Hello world,
below is a patch which improves dependency checking for array
assignments and calculation of string lengths.
The new function gfc_dep_difference is used for both. This allows
us to detect, for example, that the difference between the lower
indices of
a(n:m:2) = a(n+1:m+1:2)
is one, thus making an array temporary unnecessary.
I have tried to cover every code path through gfc_dep_difference in
string_length_2.f90. dependency_40.f90 is just there to test
the basic functionality.
OK for trunk?
Thomas
2013-03-16 Thomas Koenig <tkoe...@gcc.gnu.org>
PR fortran/45159
* gfortran.h (gfc_dep_difference): Add prototype.
* dependency.c (discard_nops): New function.
(gfc_dep_difference): New function.
(check_section_vs_section): Use gfc_dep_difference
to calculate the difference of starting indices.
* trans-expr.c (gfc_conv_substring): Use
gfc_dep_difference to calculate the length of
substrings where possible.
2013-03-16 Thomas Koenig <tkoe...@gcc.gnu.org>
PR fortran/45159
* gfortran.dg/string_length_2.f90: New test.
* gfortran.dg/dependency_40.f90: New test.
Index: gfortran.h
===================================================================
--- gfortran.h (Revision 196574)
+++ gfortran.h (Arbeitskopie)
@@ -2959,6 +2959,7 @@ gfc_namespace* gfc_build_block_ns (gfc_namespace *
/* dependency.c */
int gfc_dep_compare_functions (gfc_expr *, gfc_expr *, bool);
int gfc_dep_compare_expr (gfc_expr *, gfc_expr *);
+bool gfc_dep_difference (gfc_expr *, gfc_expr *, mpz_t *);
/* check.c */
gfc_try gfc_check_same_strlen (const gfc_expr*, const gfc_expr*, const char*);
Index: dependency.c
===================================================================
--- dependency.c (Revision 196574)
+++ dependency.c (Arbeitskopie)
@@ -500,7 +500,270 @@ gfc_dep_compare_expr (gfc_expr *e1, gfc_expr *e2)
}
}
+/* Helper function to look through parens and unary plus. */
+static gfc_expr*
+discard_nops (gfc_expr *e)
+{
+
+ while (e && e->expr_type == EXPR_OP
+ && (e->value.op.op == INTRINSIC_UPLUS
+ || e->value.op.op == INTRINSIC_PARENTHESES))
+ e = e->value.op.op1;
+
+ return e;
+}
+/* Return the difference between two expressions. Integer expressions of
+ the form
+
+ X + constant, X - constant and constant + X
+
+ are handled. Return true on success, false on failure. result is assumed
+ to be uninitialized on entry, and will be initialized on success.
+*/
+
+bool
+gfc_dep_difference (gfc_expr *e1, gfc_expr *e2, mpz_t *result)
+{
+ gfc_expr *e1_op1, *e1_op2, *e2_op1, *e2_op2;
+
+ if (e1 == NULL || e2 == NULL)
+ return false;
+
+ if (e1->ts.type != BT_INTEGER || e2->ts.type != BT_INTEGER)
+ return false;
+
+ e1 = discard_nops (e1);
+ e2 = discard_nops (e2);
+
+ /* Inizialize tentatively, clear if we don't return anything. */
+ mpz_init (*result);
+
+ /* Case 1: c1 - c2 = c1 - c2, trivially. */
+
+ if (e1->expr_type == EXPR_CONSTANT && e2->expr_type == EXPR_CONSTANT)
+ {
+ mpz_sub (*result, e1->value.integer, e2->value.integer);
+ return true;
+ }
+
+ if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_PLUS)
+ {
+ e1_op1 = discard_nops (e1->value.op.op1);
