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@@ -1,124 +0,0 @@
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-From 5865c7cb4e4ed1d63699e384ea52984448adfec9 Mon Sep 17 00:00:00 2001
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-From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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-Date: Mon, 7 May 2018 10:36:10 +0200
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-Subject: [PATCH] configure.ac: rework -latomic check
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-
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-The configure.ac logic added in commit
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-2ef7f23820a67e958c2252bd81eb0458903ebf33 ("configure: check if
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--latomic is needed for __atomic_*") makes the assumption that if a
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-64-bit atomic intrinsic test program fails to link without -latomic,
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-it is because we must use -latomic.
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-
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-Unfortunately, this is not completely correct: libatomic only appeared
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-in gcc 4.8, and therefore gcc versions before that will not have
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-libatomic, and therefore don't provide atomic intrinsics for all
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-architectures. This issue was for example encountered on PowerPC with
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-a gcc 4.7 toolchain, where the build fails with:
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-
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-powerpc-ctng_e500v2-linux-gnuspe/bin/ld: cannot find -latomic
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-
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-This commit aims at fixing that, by not assuming -latomic is
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-available. The commit re-organizes the atomic intrinsics detection as
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-follows:
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-
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- (1) Test if a program using 64-bit atomic intrinsics links properly,
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- without -latomic. If this is the case, we have atomic intrinsics,
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- and we're good to go.
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-
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- (2) If (1) has failed, then test to link the same program, but this
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- time with -latomic in LDFLAGS. If this is the case, then we have
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- atomic intrinsics, provided we link with -latomic.
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-
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-This has been tested in three situations:
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-
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- - On x86-64, where atomic instrinsics are all built-in, with no need
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- for libatomic. In this case, config.log contains:
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-
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- GCC_ATOMIC_BUILTINS_SUPPORTED_FALSE='#'
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- GCC_ATOMIC_BUILTINS_SUPPORTED_TRUE=''
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- LIBATOMIC_LIBS=''
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-
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- This means: atomic intrinsics are available, and we don't need to
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- link with libatomic.
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-
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- - On NIOS2, where atomic intrinsics are available, but some of them
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- (64-bit ones) require using libatomic. In this case, config.log
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- contains:
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-
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- GCC_ATOMIC_BUILTINS_SUPPORTED_FALSE='#'
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- GCC_ATOMIC_BUILTINS_SUPPORTED_TRUE=''
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- LIBATOMIC_LIBS='-latomic'
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-
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- This means: atomic intrinsics are available, and we need to link
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- with libatomic.
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-
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- - On PowerPC with an old gcc 4.7 toolchain, where 32-bit atomic
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- instrinsics are available, but not 64-bit atomic instrinsics, and
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- there is no libatomic. In this case, config.log contains:
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-
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- GCC_ATOMIC_BUILTINS_SUPPORTED_FALSE=''
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- GCC_ATOMIC_BUILTINS_SUPPORTED_TRUE='#'
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-
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- With means that atomic intrinsics are not usable.
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-
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-Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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-Upstream-status: https://lists.freedesktop.org/archives/mesa-dev/2018-May/194214.html
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----
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- configure.ac | 37 +++++++++++++++++++++----------------
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- 1 file changed, 21 insertions(+), 16 deletions(-)
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-
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-diff --git a/configure.ac b/configure.ac
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-index f1fbdcc6c7..c94e547874 100644
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---- a/configure.ac
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-+++ b/configure.ac
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-@@ -433,26 +433,31 @@ fi
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- AM_CONDITIONAL([SSE41_SUPPORTED], [test x$SSE41_SUPPORTED = x1])
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- AC_SUBST([SSE41_CFLAGS], $SSE41_CFLAGS)
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-
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--dnl Check for new-style atomic builtins
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--AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
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-+dnl Check for new-style atomic builtins. We first check without linking to
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-+dnl -latomic.
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-+AC_LINK_IFELSE([AC_LANG_SOURCE([[
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-+#include <stdint.h>
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- int main() {
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-- int n;
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-- return __atomic_load_n(&n, __ATOMIC_ACQUIRE);
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-+ uint64_t n;
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-+ return (int)__atomic_load_n(&n, __ATOMIC_ACQUIRE);
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- }]])], GCC_ATOMIC_BUILTINS_SUPPORTED=1)
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-+
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-+dnl If that didn't work, we try linking with -latomic, which is needed on some
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-+dnl platforms.
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-+if test "x$GCC_ATOMIC_BUILTINS_SUPPORTED" != x1; then
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-+ save_LDFLAGS=$LDFLAGS
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-+ LDFLAGS="$LDFLAGS -latomic"
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-+ AC_LINK_IFELSE([AC_LANG_SOURCE([[
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-+ #include <stdint.h>
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-+ int main() {
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-+ uint64_t n;
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-+ return (int)__atomic_load_n(&n, __ATOMIC_ACQUIRE);
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-+ }]])], GCC_ATOMIC_BUILTINS_SUPPORTED=1 LIBATOMIC_LIBS="-latomic")
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-+ LDFLAGS=$save_LDFLAGS
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-+fi
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-+
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- if test "x$GCC_ATOMIC_BUILTINS_SUPPORTED" = x1; then
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- DEFINES="$DEFINES -DUSE_GCC_ATOMIC_BUILTINS"
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-- dnl On some platforms, new-style atomics need a helper library
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-- AC_MSG_CHECKING(whether -latomic is needed)
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-- AC_LINK_IFELSE([AC_LANG_SOURCE([[
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-- #include <stdint.h>
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-- uint64_t v;
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-- int main() {
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-- return (int)__atomic_load_n(&v, __ATOMIC_ACQUIRE);
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-- }]])], GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=no, GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=yes)
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-- AC_MSG_RESULT($GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC)
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-- if test "x$GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC" = xyes; then
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-- LIBATOMIC_LIBS="-latomic"
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-- fi
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- fi
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- AC_SUBST([LIBATOMIC_LIBS])
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-
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---
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-2.14.3
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-
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