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b64d92f1a5
postgresql/config/c-compiler.m4
Andres Freund b64d92f1a5 Add a basic atomic ops API abstracting away platform/architecture details. 
Several upcoming performance/scalability improvements require atomic
operations. This new API avoids the need to splatter compiler and
architecture dependent code over all the locations employing atomic
ops.

For several of the potential usages it'd be problematic to maintain
both, a atomics using implementation and one using spinlocks or
similar. In all likelihood one of the implementations would not get
tested regularly under concurrency. To avoid that scenario the new API
provides a automatic fallback of atomic operations to spinlocks. All
properties of atomic operations are maintained. This fallback -
obviously - isn't as fast as just using atomic ops, but it's not bad
either. For one of the future users the atomics ontop spinlocks
implementation was actually slightly faster than the old purely
spinlock using implementation. That's important because it reduces the
fear of regressing older platforms when improving the scalability for
new ones.

The API, loosely modeled after the C11 atomics support, currently
provides 'atomic flags' and 32 bit unsigned integers. If the platform
efficiently supports atomic 64 bit unsigned integers those are also
provided.

To implement atomics support for a platform/architecture/compiler for
a type of atomics 32bit compare and exchange needs to be
implemented. If available and more efficient native support for flags,
32 bit atomic addition, and corresponding 64 bit operations may also
be provided. Additional useful atomic operations are implemented
generically ontop of these.

The implementation for various versions of gcc, msvc and sun studio have
been tested. Additional existing stub implementations for
* Intel icc
* HUPX acc
* IBM xlc
are included but have never been tested. These will likely require
fixes based on buildfarm and user feedback.

As atomic operations also require barriers for some operations the
existing barrier support has been moved into the atomics code.

Author: Andres Freund with contributions from Oskari Saarenmaa
Reviewed-By: Amit Kapila, Robert Haas, Heikki Linnakangas and Álvaro Herrera
Discussion: CA+TgmoYBW+ux5-8Ja=Mcyuy8=VXAnVRHp3Kess6Pn3DMXAPAEA@mail.gmail.com,
    20131015123303.GH5300@awork2.anarazel.de,
    20131028205522.GI20248@awork2.anarazel.de
2014-09-25 23:49:05 +02:00

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# Macros to detect C compiler features
# config/c-compiler.m4
# PGAC_C_SIGNED
# -------------
# Check if the C compiler understands signed types.
AC_DEFUN([PGAC_C_SIGNED],
[AC_CACHE_CHECK(for signed types, pgac_cv_c_signed,
[AC_TRY_COMPILE([],
[signed char c; signed short s; signed int i;],
[pgac_cv_c_signed=yes],
[pgac_cv_c_signed=no])])
if test x"$pgac_cv_c_signed" = xno ; then
AC_DEFINE(signed,, [Define to empty if the C compiler does not understand signed types.])
fi])# PGAC_C_SIGNED
# PGAC_C_INLINE
# -------------
# Check if the C compiler understands inline functions without being
# noisy about unused static inline functions. Some older compilers
# understand inline functions (as tested by AC_C_INLINE) but warn about
# them if they aren't used in a translation unit.
#
# This test used to just define an inline function, but some compilers
# (notably clang) got too smart and now warn about unused static
# inline functions when defined inside a .c file, but not when defined
# in an included header. Since the latter is what we want to use, test
# to see if the warning appears when the function is in a header file.
# Not pretty, but it works.
#
# Defines: inline, PG_USE_INLINE
AC_DEFUN([PGAC_C_INLINE],
[AC_C_INLINE
AC_CACHE_CHECK([for quiet inline (no complaint if unreferenced)], pgac_cv_c_inline_quietly,
[pgac_cv_c_inline_quietly=no
if test "$ac_cv_c_inline" != no; then
pgac_c_inline_save_werror=$ac_c_werror_flag
ac_c_werror_flag=yes
AC_LINK_IFELSE([AC_LANG_PROGRAM([#include "$srcdir/config/test_quiet_include.h"],[])],
[pgac_cv_c_inline_quietly=yes])
ac_c_werror_flag=$pgac_c_inline_save_werror
fi])
if test "$pgac_cv_c_inline_quietly" != no; then
AC_DEFINE_UNQUOTED([PG_USE_INLINE], 1,
[Define to 1 if "static inline" works without unwanted warnings from ]
[compilations where static inline functions are defined but not called.])