+ e1_op2 = discard_nops (e1->value.op.op2);
+
+ /* Case 2: (X + c1) - X = c1. */
+ if (e1_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op1, e2) == 0)
+ {
+ mpz_set (*result, e1_op2->value.integer);
+ return true;
+ }
+
+ /* Case 3: (c1 + X) - X = c1. */
+ if (e1_op1->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op2, e2) == 0)
+ {
+ mpz_set (*result, e1_op1->value.integer);
+ return true;
+ }
+
+ if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_PLUS)
+ {
+ e2_op1 = discard_nops (e2->value.op.op1);
+ e2_op2 = discard_nops (e2->value.op.op2);
+
+ if (e1_op2->expr_type == EXPR_CONSTANT)
+ {
+ /* Case 4: X + c1 - (X + c2) = c1 - c2. */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op1, e2_op1) == 0)
+ {
+ mpz_sub (*result, e1_op2->value.integer,
+ e2_op2->value.integer);
+ return true;
+ }
+ /* Case 5: X + c1 - (c2 + X) = c1 - c2. */
+ if (e2_op1->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op1, e2_op2) == 0)
+ {
+ mpz_sub (*result, e1_op2->value.integer,
+ e2_op1->value.integer);
+ return true;
+ }
+ }
+ else if (e1_op1->expr_type == EXPR_CONSTANT)
+ {
+ /* Case 6: c1 + X - (X + c2) = c1 - c2. */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op2, e2_op1) == 0)
+ {
+ mpz_sub (*result, e1_op1->value.integer,
+ e2_op2->value.integer);
+ return true;
+ }
+ /* Case 7: c1 + X - (c2 + X) = c1 - c2. */
+ if (e2_op1->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op2, e2_op2) == 0)
+ {
+ mpz_sub (*result, e1_op1->value.integer,
+ e2_op1->value.integer);
+ return true;
+ }
+ }
+ }
+
+ if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS)
+ {
+ e2_op1 = discard_nops (e2->value.op.op1);
+ e2_op2 = discard_nops (e2->value.op.op2);
+
+ if (e1_op2->expr_type == EXPR_CONSTANT)
+ {
+ /* Case 8: X + c1 - (X - c2) = c1 + c2. */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op1, e2_op1) == 0)
+ {
+ mpz_add (*result, e1_op2->value.integer,
+ e2_op2->value.integer);
+ return true;
+ }
+ }
+ if (e1_op1->expr_type == EXPR_CONSTANT)
+ {
+ /* Case 9: c1 + X - (X - c2) = c1 + c2. */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op2, e2_op1) == 0)
+ {
+ mpz_add (*result, e1_op1->value.integer,
+ e2_op2->value.integer);
+ return true;
+ }
+ }
+ }
+ }
+
+ if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_MINUS)
+ {
+ e1_op1 = discard_nops (e1->value.op.op1);
+ e1_op2 = discard_nops (e1->value.op.op2);
+
+ if (e1_op2->expr_type == EXPR_CONSTANT)
+ {
+ /* Case 10: (X - c1) - X = -c1 */
+
+ if (gfc_dep_compare_expr (e1_op1, e2) == 0)
+ {
+ mpz_neg (*result, e1_op2->value.integer);
+ return true;
+ }
+
+ if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_PLUS)
+ {
+ e2_op1 = discard_nops (e2->value.op.op1);
+ e2_op2 = discard_nops (e2->value.op.op2);
+
+ /* Case 11: (X - c1) - (X + c2) = -( c1 + c2). */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op1, e2_op1) == 0)
+ {
+ mpz_add (*result, e1_op2->value.integer,
+ e2_op2->value.integer);
+ mpz_neg (*result, *result);
+ return true;
+ }
+
+ /* Case 12: X - c1 - (c2 + X) = - (c1 + c2). */
