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re PR fortran/52861 ((missed optimisation) missed transformation to memset with -O3)

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2012-06-07  Thomas König  <tkoenig@gcc.gnu.org>

	PR fortran/52861
	* frontend-passes (empty_string):  Add prototype.
	(optimize_assignment):  Set the length of an empty string
	constant to zero.

2012-06-07  Thomas König  <tkoenig@gcc.gnu.org>

	PR fortran/52861
	* gfortran.dg/string_assign_1.f90:  New test case.

From-SVN: r188300
This commit is contained in:
Thomas Koenig 2012-06-07 11:11:55 +00:00
parent d8a5e488d5
commit 94d145bf5b
4 changed files with 33 additions and 4 deletions
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7
gcc/fortran/ChangeLog
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@ -1,3 +1,10 @@
2012-06-07 Thomas König <tkoenig@gcc.gnu.org>
PR fortran/52861
* frontend-passes (empty_string): Add prototype.
(optimize_assignment): Set the length of an empty string
constant to zero.
2012-06-04 Tobias Burnus <burnus@net-b.de>
PR fortran/50619

14
gcc/fortran/frontend-passes.c
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@ -1,5 +1,5 @@
/* Pass manager for Fortran front end.
Copyright (C) 2010, 2011 Free Software Foundation, Inc.
Copyright (C) 2010, 2011, 2012 Free Software Foundation, Inc.
Contributed by Thomas König.
This file is part of GCC.
@ -37,6 +37,7 @@ static bool optimize_comparison (gfc_expr *, gfc_intrinsic_op);
static bool optimize_trim (gfc_expr *);
static bool optimize_lexical_comparison (gfc_expr *);
static void optimize_minmaxloc (gfc_expr **);
static bool empty_string (gfc_expr *e);
/* How deep we are inside an argument list. */
@ -734,10 +735,15 @@ optimize_assignment (gfc_code * c)
lhs = c->expr1;
rhs = c->expr2;
/* Optimize away a = trim(b), where a is a character variable. */
if (lhs->ts.type == BT_CHARACTER)
remove_trim (rhs);
{
/* Optimize away a = trim(b), where a is a character variable. */
remove_trim (rhs);
/* Replace a = ' ' by a = '' to optimize away a memcpy. */
if (empty_string(rhs))
rhs->value.character.length = 0;
}
if (lhs->rank > 0 && gfc_check_dependency (lhs, rhs, true) == 0)
optimize_binop_array_assignment (c, &rhs, false);

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2012-06-07 Thomas König <tkoenig@gcc.gnu.org>
PR fortran/52861
* gfortran.dg/string_assign_1.f90: New test case.
2012-06-07 Jakub Jelinek <jakub@redhat.com>
PR middle-end/53580

11
gcc/testsuite/gfortran.dg/string_assign_1.f90 Normal file
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@ -0,0 +1,11 @@
! { dg-do compile }
! { dg-options "-ffrontend-optimize -fdump-tree-original" }
! PR 52861 - optimize this to c = '' so that there is
! no memcpy in the generated code.
program main
character (len=20) :: c
c = ' '
print *,c
end program main
! { dg-final { scan-tree-dump-times "memcpy" 0 "original" } }
! { dg-final { cleanup-tree-dump "original" } }