fi
])# PGAC_C_INLINE
# PGAC_TYPE_64BIT_INT(TYPE)
# -------------------------
# Check if TYPE is a working 64 bit integer type. Set HAVE_TYPE_64 to
# yes or no respectively, and define HAVE_TYPE_64 if yes.
AC_DEFUN([PGAC_TYPE_64BIT_INT],
[define([Ac_define], [translit([have_$1_64], [a-z *], [A-Z_P])])dnl
define([Ac_cachevar], [translit([pgac_cv_type_$1_64], [ *], [_p])])dnl
AC_CACHE_CHECK([whether $1 is 64 bits], [Ac_cachevar],
[AC_TRY_RUN(
[typedef $1 ac_int64;
/*
* These are globals to discourage the compiler from folding all the
* arithmetic tests down to compile-time constants.
*/
ac_int64 a = 20000001;
ac_int64 b = 40000005;
int does_int64_work()
{
ac_int64 c,d;
if (sizeof(ac_int64) != 8)
return 0; /* definitely not the right size */
/* Do perfunctory checks to see if 64-bit arithmetic seems to work */
c = a * b;
d = (c + b) / b;
if (d != a+1)
return 0;
return 1;
}
main() {
exit(! does_int64_work());
}],
[Ac_cachevar=yes],
[Ac_cachevar=no],
[# If cross-compiling, check the size reported by the compiler and
# trust that the arithmetic works.
AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([], [sizeof($1) == 8])],
Ac_cachevar=yes,
Ac_cachevar=no)])])
Ac_define=$Ac_cachevar
if test x"$Ac_cachevar" = xyes ; then
AC_DEFINE(Ac_define, 1, [Define to 1 if `]$1[' works and is 64 bits.])
fi
undefine([Ac_define])dnl
undefine([Ac_cachevar])dnl
])# PGAC_TYPE_64BIT_INT
# PGAC_C_FUNCNAME_SUPPORT
# -----------------------
# Check if the C compiler understands __func__ (C99) or __FUNCTION__ (gcc).
# Define HAVE_FUNCNAME__FUNC or HAVE_FUNCNAME__FUNCTION accordingly.
AC_DEFUN([PGAC_C_FUNCNAME_SUPPORT],
[AC_CACHE_CHECK(for __func__, pgac_cv_funcname_func_support,
[AC_TRY_COMPILE([#include <stdio.h>],
[printf("%s\n", __func__);],
[pgac_cv_funcname_func_support=yes],
[pgac_cv_funcname_func_support=no])])
if test x"$pgac_cv_funcname_func_support" = xyes ; then
AC_DEFINE(HAVE_FUNCNAME__FUNC, 1,
[Define to 1 if your compiler understands __func__.])
else
AC_CACHE_CHECK(for __FUNCTION__, pgac_cv_funcname_function_support,
[AC_TRY_COMPILE([#include <stdio.h>],
[printf("%s\n", __FUNCTION__);],
[pgac_cv_funcname_function_support=yes],
[pgac_cv_funcname_function_support=no])])
if test x"$pgac_cv_funcname_function_support" = xyes ; then
AC_DEFINE(HAVE_FUNCNAME__FUNCTION, 1,
[Define to 1 if your compiler understands __FUNCTION__.])
fi
fi])# PGAC_C_FUNCNAME_SUPPORT
# PGAC_C_STATIC_ASSERT
# --------------------
# Check if the C compiler understands _Static_assert(),
# and define HAVE__STATIC_ASSERT if so.
#
# We actually check the syntax ({ _Static_assert(...) }), because we need
# gcc-style compound expressions to be able to wrap the thing into macros.
AC_DEFUN([PGAC_C_STATIC_ASSERT],
[AC_CACHE_CHECK(for _Static_assert, pgac_cv__static_assert,
[AC_TRY_LINK([],
[({ _Static_assert(1, "foo"); })],
[pgac_cv__static_assert=yes],
[pgac_cv__static_assert=no])])
if test x"$pgac_cv__static_assert" = xyes ; then
AC_DEFINE(HAVE__STATIC_ASSERT, 1,
[Define to 1 if your compiler understands _Static_assert.])
