statement

[samueldotj at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

--- Comment #1 from Samuel Jacob <samueldotj at gmail dot com> 2012-06-27 21:18:03 UTC ---
Adding back trace just in case if it is needed..

(gdb) bt
#0  0x00000000005b999e in expand_expr_real_1 (exp=0x7ffff70b9580,
target=<optimized out>, tmode=VOIDmode, modifier=EXPAND_NORMAL,
alt_rtl=<optimized out>)
    at ../.././gcc/expr.c:9187
#1  0x00000000005bb50d in expand_expr_real (alt_rtl=<optimized out>,
modifier=<optimized out>, tmode=<optimized out>, target=<optimized out>,
exp=0x7ffff70b9580)
    at ../.././gcc/expr.c:7383
#2  expand_expr_real (exp=0x7ffff70b9580, target=<optimized out>,
tmode=<optimized out>, modifier=<optimized out>, alt_rtl=<optimized out>) at
../.././gcc/expr.c:7351
#3  0x00000000005b8e20 in expand_expr (modifier=EXPAND_NORMAL, mode=VOIDmode,
target=0x0, exp=<optimized out>) at ../.././gcc/expr.h:424
#4  expand_expr_real_1 (exp=0x7ffff70ba528, target=<optimized out>,
tmode=VOIDmode, modifier=EXPAND_NORMAL, alt_rtl=<optimized out>) at
../.././gcc/expr.c:8992
#5  0x000000000070d4c3 in expand_expr (modifier=<optimized out>, mode=VOIDmode,
target=0x0, exp=0x7ffff70ba528) at ../.././gcc/expr.h:424
#6  expand_asm_operands (string=0x7ffff70bd168, outputs=<optimized out>,
inputs=<optimized out>, clobbers=0x7ffff70bd438, labels=0x0, vol=1, locus=1486)
    at ../.././gcc/stmt.c:898
#7  0x000000000070e20a in expand_asm_stmt (stmt=<optimized out>) at
../.././gcc/stmt.c:1187
#8  0x0000000000531b68 in expand_gimple_stmt_1 (stmt=0x7ffff70a33c0) at
../.././gcc/cfgexpand.c:1922
#9  expand_gimple_stmt (stmt=0x7ffff70a33c0) at ../.././gcc/cfgexpand.c:2084
#10 0x0000000000532ca8 in expand_gimple_basic_block (bb=0x7ffff709a1a0) at
../.././gcc/cfgexpand.c:3626
#11 0x000000000053664e in gimple_expand_cfg () at ../.././gcc/cfgexpand.c:4109
#12 0x0000000000688ee9 in execute_one_pass (pass=0x1084cc0) at
../.././gcc/passes.c:1556
#13 0x0000000000689195 in execute_pass_list (pass=0x1084cc0) at
../.././gcc/passes.c:1611
#14 0x00000000007553c1 in tree_rest_of_compilation (fndecl=0x7ffff709c800) at
../.././gcc/tree-optimize.c:422
#15 0x00000000008955af in cgraph_expand_function (node=0x7ffff7e926e0) at
../.././gcc/cgraphunit.c:1576
#16 0x000000000089720a in cgraph_expand_all_functions () at
../.././gcc/cgraphunit.c:1635
#17 cgraph_optimize () at ../.././gcc/cgraphunit.c:1899
#18 0x000000000089760a in cgraph_finalize_compilation_unit () at
../.././gcc/cgraphunit.c:1096
#19 0x000000000049ffd5 in c_write_global_declarations () at
../.././gcc/c-decl.c:9878
#20 0x000000000071a1a8 in compile_file () at ../.././gcc/toplev.c:591
#21 do_compile () at ../.././gcc/toplev.c:1900
#22 toplev_main (argc=13, argv=0x7fffffffe318) at ../.././gcc/toplev.c:1963
#23 0x00007ffff71b1c4d in __libc_start_main () from /lib/libc.so.6
#24 0x000000000048f971 in _start ()

[Bug middle-end/53790] ICE on dereferencing a extern union in asm statement

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-06-27 21:19:47 UTC ---
I think this could should be rejected as "extern u_t extern_var;" is declaring
a variable with an unknown size.

[Bug middle-end/53790] ICE on dereferencing a extern union in asm statement

[samueldotj at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

Samuel Jacob <samueldotj at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |4.5.3

--- Comment #3 from Samuel Jacob <samueldotj at gmail dot com> 2012-06-27 21:25:43 UTC ---
(In reply to comment #2)
> I think this could should be rejected as "extern u_t extern_var;" is declaring
> a variable with an unknown size.

