[tree-ssa] jump threading for switch_expr

[Richard Henderson <rth at redhat dot com>]

Even fixes

-FAIL: gcc.dg/tree-ssa/20030703-2.c scan-tree-dump-times if  1
-FAIL: gcc.dg/tree-ssa/20030708-1.c scan-tree-dump-times if  0
-FAIL: gcc.dg/tree-ssa/20030808-1.c scan-tree-dump-times if  0

though you'll note that none of these have switches...


r~


        * tree-cfg.c (thread_jumps): Allow SWITCH_EXPR.
        (thread_edge): Handle it.  Tidy surrounding code.

Index: tree-cfg.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-cfg.c,v
retrieving revision 1.1.4.187
diff -c -p -d -r1.1.4.187 tree-cfg.c
*** tree-cfg.c	30 Oct 2003 21:39:58 -0000	1.1.4.187
--- tree-cfg.c	31 Oct 2003 00:27:20 -0000
*************** thread_jumps (void)
*** 4424,4430 ****
        if (stmt
  	  && stmt_ends_bb_p (stmt)
  	  && TREE_CODE (stmt) != GOTO_EXPR
! 	  && TREE_CODE (stmt) != COND_EXPR)
  	continue;
  
        /* This block is now part of a forwarding path, mark it as not
--- 4424,4431 ----
        if (stmt
  	  && stmt_ends_bb_p (stmt)
  	  && TREE_CODE (stmt) != GOTO_EXPR
! 	  && TREE_CODE (stmt) != COND_EXPR
! 	  && TREE_CODE (stmt) != SWITCH_EXPR)
  	continue;
  
        /* This block is now part of a forwarding path, mark it as not
*************** thread_jumps (void)
*** 4522,4541 ****
  edge
  thread_edge (edge e, basic_block dest)
  {
-   block_stmt_iterator dest_iterator = bsi_start (dest);
    tree dest_stmt = first_stmt (dest);
!   tree label, goto_stmt, stmt;
    basic_block bb = e->src, new_bb;
    int flags;
  
    /* We need a label at our final destination.  If it does not already exist,
       create it.  */
!   if (!dest_stmt
!       || TREE_CODE (dest_stmt) != LABEL_EXPR)
      {
!       if (dest_stmt && TREE_CODE (dest_stmt) == CASE_LABEL_EXPR)
! 	abort ();
! 
        label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
        DECL_CONTEXT (label) = current_function_decl;
        dest_stmt = build1 (LABEL_EXPR, void_type_node, label);
--- 4523,4538 ----
  edge
  thread_edge (edge e, basic_block dest)
  {
    tree dest_stmt = first_stmt (dest);
!   tree label, stmt;
    basic_block bb = e->src, new_bb;
    int flags;
  
    /* We need a label at our final destination.  If it does not already exist,
       create it.  */
!   if (!dest_stmt || TREE_CODE (dest_stmt) != LABEL_EXPR)
      {
!       block_stmt_iterator dest_iterator = bsi_start (dest);
        label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
        DECL_CONTEXT (label) = current_function_decl;
        dest_stmt = build1 (LABEL_EXPR, void_type_node, label);
*************** thread_edge (edge e, basic_block dest)
*** 4544,4573 ****
    else
      label = LABEL_EXPR_LABEL (dest_stmt);
  
!   /* If our block does not end with a GOTO, then create one.  Otherwise redirect
!      the existing GOTO_EXPR to LABEL.  */
    stmt = last_stmt (bb);
!   if (stmt && TREE_CODE (stmt) == COND_EXPR)
      {
        stmt = (e->flags & EDGE_TRUE_VALUE
  	      ? COND_EXPR_THEN (stmt)
  	      : COND_EXPR_ELSE (stmt));
        flags = e->flags;
!       if (TREE_CODE (stmt) != GOTO_EXPR)
! 	abort ();
!     }
!   else
!     flags = 0;
  
!   if (!stmt || TREE_CODE (stmt) != GOTO_EXPR)
!     {
!       goto_stmt = build1 (GOTO_EXPR, void_type_node, label);
!       bsi_insert_on_edge_immediate (e, goto_stmt, NULL, &new_bb);
!     }
!   else
!     {
        GOTO_DESTINATION (stmt) = label;
!       new_bb = NULL;
      }
  
    /* Update/insert PHI nodes as necessary.  */
--- 4541,4584 ----
    else
      label = LABEL_EXPR_LABEL (dest_stmt);
  
!   /* If our block does not end with a GOTO, then create one.
!      Otherwise redirect the existing GOTO_EXPR to LABEL.  */
! 
    stmt = last_stmt (bb);
!   new_bb = NULL;
!   flags = 0;
! 
!   switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
      {
+     case COND_EXPR:
        stmt = (e->flags & EDGE_TRUE_VALUE
  	      ? COND_EXPR_THEN (stmt)
  	      : COND_EXPR_ELSE (stmt));
        flags = e->flags;
!       /* FALLTHRU */
  
!     case GOTO_EXPR:
        GOTO_DESTINATION (stmt) = label;
!       break;
! 
!     case SWITCH_EXPR:
!       {
! 	tree vec = SWITCH_LABELS (stmt);
! 	size_t i, n = TREE_VEC_LENGTH (vec);
! 
! 	for (i = 0; i < n; ++i)
! 	  {
! 	    tree elt = TREE_VEC_ELT (vec, i);
! 	    if (label_to_block (CASE_LABEL (elt)) == e->dest)
! 	      CASE_LABEL (elt) = label;
! 	  }
!       }
!       break;
! 
!     default:
!       stmt = build1 (GOTO_EXPR, void_type_node, label);
!       bsi_insert_on_edge_immediate (e, stmt, NULL, &new_bb);
!       break;
      }
  
    /* Update/insert PHI nodes as necessary.  */