Add, optional, support for 128bit integers.

We will, for the foreseeable future, not expose 128 bit datatypes to
SQL. But being able to use 128bit math will allow us, in a later patch,
to use 128bit accumulators for some aggregates; leading to noticeable
speedups over using numeric.

So far we only detect a gcc/clang extension that supports 128bit math,
but no 128bit literals, and no *printf support. We might want to expand
this in the future to further compilers; if there are any that that
provide similar support.

Discussion: 544BB5F1.50709@proxel.se
Author: Andreas Karlsson, with significant editorializing by me
Reviewed-By: Peter Geoghegan, Oskari Saarenmaa

1 files changed, 3 insertions, 0 deletions

diff --git a/configure.in b/configure.in
index ca29e93eee1..b2c1ce71d23 100644
--- a/configure.in
+++ b/configure.in
@@ -1771,6 +1771,9 @@ AC_CHECK_TYPES([int8, uint8, int64, uint64], [], [],
 # C, but is missing on some old platforms.
 AC_CHECK_TYPES(sig_atomic_t, [], [], [#include <signal.h>])
 
+# Check for extensions offering the integer scalar type __int128.
+PGAC_TYPE_128BIT_INT
+
 # Check for various atomic operations now that we have checked how to declare
 # 64bit integers.
 PGAC_HAVE_GCC__SYNC_CHAR_TAS