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[patch, fortran] Optimize some more string comparisons
- From: Thomas Koenig <tkoenig at netcologne dot de>
- To: fortran at gcc dot gnu dot org
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sat, 09 Oct 2010 10:21:41 +0200
- Subject: [patch, fortran] Optimize some more string comparisons
Hello world,
the attached patch simplifies some more cases of string comparisons. For
example, when comparing 'a' // x vs. 'b' // y, the result can be
calculated directly. Also, for 'a' // x vs. 'a' // y, it is sufficient
to compare x vs. y.
Regression-tested. OK for trunk?
Thomas
2010-10-09 Thomas Koenig <tkoenig@gcc.gnu.org>
* frontend-passes.c: Include opts.h.
(optimize_comparison): Renamed from optimize_equality.
Change second argument to operation to be compared.
Use flag_finite_math_only to avoid comparing REAL and
COMPLEX only when NANs are honored. Simplify comparing
of string concatenations where left or right operands are
equal. Simplify all comparison operations, based on the result
of gfc_dep_compare_expr.
* dependency.c: Include arith.h.
(gfc_are_identical_variables): Volatile variables should not
compare equal to themselves.
(gfc_dep_compare_expr): Handle string constants and string
concatenations.
2010-10-09 Thomas Koenig <tkoenig@gcc.gnu.org>
* gfortran.dg/character_comparison_4.f90: New test.
* gfortran.dg/character_comparison_5.f90: New test.
* gfortran.dg/character_comparison_6.f90: New test.
Index: frontend-passes.c
===================================================================
--- frontend-passes.c (Revision 165124)
+++ frontend-passes.c (Arbeitskopie)
@@ -25,6 +25,7 @@ along with GCC; see the file COPYING3. If not see
#include "flags.h"
#include "dependency.h"
#include "constructor.h"
+#include "opts.h"
/* Forward declarations. */
@@ -32,7 +33,7 @@ static void strip_function_call (gfc_expr *);
static void optimize_namespace (gfc_namespace *);
static void optimize_assignment (gfc_code *);
static bool optimize_op (gfc_expr *);
-static bool optimize_equality (gfc_expr *, bool);
+static bool optimize_comparison (gfc_expr *, gfc_intrinsic_op);
/* Entry point - run all passes for a namespace. So far, only an
optimization pass is run. */
@@ -226,15 +227,13 @@ optimize_op (gfc_expr *e)
case INTRINSIC_GE_OS:
case INTRINSIC_LE:
case INTRINSIC_LE_OS:
- return optimize_equality (e, true);
-
case INTRINSIC_NE:
case INTRINSIC_NE_OS:
case INTRINSIC_GT:
case INTRINSIC_GT_OS:
case INTRINSIC_LT:
case INTRINSIC_LT_OS:
- return optimize_equality (e, false);
+ return optimize_comparison (e, op);
default:
break;
@@ -246,10 +245,12 @@ optimize_op (gfc_expr *e)
/* Optimize expressions for equality. */
static bool
-optimize_equality (gfc_expr *e, bool equal)
+optimize_comparison (gfc_expr *e, gfc_intrinsic_op op)
{
gfc_expr *op1, *op2;
bool change;
+ int eq;
+ bool result;
op1 = e->value.op.op1;
op2 = e->value.op.op2;
@@ -276,7 +277,7 @@ static bool
if (change)
{
- optimize_equality (e, equal);
+ optimize_comparison (e, op);
return true;
}
@@ -287,22 +288,106 @@ static bool
if (e->rank > 0)
return false;
- /* Check for direct comparison between identical variables. Don't compare