fi])# PGAC_C_STATIC_ASSERT
# PGAC_C_TYPES_COMPATIBLE
# -----------------------
# Check if the C compiler understands __builtin_types_compatible_p,
# and define HAVE__BUILTIN_TYPES_COMPATIBLE_P if so.
#
# We check usage with __typeof__, though it's unlikely any compiler would
# have the former and not the latter.
AC_DEFUN([PGAC_C_TYPES_COMPATIBLE],
[AC_CACHE_CHECK(for __builtin_types_compatible_p, pgac_cv__types_compatible,
[AC_TRY_COMPILE([],
[ int x; static int y[__builtin_types_compatible_p(__typeof__(x), int)]; ],
[pgac_cv__types_compatible=yes],
[pgac_cv__types_compatible=no])])
if test x"$pgac_cv__types_compatible" = xyes ; then
AC_DEFINE(HAVE__BUILTIN_TYPES_COMPATIBLE_P, 1,
[Define to 1 if your compiler understands __builtin_types_compatible_p.])
fi])# PGAC_C_TYPES_COMPATIBLE
# PGAC_C_BUILTIN_CONSTANT_P
# -------------------------
# Check if the C compiler understands __builtin_constant_p(),
# and define HAVE__BUILTIN_CONSTANT_P if so.
AC_DEFUN([PGAC_C_BUILTIN_CONSTANT_P],
[AC_CACHE_CHECK(for __builtin_constant_p, pgac_cv__builtin_constant_p,
[AC_TRY_COMPILE([static int x; static int y[__builtin_constant_p(x) ? x : 1];],
[],
[pgac_cv__builtin_constant_p=yes],
[pgac_cv__builtin_constant_p=no])])
if test x"$pgac_cv__builtin_constant_p" = xyes ; then
AC_DEFINE(HAVE__BUILTIN_CONSTANT_P, 1,
[Define to 1 if your compiler understands __builtin_constant_p.])
fi])# PGAC_C_BUILTIN_CONSTANT_P
# PGAC_C_BUILTIN_UNREACHABLE
# --------------------------
# Check if the C compiler understands __builtin_unreachable(),
# and define HAVE__BUILTIN_UNREACHABLE if so.
#
# NB: Don't get the idea of putting a for(;;); or such before the
# __builtin_unreachable() call. Some compilers would remove it before linking
# and only a warning instead of an error would be produced.
AC_DEFUN([PGAC_C_BUILTIN_UNREACHABLE],
[AC_CACHE_CHECK(for __builtin_unreachable, pgac_cv__builtin_unreachable,
[AC_TRY_LINK([],
[__builtin_unreachable();],
[pgac_cv__builtin_unreachable=yes],
[pgac_cv__builtin_unreachable=no])])
if test x"$pgac_cv__builtin_unreachable" = xyes ; then
AC_DEFINE(HAVE__BUILTIN_UNREACHABLE, 1,
[Define to 1 if your compiler understands __builtin_unreachable.])
fi])# PGAC_C_BUILTIN_UNREACHABLE
# PGAC_C_VA_ARGS
# --------------
# Check if the C compiler understands C99-style variadic macros,
# and define HAVE__VA_ARGS if so.
AC_DEFUN([PGAC_C_VA_ARGS],
[AC_CACHE_CHECK(for __VA_ARGS__, pgac_cv__va_args,
[AC_TRY_COMPILE([#include <stdio.h>],
[#define debug(...) fprintf(stderr, __VA_ARGS__)
debug("%s", "blarg");
],
[pgac_cv__va_args=yes],
[pgac_cv__va_args=no])])
if test x"$pgac_cv__va_args" = xyes ; then
AC_DEFINE(HAVE__VA_ARGS, 1,
[Define to 1 if your compiler understands __VA_ARGS__ in macros.])
fi])# PGAC_C_VA_ARGS
# PGAC_PROG_CC_CFLAGS_OPT
# -----------------------
# Given a string, check if the compiler supports the string as a
# command-line option. If it does, add the string to CFLAGS.
AC_DEFUN([PGAC_PROG_CC_CFLAGS_OPT],
[define([Ac_cachevar], [AS_TR_SH([pgac_cv_prog_cc_cflags_$1])])dnl
AC_CACHE_CHECK([whether $CC supports $1], [Ac_cachevar],
[pgac_save_CFLAGS=$CFLAGS
CFLAGS="$pgac_save_CFLAGS $1"
ac_save_c_werror_flag=$ac_c_werror_flag
ac_c_werror_flag=yes
_AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
[Ac_cachevar=yes],
[Ac_cachevar=no])
ac_c_werror_flag=$ac_save_c_werror_flag
CFLAGS="$pgac_save_CFLAGS"])
if test x"$Ac_cachevar" = x"yes"; then
CFLAGS="$CFLAGS $1"
