Re: PATCH] PR 49580

[Zdenek Dvorak <rakdver at kam dot mff dot cuni dot cz>]

Hi,

> I moved the adjustment of the loop's iterations from 
> gimple_duplicate_sese_tail
> to tree-parloops.c, right before the call to gimple_duplicate_sese_tail.
> I repeated the bootstrap, regression and spec runs - no new regressions.
> 
> OK to commit?

OK,

Zdenek

> Index: gcc/tree-parloops.c
> ===================================================================
> --- gcc/tree-parloops.c	(revision 174166)
> +++ gcc/tree-parloops.c	(working copy)
> @@ -1464,6 +1464,8 @@ transform_to_exit_first_loop (struct loop *loop, h
>    gimple phi, nphi, cond_stmt, stmt, cond_nit;
>    gimple_stmt_iterator gsi;
>    tree nit_1;
> +  edge exit_1;
> +  tree new_rhs;
>  
>    split_block_after_labels (loop->header);
>    orig_header = single_succ (loop->header);
> @@ -1492,6 +1494,38 @@ transform_to_exit_first_loop (struct loop *loop, h
>  	  control = t;
>  	}
>      }
> +
> + /* Setting the condition towards peeling the last iteration:
> +    If the block consisting of the exit condition has the latch as
> +    successor, then the body of the loop is executed before
> +    the exit condition is tested.  In such case, moving the
> +    condition to the entry, causes that the loop will iterate
> +    one less iteration (which is the wanted outcome, since we
> +    peel out the last iteration).  If the body is executed after
> +    the condition, moving the condition to the entry requires
> +    decrementing one iteration.  */
> +  exit_1 = EDGE_SUCC (exit->src, EDGE_SUCC (exit->src, 0) == exit); 
> +  if (exit_1->dest == loop->latch)
> +    new_rhs = gimple_cond_rhs (cond_stmt);
> +  else
> +  {
> +    new_rhs = fold_build2 (MINUS_EXPR, TREE_TYPE (gimple_cond_rhs (cond_stmt)),
> +			   gimple_cond_rhs (cond_stmt),
> +			   build_int_cst (TREE_TYPE (gimple_cond_rhs (cond_stmt)), 1));
> +    if (TREE_CODE (gimple_cond_rhs (cond_stmt)) == SSA_NAME)
> +      {
> + 	basic_block preheader;
> +  	gimple_stmt_iterator gsi1;
> +
> +  	preheader = loop_preheader_edge(loop)->src;
> +    	gsi1 = gsi_after_labels (preheader);
> +	new_rhs = force_gimple_operand_gsi (&gsi1, new_rhs, true,
> +					    NULL_TREE,false,GSI_CONTINUE_LINKING);
> +      }
> +  }
> +  gimple_cond_set_rhs (cond_stmt, unshare_expr (new_rhs));
> +  gimple_cond_set_lhs (cond_stmt, unshare_expr (gimple_cond_lhs (cond_stmt)));
> +  
>    bbs = get_loop_body_in_dom_order (loop);
>  
>    for (n = 0; bbs[n] != loop->latch; n++)
> Index: gcc/tree-cfg.c
> ===================================================================
> --- gcc/tree-cfg.c	(revision 174166)
> +++ gcc/tree-cfg.c	(working copy)
> @@ -5397,12 +5397,10 @@ gimple_duplicate_sese_tail (edge entry ATTRIBUTE_U
>    int total_freq = 0, exit_freq = 0;
>    gcov_type total_count = 0, exit_count = 0;
>    edge exits[2], nexits[2], e;
> -  gimple_stmt_iterator gsi,gsi1;
> +  gimple_stmt_iterator gsi;
>    gimple cond_stmt;
>    edge sorig, snew;
>    basic_block exit_bb;
> -  basic_block iters_bb;
> -  tree new_rhs;
>    gimple_stmt_iterator psi;
>    gimple phi;
>    tree def;
> @@ -5483,35 +5481,6 @@ gimple_duplicate_sese_tail (edge entry ATTRIBUTE_U
>    gcc_assert (gimple_code (cond_stmt) == GIMPLE_COND);
>    cond_stmt = gimple_copy (cond_stmt);
>  
> - /* If the block consisting of the exit condition has the latch as
> -    successor, then the body of the loop is executed before
> -    the exit condition is tested.  In such case, moving the
> -    condition to the entry, causes that the loop will iterate
> -    one less iteration (which is the wanted outcome, since we
> -    peel out the last iteration).  If the body is executed after
> -    the condition, moving the condition to the entry requires
> -    decrementing one iteration.  */
> -  if (exits[1]->dest == orig_loop->latch)
> -    new_rhs = gimple_cond_rhs (cond_stmt);
> -  else
> -  {
> -    new_rhs = fold_build2 (MINUS_EXPR, TREE_TYPE (gimple_cond_rhs (cond_stmt)),
> -			   gimple_cond_rhs (cond_stmt),
> -			   build_int_cst (TREE_TYPE (gimple_cond_rhs (cond_stmt)), 1));
> -
> -    if (TREE_CODE (gimple_cond_rhs (cond_stmt)) == SSA_NAME)
> -      {
> -	iters_bb = gimple_bb (SSA_NAME_DEF_STMT (gimple_cond_rhs (cond_stmt)));
> -	for (gsi1 = gsi_start_bb (iters_bb); !gsi_end_p (gsi1); gsi_next (&gsi1))
> -	  if (gsi_stmt (gsi1) == SSA_NAME_DEF_STMT (gimple_cond_rhs (cond_stmt)))
> -	    break;
> -
> -	new_rhs = force_gimple_operand_gsi (&gsi1, new_rhs, true,
> -					    NULL_TREE,false,GSI_CONTINUE_LINKING);
> -      }
> -  }
> -  gimple_cond_set_rhs (cond_stmt, unshare_expr (new_rhs));
> -  gimple_cond_set_lhs (cond_stmt, unshare_expr (gimple_cond_lhs (cond_stmt)));
>    gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);
>  
>    sorig = single_succ_edge (switch_bb);

> 
> 07-05-2011  Razya Ladelsky  <razya@il.ibm.com>
> 
> 	* tree-cfg.c (gimple_duplicate_sese_tail): Remove handling of 
> 	the loop's number of iterations.
>         * tree-parloops.c (transform_to_exit_first_loop): Add the 
> 	handling of the loop's number of iterations before the call 
> 	to gimple_duplicate_sese_tail.
>         Insert the stmt caclculating the new rhs of the loop's
> 	condition stmt to the preheader instead of iters_bb.