Revert "For all ppc compilers, implement pg_atomic_fetch_add_ with inline asm."

This reverts commit e7ff59686eacf5021fb84be921116986c3828d8a.  It
defined pg_atomic_fetch_add_u32_impl() without defining
pg_atomic_compare_exchange_u32_impl(), which is incompatible with
src/include/port/atomics/fallback.h.  Per buildfarm member prairiedog.

Discussion: https://postgr.es/m/7517.1568470247@sss.pgh.pa.us

1 files changed, 0 insertions, 40 deletions

diff --git a/configure b/configure
index 731d12c6ac..b3c92764be 100755
--- a/configure
+++ b/configure
@@ -14594,46 +14594,6 @@ $as_echo "$pgac_cv_have_ppc_mutex_hint" >&6; }
 $as_echo "#define HAVE_PPC_LWARX_MUTEX_HINT 1" >>confdefs.h
 
     fi
-    # Check if compiler accepts "i"(x) when __builtin_constant_p(x).
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether __builtin_constant_p(x) implies \"i\"(x) acceptance" >&5
-$as_echo_n "checking whether __builtin_constant_p(x) implies \"i\"(x) acceptance... " >&6; }
-if ${pgac_cv_have_i_constraint__builtin_constant_p+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-static inline int
-     addi(int ra, int si)
-     {
-         int res = 0;
-         if (__builtin_constant_p(si))
-             __asm__ __volatile__(
-                 " addi %0,%1,%2\n" : "=r"(res) : "r"(ra), "i"(si));
-         return res;
-     }
-     int test_adds(int x) { return addi(3, x) + addi(x, 5); }
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv_have_i_constraint__builtin_constant_p=yes
-else
-  pgac_cv_have_i_constraint__builtin_constant_p=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_have_i_constraint__builtin_constant_p" >&5
-$as_echo "$pgac_cv_have_i_constraint__builtin_constant_p" >&6; }
-    if test x"$pgac_cv_have_i_constraint__builtin_constant_p" = xyes ; then
-
-$as_echo "#define HAVE_I_CONSTRAINT__BUILTIN_CONSTANT_P 1" >>confdefs.h
-
-    fi
   ;;
 esac