[PATCH i386] Allow sibcalls in no-PLT PIC

[Alexander Monakov <amonakov@ispras.ru>]

With -fno-plt, we don't have to reject even direct calls as sibcall
candidates.

This patch depends on '-fplt' flag that is introduced in another patch.

This patch requires that with -fno-plt all sibcall candidates go through
prepare_call_address that transforms the call to a GOT lookup.

OK?
	* config/i386/i386.c (ix86_function_ok_for_sibcall): Check flag_plt.

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index f29e053..b734350 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -5448,12 +5448,13 @@ ix86_function_ok_for_sibcall (tree decl, tree exp)
   /* If we are generating position-independent code, we cannot sibcall
      optimize any indirect call, or a direct call to a global function,
      as the PLT requires %ebx be live. (Darwin does not have a PLT.)  */
   if (!TARGET_MACHO
       && !TARGET_64BIT
       && flag_pic
+      && flag_plt
       && (decl && !targetm.binds_local_p (decl)))
     return false;
 
   /* If we need to align the outgoing stack, then sibcalling would
      unalign the stack, which may break the called function.  */
   if (ix86_minimum_incoming_stack_boundary (true)