- REAL or COMPLEX because of NaN checks. */
- if (op1->expr_type == EXPR_VARIABLE
- && op2->expr_type == EXPR_VARIABLE
- && op1->ts.type != BT_REAL && op2->ts.type != BT_REAL
- && op1->ts.type != BT_COMPLEX && op2->ts.type !=BT_COMPLEX
- && gfc_are_identical_variables (op1, op2))
+ /* Don't compare REAL or COMPLEX expressions when honoring NaNs. */
+
+ if (flag_finite_math_only
+ || (op1->ts.type != BT_REAL && op2->ts.type != BT_REAL
+ && op1->ts.type != BT_COMPLEX && op2->ts.type != BT_COMPLEX))
{
- /* Replace the expression by a constant expression. The typespec
- and where remains the way it is. */
- gfc_free (op1);
- gfc_free (op2);
- e->expr_type = EXPR_CONSTANT;
- e->value.logical = equal;
- return true;
+ eq = gfc_dep_compare_expr (op1, op2);
+ if (eq == -2)
+ {
+ /* Replace A // B < A // C with B < C, and A // B < C // B
+ with A < C. */
+ if (op1->ts.type == BT_CHARACTER && op2->ts.type == BT_CHARACTER
+ && op1->value.op.op == INTRINSIC_CONCAT
+ && op2->value.op.op == INTRINSIC_CONCAT)
+ {
+ gfc_expr *op1_left = op1->value.op.op1;
+ gfc_expr *op2_left = op2->value.op.op1;
+ gfc_expr *op1_right = op1->value.op.op2;
+ gfc_expr *op2_right = op2->value.op.op2;
+
+ if (gfc_dep_compare_expr (op1_left, op2_left) == 0)
+ {
+ /* Watch out for 'A ' // x vs. 'A' // x. */
+
+ if (op1_left->expr_type == EXPR_CONSTANT
+ && op2_left->expr_type == EXPR_CONSTANT
+ && op1_left->value.character.length
+ != op2_left->value.character.length)
+ return -2;
+ else
+ {
+ gfc_free (op1_left);
+ gfc_free (op2_left);
+ e->value.op.op1 = op1_right;
+ e->value.op.op2 = op2_right;
+ optimize_comparison (e, op);
+ return true;
+ }
+ }
+ if (gfc_dep_compare_expr (op1_right, op2_right) == 0)
+ {
+ gfc_free (op1_right);
+ gfc_free (op2_right);
+ e->value.op.op1 = op1_left;
+ e->value.op.op2 = op2_left;
+ optimize_comparison (e, op);
+ return true;
+ }
+ }
+ }
+ else
+ {
+ /* eq can only be -1, 0 or 1 at this point. */
+ switch (op)
+ {
+ case INTRINSIC_EQ:
+ case INTRINSIC_EQ_OS:
+ result = eq == 0;
+ break;
+
+ case INTRINSIC_GE:
+ case INTRINSIC_GE_OS:
+ result = eq >= 0;
+ break;
+
+ case INTRINSIC_LE:
+ case INTRINSIC_LE_OS:
+ result = eq <= 0;
+ break;
+
+ case INTRINSIC_NE:
+ case INTRINSIC_NE_OS:
+ result = eq != 0;
+ break;
+
+ case INTRINSIC_GT:
+ case INTRINSIC_GT_OS:
+ result = eq > 0;
+ break;
+
+ case INTRINSIC_LT:
+ case INTRINSIC_LT_OS:
+ result = eq < 0;
+ break;
+
+ default:
+ gfc_internal_error ("illegal OP in optimize_comparison");
+ break;
+ }
+
+ /* Replace the expression by a constant expression. The typespec
+ and where remains the way it is. */
+ gfc_free (op1);
+ gfc_free (op2);
+ e->expr_type = EXPR_CONSTANT;
+ e->value.logical = result;
+ return true;
+ }
}
+
return false;
}
Index: dependency.c
===================================================================
--- dependency.c (Revision 165124)
+++ dependency.c (Arbeitskopie)
@@ -29,6 +29,7 @@ along with GCC; see the file COPYING3. If not see
#include "gfortran.h"
#include "dependency.h"
#include "constructor.h"
+#include "arith.h"
/* static declarations */
/* Enums */
@@ -125,6 +126,11 @@ gfc_are_identical_variables (gfc_expr *e1, gfc_exp
if (e1->symtree->n.sym != e2->symtree->n.sym)
return false;
