[Bug c/31701] New: Program giving segmentation fault with '-O2' optimization.

[Bug c/31701] New: Program giving segmentation fault with '-O2' optimization.

[Ashay dot Jaiswal at kpitcummins dot com]

Hello all,

I have successfully built SH4-Linux toolchain based on
(binutils-2.17, gcc-4.2-20061205, glibc-2.5) for Renesas SH target.

I am facing problem while executing the following program.

 ------------------------------------------------------------------
 #include <stdio.h>        
 extern void func();          
 typedef struct abc {       
 char name[16]; 
 }ABC;  
 main()  
 {          
     int i; 
     ABC buffer[20];         
     for (i=0; i<20; i++)                 
         buffer[i].name[0] = 't';         
   if (buffer[10].name[0] == 't')       
   printf("OK\n"); 
   else   
   printf("NOT OK\n");      
}           
-------------------------------------------------------------------------       

The above program when compiled with '-O0' optimization executes successfully,
but I am getting segmentation fault error while executing the program compiled 
with '-O2' optimization.

Observations:

1. I found differences in the assembly output of the program when compiled
   with '-O0' and '-O2' optimization.
   It seems stack register get corrupted with '-O2' optimization.

   Following code corrupts the stack register
   L10:
            mov.w   .L18,r14
            mov.l     .L19,r1
            add       r14,r14
            mov      r14,r15        <<here it is corrupting the stack register
            mov.l     @r15+,r14
            jmp       @r1
            nop
            .align 1

2. Program executes successfully when compiled with '-O2' and
   '-fno-optimize-sibling-calls' options.

3. Same problem is encountered with gcc-4.0.1 and after reverting the
   patch PR21265(http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21265) the program
   executes successfully with '-O2' optimization. But this solution doesn't
work with gcc-4.2-20061205 based toolchain.

Any help on this will be appreciated.

Regards,
Ashay Jaiswal
KPIT Cummins Infosystems Ltd,
Pune (INDIA)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Free download of GNU based SH-Linux toolchains for Renesas' SH Series.          
The following site also offers free technical support to its users.             
Visit http://www.kpitgnutools.com for details.           
Latest versions of KPIT GNU SH-Linux tools were released on April 5, 2007.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


-- 
           Summary: Program giving segmentation fault with '-O2'
                    optimization.
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Ashay dot Jaiswal at kpitcummins dot com
 GCC build triplet: i686-pc-linux
  GCC host triplet: sh4-unknown-linux
GCC target triplet: sh4-unknown-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701

[Bug target/31701] Program giving segmentation fault with '-O2' optimization.

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|major                       |normal
          Component|c                           |target
           Keywords|                            |wrong-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701

[Bug target/31701] [4.1/4.2/4.3 Regression] SH: wrong epilogue for sibling calls

[kkojima at gcc dot gnu dot org]

------- Comment #1 from kkojima at gcc dot gnu dot org  2007-04-26 08:17 -------
I've confirmed that the test case fails also on trunk.
sh.c:output_stack_adjust tries to find a register for a constant
to unwind the frame and wrongly finds a frame register itself
in the problematic case.  I'm testing the attached patch.

diff -uprN ORIG/trunk/gcc/config/sh/sh.c LOCAL/trunk/gcc/config/sh/sh.c
--- ORIG/trunk/gcc/config/sh/sh.c       2007-03-22 09:50:40.000000000 +0900
+++ LOCAL/trunk/gcc/config/sh/sh.c      2007-04-26 08:06:16.000000000 +0900
@@ -5619,7 +5619,13 @@ output_stack_adjust (int size, rtx reg, 
              temp = scavenge_reg (&temps);
            }
          if (temp < 0 && live_regs_mask)
-           temp = scavenge_reg (live_regs_mask);
+           {
+             HARD_REG_SET temps;
+
+             COPY_HARD_REG_SET (temps, *live_regs_mask);
+             CLEAR_HARD_REG_BIT (temps, REGNO (reg));
+             temp = scavenge_reg (&temps);
+           }
          if (temp < 0)
            {
              rtx adj_reg, tmp_reg, mem;
@@ -5668,6 +5674,9 @@ output_stack_adjust (int size, rtx reg, 
              emit_move_insn (adj_reg, mem);
              mem = gen_tmp_stack_mem (Pmode, gen_rtx_POST_INC (Pmode, reg));
              emit_move_insn (tmp_reg, mem);
+             /* Tell flow the insns that pop r4/r5 aren't dead.  */
+             emit_insn (gen_rtx_USE (VOIDmode, tmp_reg));
+             emit_insn (gen_rtx_USE (VOIDmode, adj_reg));
              return;
            }
          const_reg = gen_rtx_REG (GET_MODE (reg), temp);


-- 

kkojima at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kkojima at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
      Known to fail|4.1.0                       |4.1.0 4.2.0 4.3.0
   Last reconfirmed|0000-00-00 00:00:00         |2007-04-26 08:17:49
               date|                            |
            Summary|Program giving segmentation |[4.1/4.2/4.3 Regression] SH:
                   |fault with '-O2'            |wrong epilogue for sibling
                   |optimization.               |calls


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701

[Bug target/31701] [4.1/4.2/4.3 Regression] SH: wrong epilogue for sibling calls

[kkojima at gcc dot gnu dot org]

------- Comment #2 from kkojima at gcc dot gnu dot org  2007-04-28 01:07 -------
Subject: Bug 31701

Author: kkojima
Date: Sat Apr 28 01:07:40 2007
New Revision: 124248

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=124248
Log:
        PR target/31701
        * config/sh/sh.c (output_stack_adjust): Avoid using the frame
        register itself to hold the offset constant.  Tell flow the use
        of r4 and r5 when they are used.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/sh/sh.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701

[Bug target/31701] [4.1/4.2/4.3 Regression] SH: wrong epilogue for sibling calls

[kkojima at gcc dot gnu dot org]

------- Comment #3 from kkojima at gcc dot gnu dot org  2007-05-21 00:27 -------
Subject: Bug 31701

Author: kkojima
Date: Sun May 20 23:27:22 2007
New Revision: 124882

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=124882
Log:
        PR target/31701
        Backport from mainline.
        * config/sh/sh.c (output_stack_adjust): Avoid using the frame
        register itself to hold the offset constant.  Tell flow the use
        of r4 and r5 when they are used.


Modified:
    branches/gcc-4_2-branch/gcc/ChangeLog
    branches/gcc-4_2-branch/gcc/config/sh/sh.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701

[Bug target/31701] [4.1/4.2/4.3 Regression] SH: wrong epilogue for sibling calls

[kkojima at gcc dot gnu dot org]

------- Comment #4 from kkojima at gcc dot gnu dot org  2007-05-21 00:57 -------
Subject: Bug 31701

Author: kkojima
Date: Sun May 20 23:57:32 2007
New Revision: 124885

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=124885
Log:
        PR target/31701
        Backport from mainline.
        * config/sh/sh.c (output_stack_adjust): Avoid using the frame
        register itself to hold the offset constant.  Tell flow the use
        of r4 and r5 when they are used.


Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/config/sh/sh.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701

[Bug target/31701] [4.1/4.2/4.3 Regression] SH: wrong epilogue for sibling calls

[kkojima at gcc dot gnu dot org]

------- Comment #5 from kkojima at gcc dot gnu dot org  2007-05-21 01:02 -------
Fixed.


-- 

kkojima at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701

[Bug target/31701] [4.1/4.2/4.3 Regression] SH: wrong epilogue for sibling calls

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|4.0.0                       |4.0.0 4.2.1
   Target Milestone|---                         |4.1.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31701