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Re: [RFA] c++/16675 (incorrect sizeof reference types)
- From: Keith Seitz <keiths at redhat dot com>
- To: "gp >> \"gdb-patches at sourceware dot org ml\"" <gdb-patches at sourceware dot org>
- Date: Fri, 11 Apr 2014 14:22:33 -0700
- Subject: Re: [RFA] c++/16675 (incorrect sizeof reference types)
- Authentication-results: sourceware.org; auth=none
- References: <532C8408 dot 9030905 at redhat dot com> <87y4zdp123 dot fsf at fleche dot redhat dot com>
On 04/10/2014 10:05 AM, Tom Tromey wrote:
"Keith" == Keith Seitz <keiths@redhat.com> writes:
Keith> 2014-03-20 Keith Seitz <keiths@redhat.com>
Keith> PR c++/16675
Keith> * c-exp.y (exp : SIZEOF '(' type ')'): Handle reference types.
Keith> * eval.c (evaluate_subexp_for_sizeof): Refactor and handle
Keith> reference types.
Keith> testsuite/ChangeLog
Keith> 2014-03-20 Keith Seitz <keiths@redhat.com>
Keith> PR c++/16675
Keith> * gdb.cp/cpsizeof.exp: New file.
Keith> * gdb.cp/cpsizeof.cc: New file.
This is ok. Thanks.
I've pushed this patch. A patch from yesterday conflicted in
eval.c:evaluate_subexp_for_sizeof. I'm attaching the patch again for
reference.
Thank you for the review, Tom.
Keith
ChangeLog
2014-04-11 Keith Seitz <keiths@redhat.com>
PR c++/16675
* c-exp.y (exp : SIZEOF '(' type ')'): Handle reference types.
* eval.c (evaluate_subexp_for_sizeof): Refactor and handle
reference types.
testsuite/ChangeLog
2014-04-11 Keith Seitz <keiths@redhat.com>
PR c++/16675
* gdb.cp/cpsizeof.exp: New file.
* gdb.cp/cpsizeof.cc: New file.
diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index fc79807..f39391c 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -787,14 +787,22 @@ exp : SELECTOR '(' name ')'
;
exp : SIZEOF '(' type ')' %prec UNARY
- { write_exp_elt_opcode (pstate, OP_LONG);
+ { struct type *type = $3;
+ write_exp_elt_opcode (pstate, OP_LONG);
write_exp_elt_type (pstate, lookup_signed_typename
(parse_language (pstate),
parse_gdbarch (pstate),
"int"));
- CHECK_TYPEDEF ($3);
+ CHECK_TYPEDEF (type);
+
+ /* $5.3.3/2 of the C++ Standard (n3290 draft)
+ says of sizeof: "When applied to a reference
+ or a reference type, the result is the size of
+ the referenced type." */
+ if (TYPE_CODE (type) == TYPE_CODE_REF)
+ type = check_typedef (TYPE_TARGET_TYPE (type));
write_exp_elt_longcst (pstate,
- (LONGEST) TYPE_LENGTH ($3));
+ (LONGEST) TYPE_LENGTH (type));
write_exp_elt_opcode (pstate, OP_LONG); }
;
diff --git a/gdb/eval.c b/gdb/eval.c
index d29960a..c6ddd31 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -3030,21 +3030,22 @@ evaluate_subexp_for_sizeof (struct expression *exp, int *pos,
&& TYPE_CODE (type) != TYPE_CODE_REF
&& TYPE_CODE (type) != TYPE_CODE_ARRAY)
error (_("Attempt to take contents of a non-pointer value."));
- type = check_typedef (TYPE_TARGET_TYPE (type));
if (is_dynamic_type (type))
type = value_type (value_ind (val));
- return value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
+ else
+ type = TYPE_TARGET_TYPE (type);
+ break;
case UNOP_MEMVAL:
(*pos) += 3;
- type = check_typedef (exp->elts[pc + 1].type);
- return value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
+ type = exp->elts[pc + 1].type;
+ break;
case UNOP_MEMVAL_TYPE:
(*pos) += 1;
val = evaluate_subexp (NULL, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
- type = check_typedef (value_type (val));
- return value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
