[v6,10/15] vla: evaluate operand of sizeof if its type is a vla
Commit Message
The c99 standard in "6.5.3.4 The sizeof operator" states:
If the type of the operand is a variable length array type, the operand
is evaluated;[...]
This patch mirrors the following c99 semantic in gdb:
1| int vla[n][m];
2| int i = 1;
3| sizeof(vla[i++][0]); // No sideffect
4| assert (i == 1);
5| sizeof(vla[i++]); // With sideffect
6| assert (i == 2);
Note: ptype/whatsis still do not allow any sideeffects.
This patch was motivated by:
https://sourceware.org/ml/gdb-patches/2014-01/msg00732.html
2014-02-05 Sanimir Agovic <sanimir.agovic@intel.com>
Keven Boell <keven.boell@intel.com>
* eval.c (evaluate_subexp_for_sizeof): Add enum noside argument.
(evaluate_subexp_standard): Pass noside argument.
(evaluate_subexp_for_sizeof) <BINOP_SUBSCRIPT>: Handle subscript case
if noside equals EVAL_NORMAL. If the subscript yields a vla type
re-evaluate subscript operation with EVAL_NORMAL to enable sideffects.
* gdbtypes.c (resolve_dynamic_bounds): Mark bound as evaluated.
* gdbtypes.h (enum range_flags): Add RANGE_EVALUATED case.
testsuite/gdb.base/
* vla-sideeffect.c: New file.
* vla-sideeffect.exp: New file.
Signed-off-by: Sanimir Agovic <sanimir.agovic@intel.com>
---
gdb/eval.c | 43 +++++++++++++--
gdb/gdbtypes.c | 1 +
gdb/gdbtypes.h | 5 ++
gdb/testsuite/gdb.base/vla-sideeffect.c | 42 +++++++++++++++
gdb/testsuite/gdb.base/vla-sideeffect.exp | 89 +++++++++++++++++++++++++++++++
5 files changed, 176 insertions(+), 4 deletions(-)
create mode 100644 gdb/testsuite/gdb.base/vla-sideeffect.c
create mode 100644 gdb/testsuite/gdb.base/vla-sideeffect.exp
Comments
> 2014-02-05 Sanimir Agovic <sanimir.agovic@intel.com>
> Keven Boell <keven.boell@intel.com>
>
> * eval.c (evaluate_subexp_for_sizeof): Add enum noside argument.
> (evaluate_subexp_standard): Pass noside argument.
> (evaluate_subexp_for_sizeof) <BINOP_SUBSCRIPT>: Handle subscript case
> if noside equals EVAL_NORMAL. If the subscript yields a vla type
> re-evaluate subscript operation with EVAL_NORMAL to enable sideffects.
> * gdbtypes.c (resolve_dynamic_bounds): Mark bound as evaluated.
> * gdbtypes.h (enum range_flags): Add RANGE_EVALUATED case.
>
> testsuite/gdb.base/
>
> * vla-sideeffect.c: New file.
> * vla-sideeffect.exp: New file.
Approved with some minor trivial modifications.
> /* Evaluate a subexpression of EXP, at index *POS,
> and return a value for the size of that subexpression.
> - Advance *POS over the subexpression. */
> + Advance *POS over the subexpression. If NOSIDE is EVAL_NORMAL
^^^^^^^
Minor style nit: Two spaces after a period ("If NOSIDE")
> + if (TYPE_RANGE_DATA (type)->flag_bound_evaluated)
> + {
> + val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_NORMAL);
> + return value_from_longest
> + (size_type, (LONGEST)TYPE_LENGTH (value_type (val)));
I missed this one in the my first review, but there should be a space
after "(LONGEST)".
> +set sizeof_vla [ expr "10" * "$sizeof_int" ]
> +
> +gdb_test "print sizeof (vla1\[i++\])" "= ${sizeof_int}" \
Just to be consistent, let's add a space before the "=" sign.
> + "print sizeof (vla1\[i++\])"
Thanks,
@@ -51,7 +51,8 @@ extern int overload_resolution;
/* Prototypes for local functions. */
-static struct value *evaluate_subexp_for_sizeof (struct expression *, int *);
+static struct value *evaluate_subexp_for_sizeof (struct expression *, int *,
+ enum noside);
static struct value *evaluate_subexp_for_address (struct expression *,
int *, enum noside);
@@ -2563,7 +2564,7 @@ evaluate_subexp_standard (struct type *expect_type,
evaluate_subexp (NULL_TYPE, exp, pos, EVAL_SKIP);
goto nosideret;
}
- return evaluate_subexp_for_sizeof (exp, pos);
+ return evaluate_subexp_for_sizeof (exp, pos, noside);
case UNOP_CAST:
(*pos) += 2;
@@ -2998,10 +2999,13 @@ evaluate_subexp_with_coercion (struct expression *exp,
/* Evaluate a subexpression of EXP, at index *POS,
and return a value for the size of that subexpression.