+ /* Volatile variables should never compare equal to themselves. */
+
+ if (e1->symtree->n.sym->attr.volatile_)
+ return false;
+
r1 = e1->ref;
r2 = e2->ref;
@@ -306,6 +312,42 @@ gfc_dep_compare_expr (gfc_expr *e1, gfc_expr *e2)
}
}
+ /* Compare A // B vs. C // D. */
+
+ if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_CONCAT
+ && e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_CONCAT)
+ {
+ int l, r;
+
+ l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1);
+ r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2);
+
+ if (l == -2)
+ return -2;
+
+ if (l == 0)
+ {
+ /* Watch out for 'A ' // x vs. 'A' // x. */
+ gfc_expr *e1_left = e1->value.op.op1;
+ gfc_expr *e2_left = e2->value.op.op1;
+
+ if (e1_left->expr_type == EXPR_CONSTANT
+ && e2_left->expr_type == EXPR_CONSTANT
+ && e1_left->value.character.length
+ != e2_left->value.character.length)
+ return -2;
+ else
+ return r;
+ }
+ else
+ {
+ if (l != 0)
+ return l;
+ else
+ return r;
+ }
+ }
+
/* Compare X vs. X-C. */
if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS)
{
@@ -321,6 +363,10 @@ gfc_dep_compare_expr (gfc_expr *e1, gfc_expr *e2)
switch (e1->expr_type)
{
case EXPR_CONSTANT:
+ /* Compare strings for equality. */
+ if (e1->ts.type == BT_CHARACTER && e2->ts.type == BT_CHARACTER)
+ return gfc_compare_string (e1, e2);
+
if (e1->ts.type != BT_INTEGER || e2->ts.type != BT_INTEGER)
return -2;
! { dg-do run }
! { dg-options "-O -fdump-tree-original" }
program main
implicit none
character(len=4) :: c, d
integer :: n
integer :: i
common /foo/ i
n = 0
i = 0
c = 'abcd'
d = 'efgh'
n = n + 1 ; if ('a' // c == 'a' // c) call yes
n = n + 1 ; if (c // 'a' == c // 'a') call yes
n = n + 1; if ('b' // c > 'a' // d) call yes
n = n + 1; if (c // 'b' > c // 'a') call yes
if ('a' // c /= 'a' // c) call abort
if ('a' // c // 'b' == 'a' // c // 'a') call abort
if ('b' // c == 'a' // c) call abort
if (c // 'a' == c // 'b') call abort
if (c // 'a ' /= c // 'a') call abort
if (c // 'b' /= c // 'b ') call abort
if (n /= i) call abort
end program main
subroutine yes
implicit none
common /foo/ i
integer :: i
i = i + 1
end subroutine yes
! { dg-final { scan-tree-dump-times "gfortran_compare_string" 0 "original" } }
! { dg-final { cleanup-tree-dump "original" } }
! { dg-do run }
! { dg-options "-O -fdump-tree-original" }
program main
implicit none
character(len=4) :: c, d
integer :: n
integer :: i
common /foo/ i
n = 0
i = 0
c = 'abcd'
d = 'efgh'
if (c // 'a' >= d // 'a') call abort
if ('a' // c >= 'a' // d) call abort
end program main
! { dg-final { scan-tree-dump-times "gfortran_concat_string" 0 "original" } }
! { dg-final { scan-tree-dump-times "gfortran_compare_string" 2 "original" } }
! { dg-final { cleanup-tree-dump "original" } }
! { dg-do run }
! { dg-options "-O -fdump-tree-original" }
program main
implicit none
character(len=4) :: c
integer :: n
integer :: i
common /foo/ i
n = 0
i = 0
c = 'abcd'
if ('a ' // c == 'a' // c) call abort
if ('a' // c == 'a ' // c) call abort
end program main
! { dg-final { scan-tree-dump-times "gfortran_concat_string" 4 "original" } }
! { dg-final { scan-tree-dump-times "gfortran_compare_string" 2 "original" } }
! { dg-final { cleanup-tree-dump "original" } }