+ if (e2_op1->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op1, e2_op2) == 0)
+ {
+ mpz_add (*result, e1_op2->value.integer,
+ e2_op1->value.integer);
+ mpz_neg (*result, *result);
+ return true;
+ }
+ }
+
+ if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS)
+ {
+ e2_op1 = discard_nops (e2->value.op.op1);
+ e2_op2 = discard_nops (e2->value.op.op2);
+
+ /* Case 13: (X - c1) - (X - c2) = c2 - c1. */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1_op1, e2_op1) == 0)
+ {
+ mpz_sub (*result, e2_op2->value.integer,
+ e1_op2->value.integer);
+ return true;
+ }
+ }
+ }
+ if (e1_op1->expr_type == EXPR_CONSTANT)
+ {
+ if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS)
+ {
+ e2_op1 = discard_nops (e2->value.op.op1);
+ e2_op2 = discard_nops (e2->value.op.op2);
+
+ /* Case 14: (c1 - X) - (c2 - X) == c1 - c2. */
+ if (gfc_dep_compare_expr (e1_op2, e2_op2) == 0)
+ {
+ mpz_sub (*result, e1_op1->value.integer,
+ e2_op1->value.integer);
+ return true;
+ }
+ }
+
+ }
+ }
+
+ if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_PLUS)
+ {
+ e2_op1 = discard_nops (e2->value.op.op1);
+ e2_op2 = discard_nops (e2->value.op.op2);
+
+ /* Case 15: X - (X + c2) = -c2. */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1, e2_op1) == 0)
+ {
+ mpz_neg (*result, e2_op2->value.integer);
+ return true;
+ }
+ /* Case 16: X - (c2 + X) = -c2. */
+ if (e2_op1->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1, e2_op2) == 0)
+ {
+ mpz_neg (*result, e2_op1->value.integer);
+ return true;
+ }
+ }
+
+ if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS)
+ {
+ e2_op1 = discard_nops (e2->value.op.op1);
+ e2_op2 = discard_nops (e2->value.op.op2);
+
+ /* Case 17: X - (X - c2) = c2. */
+ if (e2_op2->expr_type == EXPR_CONSTANT
+ && gfc_dep_compare_expr (e1, e2_op1) == 0)
+ {
+ mpz_set (*result, e2_op2->value.integer);
+ return true;
+ }
+ }
+
+ if (gfc_dep_compare_expr(e1, e2) == 0)
+ {
+ /* Case 18: X - X = 0. */
+ mpz_set_si (*result, 0);
+ return true;
+ }
+
+ mpz_clear (*result);
+ return false;
+}
+
/* Returns 1 if the two ranges are the same and 0 if they are not (or if the
results are indeterminate). 'n' is the dimension to compare. */
@@ -1140,6 +1403,7 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc
int r_dir;
int stride_comparison;
int start_comparison;
+ mpz_t tmp;
/* If they are the same range, return without more ado. */
if (is_same_range (l_ar, r_ar, n))
@@ -1282,23 +1546,20 @@ check_section_vs_section (gfc_array_ref *l_ar, gfc
#define IS_CONSTANT_INTEGER(a) ((a) && ((a)->expr_type == EXPR_CONSTANT) \
&& (a)->ts.type == BT_INTEGER)
- if (IS_CONSTANT_INTEGER(l_start) && IS_CONSTANT_INTEGER(r_start)
- && IS_CONSTANT_INTEGER(l_stride) && IS_CONSTANT_INTEGER(r_stride))
+ if (IS_CONSTANT_INTEGER(l_stride) && IS_CONSTANT_INTEGER(r_stride)
+ && gfc_dep_difference (l_start, r_start, &tmp))
{
- mpz_t gcd, tmp;
+ mpz_t gcd;
int result;
mpz_init (gcd);
- mpz_init (tmp);
-
mpz_gcd (gcd, l_stride->value.integer, r_stride->value.integer);
- mpz_sub (tmp, l_start->value.integer, r_start->value.integer);
mpz_fdiv_r (tmp, tmp, gcd);
