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re PR fortran/45159 (Unnecessary temporaries) 

2010-12-02  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/45159
	* dependency.c (check_section_vs_section):  Pre-calculate
	the relationship between the strides and the relationship
	between the start values.  Use an integer constant one for
	that purpose.
	Forward dependencies for positive strides apply for where
	the lhs start <= rhs start and lhs stride <= rhs stride
	and vice versa for negative stride.  No need to compare
	end expressions in either case (assume no bounds violation).

2010-12-02  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/45159
	* gfortran.dg/dependency_38.f90:  New test.

From-SVN: r167413
parent 272cec5d
Showing with 81 additions and 47 deletions
gcc/fortran/ChangeLog
2010-12-02 Thomas Koenig <tkoenig@gcc.gnu.org>
PR fortran/45159
* dependency.c (check_section_vs_section): Pre-calculate
the relationship between the strides and the relationship
between the start values. Use an integer constant one for
that purpose.
Forward dependencies for positive strides apply for where
the lhs start <= rhs start and lhs stride <= rhs stride
and vice versa for negative stride. No need to compare
end expressions in either case (assume no bounds violation).
2010-12-02 Thomas Koenig <tkoenig@gcc.gnu.org>
* trans-array.c (gfc_could_be_alias): Handle BT_CLASS
as well as BT_DERIVED.
(gfc_array_allocate): Likewise.
......
gcc/fortran/dependency.c
......@@ -1071,8 +1071,10 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n)
gfc_expr *r_stride;
gfc_expr *r_lower;
gfc_expr *r_upper;
gfc_expr *one_expr;
int r_dir;
bool identical_strides;
int stride_comparison;
int start_comparison;
/* If they are the same range, return without more ado. */
if (gfc_is_same_range (l_ar, r_ar, n, 0))
......@@ -1126,22 +1128,24 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n)
if (l_dir == 0 || r_dir == 0)
return GFC_DEP_OVERLAP;
/* Determine if the strides are equal. */
/* Determine the relationship between the strides. Set stride_comparison to
-2 if the dependency cannot be determined
-1 if l_stride < r_stride
0 if l_stride == r_stride
1 if l_stride > r_stride
as determined by gfc_dep_compare_expr. */
if (l_stride)
{
if (r_stride)
identical_strides = gfc_dep_compare_expr (l_stride, r_stride) == 0;
else
identical_strides = gfc_expr_is_one (l_stride, 0) == 1;
}
one_expr = gfc_get_int_expr (gfc_index_integer_kind, NULL, 1);
stride_comparison = gfc_dep_compare_expr (l_stride ? l_stride : one_expr,
r_stride ? r_stride : one_expr);
if (l_start && r_start)
start_comparison = gfc_dep_compare_expr (l_start, r_start);
else
{
if (r_stride)
identical_strides = gfc_expr_is_one (r_stride, 0) == 1;
else
identical_strides = true;
}
start_comparison = -2;
gfc_free (one_expr);
/* Determine LHS upper and lower bounds. */
if (l_dir == 1)
......@@ -1237,61 +1241,60 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n)
#undef IS_CONSTANT_INTEGER
/* Check for forward dependencies x:y vs. x+1:z. */
if (l_dir == 1 && r_dir == 1
&& l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == -1
&& l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == -1)
{
if (identical_strides)
return GFC_DEP_FORWARD;
}
/* Check for forward dependencies x:y vs. x+1:z and x:y:z vs. x:y:z+1. */
/* Check for forward dependencies x:y:-1 vs. x-1:z:-1. */
if (l_dir == -1 && r_dir == -1
&& l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == 1
&& l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == 1)
{
if (identical_strides)
return GFC_DEP_FORWARD;
}
if (l_dir == 1 && r_dir == 1 &&
(start_comparison == 0 || start_comparison == -1)
&& (stride_comparison == 0 || stride_comparison == -1))
return GFC_DEP_FORWARD;
/* Check for forward dependencies x:y:-1 vs. x-1:z:-1 and
x:y:-1 vs. x:y:-2. */
if (l_dir == -1 && r_dir == -1 &&
(start_comparison == 0 || start_comparison == 1)
&& (stride_comparison == 0 || stride_comparison == 1))
return GFC_DEP_FORWARD;
if (identical_strides)
if (stride_comparison == 0 || stride_comparison == -1)
{
if (l_start && IS_ARRAY_EXPLICIT (l_ar->as))
{
/* Check for a(low:y:s) vs. a(z:a:s) where a has a lower bound
/* Check for a(low:y:s) vs. a(z:x:s) or
a(low:y:s) vs. a(z:x:s+1) where a has a lower bound
of low, which is always at least a forward dependence. */
if (r_dir == 1
&& gfc_dep_compare_expr (l_start, l_ar->as->lower[n]) == 0)
return GFC_DEP_FORWARD;
}
}
/* Check for a(high:y:-s) vs. a(z:a:-s) where a has a higher bound
if (stride_comparison == 0 || stride_comparison == 1)
{
if (l_start && IS_ARRAY_EXPLICIT (l_ar->as))
{
/* Check for a(high:y:-s) vs. a(z:x:-s) or
a(high:y:-s vs. a(z:x:-s-1) where a has a higher bound
of high, which is always at least a forward dependence. */
if (r_dir == -1
&& gfc_dep_compare_expr (l_start, l_ar->as->upper[n]) == 0)
return GFC_DEP_FORWARD;
}
}
if (stride_comparison == 0)
{
/* From here, check for backwards dependencies. */
/* x:y vs. x+1:z. */
if (l_dir == 1 && r_dir == 1
&& l_start && r_start
&& gfc_dep_compare_expr (l_start, r_start) == 1
&& l_end && r_end
&& gfc_dep_compare_expr (l_end, r_end) == 1)
/* x+1:y vs. x:z. */
if (l_dir == 1 && r_dir == 1 && start_comparison == 1)
return GFC_DEP_BACKWARD;
/* x:y:-1 vs. x-1:z:-1. */
if (l_dir == -1 && r_dir == -1
&& l_start && r_start
&& gfc_dep_compare_expr (l_start, r_start) == -1
&& l_end && r_end
&& gfc_dep_compare_expr (l_end, r_end) == -1)
/* x-1:y:-1 vs. x:z:-1. */
if (l_dir == -1 && r_dir == -1 && start_comparison == -1)
return GFC_DEP_BACKWARD;
}
......
gcc/testsuite/ChangeLog
2010-12-02 Thomas Koenig <tkoenig@gcc.gnu.org>
PR fortran/45159
* gfortran.dg/dependency_38.f90: New test.
2010-12-02 Ian Lance Taylor <iant@google.com>
* lib/go.exp: New file.
......
gcc/testsuite/gfortran.dg/dependency_38.f90 0 → 100644
! { dg-do compile }
! { dg-options "-Warray-temporaries" }
! PR 45159 - No temporary should be created for this.
program main
integer a(100)
a(10:16:2) = a(10:16:2)
a(10:16:2) = a(10:19:3)
a(10:18:2) = a(12:20:2)
a(1:10) = a(2:20:2)
a(16:10:-2) = a(16:10:-2)
a(19:10:-1) = a(19:1:-2)
a(19:10:-1) = a(18:9:-1)
a(19:11:-1) = a(18:2:-2)
end program main
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