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re PR fortran/42131 (Weird translation of DO loops)

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2009-11-30  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/42131
	* trans-stmt.c (gfc_trans_do):  Calculate loop count
	without if statements.

From-SVN: r154839
This commit is contained in:
Thomas Koenig 2009-11-30 20:35:41 +00:00
parent 12d210d9f0
commit 8146bb5887
2 changed files with 43 additions and 20 deletions
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6
gcc/fortran/ChangeLog
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@ -1,3 +1,9 @@
2009-11-30 Thomas Koenig <tkoenig@gcc.gnu.org>
PR fortran/42131
* trans-stmt.c (gfc_trans_do): Calculate loop count
without if statements.
2009-11-28 Jakub Jelinek <jakub@redhat.com>
* trans-common.c (create_common): Remove unused offset variable.

57
gcc/fortran/trans-stmt.c
View file

@ -1009,44 +1009,61 @@ gfc_trans_do (gfc_code * code)
/* Initialize loop count and jump to exit label if the loop is empty.
This code is executed before we enter the loop body. We generate:
step_sign = sign(1,step);
if (step > 0)
{
if (to < from) goto exit_label;
countm1 = (to - from) / step;
if (to < from)
goto exit_label;
}
else
{
if (to > from) goto exit_label;
countm1 = (from - to) / -step;
} */
if (to > from)
goto exit_label;
}
countm1 = (to*step_sign - from*step_sign) / (step*step_sign);
*/
if (TREE_CODE (type) == INTEGER_TYPE)
{
tree pos, neg;
tree pos, neg, step_sign, to2, from2, step2;
/* Calculate SIGN (1,step) */
tmp = fold_build2 (RSHIFT_EXPR, type, step,
build_int_cst (type,
TYPE_PRECISION (type) - 1));
tmp = fold_build2 (MULT_EXPR, type, tmp,
build_int_cst (type, 2));
step_sign = fold_build2 (PLUS_EXPR, type, tmp,
fold_convert (type, integer_one_node));
tmp = fold_build2 (LT_EXPR, boolean_type_node, to, from);
pos = fold_build3 (COND_EXPR, void_type_node, tmp,
build1_v (GOTO_EXPR, exit_label),
build_empty_stmt (input_location));
tmp = fold_build2 (MINUS_EXPR, type, to, from);
tmp = fold_convert (utype, tmp);
tmp = fold_build2 (TRUNC_DIV_EXPR, utype, tmp,
fold_convert (utype, step));
tmp = fold_build2 (MODIFY_EXPR, void_type_node, countm1, tmp);
pos = fold_build2 (COMPOUND_EXPR, void_type_node, pos, tmp);
tmp = fold_build2 (GT_EXPR, boolean_type_node, to, from);
neg = fold_build3 (COND_EXPR, void_type_node, tmp,
build1_v (GOTO_EXPR, exit_label),
build_empty_stmt (input_location));
tmp = fold_build2 (MINUS_EXPR, type, from, to);
tmp = fold_convert (utype, tmp);
tmp = fold_build2 (TRUNC_DIV_EXPR, utype, tmp,
fold_convert (utype, fold_build1 (NEGATE_EXPR,
type, step)));
tmp = fold_build2 (MODIFY_EXPR, void_type_node, countm1, tmp);
neg = fold_build2 (COMPOUND_EXPR, void_type_node, neg, tmp);
tmp = fold_build3 (COND_EXPR, void_type_node, pos_step, pos, neg);
gfc_add_expr_to_block (&block, tmp);
/* Calculate the loop count. to-from can overflow, so
we cast to unsigned. */
to2 = fold_build2 (MULT_EXPR, type, step_sign, to);
from2 = fold_build2 (MULT_EXPR, type, step_sign, from);
step2 = fold_build2 (MULT_EXPR, type, step_sign, step);
step2 = fold_convert (utype, step2);
tmp = fold_build2 (MINUS_EXPR, type, to2, from2);
tmp = fold_convert (utype, tmp);
tmp = fold_build2 (TRUNC_DIV_EXPR, utype, tmp, step2);
tmp = fold_build2 (MODIFY_EXPR, void_type_node, countm1, tmp);
gfc_add_expr_to_block (&block, tmp);
}
else