result = mpz_cmp_si (tmp, 0L);
mpz_clear (gcd);
- mpz_clear (tmp);
+ mpz_clear (tmp); /* gfc_dep_difference returned true, so tmp was initialized. */
if (result != 0)
return GFC_DEP_NODEP;
Index: trans-expr.c
===================================================================
--- trans-expr.c (Revision 196574)
+++ trans-expr.c (Arbeitskopie)
@@ -1437,6 +1437,7 @@ gfc_conv_substring (gfc_se * se, gfc_ref * ref, in
gfc_se start;
gfc_se end;
char *msg;
+ mpz_t length;
type = gfc_get_character_type (kind, ref->u.ss.length);
type = build_pointer_type (type);
@@ -1520,10 +1521,19 @@ gfc_conv_substring (gfc_se * se, gfc_ref * ref, in
free (msg);
}
- /* If the start and end expressions are equal, the length is one. */
+ /* Try to calculate the length from the start and end expressions. */
if (ref->u.ss.end
- && gfc_dep_compare_expr (ref->u.ss.start, ref->u.ss.end) == 0)
- tmp = build_int_cst (gfc_charlen_type_node, 1);
+ && gfc_dep_difference (ref->u.ss.end, ref->u.ss.start, &length))
+ {
+ int i_len;
+
+ i_len = mpz_get_si (length) + 1;
+ if (i_len < 0)
+ i_len = 0;
+
+ tmp = build_int_cst (gfc_charlen_type_node, i_len);
+ mpz_clear (length); /* Was initialized by gfc_dep_difference. */
+ }
else
{
tmp = fold_build2_loc (input_location, MINUS_EXPR, gfc_charlen_type_node,
! { dg-compile }
! { dg-options "-Warray-temporaries" }
! No temporary should be generated in this case.
subroutine f1(a,n,m)
real, intent(inout) :: a(n)
integer, intent(in) :: n,m
a(m+1:n:2) = a(m:n-1:2)
end subroutine f1
! { dg-run }
! { dg-options "-fdump-tree-original" }
! Test that all string length calculations are
! optimized away.
program main
character (len=999) :: c
character (len=5) :: unit
unit = ' '
read (unit=unit,fmt='(I5)') i ! Hide from optimizers
j = 7
c = '123456789'
if (len(c( 3 : 5 )) /= 3) call abort ! Case 1
if (len(c( i*(i+1) : (i+1)*i + 2 )) /= 3) call abort ! Case 2
if (len(c( i*(i+1) : 2 + (i+1)*i )) /= 3) call abort ! Case 3
if (len(c( i*(i+1) + 2 : (i+1)*i + 3 )) /= 2) call abort ! Case 4
if (len(c( 2 + i*(i+1) : (i+1)*i + 3 )) /= 2) call abort ! Case 5
if (len(c( i*(i+1) + 2 : 3 + (i+1)*i )) /= 2) call abort ! Case 6
if (len(c( 2 + i*(i+1) : 3 + (i+1)*i )) /= 2) call abort ! Case 7
if (len(c( i*(i+1) - 1 : (i+1)*i + 1 )) /= 3) call abort ! Case 8
if (len(c( i*(i+1) - 1 : 1 + (i+1)*i )) /= 3) call abort ! Case 9
if (len(c( i*(i+1) : (i+1)*i -(-1))) /= 2) call abort ! Case 10
if (len(c( i*(i+1) +(-2): (i+1)*i - 1 )) /= 2) call abort ! Case 11
if (len(c( i*(i+1) + 2 : (i+1)*i -(-4))) /= 3) call abort ! Case 12
if (len(c( i*(i+1) - 3 : (i+1)*i - 1 )) /= 3) call abort ! Case 13
if (len(c(13 - i*(i+1) :15 - (i+1)*i )) /= 3) call abort ! Case 14
if (len(c( i*(i+1) +(-1): (i+1)*i )) /= 2) call abort ! Case 15
if (len(c(-1 + i*(i+1) : (i+1)*i )) /= 2) call abort ! Case 16
if (len(c( i*(i+1) - 2 : (i+1)*i )) /= 3) call abort ! Case 17
if (len(c( (i-2)*(i-3) : (i-3)*(i-2) )) /= 1) call abort ! Case 18
end program main
! { dg-final { scan-tree-dump-times "_abort" 0 "original" } }
! { dg-final { cleanup-tree-dump "original" } }