I dont understand can you please elaborate - Why declaring a variable of
unknown size is problematic?

[Bug middle-end/53790] ICE on dereferencing a extern union in asm statement

[samueldotj at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

--- Comment #4 from Samuel Jacob <samueldotj at gmail dot com> 2012-06-27 21:31:25 UTC ---
Also this doesnt happen with extern structures and variables.

ie
typedef struct u u_t;  or typedef int u_t;
is not causing the ICE.

[Bug middle-end/53790] [4.6/4.7/4.8 Regression] ICE on dereferencing a extern union in asm statement

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
           Keywords|                            |ice-on-valid-code
   Last reconfirmed|                            |2012-06-28
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1
            Summary|ICE on dereferencing a      |[4.6/4.7/4.8 Regression]
                   |extern union in asm         |ICE on dereferencing a
                   |statement                   |extern union in asm
                   |                            |statement
   Target Milestone|---                         |4.6.4
      Known to fail|                            |4.8.0

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-28 09:59:40 UTC ---
Confirmed.  There is nothing invalid here, you can take the address of
such variable - you just cannot inspect it.  Of course that is what
inlining exposes here (and via MEM_REF we get to see the external decl).

Hmhm.

I'll look at it.

[Bug middle-end/53790] [4.6/4.7/4.8 Regression] ICE on dereferencing a extern union in asm statement

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

--- Comment #6 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-28 11:45:18 UTC ---
Author: rguenth
Date: Thu Jun 28 11:45:14 2012
New Revision: 189045

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189045
Log:
2012-06-28  Richard Guenther  <rguenther@suse.de>

    PR middle-end/53790
    * expr.c (expand_expr_real_1): Verify if the type is complete
    before inspecting its size.

    * gcc.dg/torture/pr53790.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr53790.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/expr.c
    trunk/gcc/testsuite/ChangeLog

[Bug middle-end/53790] [4.6/4.7/4.8 Regression] ICE on dereferencing a extern union in asm statement

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

--- Comment #7 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-28 11:52:54 UTC ---
Author: rguenth
Date: Thu Jun 28 11:52:49 2012
New Revision: 189047

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189047
Log:
2012-06-28  Richard Guenther  <rguenther@suse.de>

    PR middle-end/53790
    * expr.c (expand_expr_real_1): Verify if the type is complete
    before inspecting its size.

    * gcc.dg/torture/pr53790.c: New testcase.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/gcc.dg/torture/pr53790.c
Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/expr.c
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog

[Bug middle-end/53790] [4.6/4.7/4.8 Regression] ICE on dereferencing a extern union in asm statement

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

--- Comment #8 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-28 12:01:22 UTC ---
Author: rguenth
Date: Thu Jun 28 12:01:16 2012
New Revision: 189048

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189048
Log:
2012-06-28  Richard Guenther  <rguenther@suse.de>

    PR middle-end/53790
    * expr.c (expand_expr_real_1): Verify if the type is complete
    before inspecting its size.

    * gcc.dg/torture/pr53790.c: New testcase.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/gcc.dg/torture/pr53790.c
Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/expr.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug middle-end/53790] [4.6/4.7/4.8 Regression] ICE on dereferencing a extern union in asm statement

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

Richard Guenther <rguenth at gcc dot gnu.org> changed:

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

--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-28 12:01:38 UTC ---
Fixed.

[Bug middle-end/53790] [4.6/4.7/4.8 Regression] ICE on dereferencing a extern union in asm statement

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

Richard Guenther <rguenth at gcc dot gnu.org> changed:

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

--- Comment #8 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-28 12:01:22 UTC ---
Author: rguenth
Date: Thu Jun 28 12:01:16 2012
New Revision: 189048

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189048
Log:
2012-06-28  Richard Guenther  <rguenther@suse.de>

    PR middle-end/53790
    * expr.c (expand_expr_real_1): Verify if the type is complete
    before inspecting its size.

    * gcc.dg/torture/pr53790.c: New testcase.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/gcc.dg/torture/pr53790.c
Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/expr.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-28 12:01:38 UTC ---
Fixed.

[Bug middle-end/53790] [4.6/4.7/4.8 Regression] ICE on dereferencing a extern union in asm statement

[samueldotj at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53790

--- Comment #10 from Samuel Jacob <samueldotj at gmail dot com> 2012-06-29 00:26:44 UTC ---
(In reply to comment #9)
> Fixed.

Thanks Richard for the quick response.