fi
undefine([Ac_cachevar])dnl
])# PGAC_PROG_CC_CFLAGS_OPT
# PGAC_PROG_CC_VAR_OPT
# -----------------------
# Given a variable name and a string, check if the compiler supports
# the string as a command-line option. If it does, add the string to
# the given variable.
AC_DEFUN([PGAC_PROG_CC_VAR_OPT],
[define([Ac_cachevar], [AS_TR_SH([pgac_cv_prog_cc_cflags_$2])])dnl
AC_CACHE_CHECK([whether $CC supports $2], [Ac_cachevar],
[pgac_save_CFLAGS=$CFLAGS
CFLAGS="$pgac_save_CFLAGS $2"
ac_save_c_werror_flag=$ac_c_werror_flag
ac_c_werror_flag=yes
_AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
[Ac_cachevar=yes],
[Ac_cachevar=no])
ac_c_werror_flag=$ac_save_c_werror_flag
CFLAGS="$pgac_save_CFLAGS"])
if test x"$Ac_cachevar" = x"yes"; then
$1="${$1} $2"
fi
undefine([Ac_cachevar])dnl
])# PGAC_PROG_CC_CFLAGS_OPT
# PGAC_PROG_CC_LDFLAGS_OPT
# ------------------------
# Given a string, check if the compiler supports the string as a
# command-line option. If it does, add the string to LDFLAGS.
# For reasons you'd really rather not know about, this checks whether
# you can link to a particular function, not just whether you can link.
# In fact, we must actually check that the resulting program runs :-(
AC_DEFUN([PGAC_PROG_CC_LDFLAGS_OPT],
[define([Ac_cachevar], [AS_TR_SH([pgac_cv_prog_cc_ldflags_$1])])dnl
AC_CACHE_CHECK([whether $CC supports $1], [Ac_cachevar],
[pgac_save_LDFLAGS=$LDFLAGS
LDFLAGS="$pgac_save_LDFLAGS $1"
AC_RUN_IFELSE([AC_LANG_PROGRAM([extern void $2 (); void (*fptr) () = $2;],[])],
[Ac_cachevar=yes],
[Ac_cachevar=no],
[Ac_cachevar="assuming no"])
LDFLAGS="$pgac_save_LDFLAGS"])
if test x"$Ac_cachevar" = x"yes"; then
LDFLAGS="$LDFLAGS $1"
fi
undefine([Ac_cachevar])dnl
])# PGAC_PROG_CC_LDFLAGS_OPT
# PGAC_HAVE_GCC__SYNC_CHAR_TAS
# -------------------------
# Check if the C compiler understands __sync_lock_test_and_set(char),
# and define HAVE_GCC__SYNC_CHAR_TAS
#
# NB: There are platforms where test_and_set is available but compare_and_swap
# is not, so test this separately.
# NB: Some platforms only do 32bit tas, others only do 8bit tas. Test both.
AC_DEFUN([PGAC_HAVE_GCC__SYNC_CHAR_TAS],
[AC_CACHE_CHECK(for builtin __sync char locking functions, pgac_cv_gcc_sync_char_tas,
[AC_TRY_LINK([],
[char lock = 0;
__sync_lock_test_and_set(&lock, 1);
__sync_lock_release(&lock);],
[pgac_cv_gcc_sync_char_tas="yes"],
[pgac_cv_gcc_sync_char_tas="no"])])
if test x"$pgac_cv_gcc_sync_char_tas" = x"yes"; then
AC_DEFINE(HAVE_GCC__SYNC_CHAR_TAS, 1, [Define to 1 if you have __sync_lock_test_and_set(char *) and friends.])
fi])# PGAC_HAVE_GCC__SYNC_CHAR_TAS
# PGAC_HAVE_GCC__SYNC_INT32_TAS
# -------------------------
# Check if the C compiler understands __sync_lock_test_and_set(),
# and define HAVE_GCC__SYNC_INT32_TAS
AC_DEFUN([PGAC_HAVE_GCC__SYNC_INT32_TAS],
[AC_CACHE_CHECK(for builtin __sync int32 locking functions, pgac_cv_gcc_sync_int32_tas,
[AC_TRY_LINK([],
[int lock = 0;
__sync_lock_test_and_set(&lock, 1);
__sync_lock_release(&lock);],
[pgac_cv_gcc_sync_int32_tas="yes"],
[pgac_cv_gcc_sync_int32_tas="no"])])
if test x"$pgac_cv_gcc_sync_int32_tas" = x"yes"; then
AC_DEFINE(HAVE_GCC__SYNC_INT32_TAS, 1, [Define to 1 if you have __sync_lock_test_and_set(int *) and friends.])
