runtime: Support broken makecontext on Solaris 8/9.

From Rainer Orth.

From-SVN: r184289

libgo/config.h.in

@@ -182,6 +182,9 @@
    */
 #undef LT_OBJDIR
 
+/* Define if makecontext expects top of stack in uc_stack. */
+#undef MAKECONTEXT_STACK_TOP
+
 /* Name of package */
 #undef PACKAGE
 

libgo/configure

@@ -14873,6 +14873,20 @@ $as_echo "#define HAVE_STRUCT_EXCEPTION 1" >>confdefs.h
 
 fi
 
+case "$target" in
+  sparc*-*-solaris2.[89]*)
+    libgo_cv_lib_makecontext_stack_top=yes
+    ;;
+  *)
+    libgo_cv_lib_makecontext_stack_top=no
+    ;;
+esac
+if test "$libgo_cv_lib_makecontext_stack_top" = "yes"; then
+
+$as_echo "#define MAKECONTEXT_STACK_TOP 1" >>confdefs.h
+
+fi
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether setcontext clobbers TLS variables" >&5
 $as_echo_n "checking whether setcontext clobbers TLS variables... " >&6; }
 if test "${libgo_cv_lib_setcontext_clobbers_tls+set}" = set; then :
@@ -14974,6 +14988,9 @@ main ()
     abort ();
 
   c.uc_stack.ss_sp = stack;
+#ifdef MAKECONTEXT_STACK_TOP
+  c.uc_stack.ss_sp += sizeof stack;
+#endif
   c.uc_stack.ss_flags = 0;
   c.uc_stack.ss_size = sizeof stack;
   c.uc_link = NULL;

libgo/configure.ac

@@ -611,6 +611,21 @@ if test "$libgo_has_struct_exception" = "yes"; then
             [Define to 1 if <math.h> defines struct exception])
 fi
 
+dnl Check if makecontext expects the uc_stack member of ucontext to point
+dnl to the top of the stack.
+case "$target" in
+  sparc*-*-solaris2.[[89]]*)
+    libgo_cv_lib_makecontext_stack_top=yes
+    ;;
+  *)
+    libgo_cv_lib_makecontext_stack_top=no
+    ;;
+esac
+if test "$libgo_cv_lib_makecontext_stack_top" = "yes"; then
+  AC_DEFINE(MAKECONTEXT_STACK_TOP, 1,
+	    [Define if makecontext expects top of stack in uc_stack.])
+fi
+
 dnl See whether setcontext changes the value of TLS variables.
 AC_CACHE_CHECK([whether setcontext clobbers TLS variables],
 [libgo_cv_lib_setcontext_clobbers_tls],
@@ -667,6 +682,9 @@ main ()
     abort ();
 
   c.uc_stack.ss_sp = stack;
+#ifdef MAKECONTEXT_STACK_TOP
+  c.uc_stack.ss_sp += sizeof stack;
+#endif
   c.uc_stack.ss_flags = 0;
   c.uc_stack.ss_size = sizeof stack;
   c.uc_link = NULL;

libgo/runtime/proc.c

@@ -1316,6 +1316,9 @@ __go_go(void (*fn)(void*), void* arg)
 
 	getcontext(&newg->context);
 	newg->context.uc_stack.ss_sp = sp;
+#ifdef MAKECONTEXT_STACK_TOP
+	newg->context.uc_stack.ss_sp += spsize;
+#endif
 	newg->context.uc_stack.ss_size = spsize;
 	makecontext(&newg->context, kickoff, 0);