Make use of compiler builtins and/or assembly for CLZ, CTZ, POPCNT.

Test for the compiler builtins __builtin_clz, __builtin_ctz, and
__builtin_popcount, and make use of these in preference to
handwritten C code if they're available.  Create src/port
infrastructure for "leftmost one", "rightmost one", and "popcount"
so as to centralize these decisions.

On x86_64, __builtin_popcount generally won't make use of the POPCNT
opcode because that's not universally supported yet.  Provide code
that checks CPUID and then calls POPCNT via asm() if available.
This requires indirecting through a function pointer, which is
an annoying amount of overhead for a one-instruction operation,
but it's probably not worth working harder than this for our
current use-cases.

I'm not sure we've found all the existing places that could profit
from this new infrastructure; but we at least touched all the
ones that used copied-and-pasted versions of the bitmapset.c code,
and got rid of multiple copies of the associated constant arrays.

While at it, replace c-compiler.m4's one-per-builtin-function
macros with a single one that can handle all the cases we need
to worry about so far.  Also, because I'm paranoid, make those
checks into AC_LINK checks rather than just AC_COMPILE; the
former coding failed to verify that libgcc has support for the
builtin, in cases where it's not inline code.

David Rowley, Thomas Munro, Alvaro Herrera, Tom Lane

Discussion: https://postgr.es/m/CAKJS1f9WTAGG1tPeJnD18hiQW5gAk59fQ6WK-vfdAKEHyRg2RA@mail.gmail.com

1 files changed, 272 insertions, 75 deletions

diff --git a/configure b/configure
index 849a7ebdf3..de3153f2eb 100755
--- a/configure
+++ b/configure
@@ -13961,78 +13961,6 @@ if test x"$pgac_cv__types_compatible" = xyes ; then
 $as_echo "#define HAVE__BUILTIN_TYPES_COMPATIBLE_P 1" >>confdefs.h
 
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_bswap16" >&5
-$as_echo_n "checking for __builtin_bswap16... " >&6; }
-if ${pgac_cv__builtin_bswap16+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-static unsigned long int x = __builtin_bswap16(0xaabb);
-
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv__builtin_bswap16=yes
-else
-  pgac_cv__builtin_bswap16=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_bswap16" >&5
-$as_echo "$pgac_cv__builtin_bswap16" >&6; }
-if test x"$pgac_cv__builtin_bswap16" = xyes ; then
-
-$as_echo "#define HAVE__BUILTIN_BSWAP16 1" >>confdefs.h
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_bswap32" >&5
-$as_echo_n "checking for __builtin_bswap32... " >&6; }
-if ${pgac_cv__builtin_bswap32+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-static unsigned long int x = __builtin_bswap32(0xaabbccdd);
-
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv__builtin_bswap32=yes
-else
-  pgac_cv__builtin_bswap32=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_bswap32" >&5
-$as_echo "$pgac_cv__builtin_bswap32" >&6; }
-if test x"$pgac_cv__builtin_bswap32" = xyes ; then
-
-$as_echo "#define HAVE__BUILTIN_BSWAP32 1" >>confdefs.h
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_bswap64" >&5
-$as_echo_n "checking for __builtin_bswap64... " >&6; }
-if ${pgac_cv__builtin_bswap64+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-static unsigned long int x = __builtin_bswap64(0xaabbccddeeff0011);
-
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  pgac_cv__builtin_bswap64=yes
-else
-  pgac_cv__builtin_bswap64=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_bswap64" >&5
-$as_echo "$pgac_cv__builtin_bswap64" >&6; }
-if test x"$pgac_cv__builtin_bswap64" = xyes ; then
-
-$as_echo "#define HAVE__BUILTIN_BSWAP64 1" >>confdefs.h
-
-fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_constant_p" >&5
 $as_echo_n "checking for __builtin_constant_p... " >&6; }
 if ${pgac_cv__builtin_constant_p+:} false; then :
@@ -14687,12 +14615,49 @@ fi
 
