[Bug rtl-optimization/59649] New: [4.9 regression] conftest.c miscompiled

[Bug rtl-optimization/59649] New: [4.9 regression] conftest.c miscompiled

[schwab@linux-m68k.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

            Bug ID: 59649
           Summary: [4.9 regression] conftest.c miscompiled
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: build, wrong-code
          Severity: critical
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: schwab@linux-m68k.org
                CC: nickc at gcc dot gnu.org
            Blocks: 59613
            Target: ia64-*-*

>From ia64-suse-linux/libgomp/config.log:

configure:16188:  /usr/local/gcc/test/Build/./gcc/xgcc
-B/usr/local/gcc/test/Build/./gcc/ -B/usr/ia64-suse-linux/bin/
-B/usr/ia64-suse-linux/lib/ -isystem /usr/ia64-suse-linux/include -isystem
/usr/ia64-suse-linux/sys-include    -o conftest -g -O2 -include confdefs.h
-include ../../../libgomp/config/linux/omp-lock.h   conftest.c -lrt  >&5
configure:16188: $? = 0
configure:16188: ./conftest
configure:16188: $? = 1
configure: program exited with status 1
configure: failed program was:
| /* confdefs.h */
| #define PACKAGE_NAME "GNU OpenMP Runtime Library"
| #define PACKAGE_TARNAME "libgomp"
| #define PACKAGE_VERSION "1.0"
| #define PACKAGE_STRING "GNU OpenMP Runtime Library 1.0"
| #define PACKAGE_BUGREPORT ""
| #define PACKAGE_URL "http://www.gnu.org/software/libgomp/"
| #define PACKAGE "libgomp"
| #define VERSION "1.0"
| #define HAVE_SYS_TYPES_H 1
| #define HAVE_SYS_STAT_H 1
| #define HAVE_STDLIB_H 1
| #define HAVE_STRING_H 1
| #define HAVE_MEMORY_H 1
| #define HAVE_STRINGS_H 1
| #define HAVE_INTTYPES_H 1
| #define HAVE_STDINT_H 1
| #define HAVE_UNISTD_H 1
| #define HAVE_DLFCN_H 1
| #define LT_OBJDIR ".libs/"
| #define TIME_WITH_SYS_TIME 1
| #define STRING_WITH_STRINGS 1
| #define HAVE_UNISTD_H 1
| #define HAVE_SEMAPHORE_H 1
| #define HAVE_SYS_TIME_H 1
| #define HAVE_SYS_TIME_H 1
| #define HAVE_GETLOADAVG 1
| #define HAVE_STRTOULL 1
| #define HAVE_PTHREAD_AFFINITY_NP 1
| #define HAVE_CLOCK_GETTIME 1
| #define HAVE_TLS 1
| #define HAVE_ATTRIBUTE_VISIBILITY 1
| #define HAVE_ATTRIBUTE_ALIAS 1
| #define HAVE_AS_SYMVER_DIRECTIVE 1
| #define HAVE_SYMVER_SYMBOL_RENAMING_RUNTIME_SUPPORT 1
| #define LIBGOMP_GNU_SYMBOL_VERSIONING 1
| #define HAVE_SYNC_BUILTINS 1
| /* end confdefs.h.  */
| 
| static long int longval () { return sizeof (omp_lock_t); }
| static unsigned long int ulongval () { return sizeof (omp_lock_t); }
| #include <stdio.h>
| #include <stdlib.h>
| int
| main ()
| {
| 
|   FILE *f = fopen ("conftest.val", "w");
|   if (! f)
|     return 1;
|   if ((sizeof (omp_lock_t)) < 0)
|     {
|       long int i = longval ();
|       if (i != (sizeof (omp_lock_t)))
|       return 1;
|       fprintf (f, "%ld", i);
|     }
|   else
|     {
|       unsigned long int i = ulongval ();
|       if (i != (sizeof (omp_lock_t)))
|       return 1;
|       fprintf (f, "%lu", i);
|     }
|   /* Do not output a trailing newline, as this causes \r\n confusion
|      on some platforms.  */
|   return ferror (f) || fclose (f) != 0;
| 
|   ;
|   return 0;
| }
configure:16191: error: unsupported system, cannot find sizeof (omp_lock_t)

The test program is miscompiled to always return 1.

