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 <ra...@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.