+ type = value_type (val);
+ break;
case OP_VAR_VALUE:
type = check_typedef (SYMBOL_TYPE (exp->elts[pc + 2].symbol));
@@ -3055,8 +3056,7 @@ evaluate_subexp_for_sizeof (struct expression *exp, int *pos,
}
else
(*pos) += 4;
- return
- value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
+ break;
/* 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
@@ -3080,8 +3080,8 @@ evaluate_subexp_for_sizeof (struct expression *exp, int *pos,
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)));
+ type = value_type (val);
+ break;
}
}
}
@@ -3091,9 +3091,18 @@ evaluate_subexp_for_sizeof (struct expression *exp, int *pos,
default:
val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
- return value_from_longest (size_type,
- (LONGEST) TYPE_LENGTH (value_type (val)));
+ type = value_type (val);
+ break;
}
+
+ /* $5.3.3/2 of the C++ Standard (n3290 draft) says of sizeof:
+ "When applied to a reference or a reference type, the result is
+ the size of the referenced type." */
+ CHECK_TYPEDEF (type);
+ if (exp->language_defn->la_language == language_cplus
+ && TYPE_CODE (type) == TYPE_CODE_REF)
+ type = check_typedef (TYPE_TARGET_TYPE (type));
+ return value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
}
/* Parse a type expression in the string [P..P+LENGTH). */
diff --git a/gdb/testsuite/gdb.cp/cpsizeof.cc b/gdb/testsuite/gdb.cp/cpsizeof.cc
new file mode 100644
index 0000000..0760cfc
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/cpsizeof.cc
@@ -0,0 +1,71 @@
+/* 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/>. */
+
+struct Class
+{
+ int a;
+ char b;
+ long c;
+
+ Class () : a (1), b ('2'), c (3) { }
+};
+
+union Union
+{
+ Class *kp;
+ char a;
+ int b;
+ long c;
+};
+
+enum Enum { A, B, C, D };
+
+typedef unsigned char a4[4];
+typedef unsigned char a8[8];
+typedef unsigned char a12[12];
+typedef Class c4[4];
+typedef Union u8[8];
+typedef Enum e12[12];
+
+#define T(N) \
+ N N ## obj; \
+ N& N ## _ref = N ## obj; \
+ N* N ## p = &(N ## obj); \
+ N*& N ## p_ref = N ## p; \
+ int size_ ## N = sizeof (N ## _ref); \
+ int size_ ## N ## p = sizeof (N ## p_ref); \
+
+int
+main (void)
+{
+ T (char);
+ T (int);
+ T (long);
+ T (float);
+ T (double);
+ T (a4);
+ T (a8);
+ T (a12);
+ T (Class);
+ T (Union);
+ T (Enum);
+ T (c4);
+ T (u8);
+ T (e12);
+
+ return 0; /* break here */
+}
diff --git a/gdb/testsuite/gdb.cp/cpsizeof.exp b/gdb/testsuite/gdb.cp/cpsizeof.exp
new file mode 100644
index 0000000..f55af9c
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/cpsizeof.exp
@@ -0,0 +1,40 @@
+# sizeof() tests [c++/16675]
+# 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/>.
+
+standard_testfile .cc
+
+if {[skip_cplus_tests]} { continue }
+
+if {[prepare_for_testing ${testfile}.exp $testfile $srcfile {debug c++}] } {
+ return -1
+}
+
+if {![runto_main]} {
+ perror "could not run to main"
+ continue
+}
+
+gdb_breakpoint [gdb_get_line_number "break here"]
+gdb_continue_to_breakpoint "break here"
+
+# Compare sizeof from the compiler and gdb. Do this once with the actual
+# type name and once with a reference variable.
+foreach v {char int long float double a4 a8 a12 Class Union Enum c4 u8 e12} {
+ gdb_test "print size_$v == sizeof (${v}&)" "= true"
+ gdb_test "print size_$v == sizeof (${v}_ref)" "= true"
+ gdb_test "print size_${v}p == sizeof (${v}*&)" "= true"
+ gdb_test "print size_${v}p == sizeof (${v}p_ref)" "= true"
+}