(gdb) disass main
Dump of assembler code for function main:
   0x4000000000000600 <+0>:     [MMB]       alloc r34=ar.pfs,7,4,0
   0x4000000000000601 <+1>:                 addl r37=288,r1
   0x4000000000000602 <+2>:                 nop.b 0x0
   0x4000000000000610 <+16>:    [MII]       addl r36=280,r1
   0x4000000000000611 <+17>:                mov r33=b0
   0x4000000000000612 <+18>:                mov r35=r1;;
   0x4000000000000620 <+32>:    [MMI]       nop.m 0x0
   0x4000000000000621 <+33>:                ld8 r37=[r37]
   0x4000000000000622 <+34>:                nop.i 0x0
   0x4000000000000630 <+48>:    [MMB]       ld8 r36=[r36]
   0x4000000000000631 <+49>:                nop.m 0x0
   0x4000000000000632 <+50>:                br.call.sptk.many
b0=0x4000000000000540;;
   0x4000000000000640 <+64>:    [MMI]       mov r1=r35
   0x4000000000000641 <+65>:                nop.m 0x0
   0x4000000000000642 <+66>:                mov r32=r8
   0x4000000000000650 <+80>:    [MII]       mov r38=4
   0x4000000000000651 <+81>:                mov r36=r8;;
   0x4000000000000652 <+82>:                addl r37=296,r1;;
   0x4000000000000660 <+96>:    [MIB]       ld8 r37=[r37]
   0x4000000000000661 <+97>:                nop.i 0x0
   0x4000000000000662 <+98>:                br.call.sptk.many
b0=0x40000000000005c0;;
   0x4000000000000670 <+112>:   [MIB]       mov r1=r35
   0x4000000000000671 <+113>:               mov r36=r32
   0x4000000000000672 <+114>:               br.call.sptk.many
b0=0x4000000000000560;;
   0x4000000000000680 <+128>:   [MMI]       mov r8=1
   0x4000000000000681 <+129>:               mov r1=r35
   0x4000000000000682 <+130>:               mov.i ar.pfs=r34;;
   0x4000000000000690 <+144>:   [MIB]       nop.m 0x0
   0x4000000000000691 <+145>:               mov b0=r33
   0x4000000000000692 <+146>:               br.ret.sptk.many b0;;

[Bug rtl-optimization/59649] [4.9 regression] conftest.c miscompiled

[schwab@linux-m68k.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

--- Comment #1 from Andreas Schwab <schwab@linux-m68k.org> ---
gen_int_mode(-1, BImode) returning (const_int 1) looks wrong.

[Bug rtl-optimization/59649] [4.9 regression] conftest.c miscompiled

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-01-02
                 CC|                            |ebotcazou at gcc dot gnu.org
   Target Milestone|---                         |4.9.0
     Ever confirmed|0                           |1

--- Comment #2 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
I have it too.

[Bug rtl-optimization/59649] [4.9 regression] conftest.c miscompiled

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, IMHO either get_mode_bounds needs to special case BImode like
trunc_int_for_mode does and make the bounds of BImode include values of 0 and
STORE_FLAG_VALUE, or the BImode hunk in trunc_int_for_mode needs to be dropped
and everything analyzed for assumption that BImode true is CONST_INT equal to
STORE_FLAG_VALUE, or ia64 needs to use STORE_FLAG_VALUE -1 (there is a comment
about it in ia64.h that it should be investigated).

[Bug rtl-optimization/59649] [4.9 regression] conftest.c miscompiled

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

--- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> So, IMHO either get_mode_bounds needs to special case BImode like
> trunc_int_for_mode does and make the bounds of BImode include values of 0
> and STORE_FLAG_VALUE, or the BImode hunk in trunc_int_for_mode needs to be
> dropped and everything analyzed for assumption that BImode true is CONST_INT
> equal to STORE_FLAG_VALUE, or ia64 needs to use STORE_FLAG_VALUE -1 (there
> is a comment about it in ia64.h that it should be investigated).

Given that ia64 is barely maintained these days, the 3rd approach doesn't look
very realistic and the 2nd one a little risky, so the 1st approach is very
likely the way to go I'd think (e.g. if_then_else_cond also special-cases
BImode).

[Bug rtl-optimization/59649] [4.9 regression] conftest.c miscompiled

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 31767
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31767&action=edit
gcc49-pr59649.patch

Untested fix (well, tested on the conftest.c and eyeballing it using cross).
Don't have spare cycles to waste on a ia64 though, so if somebody is willing to
bootstrap/regtest it, I'd appreciate it.

[Bug rtl-optimization/59649] [4.9 regression] conftest.c miscompiled

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Two out of the 3 get_mode_bounds calls pass the same mode as the first and
third argument, so in that case it would be BImode in both cases and even
before Nick's change while min_val/max_val would be -128/127 for signed and
0/255 otherwise,
as the value is then trunc_int_for_mode (into BImode again), which will return
STORE_FLAG_VALUE for & 1 and 0 otherwise, the function returned 0 and
STORE_FLAG_VALUE (for STORE_FLAG_VALUE == -1 a wrong thing to do supposedly,
but that is not the case of ia64).
I wonder if get_mode_bounds is ever called with BImode and some wider mode,
that would mean there would need to be a conversion of some wider mode to
BImode in the IL I think, which is quite unlikely.  Normally BImode is the
result of some comparison instead.

[Bug rtl-optimization/59649] [4.9 regression] conftest.c miscompiled

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

--- Comment #8 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
Everything seems to be OK with the patch.

[Bug rtl-optimization/59649] [4.9 regression] BImode miscompiled

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Wed Jan  8 10:01:29 2014
New Revision: 206422

URL: http://gcc.gnu.org/viewcvs?rev=206422&root=gcc&view=rev
Log:
    PR rtl-optimization/59649
    * stor-layout.c (get_mode_bounds): For BImode return
    0 and STORE_FLAG_VALUE.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/stor-layout.c

[Bug rtl-optimization/59649] [4.9 regression] BImode miscompiled

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59649

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

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

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Thanks to you both.