IV49970: DIS OUTPUT DOES NOT SHOW CMPB MNEMONIC

XL C/C++ for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C/C++ for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 21 (January 2019 Update) for 12.1
XL C for AIX Fix Pack 21 (January 2019 Update) for 12.1

APAR status

• Closed as program error.

Error description

• When using the dis-assembler, the cmpb instruction is not shown
  in the .s output file for the corresponding source code:
  
  ======Testcase:
  $ cat test.C
  #include <string.h>
  #include <builtins.h>
  #include <stdio.h>
  
  #define Uint64 unsigned long long
  #define Uint32 unsigned int
  #define Uint unsigned long long
  #define UintPtr intptr_t
  
  extern "C" size_t strlen_org(const char *s) { return strlen(s);
  }
  
  extern "C" size_t strlen_pwr6(const char *s)
  {
     UintPtr offset = ((UintPtr)s) & 7;
     Uint64 *alignedPtr = (Uint64 *)(s-offset);
     Uint64 a = *alignedPtr;
     Uint64 mask = -1;
     mask <<= offset*8;
     a |=  ~mask;
     Uint64 cmpb = __cmpb(a,0);
     while (cmpb == 0)
     {
        alignedPtr++;
        a = *alignedPtr;
        cmpb = __cmpb(a,0);
  
        if (cmpb != 0) break;
  
        alignedPtr++;
        a = *alignedPtr;
        cmpb = __cmpb(a,0);
     }
     size_t res = (size_t)((const char *)alignedPtr - s);
     res += __cntlz8(cmpb)/8;
     return res;
  }
  
  int main(int argc, char *argv[])
  {
    size_t s;
    char dest[1024*1024];
    memset(dest, 'x', sizeof(dest));
    dest[sizeof(dest)-1] = '\0';
  
    switch(argv[1][0])
    {
    case 'a' : for (int i=0; i < 10000; i++) s = strlen_org(dest);
  break;
    case 'c' : for (int i=0; i < 10000; i++) s =
  strlen_pwr6(dest); break;
    }
    printf("%ull\n", s);
    return s;
  }
  $
  
  ===== COMPILE COMMAND:
  xlC -q64 -O2 strlen.C -qlist -qarch=pwr7
  /usr/vac/exe/dis a.out
  
  ===== ACTUAL OUTPUT:
  When analyzing the .s file, the cmpb instruction is missing:
  
  .strlen_pwr6:                           # 0x00000001000007a0
  (H.155.
  NO_SYMBOL+0x040)
          rlwinm     r4,r3,0,29,31
          addi       r0,r0,-1
          addi       r5,r0,0
          subf       r4,r4,r3
          rlwinm     r6,r3,3,26,28
          ld         r7,0(r4)
          sld        r0,r0,r6
          orc        r0,r7,r0
          .long   0x7ca003f8              # "|\240\003\370"
          .long   0x2c200000              # ", \0\0"
          .long   0x40820048              # "@\202\0H"
          .long   0x60000000              # "`\0\0\0"
  
  
  ===== EXPECTED OUTPUT:
  The cmpb instruction needs to be there.
  

Local fix

• Use the -qlist option instead of -s
  

Problem summary

• USERS AFFECTED:
  Users who want to read assembly files that include any one of
  the cmpb, frsqrtes, frsqrtes and wait mnemonics are affected by
  this issue.
  
  PROBLEM DESCRIPTION:
  The disassembler (ie dis) cannot figure out cmpb, frsqrtes,
  frsqrtes and wait mnemonic instructions.
  

Problem conclusion

• The disassembler has been taught to handle the above mnemonics.
  

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:

  LI77647

Fix information

• Fixed component name

  XL C FOR AIX

• Fixed component ID

  5725C7100

Applicable component levels