LI76228: INCORRECT OFFSET IN PROG WITH LARGE STACK

June 2011 Update for XL C/C++ for Linux, V10.1
XL C/C++ for Linux Fix Pack 8 (January 2014 Update) for 10.1
January 2012 Update for XL C/C++ for Linux, V10.1
July 2012 Update for XL C/C++ for Linux, V10.1

APAR status

• Closed as program error.

Error description

• The following test case produces an illegal instruction when
  compiled in 64 bit mode.
  
  ====Compile Command:
  cc -qlargetype -bmaxstack:0xA0000000 -q64  -qlist test.c
  
  ====Testcase:
  $cat test.c
   #include <stdio.h>
   #include <procinfo.h>
  
   #include <unistd.h>
  
  struct sub_test{
  int num;
  char CC[3];
  char AA[500];
  char BB[3];
  };
  
  struct St_test{
  int AA;
  char BB[3];
  char CC[100];
  struct sub_test subtest[1105];
  };
  
  struct St_test STTest[300];
  
  void init()
  {
  
   for(int i=0; i<100; i++)
  {
     STTest[i].AA=i;
      strcpy(STTest[i].BB,"aa");
     strcpy(STTest[i].CC,
  "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
  ccccccccccccccccccc");
    for(int j=0;j<600;j++)
    {
      STTest[i].subtest[j].num=j;
  
  strcpy(STTest[i].subtest[j].AA,"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
  );
      strcpy(STTest[i].subtest[j].BB,"1");
      strcpy(STTest[i].subtest[j].CC,"cc");
   }
  }
  
  }
  
   void getallproc(struct St_test *test)
   {
      char args[25];
  
    struct St_test  tests;
     tests.AA=1;
     strcpy(tests.BB,"1");
     strcpy(tests.CC,"2");
     *test=tests;
    strcpy(test->subtest[100].AA,"20");
    for(int i=0;i<100;i++)
     {
         if(STTest[i].AA==90)
         {
     printf("CC:%s\n",STTest[i].CC);
      *test=STTest[i];
     printf("CC:%s\n",STTest[i].CC);
            printf("result:%s\n", test->CC);
         }
  
  }
  return ;
  /*
     return ;*/
   }
  
  void getsub(struct St_test test,char *test1)
  {
      int i;
      int j=10;
       char str1[81];
  
  printf("test:%p,%d,%s,%s,%s\n",&test,test.AA,test.BB,test.CC,tes
  t.subtest[100].AA);
      strcpy(str1,"test1");
      strcpy(test1,str1);
  }
  
   int main(int argc, char *argv[])
   {
      struct St_test test;
     char test1[101];
   init();
     printf("test:%p\n",&test);
     getsub(test,test1);
   getallproc(&test);
     printf("LINE:%d, CC:%s\n",__LINE__,test.CC);
  
     printf("LINE:%d, %d, %s,
  %s\n",__LINE__,test.AA,test.BB,test.CC);
     printf("LINE:%d, %s,CC:%s\n",__LINE__,test.BB,test.CC);
     printf("test:%p\n",&test);
      getsub(test,test1);
  }
  
  
  =====Actual Output:
  $ ./a.out
  test:ffffffffff75390
  Illegal instruction
  $
  
  
  =====Expected Output:
  $ ./a.out
  test:ffffffffff75390
  test:fffffffffeeb110,0,,,
  CC:ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
  ccccccccccccccccccccc
  CC:ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
  ccccccccccccccccccccc
  result:ccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
  ccccccccccccccccccccccccc
  LINE:85,
  CC:ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
  ccccccccccccccccccccc
  LINE:87, 90, aa,
  cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
  cccccccccccccccccc
  LINE:88,
  aa,CC:cccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
  cccccccccccccccccccccccc
  test:ffffffffff75390
  test:fffffffffeeb110,90,aa,ccccccccccccccccccccccccccccccccccccc
  ccccccccccccccccccccccccccccccccccccccccccccc,aaaaaaaaaaaaaaaaaa
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  aaaaaaaaaaaaa
  $
  

Local fix

• Compile in 32 bit mode as a workaround.
  

Problem summary

• USERS AFFECTED:
  Users using 64 bit mode and large stack frames with odd-sized
  variables may be affected by this issue.
  
  PROBLEM DESCRIPTION:
  The application will give an illegal instruction opcode in
  function with large stack frame in 64 bit mode during runtime.
  

Problem conclusion

• The compiler has been fixed to align stack frame sizes to
  multiples of 4 after mapping auto variables to it, instead of
  later.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IZ92059

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL C/C++ RHEL52

• Fixed component ID

  5724U8310

Applicable component levels

• RA10 PSN IZ92059

     UP06/09/13