Re: [tree-ssa] fix spec2k perl miscompilation [patch]

[Diego Novillo <dnovillo at redhat dot com>]

On Wed, 2003-06-18 at 13:07, Jason Merrill wrote:
> This patch only warns about a return statement as the last thing in a
> statement-expression; it should handle other non-expressions, too, and void
> expressions, for that matter.
> 
> Looking at this again, the last_expr_stmt stuff is unnecessarily
> complicated; we are interested in the last statement period, not the last
> expression statement.
> 
OK, thanks.  This is the new version of the patch.  It's in the last
stages of bootstrapping, fixes SPEC's perl and emits the warning:

universal.c: In function `XS_UNIVERSAL_VERSION':
universal.c:202: warning: statement-expressions should end with a non-void expression

OK if it passes all tests?


Thanks.  Diego.


	* c-simplify.c (gimplify_stmt_expr): Handle statement-expressions
	that don't end in a non-void expression.  Emit a warning in that
	case.


Index: c-simplify.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/c-simplify.c,v
retrieving revision 1.1.4.61
diff -d -c -p -r1.1.4.61 c-simplify.c
*** c-simplify.c	25 Jun 2003 07:32:19 -0000	1.1.4.61
--- c-simplify.c	26 Jun 2003 16:33:02 -0000
*************** gimplify_stmt_expr (expr_p)
*** 962,987 ****
      c_gimplify_stmt (&body);
    else
      {
!       tree substmt, last_expr_stmt, last_expr, bind;
  
        bind = NULL_TREE;	/* [GIMPLE] Avoid uninitialized use warning.  */
  
        /* Splice the last expression out of the STMT chain.  */
!       last_expr_stmt = NULL_TREE;
        for (substmt = COMPOUND_BODY (body); substmt;
  	   substmt = TREE_CHAIN (substmt))
  	{
! 	  if (TREE_CODE (substmt) == EXPR_STMT)
! 	    last_expr_stmt = substmt;
  	}
  
-       last_expr = EXPR_STMT_EXPR (last_expr_stmt);
-       if (stmts_are_full_exprs_p ())
- 	last_expr = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (last_expr),
- 			    last_expr);
-       EXPR_STMT_EXPR (last_expr_stmt) = build_empty_stmt ();
  #if defined ENABLE_CHECKING
!       if (!is_last_stmt_of_scope (last_expr_stmt))
  	abort ();
  #endif
  
--- 962,1000 ----
      c_gimplify_stmt (&body);
    else
      {
!       tree substmt, last_stmt, last_expr, bind;
  
        bind = NULL_TREE;	/* [GIMPLE] Avoid uninitialized use warning.  */
  
        /* Splice the last expression out of the STMT chain.  */
!       last_stmt = NULL_TREE;
        for (substmt = COMPOUND_BODY (body); substmt;
  	   substmt = TREE_CHAIN (substmt))
+ 	if (TREE_CODE (substmt) != SCOPE_STMT)
+ 	  last_stmt = substmt;
+ 
+       if (TREE_CODE (last_stmt) != EXPR_STMT
+ 	  || (TREE_TYPE (last_stmt)
+ 	      && VOID_TYPE_P (TREE_TYPE (last_stmt))))
  	{
! 	  location_t loc;
! 	  loc.file = input_filename;
! 	  loc.line = STMT_LINENO (last_stmt);
! 	  warning ("%Hstatement-expressions should end with a non-void expression", &loc);
! 	  last_expr = NULL_TREE;
! 	}
!       else
! 	{
! 	  last_expr = EXPR_STMT_EXPR (last_stmt);
! 
! 	  if (stmts_are_full_exprs_p ())
! 	    last_expr = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (last_expr),
! 				last_expr);
! 	  EXPR_STMT_EXPR (last_stmt) = build_empty_stmt ();
  	}
  
  #if defined ENABLE_CHECKING
!       if (!is_last_stmt_of_scope (last_stmt))
  	abort ();
  #endif
  
*************** gimplify_stmt_expr (expr_p)
*** 989,1015 ****
        c_gimplify_stmt (&body);
  
        /* Now retrofit that last expression into the BIND_EXPR.  */
!       if (!STMT_EXPR_NO_SCOPE (*expr_p))
  	{
! 	  bind = body;
! 	  substmt = BIND_EXPR_BODY (bind);
! 	}
!       else
! 	substmt = body;
  
!       if (IS_EMPTY_STMT (substmt))
! 	substmt = last_expr;
!       else
! 	substmt = build (COMPOUND_EXPR, TREE_TYPE (last_expr),
! 			 substmt, last_expr);
  
!       if (!STMT_EXPR_NO_SCOPE (*expr_p))
! 	{
! 	  BIND_EXPR_BODY (bind) = substmt;
! 	  TREE_TYPE (bind) = TREE_TYPE (body) = TREE_TYPE (last_expr);
  	}
-       else
- 	body = substmt;
      }
  
    *expr_p = body;
--- 1002,1031 ----
        c_gimplify_stmt (&body);
  
        /* Now retrofit that last expression into the BIND_EXPR.  */
!       if (last_expr)
  	{
! 	  if (!STMT_EXPR_NO_SCOPE (*expr_p))
! 	    {
! 	      bind = body;
! 	      substmt = BIND_EXPR_BODY (bind);
! 	    }
! 	  else
! 	    substmt = body;
  
! 	  if (IS_EMPTY_STMT (substmt))
! 	    substmt = last_expr;
! 	  else
! 	    substmt = build (COMPOUND_EXPR, TREE_TYPE (last_expr),
! 			    substmt, last_expr);
  
! 	  if (!STMT_EXPR_NO_SCOPE (*expr_p))
! 	    {
! 	      BIND_EXPR_BODY (bind) = substmt;
! 	      TREE_TYPE (bind) = TREE_TYPE (body) = TREE_TYPE (last_expr);
! 	    }
! 	  else
! 	    body = substmt;
  	}
      }
  
    *expr_p = body;