- Advance *POS over the subexpression. */
+ Advance *POS over the subexpression. If NOSIDE is EVAL_NORMAL
+ we allow side-effects on the operand if its type is a variable
+ length array. */
static struct value *
-evaluate_subexp_for_sizeof (struct expression *exp, int *pos)
+evaluate_subexp_for_sizeof (struct expression *exp, int *pos,
+ enum noside noside)
{
/* FIXME: This should be size_t. */
struct type *size_type = builtin_type (exp->gdbarch)->builtin_int;
@@ -3055,6 +3059,37 @@ evaluate_subexp_for_sizeof (struct expression *exp, int *pos)
return
value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
+ /* Deal with the special case if NOSIDE is EVAL_NORMAL and the resulting
+ type of the subscript is a variable length array type. In this case we
+ must re-evaluate the right hand side of the subcription to allow
+ side-effects. */
+ case BINOP_SUBSCRIPT:
+ if (noside == EVAL_NORMAL)
+ {
+ int pc = (*pos) + 1;
+
+ val = evaluate_subexp (NULL_TYPE, exp, &pc, EVAL_AVOID_SIDE_EFFECTS);
+ type = check_typedef (value_type (val));
+ if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
+ {
+ type = check_typedef (TYPE_TARGET_TYPE (type));
+ if (TYPE_CODE (type) == TYPE_CODE_ARRAY)
+ {
+ type = TYPE_INDEX_TYPE (type);
+ /* Only re-evaluate the right hand side if the resulting type
+ is a variable length type. */
+ if (TYPE_RANGE_DATA (type)->flag_bound_evaluated)
+ {
+ val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_NORMAL);
+ return value_from_longest
+ (size_type, (LONGEST)TYPE_LENGTH (value_type (val)));
+ }
+ }
+ }
+ }
+
+ /* Fall through. */
+
default:
val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
return value_from_longest (size_type,
@@ -1647,6 +1647,7 @@ resolve_dynamic_bounds (struct type *type, CORE_ADDR addr)
= create_range_type (NULL,
TYPE_TARGET_TYPE (range_type),
&low_bound, &high_bound);
+ TYPE_RANGE_DATA (range_type)->flag_bound_evaluated = 1;
elt_type = create_array_type (copy_type (type),
elt_type,
range_type);
@@ -626,6 +626,11 @@ struct main_type
subrange. This affects how the final hight bound is computed. */
int flag_upper_bound_is_count : 1;
+
+ /* True if LOW or/and HIGH are resolved into a static bound from
+ a dynamic one. */
+
+ int flag_bound_evaluated : 1;
} *bounds;
} flds_bnds;
new file mode 100644
@@ -0,0 +1,42 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2014 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#include <stddef.h>
+#define SIZE 10
+
+int
+main (void)
+{
+ int n = SIZE;
+ int i = 0;
+ int j = 0;
+ int vla2[SIZE][n];
+ int vla1[n];
+
+ for (i = 0; i < n; i++)
+ vla1[i] = (i * 2) + n;
+
+ for (i = 0; i < SIZE; i++)
+ for (j = 0; j < n; j++)
+ vla2[i][j] = (i + j) + n;
+
+
+ i = 0;
+ j = 0;
+
+ return 0; /* vla-filled */
+}
new file mode 100644
@@ -0,0 +1,89 @@
+# Copyright 2014 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Tests side-effects of sizeof evaluation.
+# Based on gcc/testsuite/gcc.dg/vla-4.c; vla-15.c
+
+standard_testfile
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+ return -1
+}
+
+if ![runto_main] {
+ return -1
+}
+
+gdb_breakpoint [gdb_get_line_number "vla-filled"]
+gdb_continue_to_breakpoint "vla-filled"
+
+# Check side effects for sizeof argument.
+set sizeof_int [get_sizeof "int" 4]
+set sizeof_vla [ expr "10" * "$sizeof_int" ]
+
+gdb_test "print sizeof (vla1\[i++\])" "= ${sizeof_int}" \
+ "print sizeof (vla1\[i++\])"
+gdb_test "print i" " = 0" \
+ "print i - sizeof no side effects"
+
+gdb_test "print sizeof (++vla1\[0\])" " = ${sizeof_int}" \
+ "print sizeof (++vla1\[0\])"
+gdb_test "print vla1\[0\]" " = 10" \
+ "print vla1\[0\] - sizeof no side effects"
+
+gdb_test "ptype ++vla1\[0\]" "type = int" "ptype ++vla1\[0\]"
+gdb_test "print vla1\[0\]" " = 10" \
+ "print vla1\[0\] - ptype no side effects"
+
+gdb_test "whatis ++vla1\[0\]" "type = int" "whatis ++vla1\[0\]"
+gdb_test "print vla1\[0\]" " = 10" \
+ "print vla1\[0\] - whatis no side effects"
+
+
+gdb_test "print sizeof (vla2\[i++\])" " = ${sizeof_vla}" \
+ "print sizeof (vla2\[i++\])"
+gdb_test "print i" " = 1" \
+ "print i - sizeof with side effects (1)"
+
+gdb_test "print sizeof (vla2\[i++ + sizeof(j++)\])" " = ${sizeof_vla}" \
+ "print sizeof (vla2\[i++ + sizeof(j++)\])"
+gdb_test "print i" " = 2" \
+ "print i - sizeof with side effects (2)"
+gdb_test "print j" " = 0" \
+ "print j - sizeof with no side effects"
+
+gdb_test "ptype vla2\[i++\]" "type = int \\\[10\\\]" \
+ "ptype vla2\[i++\]"
+gdb_test "print i" " = 2" \
+ "print i - ptype with side effects (1)"
+
+gdb_test "ptype vla2\[i++ + sizeof(j++)\]" "type = int \\\[10\\\]" \
+ "ptype vla2\[i++ + sizeof(j++)\]"
+gdb_test "print i" " = 2" \
+ "print i - ptype with side effects (2)"
+gdb_test "print j" " = 0" \
+ "print j - ptype with no side effects"
+
+gdb_test "whatis vla2\[i++\]" "type = int \\\[10\\\]" \
+ "whatis vla2\[i++\]"
+gdb_test "print i" " = 2" \
+ "print i - whatis with side effects (1)"
+
+gdb_test "whatis vla2\[i++ + sizeof(j++)\]" "type = int \\\[10\\\]" \
+ "whatis vla2\[i++ + sizeof(j++)\]"
+gdb_test "print i" " = 2" \
+ "print i - whatis with side effects (2)"
+gdb_test "print j" " = 0" \
+ "print j - whatis with no side effects"