sh.c (sh_expand_prologue): Insns that set up the PIC register may be dead.

* config/sh/sh.c (sh_expand_prologue): Insns that set up the PIC
register may be dead.

From-SVN: r40550

gcc/ChangeLog

+2001-03-16  Alexandre Oliva  <aoliva@redhat.com>
+
+	* config/sh/sh.c (sh_expand_prologue): Insns that set up the PIC
+	register may be dead.
+
 2001-03-16  Brad Lucier  <lucier@math.purdue.edu>
 
 	* Makefile.in (hash.o): Depend on CONFIG_H.

gcc/config/sh/sh.c

@@ -3987,7 +3987,23 @@ sh_expand_prologue ()
   push_regs (live_regs_mask, live_regs_mask2);
 
   if (flag_pic && regs_ever_live[PIC_OFFSET_TABLE_REGNUM])
-    emit_insn (gen_GOTaddr2picreg ());
+    {
+      rtx insn = get_last_insn ();
+      rtx last = emit_insn (gen_GOTaddr2picreg ());
+
+      /* Mark these insns as possibly dead.  Sometimes, flow2 may
+	 delete all uses of the PIC register.  In this case, let it
+	 delete the initialization too.  */
+      do
+	{
+	  insn = NEXT_INSN (insn);
+
+	  REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD,
+						const0_rtx,
+						REG_NOTES (insn));
+	}
+      while (insn != last);
+    }
 
   if (target_flags != save_flags)
     {