For all ppc compilers, implement pg_atomic_fetch_add_ with inline asm.

This is more like how we handle s_lock.h and arch-x86.h.  This does not
materially affect code generation for gcc 7.2.0 or xlc 13.1.3.

Reviewed by Tom Lane.

Discussion: https://postgr.es/m/[email protected]

1 files changed, 40 insertions, 0 deletions

diff --git a/configure b/configure
index b3c92764be8..731d12c6acb 100755
--- a/configure
+++ b/configure
@@ -14594,6 +14594,46 @@ $as_echo "$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