Hi,
libcilkrts is compiled with "-nostdlib", that means we have to
explicitly specify the pthread library we should link with (e.g. we
don't have such problem with libgomp, because it is C). And, indeed,
"-lpthread" is hard-coded in the Makefile for cilkrts. For Android
this doesn't work, because lpthread is absent and pthreads are part of
libc.
I also noticed, that configure check for
"pthread_{,attr_}[sg]etaffinity_np" always fails, because at the point
where it is placed in configure.ac, "-pthread" is not set. We just
have to put this check after we added "-pthread" to CFLAGS. This patch
addresses this as well.
diff --git a/libcilkrts/ChangeLog b/libcilkrts/ChangeLog
index 3881c82..ab10a0b 100644
--- a/libcilkrts/ChangeLog
+++ b/libcilkrts/ChangeLog
@@ -1,3 +1,15 @@
+2014-08-01 Alexander Ivchenko <alexander.ivche...@intel.com>
+
+ * configure.ac: Move pthread affinity test to the place where
+ '-pthread' passed to CFLAGS. Otherwise the test always fails.
+ (XCFLAGS): New variable for correctly passing
+ '-pthread'.
+ (XLDFLAGS): New variable for passing the correct pthread lib.
+ * configure: Regenerate.
+ * Makefile.am (AM_CFLAGS): Add $XCFLAGS.
+ (AM_LDFLAGS): Add $XLDFLAGS.
+ * Makefile.in: Regenerate.
+
2014-05-21 John Marino <gnu...@marino.st>
* runtime/os-unix.c (__DragonFly__): New target.
diff --git a/libcilkrts/Makefile.am b/libcilkrts/Makefile.am
index 84551c8..70538a2 100644
--- a/libcilkrts/Makefile.am
+++ b/libcilkrts/Makefile.am
@@ -43,9 +43,9 @@ GENERAL_FLAGS = -I$(top_srcdir)/include
-I$(top_srcdir)/runtime -I$(top_srcdir)/
# Enable Intel Cilk Plus extension
GENERAL_FLAGS += -fcilkplus
-AM_CFLAGS = $(GENERAL_FLAGS) -std=c99
+AM_CFLAGS = $(XCFLAGS) $(GENERAL_FLAGS) -std=c99
AM_CPPFLAGS = $(GENERAL_FLAGS)
-AM_LDFLAGS = -lpthread
+AM_LDFLAGS = $(XLDFLAGS)
# May be used by toolexeclibdir.
gcc_version := $(shell cat $(top_srcdir)/../gcc/BASE-VER)
@@ -92,7 +92,8 @@ include include/internal/rev.mk
#libcilkrts_la_LDFLAGS = -rpath '$(libdir)'
libcilkrts_la_LDFLAGS = -version-info 5:0:0
-libcilkrts_la_LDFLAGS += -lpthread @lt_cv_dlopen_libs@
+libcilkrts_la_LDFLAGS += @lt_cv_dlopen_libs@
+libcilkrts_la_LDFLAGS += $(AM_LDFLAGS)
# If we're building on Linux, use the Linux version script
if LINUX_LINKER_SCRIPT
diff --git a/libcilkrts/configure.ac b/libcilkrts/configure.ac
index fb21505..cc9a39f 100644
--- a/libcilkrts/configure.ac
+++ b/libcilkrts/configure.ac
@@ -164,6 +164,27 @@ AC_SUBST(toolexeclibdir)
AC_SUBST(lt_cv_dlopen_libs)
+# Check to see if -pthread or -lpthread is needed. Prefer the former.
+# Note that the CILK_SELF_SPEC in gcc.c may force -pthread.
+# In case the pthread.h system header is not found, this test will fail.
+XCFLAGS=""
+XLDFLAGS=""
+CFLAGS="$CFLAGS -pthread"
+AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <pthread.h>
+ void *g(void *d) { return NULL; }],
+ [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
+ [XCFLAGS=" -Wc,-pthread"],
+ [CFLAGS="$save_CFLAGS" LIBS="-lpthread $LIBS"
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <pthread.h>
+ void *g(void *d) { return NULL; }],
+ [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
+ [],
+ [AC_MSG_ERROR([Pthreads are required to build libcilkrts])])])
+
# Check for pthread_{,attr_}[sg]etaffinity_np.
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
@@ -183,24 +204,24 @@ AC_LINK_IFELSE(
AC_DEFINE(HAVE_PTHREAD_AFFINITY_NP, 1,
[ Define if pthread_{,attr_}{g,s}etaffinity_np is supported.]))
-# Check to see if -pthread or -lpthread is needed. Prefer the former.
-# Note that the CILK_SELF_SPEC in gcc.c may force -pthread.
-# In case the pthread.h system header is not found, this test will fail.
-CFLAGS="$CFLAGS -pthread"
-AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [#include <pthread.h>
- void *g(void *d) { return NULL; }],
- [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
- [],
- [CFLAGS="$save_CFLAGS" LIBS="-lpthread $LIBS"
- AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [#include <pthread.h>
- void *g(void *d) { return NULL; }],
- [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
- [],
- [AC_MSG_ERROR([Pthreads are required to build libcilkrts])])])
+# Every c++ lib is linking by default with -nostdlib, which leads to the
+# fact, that proper pthread library will not be given at link time. We have
+# to hard-code that.
+case "${target}" in
+
+ *android*)
+ XLDFLAGS="$XLDFLAGS -lc"
+ ;;
+ *)
+ XLDFLAGS="$XLDFLAGS -lpthread"
+ ;;
+
+esac
+
+AC_SUBST(XCFLAGS)
+AC_SUBST(XLDFLAGS)
+
+CFLAGS="$save_CFLAGS"
if test $enable_shared = yes; then
link_cilkrts="-lcilkrts %{static: $LIBS}"
Is it ok?
--Alexander
