libgo: If compiler can split-stack and linker can not, use -fno-split-stack.

    
    If the compiler supports split-stack but we are using a gold linker that
    does not, as happens on PPC with current GCC but old gold, then we need
    to compile the Go code with -fno-split-stack to avoid a linker error
    avoid the inability to call from split-stack code to non-split-stack
    code.
    
    Reviewed-on: https://go-review.googlesource.com/14598

From-SVN: r227811

gcc/go/gofrontend/MERGE

-6f0ac34e139755c319368757fe2a093f1e5bde49
+eac8b31fec761c8da0606a70ae0547ff0b12e8db
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/Makefile.am

@@ -2074,7 +2074,7 @@ libnetgo_a_LIBADD = netgo.o
 LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
 
 GOCFLAGS = $(CFLAGS)
-AM_GOCFLAGS = $(STRINGOPS_FLAG)
+AM_GOCFLAGS = $(STRINGOPS_FLAG) $(GO_SPLIT_STACK)
 GOCOMPILE = $(GOC) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_GOCFLAGS) $(GOCFLAGS)
 
 LTGOCOMPILE = $(LIBTOOL) --tag GO --mode=compile $(GOC) $(INCLUDES) \

libgo/Makefile.in

@@ -366,6 +366,7 @@ GOCFLAGS = $(CFLAGS)
 GOOS = @GOOS@
 GO_LIBCALL_OS_ARCH_FILE = @GO_LIBCALL_OS_ARCH_FILE@
 GO_LIBCALL_OS_FILE = @GO_LIBCALL_OS_FILE@
+GO_SPLIT_STACK = @GO_SPLIT_STACK@
 GO_SYSCALL_OS_ARCH_FILE = @GO_SYSCALL_OS_ARCH_FILE@
 GO_SYSCALL_OS_FILE = @GO_SYSCALL_OS_FILE@
 GREP = @GREP@
@@ -2153,7 +2154,7 @@ libgolibbegin_a_CFLAGS = $(AM_CFLAGS) -fPIC
 libnetgo_a_SOURCES = $(go_netgo_files)
 libnetgo_a_LIBADD = netgo.o
 LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
-AM_GOCFLAGS = $(STRINGOPS_FLAG)
+AM_GOCFLAGS = $(STRINGOPS_FLAG) $(GO_SPLIT_STACK)
 GOCOMPILE = $(GOC) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_GOCFLAGS) $(GOCFLAGS)
 LTGOCOMPILE = $(LIBTOOL) --tag GO --mode=compile $(GOC) $(INCLUDES) \
 	$(AM_GOCFLAGS) $(GOCFLAGS)

libgo/configure

@@ -620,6 +620,7 @@ NET_LIBS
 MATH_LIBS
 GOC_IS_LLGO_FALSE
 GOC_IS_LLGO_TRUE
+GO_SPLIT_STACK
 USING_SPLIT_STACK_FALSE
 USING_SPLIT_STACK_TRUE
 SPLIT_STACK
@@ -11123,7 +11124,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11126 "configure"
+#line 11127 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11229,7 +11230,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11232 "configure"
+#line 11233 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -14050,6 +14051,13 @@ else
 fi
 
 
+if test "$libgo_cv_c_split_stack_supported" = yes -a "$libgo_cv_c_linker_split_non_split" = no; then
+  GO_SPLIT_STACK=-fno-split-stack
+else
+  GO_SPLIT_STACK=
+fi
+
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether linker supports split stack" >&5
 $as_echo_n "checking whether linker supports split stack... " >&6; }
 if test "${libgo_cv_c_linker_supports_split_stack+set}" = set; then :

libgo/configure.ac

@@ -407,6 +407,15 @@ AC_SUBST(SPLIT_STACK)
 AM_CONDITIONAL(USING_SPLIT_STACK,
 	test "$libgo_cv_c_split_stack_supported" = yes -a "$libgo_cv_c_linker_split_non_split" = yes)
 
+dnl If the compiler supports split-stack but the linker does not, then
+dnl we need to explicitly disable split-stack for Go.
+if test "$libgo_cv_c_split_stack_supported" = yes -a "$libgo_cv_c_linker_split_non_split" = no; then
+  GO_SPLIT_STACK=-fno-split-stack
+else
+  GO_SPLIT_STACK=
+fi
+AC_SUBST(GO_SPLIT_STACK)
+
 dnl Check whether the linker does stack munging when calling from
 dnl split-stack into non-split-stack code.  We check this by looking
 dnl at the --help output.  FIXME: This is only half right: it's

libgo/testsuite/Makefile.in

@@ -108,6 +108,7 @@ GOCFLAGS = @GOCFLAGS@
 GOOS = @GOOS@
 GO_LIBCALL_OS_ARCH_FILE = @GO_LIBCALL_OS_ARCH_FILE@
 GO_LIBCALL_OS_FILE = @GO_LIBCALL_OS_FILE@
+GO_SPLIT_STACK = @GO_SPLIT_STACK@
 GO_SYSCALL_OS_ARCH_FILE = @GO_SYSCALL_OS_ARCH_FILE@
 GO_SYSCALL_OS_FILE = @GO_SYSCALL_OS_FILE@
 GREP = @GREP@