fi])# PGAC_HAVE_GCC__SYNC_INT32_TAS
# PGAC_HAVE_GCC__SYNC_INT32_CAS
# -------------------------
# Check if the C compiler understands __sync_compare_and_swap() for 32bit
# types, and define HAVE_GCC__SYNC_INT32_CAS if so.
AC_DEFUN([PGAC_HAVE_GCC__SYNC_INT32_CAS],
[AC_CACHE_CHECK(for builtin __sync int32 atomic operations, pgac_cv_gcc_sync_int32_cas,
[AC_TRY_LINK([],
[int val = 0;
__sync_val_compare_and_swap(&val, 0, 37);],
[pgac_cv_gcc_sync_int32_cas="yes"],
[pgac_cv_gcc_sync_int32_cas="no"])])
if test x"$pgac_cv_gcc_sync_int32_cas" = x"yes"; then
AC_DEFINE(HAVE_GCC__SYNC_INT32_CAS, 1, [Define to 1 if you have __sync_compare_and_swap(int *, int, int).])
fi])# PGAC_HAVE_GCC__SYNC_INT32_CAS
# PGAC_HAVE_GCC__SYNC_INT64_CAS
# -------------------------
# Check if the C compiler understands __sync_compare_and_swap() for 64bit
# types, and define HAVE_GCC__SYNC_INT64_CAS if so.
AC_DEFUN([PGAC_HAVE_GCC__SYNC_INT64_CAS],
[AC_CACHE_CHECK(for builtin __sync int64 atomic operations, pgac_cv_gcc_sync_int64_cas,
[AC_TRY_LINK([],
[PG_INT64_TYPE lock = 0;
__sync_val_compare_and_swap(&lock, 0, (PG_INT64_TYPE) 37);],
[pgac_cv_gcc_sync_int64_cas="yes"],
[pgac_cv_gcc_sync_int64_cas="no"])])
if test x"$pgac_cv_gcc_sync_int64_cas" = x"yes"; then
AC_DEFINE(HAVE_GCC__SYNC_INT64_CAS, 1, [Define to 1 if you have __sync_compare_and_swap(int64 *, int64, int64).])
fi])# PGAC_HAVE_GCC__SYNC_INT64_CAS
# PGAC_HAVE_GCC__ATOMIC_INT32_CAS
# -------------------------
# Check if the C compiler understands __atomic_compare_exchange_n() for 32bit
# types, and define HAVE_GCC__ATOMIC_INT32_CAS if so.
AC_DEFUN([PGAC_HAVE_GCC__ATOMIC_INT32_CAS],
[AC_CACHE_CHECK(for builtin __atomic int32 atomic operations, pgac_cv_gcc_atomic_int32_cas,
[AC_TRY_LINK([],
[int val = 0;
int expect = 0;
__atomic_compare_exchange_n(&val, &expect, 37, 0, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED);],
[pgac_cv_gcc_atomic_int32_cas="yes"],
[pgac_cv_gcc_atomic_int32_cas="no"])])
if test x"$pgac_cv_gcc_atomic_int32_cas" = x"yes"; then
AC_DEFINE(HAVE_GCC__ATOMIC_INT32_CAS, 1, [Define to 1 if you have __atomic_compare_exchange_n(int *, int *, int).])
fi])# PGAC_HAVE_GCC__ATOMIC_INT32_CAS
# PGAC_HAVE_GCC__ATOMIC_INT64_CAS
# -------------------------
# Check if the C compiler understands __atomic_compare_exchange_n() for 64bit
# types, and define HAVE_GCC__ATOMIC_INT64_CAS if so.
AC_DEFUN([PGAC_HAVE_GCC__ATOMIC_INT64_CAS],
[AC_CACHE_CHECK(for builtin __atomic int64 atomic operations, pgac_cv_gcc_atomic_int64_cas,
[AC_TRY_LINK([],
[PG_INT64_TYPE val = 0;
PG_INT64_TYPE expect = 0;
__atomic_compare_exchange_n(&val, &expect, 37, 0, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED);],
[pgac_cv_gcc_atomic_int64_cas="yes"],
[pgac_cv_gcc_atomic_int64_cas="no"])])
if test x"$pgac_cv_gcc_atomic_int64_cas" = x"yes"; then
AC_DEFINE(HAVE_GCC__ATOMIC_INT64_CAS, 1, [Define to 1 if you have __atomic_compare_exchange_n(int64 *, int *, int64).])
fi])# PGAC_HAVE_GCC__ATOMIC_INT64_CAS
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