IJ12232: PROGRAM GETS A STACK ADDRESS WHEN LINKING WITH -QLIBANSI AND -QPDF2

XL C/C++ for AIX Fix Pack 11 (November 2018 PTF) for 13.1
XL C for AIX Fix Pack 11 (November 2018) for 13.1

APAR status

• Closed as program error.

Error description

• When using -qpdf2 together with the modified config file that
  has -qlibansi, the resulting exe gets a stack address instead of
  a heap address as shown in the "ACTUAL OUTPUT" section.
  
  If you remove either -qpdf2 or -qlibansi, you get a heap
  address.
  
  ===Testcase:
  $ cat t.c
  #include <stdio.h>
  
  typedef struct tc {
  FILE *fp;
  int version;
  } tc;
  
  int
  func1(void **outp)
  {
  tc *tc_ptr = (tc *) NULL;
  
  tc_ptr = (tc *) malloc(sizeof(tc)); /* allocate 16 bytes */
  if (tc_ptr == NULL) /* if NULL, goto cleanup */
  goto cleanup;
  
  tc_ptr->fp = (FILE *) NULL; /* set members of struct tc */
  tc_ptr->version = 0;
  *outp = (void *) tc_ptr; /* return tc_ptr in *outp */
  tc_ptr = NULL; /* set to NULL, so it is not freed */
  /* when we fall through label cleanup */
  cleanup:
  if (tc_ptr) free(tc_ptr);
  return 0;
  }
  
  main()
  {
  void *ptr;
  
  func1(&ptr); /* allocate memory for ptr pointing to 'struct tc'
  */
  printf("ptr 0x%lx\n", ptr); /* print allocated ptr */
  }
  $
  
  ===== ACTUAL OUTPUT:
  $ rm t.o t
  $ xlc t.c -c -o t.o -O3 -qpdf2=pdfname= -qnoipa -q64 -qflag=e:e
  1586-003 (W) Required parameters for option "-qpdf1/2=pdfname="
  are not specified.
  1586-401 (E) File "._pdf" not found.
  $ xlc -q64 -g -o t t.o
  $ ./t
  ptr 0x1100007b0 <-- heap address
  
  
  
  With a customized xlc.cfg that has libansi.a on the link step:
  
  $ rm t.o t
  $ xlc t.c -F./xlc_mod.cfg -c -o t.o -O3 -qpdf2=pdfname= -qnoipa
  -q64 -qflag=e:e
  1586-003 (W) Required parameters for option "-qpdf1/2=pdfname="
  are not specified.
  1586-401 (E) File "._pdf" not found.
  $ xlc -q64 -g -o t t.o
  ./t
  ptr 0xfffffffffff7c10  <-- stack address
  
  
  ===== EXPECTED OUTPUT:
  The expectation is heap address
  

Local fix

• N/A
  

Problem summary

• USERS AFFECTED:
  Clients who are linking with -qlibansi and -qpdf2 mayby affected
  by this issue.
  
  PROBLEM DESCRIPTION:
  There was a backend compiler optimization that was not doing a
  heap conversion calcuation correctly;
  which resulted in this issue.
  

Problem conclusion

• The heap conversion calculation in the optimization is now
  fixed.
  

Temporary fix

Comments

APAR Information

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

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

Fix information

• Fixed component name

  XL C FOR AIX

• Fixed component ID

  5725C7100

Applicable component levels

• RD10 PSY

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