Autoconf'd test for int64 - Mailing list pgsql-hackers

Attached is a patch that uses autoconf to determine whether there is
a working 64-bit-int type available.

In playing around with it on my machine, I found that gcc provides
perfectly fine support for "long long" arithmetic ... but sprintf()
and sscanf(), which are system-supplied, don't work :-(.  So the
autoconf test program does a cursory test on them too.

If we find that a lot of systems are like this, it might be worth
the trouble to implement binary<->ASCII conversion of int64 ourselves
rather than relying on sprintf/sscanf to handle the data type.

            regards, tom lane


*** src/configure.in.orig    Sat Aug 15 11:52:03 1998
--- src/configure.in    Sun Aug 16 16:41:24 1998
***************
*** 522,528 ****
  #endif
  main() { double d = DBL_MIN; if (d != DBL_MIN) exit(-1); else exit(0); }],
      AC_MSG_RESULT(yes),
!     [AC_MSG_RESULT(no) AC_DEFINE(HAVE_DBL_MIN_PROBLEM)])

  dnl Checks for library functions.
  AC_PROG_GCC_TRADITIONAL
--- 522,604 ----
  #endif
  main() { double d = DBL_MIN; if (d != DBL_MIN) exit(-1); else exit(0); }],
      AC_MSG_RESULT(yes),
!     [AC_MSG_RESULT(no) AC_DEFINE(HAVE_DBL_MIN_PROBLEM)],
!     AC_MSG_RESULT(assuming ok on target machine))
!
! dnl Check to see if we have a working 64-bit integer type.
! AC_MSG_CHECKING(whether 'long int' is 64 bits)
! AC_TRY_RUN([#include <stdio.h>
! typedef long int int64;
! #define INT64_FORMAT "%ld"
!
! int64 a = 20000001;
! int64 b = 40000005;
!
! int does_int64_work()
! {
!   int64 c,d,e;
!   char buf[100];
!
!   if (sizeof(int64) != 8)
!     return 0;            /* doesn't look like the right size */
!
!   /* we do perfunctory checks on multiply, divide, sprintf, sscanf */
!   c = a * b;
!   sprintf(buf, INT64_FORMAT, c);
!   if (strcmp(buf, "800000140000005") != 0)
!     return 0;            /* either multiply or sprintf is busted */
!   if (sscanf(buf, INT64_FORMAT, &d) != 1)
!     return 0;
!   if (d != c)
!     return 0;
!   e = d / b;
!   if (e != a)
!     return 0;
!   return 1;
! }
! main() {
!   exit(! does_int64_work());
! }],
!     [AC_MSG_RESULT(yes) AC_DEFINE(HAVE_LONG_INT_64)],
!     AC_MSG_RESULT(no),
!     AC_MSG_RESULT(assuming not on target machine))
!
! AC_MSG_CHECKING(whether 'long long int' is 64 bits)
! AC_TRY_RUN([#include <stdio.h>
! typedef long long int int64;
! #define INT64_FORMAT "%Ld"
!
! int64 a = 20000001;
! int64 b = 40000005;
!
! int does_int64_work()
! {
!   int64 c,d,e;
!   char buf[100];
!
!   if (sizeof(int64) != 8)
!     return 0;            /* doesn't look like the right size */
!
!   /* we do perfunctory checks on multiply, divide, sprintf, sscanf */
!   c = a * b;
!   sprintf(buf, INT64_FORMAT, c);
!   if (strcmp(buf, "800000140000005") != 0)
!     return 0;            /* either multiply or sprintf is busted */
!   if (sscanf(buf, INT64_FORMAT, &d) != 1)
!     return 0;
!   if (d != c)
!     return 0;
!   e = d / b;
!   if (e != a)
!     return 0;
!   return 1;
! }
! main() {
!   exit(! does_int64_work());
! }],
!     [AC_MSG_RESULT(yes) AC_DEFINE(HAVE_LONG_LONG_INT_64)],
!     AC_MSG_RESULT(no),
!     AC_MSG_RESULT(assuming not on target machine))

  dnl Checks for library functions.
  AC_PROG_GCC_TRADITIONAL
*** src/include/config.h.in.orig    Sat Aug 15 11:54:54 1998
--- src/include/config.h.in    Sun Aug 16 16:33:22 1998
***************
*** 219,224 ****
--- 219,230 ----
  /* Set to 1 if your DBL_MIN is problematic */
  #undef HAVE_DBL_MIN_PROBLEM

+ /* Set to 1 if type "long int" works and is 64 bits */
+ #undef HAVE_LONG_INT_64
+
+ /* Set to 1 if type "long long int" works and is 64 bits */
+ #undef HAVE_LONG_LONG_INT_64
+
  /*
   * Code below this point should not require changes
   */
*** src/include/utils/int8.h.orig    Wed Jul  8 10:10:30 1998
--- src/include/utils/int8.h    Sun Aug 16 16:37:51 1998
***************
*** 23,51 ****
  #ifndef INT8_H
  #define INT8_H

! #if defined(__alpha) || defined(PPC)
  typedef long int int64;
-
  #define INT64_FORMAT "%ld"
!
! #elif defined(__GNUC__) && defined(i386)
  typedef long long int int64;
-
  #define INT64_FORMAT "%Ld"
-
  #else
  typedef long int int64;
-
  #define INT64_FORMAT "%ld"
  #endif
-
-
- /*
- #if sizeof(int64) == 8
- #define HAVE_64BIT_INTS 1
  #endif
- */
-

  extern int64 *int8in(char *str);
  extern char *int8out(int64 * val);
--- 23,44 ----
  #ifndef INT8_H
  #define INT8_H

! #ifdef HAVE_LONG_INT_64
! /* Plain "long int" fits, use it */
  typedef long int int64;
  #define INT64_FORMAT "%ld"
! #else
! #ifdef HAVE_LONG_LONG_INT_64
! /* We have working support for "long long int", use that */
  typedef long long int int64;
  #define INT64_FORMAT "%Ld"
  #else
+ /* Won't actually work, but fall back to long int so that int8.c compiles */
  typedef long int int64;
  #define INT64_FORMAT "%ld"
+ #define INT64_IS_BUSTED
  #endif
  #endif

  extern int64 *int8in(char *str);
  extern char *int8out(int64 * val);