[Bug c++/57362] New: unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[Bug c++/57362] New: unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[mib.bugzilla at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

            Bug ID: 57362
           Summary: unsupported __attribute__((target())) values appear to
                    cause loop and/or pathological behavior
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mib.bugzilla at gmail dot com

Created attachment 30158
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30158&action=edit
Test case

I was experimenting with what values might be acceptable to gcc 4.8
__attribute__((target()))

I expected that the compiler would flag the targets that weren't recognized and
then quit, but it ran a very long time (5 minutes?). I stopped the job and
process cc1plus was still running.

[Bug c++/57362] unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[mib.bugzilla at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

--- Comment #1 from mib.bugzilla at gmail dot com ---
Using built-in specs.
COLLECT_GCC=/rdrive/ref/gcc/4.8.0/rhel60/efi2/bin/g++
COLLECT_LTO_WRAPPER=/site/spt/rdrive/ref/gcc/4.8.0/rhel60/efi2/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with:
/rusers/sys_cron/grab_gcc/downloads_rel/4.8.0/gcc-4.8.0/configure
--prefix=/rdrive/ref/gcc/4.8.0/rhel60/efi2
--enable-languages=c,c++,objc,fortran --disable-multilib --enable-bootstrap
--target=x86_64-unknown-linux-gnu --disable-bootstrap --enable-decimal-float
--with-gmp=/rusers/sys_cron/grab_gcc/downloads_rel/lib/efi2
--with-mpfr=/rusers/sys_cron/grab_gcc/downloads_rel/lib/efi2
--with-mpc=/rusers/sys_cron/grab_gcc/downloads_rel/lib/efi2
Thread model: posix
gcc version 4.8.0 (GCC)

[Bug c++/57362] [4.8/4.9 Regression] unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
      Known to work|                            |4.7.3
            Version|unknown                     |4.8.1
           Keywords|                            |ice-on-invalid-code
   Last reconfirmed|                            |2013-05-22
                 CC|                            |tmsriram at google dot com
     Ever confirmed|0                           |1
            Summary|unsupported                 |[4.8/4.9 Regression]
                   |__attribute__((target()))   |unsupported
                   |values appear to cause loop |__attribute__((target()))
                   |and/or pathological         |values appear to cause loop
                   |behavior                    |and/or pathological
                   |                            |behavior
   Target Milestone|---                         |4.8.1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Works fine with the C compiler, for the C++ compiler we ICE:

... lots of errors ...
t.c:18:5: error: No dispatcher found for align-stringops
 int foo(void) { return 1; }
     ^
t.c:187:20: internal compiler error: Segmentation fault
       result = foo();
                    ^
0xc647e5 crash_signal
        /space/rguenther/src/svn/gcc-4_8-branch/gcc/toplev.c:332
0x53f4cb contains_struct_check(tree_node*, tree_node_structure_enum, char
const*, int, char const*)
        /space/rguenther/src/svn/gcc-4_8-branch/gcc/tree.h:3797
0x9b6742 build_fold_addr_expr_loc(unsigned int, tree_node*)
        /space/rguenther/src/svn/gcc-4_8-branch/gcc/fold-const.c:7693
0xf498fa add_condition_to_bb
        /space/rguenther/src/svn/gcc-4_8-branch/gcc/config/i386/i386.c:28536
0xf4a6d0 dispatch_function_versions
        /space/rguenther/src/svn/gcc-4_8-branch/gcc/config/i386/i386.c:28951
0xf4c178 ix86_generate_version_dispatcher_body
        /space/rguenther/src/svn/gcc-4_8-branch/gcc/config/i386/i386.c:29517


you cannot query for acceptable values by re-annotating the same decl.

GCC 4.7 happily says

...
t.c:176:5: error: redefinition of 'int foo()'
t.c:2:5: error: 'int foo()' previously defined here
t.c: At global scope:
t.c:178:13: error: attribute(target("avx256-split-unaligned-store")) is unknown
t.c: In function 'int foo()':
t.c:178:5: error: redefinition of 'int foo()'
t.c:2:5: error: 'int foo()' previously defined here
t.c: At global scope:
t.c:180:13: error: attribute(target("rtm")) is unknown
t.c: In function 'int foo()':
t.c:180:5: error: redefinition of 'int foo()'
t.c:2:5: error: 'int foo()' previously defined here

and does not ICE.

Google folks - please have a look.

[Bug c++/57362] [4.8/4.9 Regression] unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[tmsriram at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

--- Comment #3 from Sriraman Tallam <tmsriram at google dot com> ---
Patch proposed to fix this problem,

This happens when a subset of versions are invalid because of unrecognized
target string name or if a dispatcher for that is not available.  When
constructing the versions array to dispatch, the index used here is wrong.


       PR 57362
        * config/i386/i386.c (dispatch_function_versions):  Use actual_versions 
        to index into function_version_info.

Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c  (revision 199219)
+++ config/i386/i386.c  (working copy)
@@ -29061,10 +29061,10 @@ dispatch_function_versions (tree dispatch_decl,
       if (predicate_chain == NULL_TREE)
        continue;

+      function_version_info [actual_versions].version_decl = version_decl;
+      function_version_info [actual_versions].predicate_chain =
predicate_chain;
+      function_version_info [actual_versions].dispatch_priority = priority;
       actual_versions++;
-      function_version_info [ix - 1].version_decl = version_decl;
-      function_version_info [ix - 1].predicate_chain = predicate_chain;
-      function_version_info [ix - 1].dispatch_priority = priority;
     }

   /* Sort the versions according to descending order of dispatch priority. 
The

[Bug c++/57362] [4.8/4.9 Regression] unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.1                       |4.8.2

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.8.1 has been released.

[Bug c++/57362] [4.8/4.9 Regression] unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[tmsriram at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

--- Comment #5 from Sriraman Tallam <tmsriram at google dot com> ---
Trunk rev. 200913 fixes this problem.

[Bug c++/57362] [4.8/4.9 Regression] unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> ---
What about 4_8-branch? The bug is marked as 4.8 Regression. Either way, I
suppose the bug should be closed, right?

[Bug c++/57362] [4.8/4.9 Regression] unsupported __attribute__((target())) values appear to cause loop and/or pathological behavior

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57362

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jason at gcc dot gnu.org
         Resolution|---                         |FIXED

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 4.8.2 (r201388) and 4.9.