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* [Bug fortran/53642] New: Front-end optimization: Wrong string length for deferred-length strings
@ 2012-06-12 8:09 burnus at gcc dot gnu.org
2012-06-12 15:52 ` [Bug fortran/53642] " burnus at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: burnus at gcc dot gnu.org @ 2012-06-12 8:09 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53642
Bug #: 53642
Summary: Front-end optimization: Wrong string length for
deferred-length strings
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: burnus@gcc.gnu.org
CC: damian@rouson.net, tkoenig@gcc.gnu.org
As reported by Damian Rouson at
http://gcc.gnu.org/ml/fortran/2012-06/msg00069.html
Without optimization, the following program prints - and should print:
3 3
However, with -ffrontend-optimize the result is, wrongly,
3 4
Damian: Use -fno-frontend-optimize as work-around.
character(len=4) :: string="123 "
character(:), allocatable :: trimmed
trimmed = trim(string)
print *,len_trim(string),len(trimmed)
end
>From the original dump:
(a) Without FE optimization
_gfortran_string_trim (&len.1, (void * *) &pstr.0, 4, &string);
D.1864 = len.1;
if (trimmed != 0B) goto L.1;
trimmed = (character(kind=1)[1:.trimmed] *)
__builtin_malloc ((sizetype) len.1);
...
.trimmed = len.1;
(b) With FE optimization
if (trimmed != 0B) goto L.1;
trimmed = (character(kind=1)[1:.trimmed] *) __builtin_malloc (4);
...
.trimmed = 4;
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug fortran/53642] Front-end optimization: Wrong string length for deferred-length strings
2012-06-12 8:09 [Bug fortran/53642] New: Front-end optimization: Wrong string length for deferred-length strings burnus at gcc dot gnu.org
@ 2012-06-12 15:52 ` burnus at gcc dot gnu.org
2012-06-16 18:13 ` burnus at gcc dot gnu.org
2012-06-16 18:16 ` burnus at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: burnus at gcc dot gnu.org @ 2012-06-12 15:52 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53642
Tobias Burnus <burnus at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |burnus at gcc dot gnu.org
--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-12 15:52:34 UTC ---
I was thinking about the following patch - namely, doing in optimize_assignment
the remove_trim only if "!lhs->ts.deferred".
* * *
However, that does not work; seemingly, a = trim(b) is replaced by
a = b(1:len_trim(b)) in such a way, that len(a) == 0 instead of 3.
The same issue occurs for a manual:
trimmed = string(1:len_trim(string))
Thus, the follow-up issue is not a FE optimization issue but rather a trans*.c
issue. The generated code is [some casting removed]:
trimmed = __builtin_malloc (MAX_EXPR <NON_LVALUE_EXPR <D.1861>, 0>);
.trimmed = MAX_EXPR <NON_LVALUE_EXPR <D.1861>, 0>;
D.1861 = _gfortran_string_len_trim (4, &string);
Which shows the wrong ordering, similar to bug 45170 comment 34, which is fixed
by the patch at bug 45170 comment 34. That patch also solves the len_trim issue
above.
--- a/gcc/fortran/frontend-passes.c
+++ b/gcc/fortran/frontend-passes.c
@@ -738 +738 @@ optimize_assignment (gfc_code * c)
- if (lhs->ts.type == BT_CHARACTER)
+ if (lhs->ts.type == BT_CHARACTER && !lhs->ts.deferred)
@@ -740 +740 @@ optimize_assignment (gfc_code * c)
- /* Optimize away a = trim(b), where a is a character variable. */
+ /* Optimize a = trim(b) to a = b. */
@@ -743,4 +743,2 @@ optimize_assignment (gfc_code * c)
- /* Replace a = ' ' by a = '' to optimize away a memcpy, but only
- for strings with non-deferred length (otherwise we would
- reallocate the length. */
- if (empty_string(rhs) && ! lhs->ts.deferred)
+ /* Replace a = ' ' by a = '' to optimize away a memcpy. */
+ if (empty_string(rhs))
@@ -1174 +1172 @@ optimize_trim (gfc_expr *e)
- /* Build the function call to len_trim(x, gfc_defaul_integer_kind). */
+ /* Build the function call to len_trim(x, gfc_default_integer_kind). */
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug fortran/53642] Front-end optimization: Wrong string length for deferred-length strings
2012-06-12 8:09 [Bug fortran/53642] New: Front-end optimization: Wrong string length for deferred-length strings burnus at gcc dot gnu.org
2012-06-12 15:52 ` [Bug fortran/53642] " burnus at gcc dot gnu.org
@ 2012-06-16 18:13 ` burnus at gcc dot gnu.org
2012-06-16 18:16 ` burnus at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: burnus at gcc dot gnu.org @ 2012-06-16 18:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53642
--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-16 18:13:43 UTC ---
Author: burnus
Date: Sat Jun 16 18:13:38 2012
New Revision: 188692
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188692
Log:
2012-06-16 Tobias Burnus <burnus@net-b.de>
PR fortran/53642
PR fortran/45170
* frontend-passes.c (optimize_assignment): Don't remove RHS's
trim when assigning to a deferred-length string.
* trans-expr.c (gfc_trans_assignment_1): Ensure that the RHS string
length is evaluated before the deferred-length LHS is reallocated.
2012-06-16 Tobias Burnus <burnus@net-b.de>
PR fortran/53642
PR fortran/45170
* gfortran.dg/deferred_type_param_8.f90: New.
Added:
trunk/gcc/testsuite/gfortran.dg/deferred_type_param_8.f90
Modified:
trunk/gcc/fortran/ChangeLog
trunk/gcc/fortran/frontend-passes.c
trunk/gcc/fortran/trans-expr.c
trunk/gcc/testsuite/ChangeLog
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug fortran/53642] Front-end optimization: Wrong string length for deferred-length strings
2012-06-12 8:09 [Bug fortran/53642] New: Front-end optimization: Wrong string length for deferred-length strings burnus at gcc dot gnu.org
2012-06-12 15:52 ` [Bug fortran/53642] " burnus at gcc dot gnu.org
2012-06-16 18:13 ` burnus at gcc dot gnu.org
@ 2012-06-16 18:16 ` burnus at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: burnus at gcc dot gnu.org @ 2012-06-16 18:16 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53642
Tobias Burnus <burnus at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |FIXED
--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-16 18:16:45 UTC ---
FIXED on the trunk (4.8).
Damian: Thanks for the bug report!
^ permalink raw reply [flat|nested] 4+ messages in thread
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2012-06-12 8:09 [Bug fortran/53642] New: Front-end optimization: Wrong string length for deferred-length strings burnus at gcc dot gnu.org
2012-06-12 15:52 ` [Bug fortran/53642] " burnus at gcc dot gnu.org
2012-06-16 18:13 ` burnus at gcc dot gnu.org
2012-06-16 18:16 ` burnus at gcc dot gnu.org
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