 fi
 
-# On PPC, check if assembler supports LWARX instruction's mutex hint bit
 case $host_cpu in
+  x86_64)
+    # On x86_64, check if we can compile a popcntq instruction
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether assembler supports x86_64 popcntq" >&5
+$as_echo_n "checking whether assembler supports x86_64 popcntq... " >&6; }
+if ${pgac_cv_have_x86_64_popcntq+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+long long x = 1; long long r;
+	 __asm__ __volatile__ (" popcntq %1,%0\n" : "=q"(r) : "rm"(x));
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_have_x86_64_popcntq=yes
+else
+  pgac_cv_have_x86_64_popcntq=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_have_x86_64_popcntq" >&5
+$as_echo "$pgac_cv_have_x86_64_popcntq" >&6; }
+    if test x"$pgac_cv_have_x86_64_popcntq" = xyes ; then
+
+$as_echo "#define HAVE_X86_64_POPCNTQ 1" >>confdefs.h
+
+    fi
+  ;;
   ppc*|powerpc*)
+    # On PPC, check if assembler supports LWARX instruction's mutex hint bit
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether assembler supports lwarx hint bit" >&5
 $as_echo_n "checking whether assembler supports lwarx hint bit... " >&6; }
-    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+if ${pgac_cv_have_ppc_mutex_hint+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -14710,7 +14675,8 @@ else
   pgac_cv_have_ppc_mutex_hint=no
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_have_ppc_mutex_hint" >&5
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_have_ppc_mutex_hint" >&5
 $as_echo "$pgac_cv_have_ppc_mutex_hint" >&6; }
     if test x"$pgac_cv_have_ppc_mutex_hint" = xyes ; then
 
@@ -15223,6 +15189,237 @@ fi
 done
 
 
+# These typically are compiler builtins, for which AC_CHECK_FUNCS fails.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_bswap16" >&5
+$as_echo_n "checking for __builtin_bswap16... " >&6; }
+if ${pgac_cv__builtin_bswap16+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+call__builtin_bswap16(int x)
+{
+    return __builtin_bswap16(x);
+}
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv__builtin_bswap16=yes
+else
+  pgac_cv__builtin_bswap16=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_bswap16" >&5
+$as_echo "$pgac_cv__builtin_bswap16" >&6; }
+if test x"${pgac_cv__builtin_bswap16}" = xyes ; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE__BUILTIN_BSWAP16 1
+_ACEOF
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_bswap32" >&5
+$as_echo_n "checking for __builtin_bswap32... " >&6; }
+if ${pgac_cv__builtin_bswap32+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+call__builtin_bswap32(int x)
+{
+    return __builtin_bswap32(x);
+}
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv__builtin_bswap32=yes
+else
+  pgac_cv__builtin_bswap32=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_bswap32" >&5
+$as_echo "$pgac_cv__builtin_bswap32" >&6; }
+if test x"${pgac_cv__builtin_bswap32}" = xyes ; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE__BUILTIN_BSWAP32 1
+_ACEOF
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_bswap64" >&5
+$as_echo_n "checking for __builtin_bswap64... " >&6; }
+if ${pgac_cv__builtin_bswap64+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+call__builtin_bswap64(long int x)
+{
+    return __builtin_bswap64(x);
+}
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv__builtin_bswap64=yes
+else
+  pgac_cv__builtin_bswap64=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_bswap64" >&5
+$as_echo "$pgac_cv__builtin_bswap64" >&6; }
+if test x"${pgac_cv__builtin_bswap64}" = xyes ; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE__BUILTIN_BSWAP64 1
+_ACEOF
+
+fi
+# We assume that we needn't test all widths of these explicitly:
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_clz" >&5
+$as_echo_n "checking for __builtin_clz... " >&6; }
+if ${pgac_cv__builtin_clz+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+call__builtin_clz(unsigned int x)
+{
+    return __builtin_clz(x);
+}
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv__builtin_clz=yes
+else
+  pgac_cv__builtin_clz=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_clz" >&5
+$as_echo "$pgac_cv__builtin_clz" >&6; }
+if test x"${pgac_cv__builtin_clz}" = xyes ; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE__BUILTIN_CLZ 1
+_ACEOF
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_ctz" >&5
+$as_echo_n "checking for __builtin_ctz... " >&6; }
+if ${pgac_cv__builtin_ctz+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+call__builtin_ctz(unsigned int x)
+{
+    return __builtin_ctz(x);
+}
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv__builtin_ctz=yes
+else
+  pgac_cv__builtin_ctz=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_ctz" >&5
+$as_echo "$pgac_cv__builtin_ctz" >&6; }
+if test x"${pgac_cv__builtin_ctz}" = xyes ; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE__BUILTIN_CTZ 1
+_ACEOF
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_popcount" >&5
+$as_echo_n "checking for __builtin_popcount... " >&6; }
+if ${pgac_cv__builtin_popcount+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+call__builtin_popcount(unsigned int x)
+{
+    return __builtin_popcount(x);
+}
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv__builtin_popcount=yes
+else
+  pgac_cv__builtin_popcount=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv__builtin_popcount" >&5
+$as_echo "$pgac_cv__builtin_popcount" >&6; }
+if test x"${pgac_cv__builtin_popcount}" = xyes ; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE__BUILTIN_POPCOUNT 1
+_ACEOF
+
+fi
+
 ac_fn_c_check_func "$LINENO" "fseeko" "ac_cv_func_fseeko"
 if test "x$ac_cv_func_fseeko" = xyes; then :
   $as_echo "#define HAVE_FSEEKO 1" >>confdefs.h