Hi!
As discussed in the PR, this patch performs the decrement of countm1
before the condition, so that the loop can have empty latch block.
The testcase from the PR then can be vectorized.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2013-01-16 Jakub Jelinek <ja...@redhat.com>
PR fortran/52865
* trans-stmt.c (gfc_trans_do): Put countm1-- before conditional
and use value of countm1 before the decrement in the condition.
--- gcc/fortran/trans-stmt.c.jj 2013-01-11 09:02:50.000000000 +0100
+++ gcc/fortran/trans-stmt.c 2013-01-16 12:47:44.191683738 +0100
@@ -1518,8 +1518,9 @@ gfc_trans_simple_do (gfc_code * code, st
body;
cycle_label:
dovar += step
- if (countm1 ==0) goto exit_label;
+ countm1t = countm1;
countm1--;
+ if (countm1t == 0) goto exit_label;
}
exit_label:
@@ -1739,19 +1740,23 @@ gfc_trans_do (gfc_code * code, tree exit
if (gfc_option.rtcheck & GFC_RTCHECK_DO)
gfc_add_modify_loc (loc, &body, saved_dovar, dovar);
- /* End with the loop condition. Loop until countm1 == 0. */
- cond = fold_build2_loc (loc, EQ_EXPR, boolean_type_node, countm1,
- build_int_cst (utype, 0));
- tmp = fold_build1_loc (loc, GOTO_EXPR, void_type_node, exit_label);
- tmp = fold_build3_loc (loc, COND_EXPR, void_type_node,
- cond, tmp, build_empty_stmt (loc));
- gfc_add_expr_to_block (&body, tmp);
+ /* Initialize countm1t. */
+ tree countm1t = gfc_create_var (utype, "countm1t");
+ gfc_add_modify_loc (loc, &body, countm1t, countm1);
/* Decrement the loop count. */
tmp = fold_build2_loc (loc, MINUS_EXPR, utype, countm1,
build_int_cst (utype, 1));
gfc_add_modify_loc (loc, &body, countm1, tmp);
+ /* End with the loop condition. Loop until countm1t == 0. */
+ cond = fold_build2_loc (loc, EQ_EXPR, boolean_type_node, countm1t,
+ build_int_cst (utype, 0));
+ tmp = fold_build1_loc (loc, GOTO_EXPR, void_type_node, exit_label);
+ tmp = fold_build3_loc (loc, COND_EXPR, void_type_node,
+ cond, tmp, build_empty_stmt (loc));
+ gfc_add_expr_to_block (&body, tmp);
+
/* End of loop body. */
tmp = gfc_finish_block (&body);
Jakub
