[PowerPC] Fix PR25176: Array_3 bytecode->native test fail

[Alan Modra <amodra at bigpond dot net dot au>]

On Thu, Dec 01, 2005 at 07:50:55PM +1030, Alan Modra wrote:
> A quick fix is relatively easy.

This is the powerpc fix I'm currently testing.  I've verified that it
fixes the libjava test failure for powerpc64-linux, but bootstrap and
regression test on both powerpc-linux and powerpc64-linux are not yet
complete.

gen_blockage stops all instructions from crossing the stack restore.
Perhaps it is an unnecessarily big hammer, but I was worried about
floating point instructions crossing the stack restore.

	PR target/25176
	* config/rs6000/rs6000.c (rs6000_emit_epilogue): Emit blockage at
	stack restore for dwarf2 exceptions.

Index: gcc/config/rs6000/rs6000.c
===================================================================
*** gcc/config/rs6000/rs6000.c	(revision 107758)
--- gcc/config/rs6000/rs6000.c	(working copy)
*************** rs6000_emit_epilogue (int sibcall)
*** 14711,14719 ****
        if (DEFAULT_ABI == ABI_V4)
  	frame_reg_rtx = gen_rtx_REG (Pmode, 11);
  
        emit_move_insn (frame_reg_rtx,
  		      gen_rtx_MEM (Pmode, sp_reg_rtx));
- 
      }
    else if (info->push_p)
      {
--- 14703,14717 ----
        if (DEFAULT_ABI == ABI_V4)
  	frame_reg_rtx = gen_rtx_REG (Pmode, 11);
  
+       /* Don't allow potentially trapping instructions to cross the
+ 	 stack pointer restore.  We don't emit unwind info for the
+ 	 epilogue, so the unwinder will use an incorrect cfa for any
+ 	 exception taken after the restore.  */
+       else if (!USING_SJLJ_EXCEPTIONS && flag_exceptions)
+ 	emit_insn (gen_blockage ());
+ 
        emit_move_insn (frame_reg_rtx,
  		      gen_rtx_MEM (Pmode, sp_reg_rtx));
      }
    else if (info->push_p)
      {
*************** rs6000_emit_epilogue (int sibcall)
*** 14722,14727 ****
--- 14720,14727 ----
  	sp_offset = info->total_size;
        else
  	{
+ 	  if (!USING_SJLJ_EXCEPTIONS && flag_exceptions)
+ 	    emit_insn (gen_blockage ());
  	  emit_insn (TARGET_32BIT
  		     ? gen_addsi3 (sp_reg_rtx, sp_reg_rtx,
  				   GEN_INT (info->total_size))
*************** rs6000_emit_epilogue (int sibcall)
*** 14947,14975 ****
      }
  
    /* If this is V.4, unwind the stack pointer after all of the loads
!      have been done.  We need to emit a block here so that sched
!      doesn't decide to move the sp change before the register restores
!      (which may not have any obvious dependency on the stack).  This
!      doesn't hurt performance, because there is no scheduling that can
!      be done after this point.  */
!   if (DEFAULT_ABI == ABI_V4
!       || current_function_calls_eh_return)
      {
!       if (frame_reg_rtx != sp_reg_rtx)
  	rs6000_emit_stack_tie ();
! 
!       if (use_backchain_to_restore_sp)
! 	{
! 	  emit_move_insn (sp_reg_rtx, frame_reg_rtx);
! 	}
!       else if (sp_offset != 0)
! 	{
! 	  emit_insn (TARGET_32BIT
! 		     ? gen_addsi3 (sp_reg_rtx, sp_reg_rtx,
! 				   GEN_INT (sp_offset))
! 		     : gen_adddi3 (sp_reg_rtx, sp_reg_rtx,
! 				   GEN_INT (sp_offset)));
! 	}
      }
  
    if (current_function_calls_eh_return)
--- 14947,14974 ----
      }
  
    /* If this is V.4, unwind the stack pointer after all of the loads
!      have been done.  */
!   if (frame_reg_rtx != sp_reg_rtx)
      {
!       if (!USING_SJLJ_EXCEPTIONS && flag_exceptions)
! 	/* This block is needed for proper unwinding.  See the comment
! 	   earlier in this function.  */
! 	emit_insn (gen_blockage ());
!       else
! 	/* This less rigorous block is needed so that sched doesn't
! 	   decide to move the sp change before the register restores.  */
  	rs6000_emit_stack_tie ();
!       emit_move_insn (sp_reg_rtx, frame_reg_rtx);
!     }
!   else if (sp_offset != 0)
!     {
!       if (!USING_SJLJ_EXCEPTIONS && flag_exceptions)
! 	emit_insn (gen_blockage ());
!       emit_insn (TARGET_32BIT
! 		 ? gen_addsi3 (sp_reg_rtx, sp_reg_rtx,
! 			       GEN_INT (sp_offset))
! 		 : gen_adddi3 (sp_reg_rtx, sp_reg_rtx,
! 			       GEN_INT (sp_offset)));
      }
  
    if (current_function_calls_eh_return)

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre