[PATCH 7/7][committed] Remove semicolon after do {} while (0) in DEF_SANITIZER_BUILTIN
Tom de Vries
Tom_deVries@mentor.com
Sun Nov 5 10:07:00 GMT 2017
Hi,
Consider this code in gcc/asan.c:
...
#define DEF_SANITIZER_BUILTIN(ENUM, NAME, TYPE, ATTRS) \
do { \
decl = add_builtin_function ("__builtin_" NAME, TYPE, ENUM, \
BUILT_IN_NORMAL, NAME, \
NULL_TREE); \
set_call_expr_flags (decl, ATTRS); \
set_builtin_decl (ENUM, decl, true); \
} while (0);
#include "sanitizer.def"
if ((flag_sanitize & SANITIZE_OBJECT_SIZE)
&& !builtin_decl_implicit_p (BUILT_IN_OBJECT_SIZE))
DEF_SANITIZER_BUILTIN (BUILT_IN_OBJECT_SIZE, "object_size",
BT_FN_SIZE_CONST_PTR_INT,
ATTR_PURE_NOTHROW_LEAF_LIST)
...
As explained here (
https://gcc.gnu.org/onlinedocs/cpp/Swallowing-the-Semicolon.html ), we
can wrap a multi-statement macro body in a "do {} while (0)" in order to
be able to use the macro call as if it were a single statement. However,
adding a semicolon after that "do {} while (0)", as is done in
DEF_SANITIZER_BUILTIN means you can no longer use it as a single
statement (compiling "if DEF_SANITIZER_BUILTIN (...); else ...;" will
give an "else without a previous if" compiler error). This problem is
then handled in the if stmt by leaving out the semicolon after
DEF_SANITIZER_BUILTIN, which is awkward.
OTOH, we use .def files with lists of macro calls to generate tables and
code. When generating code, it's natural to use a semicolon as the last
part of the macro body, in order to separate statements.
This patch factors out DEF_SANITIZER_BUILTIN_1 from
DEF_SANITIZER_BUILTIN, and uses DEF_SANITIZER_BUILTIN_1 in the if
statement as a normal single statement, as made possible by the "do {}
while (0)".
The original DEF_SANITIZER_BUILTIN is still used with the .def file, as
before.
Committed as obvious.
Thanks,
- Tom
2017-11-02 Tom de Vries <tom@codesourcery.com>
PR other/82784
* asan.c (DEF_SANITIZER_BUILTIN_1): Factor out of ...
(DEF_SANITIZER_BUILTIN): ... here.
(initialize_sanitizer_builtins): Use DEF_SANITIZER_BUILTIN_1
instead of DEF_SANITIZER_BUILTIN in if stmt. Add missing
semicolon.
Signed-off-by: Tom de Vries <tom@codesourcery.com>
---
gcc/asan.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
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